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PICList Thread
'[ee OT]Kynar motion'
1999\08\05@173646 by Anne Ogborn

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face
> one wall of the bag could be Kynar (Piezo Co-Polymer)plastic that
> will bend when energized (very low power) this will eject the fluid
> into the main body of reacting fluid, a chemical process will take
> place and the internal temp is monitored until another "dose" is
> needed.
> The other unopened bags could even act as a stirring source since
> their respective piezo linings could act together in a synergesis of
> stirring.
> I have experimented with Kynar... it will do this.

How about some details of where to get Kynar film, how to
attach electrodes, etc. to demonstrate this effect?
This sounds like a way cool thing to know about.

Oh, and as for my subject line - I've labelled it [ee OT] since it
seems we have 3 catagories of subject - 1. Stuff directly related to PIC,
2. Stuff related to robots, electrical gizmos, robots, and other stuff
a PIC'ish person might be interested in, 3. general 'commmunity' discussion
(the how many pics to save JFK thing)  I'm experimenting with labelling
catagory 2 topics [ee OT] since 'electrical engineering' seems as
close to describing it as anything.

--
Anniepoo
Need loco motors?
http://www.idiom.com/~anniepoo/depot/motors.html

1999\08\05@180134 by l.allen

picon face
> How about some details of where to get Kynar film, how to
> attach electrodes, etc. to demonstrate this effect?
> This sounds like a way cool thing to know about.
>

Kynar is available from AMP Inc (the big connector makers)
The only address I have here is Valley Forge P.A.
Kynar is a Piezo Film that can be used for hydrophones (my main use),
speakers (above 2kHz), contact microphones, pyro sensing (.. very
good IR detectors) and very high reliability/cycle life switches
(dynamic only though, not absolute).. Gottlieb use it in Pinball
Machines now.
Electodes are vapour deposited on the material so can either be
inserted in a pressure contact or a type of rivet attached to it.
The AMP Basic Design Kit for Piezo Film Sensors is a great start,
with many samples, applications etc.
Quite a range of off the shelf sensors/transducers in various form
factors are available from AMP.

I should be on their sales team.

Oiii... where's my commission.


_____________________________

Lance Allen
Technical Officer
Uni of Auckland
Psych Dept
New Zealand
_____________________________


'[EE] ISD & other voice chips'
2000\05\04@090935 by Hardware Engineering
picon face
I've saved some posts about interfacing to the ISD chips, but has anyone used
any other devices that are similiar - or better should I ask if there are any
others that are like these?

Application I am think of, need to address 5 groups of 10 second interval
voice storage.  In other words, 5 switches select what interval to be played.
10 seconds is a basic guess...ie...if its a 60 second device, I will chop it
into 12 second intervals.

____________________________________________________________________
Get free email and a permanent address at http://www.netaddress.com/?N=1

'[EE][OT] STRIP-X (enamel wire)'
2000\05\16@044518 by Joe McCauley

picon face
As I indicated a soldering iron is how I am doing this at the moment but
with wire as fine as 0.032mm
you can very easily damage the wire. If you are making contacts on a
precisely wound and balanced 5K turn
balanced coil system you cannot afford to loose any wire from the end of the
winding never mind at the start
of the winding. A chemical stripper is the best way to go here IMHO.

Joe

{Original Message removed}

'[EE] Labels'
2000\05\16@195058 by William K. Borsum

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<x-flowed>Hi All:

Revisiting the subject of making you own professional looking labels.....

I have located a 10-mil thick  polycarbonate film that seems to be working
very well with ink-jet printers.
The printing is done on the back, using a mirror image.  The film is then
coated with the desired background color (regular Krylon or other spray
paint), and a double sided tape or spray adhesive is applied.  Once applied
to the panel, the ink layer is fully protected by the Polycarbonate film.

The resulting label is as good as your layout software will allow (Word,
Protel, Publisher, etc), and resolution of your ink-jet printer.  BUT it is
subject to moisture (ink-jet ink is water based) wicking in around the
edges, and fading if left in full sun for a year.  There is a coating
available that I am exploring that may solve the moisture problem.

The 10-mill film is rather rigid, can cover holes, be "bubbled" to form
membrane switches, left clear for LED's to show through, etc.  This is
basically the same stuff the "pro's" use.

In my case, I even lay out the hole centers and cutouts on the label as
guides for drilling, punching, or routing after the label is applied to the
panel.

Here's the problem--I've got to buy the stuff in LARGE rolls. Something
like 3 feet by 120 feet.

THE QUESTION:  is anyone out there interested in buying kits if I get a
roll, and cut it down to 11x17 or 8.5x11 inch size, and include the really
good 3-M adhesive normally used with this type of film?  Don't have an
accurate cost yet, but guessing about $2 per letter size sheet, and maybe
$4-10 for the adhesive depending on the type.  Target price for a kit would
be maybe $25-$50..

If you are interested, please contact me OFF THE LIST, and let me know your
thoughts--sizes, quantities, etc.

Kelly
William K. Borsum, P.E. -- OEM Dataloggers and Instrumentation Systems
<spam_OUTborsumTakeThisOuTspamdascor.com> & <http://www.dascor.com>San Diego, California, USA

</x-flowed>

'[EE] Embedded Java'
2000\05\17@092232 by Jon Hylands

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On Wed, 17 May 2000 07:42:40 -0500, "Clark, John" <.....JohnCKILLspamspam@spam@ININ.COM> wrote:

> I am looking for an inexpensive microcontroller which I can program in Java.
> I have no need for advanced Java features like multithreading or garbage
> collection -- a compiler which would turn Java into assembler would be fine.
> I looked at the Scenix VM, but it has some $25,000 licensing fee.   I did
> see that IBM has a product for embedded Java:

Check out http://www.rtjcom.com

He has a RTJ that will run on a 68HC11...

Note that his version does include multi-tasking, garbage collection, and
exception handling.

Later,
Jon

--------------------------------------------------------------
  Jon Hylands      JonspamKILLspamhuv.com      http://www.huv.com/jon

 Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
          http://www.huv.com

'[EE] Interfacing PIC to automotive electrics?'
2000\05\17@210908 by Gennette, Bruce

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Hi all,

Probably been explained before, but how do I interface a 5V PIC to the
signals coming from 12V car (and 24V truck) devices like temperature and oil
pressure sensor/senders?

I suspect that cars can use CMOS comparitors set against a trim pot (with
zeners to divert any spikes), but how about truck (or boat) engines using
24V?

Could I use voltage dividers to bring the signals down to the 0-5V range and
directly connect to a PIC or TTL gates?

For this first project I'm just looking at the alarm state ( !Ok ), but
later I may want to log all parameters so that a progressive failure can be
spotted (eg cooling water temp hotter each day indicates a growing blockage
in the system or excessively worn pump).

If there is an existing FAQ could someone point me to it please?

Thanxs in advance,
Bye.

'[EE] Interfacing PIC to automotive electric's?'
2000\05\17@220437 by Plunkett, Dennis

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18/5/2000


Can of worms can of worms!
There is the simple way, then there is the correct way.
Just of interest the relevant specifications are:-

CISPIR 25 1995-11
ISO/TR 10605 1994(e)
Japanese blue book
ISO 11452 1995(e)
MIL STD 461D
ISO 7637 (Gives the impulse tests)
SAE J1112-13 1995
SAE J1113-42 1994

OK!
So for protection you can use a normal resistive divider and then pass this
into a ESD device like a California micro P002 etc.

Your main problems are susceptibility, we now are testing with values of up
to (Get this one people if you think your world is noisy! 200V/meter at
frequencies up to 0.5MHz and 40V/meter amplitude modulated by 80% up to
10MHz) Failure rates are dependant on the module requirements etc.

Dennis





> {Original Message removed}

'[EE] Interfacing to automotive (now EMI)'
2000\05\17@222323 by Chris Eddy

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Krikey, Dennis, I feel more and more behind as the standards get more and more
complicated.  I do not aspire to own a full EMC/EMI test setup at this point,
but I would like to design to pass, and intelligently.  Can you suggest:

A    How to get the standars that you referenced below without spending 6
figures?

B    Some truly comprehensive texts that direct one to practical application

I got that EMI test compliance trade magazine for a while, bot boy do they bury
the answers deep.

Feeling an emptiness inside,
Chris Eddy

"Plunkett, Dennis" wrote:

> CISPIR 25 1995-11
> ISO/TR 10605 1994(e)
> Japanese blue book
> ISO 11452 1995(e)
> MIL STD 461D
> ISO 7637 (Gives the impulse tests)
> SAE J1112-13 1995
> SAE J1113-42 1994
>

2000\05\17@230323 by Plunkett, Dennis

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18/5/2000

You can attempt to get the requirements from the vehicle manufacturer, as
often they have a cut doen version that includes the testing, but alas that
can often hide you from the intention of the original spec.

Best to to a web search and see what occurs, as you now have a list of what
is required.

There is no one practical application as the tests depend on the
clasification of the device and where it is to be located (Sigh)

Dennis






> {Original Message removed}

'[EE] Interfacing PIC to automotive electric's?'
2000\05\17@231003 by rad0

picon face
test
----- Original Message -----
From: "Plunkett, Dennis" <.....dplunkettKILLspamspam.....AIRINTER.COM.AU>
To: <EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU>
Sent: Wednesday, May 17, 2000 8:59 PM
Subject: Re: [EE] Interfacing PIC to automotive electric's?


{Quote hidden}

this
> into a ESD device like a California micro P002 etc.
>
> Your main problems are susceptibility, we now are testing with values of
up
> to (Get this one people if you think your world is noisy! 200V/meter at
> frequencies up to 0.5MHz and 40V/meter amplitude modulated by 80% up to
> 10MHz) Failure rates are dependant on the module requirements etc.
>
> Dennis
>
>
>
>
>
> > {Original Message removed}

'[EE] Interfacing PIC to automotive electrics?'
2000\05\19@021208 by Damon Hopkins

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"Gennette, Bruce" wrote:
{Quote hidden}

There's an article about the network systems in cars in the current
issue of Circuit Cellar.. If you can't find it let me know I can look up
what the documents are you need. It basically tells you about the 2
major different kinds of car networks and what SAE manuals to get w/ all
the details.  I forget which issue (MAY perhaps april) but the cover is
mostly black :)

Let me know if you can't get ahold of it and I'll throw you some
pointers from the text..

                       Damon Hopkins

2000\05\19@023747 by Plunkett, Dennis

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face
K-line?
CAN?
XDE?
JDOT?
DIS 14230?

Is a few off the top of my head, Which two is it?

Dennis


> {Original Message removed}

'[EE] Non interacting zero and span. how?'
2000\05\21@002347 by Chris Eddy

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I have a question that is just burning me up.  And when I try to solve
it I get a mental block.

To simplify the problem, say I have an op amp circuit with an input
signal of 0-5VDC and a desired output of 1-5VDC.  I have a zero and a
span pot.  Normally, I build this circuit with the zero pot and the
signal in question summed with two resistors into the + pin of the amp.
Then wrap the output back to the negative pin with a pot for the span.

The big complaint form customers is that the zero and the span interact
a lot.  My quest is to change the circuit so that the zero pot
accurately sets the 1V level at 0V in, and then adjust the span pot for
5V out at 5V in.

By the way, the application is converting to 4-20mA.  Any output where
the ratio of low to high is 1:5 is acceptable.  It does not have to be
1V and 5V.

The application in mind has split rails, but it would be nice to have a
single supply solution for those other jobs too.  Any grand ideas come
to mind?

Chris Eddy
Pioneer Microsystems, Inc.

'[EE]: RC oscillator'
2000\05\21@004213 by goflo

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Not to argue with my friend Russell, but I'm not clear on what mix of
acceleration & vibration is being discussed - Surprising how much g
many devices will tolerate - For a period. The lethal AAA proximity
fuses fielded in the last year of WW2 were vacuum-tube technology...
A vibration-rich environment is a somewhat different animal. Metal
fatigue becomes a more significant factor, for instance. This kind of
thing is exhaustively investigated by the military services - What's in
the public domain I don't know.

regards, Jack

Russell McMahon wrote:
{Quote hidden}

'[EE] Non interacting zero and span. how?'
2000\05\21@011400 by Robert A. LaBudde

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<x-flowed>At 07:22 PM 5/20/00 -0400, Chris wrote:
>To simplify the problem, say I have an op amp circuit with an input
>signal of 0-5VDC and a desired output of 1-5VDC.  I have a zero and a
>span pot.  Normally, I build this circuit with the zero pot and the
>signal in question summed with two resistors into the + pin of the amp.
>Then wrap the output back to the negative pin with a pot for the span.
>
>The big complaint form customers is that the zero and the span interact
>a lot.  My quest is to change the circuit so that the zero pot
>accurately sets the 1V level at 0V in, and then adjust the span pot for
>5V out at 5V in.
>
>By the way, the application is converting to 4-20mA.  Any output where
>the ratio of low to high is 1:5 is acceptable.  It does not have to be
>1V and 5V.
>
>The application in mind has split rails, but it would be nice to have a
>single supply solution for those other jobs too.  Any grand ideas come
>to mind?

1. What is your current circuit?

2. What type of op-amp are you using?

3. Is an inverting configuration acceptable?

================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: ralspamspam_OUTlcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
824 Timberlake Drive                            Tel: 757-467-0954
Virginia Beach, VA 23464-3239                   Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================

</x-flowed>

2000\05\21@071201 by paulb

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Chris Eddy wrote:

> Normally, I build this circuit with the zero pot and the signal in
> question summed with two resistors into the + pin of the amp.
> Then wrap the output back to the negative pin with a pot for the span.

> The big complaint form customers is that the zero and the span
> interact a lot.  My quest is to change the circuit so that the zero
> pot accurately sets the 1V level at 0V in, and then adjust the span
> pot for 5V out at 5V in.

 Unfortunately, it works the other way about.  Assuming the zero bias
potentiometer has a low impedance, the two controls do not interact much
at all.

 Your problem is that you are *not* zeroing it in the first place, but
setting an offset.  The offset of course, represents the real offset
multiplied by the scale (span) figure; of course it depends on both.

 The procedure you want is in three steps.  Set the zero control for
*zero* output with zero input.  Apply a 5V input and set the scale pot
for 4V output.  Set the input back to zero, and adjust zero bias for the
desired 1V output.
--
 Cheers,
       Paul B.

2000\05\21@074146 by Spehro Pefhany

picon face
At 07:22 PM 5/20/00 -0400, you wrote:
>I have a question that is just burning me up.  And when I try to solve
>it I get a mental block.
>
>To simplify the problem, say I have an op amp circuit with an input
>signal of 0-5VDC and a desired output of 1-5VDC.  I have a zero and a
>span pot.  Normally, I build this circuit with the zero pot and the
>signal in question summed with two resistors into the + pin of the amp.
>Then wrap the output back to the negative pin with a pot for the span.

Try a pot connected as a rheostat in *series* with the signal (summed
to the non-inverting input) and adjust the 1V level by summing to the
inverting input (fixed feedback resistor).
You'll need a -ve reference for this to work.

If you want to use a +ve reference it might be easier to buffer the
zero adjust voltage with an additional unity gain op-amp and use your
original circuit, but with the span adjust pot again in series with the
signal to the non-inverting input.

Best regards,

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
@spam@speffKILLspamspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

'[EE] Adjusting voltage output of a temperature sen'
2000\05\23@002310 by Dean Biddle

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picon face
Hi,

Are there alternative(s) to an operational amplifier (supplied by +ve and
-ve) to adjust the voltage output of an LM335 temperature sensor from
approx. 2.5 to 3.5 volts to span the 0 to 5 volt range for a P16F87x A/D
converter?  My application needs to consume minimal current and preferably
use only one battery.  Can another option for the configuration of the A/D
system be used other than limiting Vref+ to approx. 3.5 volts?

I assume this is common, so please simply refer me to a relevant past
PICLIST thread if I failed to match the thread in my "pre-post" search.

'[EE] Ethernet Chips'
2000\05\23@002608 by Damon Hopkins

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anyone have some info on where I might find a CHEAP ethernet transceiver
I found plenty of ways to hook up a microcontroller to a PC via PPP
but I want to plug straight into a hub.

                       Thanks,
                               Damon

'[EE] Adjusting voltage output of a temperature sen'
2000\05\23@002919 by Damon Hopkins

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Dean Biddle wrote:
>
> Hi,
>
> Are there alternative(s) to an operational amplifier (supplied by +ve and
> -ve) to adjust the voltage output of an LM335 temperature sensor from
> approx. 2.5 to 3.5 volts to span the 0 to 5 volt range for a P16F87x A/D
> converter?  My application needs to consume minimal current and preferably
> use only one battery.  Can another option for the configuration of the A/D
> system be used other than limiting Vref+ to approx. 3.5 volts?
>
> I assume this is common, so please simply refer me to a relevant past
> PICLIST thread if I failed to match the thread in my "pre-post" search.

Excellent question.. I await the answer because right now I'm using an
OP AMP to do it... I hope there is..

               Damon Hopkins

'[EE] Ethernet Chips'
2000\05\23@005140 by Todd Peterson

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> anyone have some info on where I might find a CHEAP ethernet
> transceiver

Damon,

Have a look at http://www.embeddedethernet.com for a cost-effective solution.  I'm
anxious to hear from anyone who has actually used this schematic; I'd
suspect that those who have played with ethernet and a micro have connected
to an ISA card or such.  The two-chip solution at the above address looks
interesting, but is for 10baseT (not 100).

 -Todd Peterson
  E-Lab Digital Engineering, Inc.

(816) 257-9954   FAX: (816)257-9945
http://www.elabinc.com

'[EE] Re: Advice needed ==>PIC to PIC wireless tran'
2000\05\23@043340 by Kčbek Tony

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Hi,
I've mentioned them before but here we go again:
http://www.nvlsi.no/

They have very easy to intergrate transiever modules.
I've used the old 9600 bps but I think they are available
in over 20kbps now.
Couldn't be easier.

/Tony


Tony KŸbek, Flintab AB            
ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ
E-mail: KILLspamtony.kubekKILLspamspamflintab.com
ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ

2000\05\23@053617 by Vasile Surducan

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On 23 May 00, at 10:19, KŸbek Tony wrote:

> Hi,
> I've mentioned them before but here we go again:
> http://www.nvlsi.no/
>
  Ok but that's with money! Some free ideas ?
 I saw something about two 16f877 connected on radio link
 It's something visible on net ?
 Vasile

****************************************
Surducan Vasile, engineer
email:RemoveMEvasileTakeThisOuTspaml30.itim-cj.ro
URL:http://www.geocities.com/vsurducan
****************************************

2000\05\23@061636 by Kčbek Tony

flavicon
face
>   Ok but that's with money! Some free ideas ?
>  I saw something about two 16f877 connected on radio link
>  It's something visible on net ?
>  Vasile

:-) , there are no such thing as free lunch, one way
or the other one must build something, that manages to
communicate by means of RF. using the chips above would
save you alot of hassle ( not to mention avoiding illegal
RF band usage ). And, trust me, these are VERY cheap
concidering bang for the buck. ( if I recall correctly
something around $10 each ).
About three wires to connect, Din, Dout, Txenable.
And, just checked it, they are at 20kbps, FSK modulated,
standby 8uA, tx 8mA, two channels etc.

Could it be any easier ?



Tony KŸbek, Flintab AB            
ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ
E-mail: spamBeGonetony.kubekspamBeGonespamflintab.com
ÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓÓ

'[EE] Adjusting voltage output of a temperature sen'
2000\05\23@095515 by Scott Dattalo

face
flavicon
face
On Tue, 23 May 2000, Damon Hopkins wrote:

> Dean Biddle wrote:
> >
> > Hi,
> >
> > Are there alternative(s) to an operational amplifier (supplied by +ve and
> > -ve) to adjust the voltage output of an LM335 temperature sensor from
> > approx. 2.5 to 3.5 volts to span the 0 to 5 volt range for a P16F87x A/D
> > converter?  My application needs to consume minimal current and preferably
> > use only one battery.  Can another option for the configuration of the A/D
> > system be used other than limiting Vref+ to approx. 3.5 volts?
> >
> > I assume this is common, so please simply refer me to a relevant past
> > PICLIST thread if I failed to match the thread in my "pre-post" search.
>
> Excellent question.. I await the answer because right now I'm using an
> OP AMP to do it... I hope there is..

Is it the op amp that's the problem or having to supply -ve? There are several
low-power, single-supply, rail-to-rail opamps in tiny SOT-23 sized packages that
would work nicely here.

All though I've never explored this, you could recover the A/D converter's
dynamic range by tying the LM335 to the 87x's vref pin and then measure a known
DC voltage source on one of the analog inputs. Perhaps two or three DC voltages
could be used as references. At first glance this would appear to prevent the
other analog inputs from being used. However, you could still switch the A/D to
use the power supply rails as the voltage reference.


Scott

'[EE] compact flash spec'
2000\05\23@171137 by mike

flavicon
picon face
I found the following link in another NG, it may be of interest for
people interfacing to compact flash cards.
http://www.compactflash.org/cfspc1_4.pdf
its about 550k
cheers Mike W

'[EE] PC board transfer'
2000\05\24@011706 by Ing. Marcelo Fornaso

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face
Hi,
I'd like to invite you all to a description of my poor's man method for PCB making.

http://www.sysameri.com/marcelo/placa.htm

I hope it to be useful for at least some of you, and I beg you please to send comments and corrections to my english to help me to improve the page readability.
Thank you.

Marcelo Fornaso

2000\05\24@100114 by tt, Gary

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Marcelo,


Excellent job!  I use the same technique outlined on your website.  The only
difference in my technique is to put something heavy and flat on the board
after heating it with the iron and letting it cool with the heavy weight on
the board for about 15 minutes.  I then put it in water and continue with
the steps you outlined.

Thanks again for sharing your information.



       ----------
       From:  Ing. Marcelo Fornaso [SMTP:TakeThisOuTmfornasoEraseMEspamspam_OUTINFOVIA.COM.AR]
       Sent:  Wednesday, May 24, 2000 1:15 AM
       To:  RemoveMEPICLISTspamTakeThisOuTMITVMA.MIT.EDU
       Subject:  [EE] PC board transfer

       Hi,
       I'd like to invite you all to a description of my poor's man method
for PCB making.

       http://www.sysameri.com/marcelo/placa.htm

       I hope it to be useful for at least some of you, and I beg you
please to send comments and corrections to my english to help me to improve
the page readability.
       Thank you.

       Marcelo Fornaso

'[EE]: 120VAC Traces'
2000\05\24@103818 by frmiller

flavicon
face
I have a board that I recently redesigned that contains nine
T90 relays that switch 110VAC. The board goes in an
industrial controller and switches lights and contactors
(mag starters). The relays all have flyback diodes across
the coils and snubbers across the contacts.

On the old version of the board (not my design), the 110VAC
traces were mixed on the board with signal traces. It
worked, but as you can imagine, we had problems in the
field. I tried to eliminate the problem by aligning the
relays so that the 110VAC traces were all on the lower area
of the board and all other traces were along the upper.
There is a "no trace zone" about .6" wide that runs under
the relays between the coil pins and the contact pins. This
is the dividing line between the 110VAC area and the rest of
the board.

This layout helped a lot, but I'm still getting a few spikes
back in the signal traces. It is sometimes enough to lock up
the NE5090 mux on the board, especially when the contactors
fire. I have bypass caps on the chips on the board, but I
really would like to eliminate the spikes.

The whole point of this long-winded explanation is to ask if
filling the "no trace zone" with a ground plane would do any
good. If so, should it be earth ground or circuit ground? Is
there any way to hack a current board (adding foil or
something) to simulate the ground plane that would give
meaningful test results before we redo the board? The board
is two-sided, through hole.

TIA,

Ryan

'[EE] PC board transfer'
2000\05\24@111350 by Ing. Marcelo Fornaso

flavicon
face
By the way: The prototype is a 16F84 based RF transmitter running at 310 MHz. Kind of beacon sending telemetry at 2400 bauds.

http://www.sysameri.com/marcelo/placa.htm

Regards
Marcelo Fornaso

'[EE]: 120VAC Traces'
2000\05\24@130031 by Dan Michaels

flavicon
face
Ryan Miller wrote:
>I have a board that I recently redesigned that contains nine
>T90 relays that switch 110VAC. The board goes in an
>industrial controller and switches lights and contactors
>(mag starters). The relays all have flyback diodes across
>the coils and snubbers across the contacts.
.......

Hi Ryan, for several years I consulted with a company that built
industrial controllers that switched multiple 220 VAC inductive loads.
They sold 1000s of these units each year, and saw every manner of
failure. Many previous comments by other picisters have indicated
that 1 or 2 things might fix this sort of problem, but in my
experience, we found it required multiple lines of attack and each
was only marginally effective. A heavy inductive switching environment
is probably the very worst place into which to put a microprocessor,
and I think the best results come from an overall systems-level
approach - which of course involves 20 or 30 or 60 aspects.

That being said, let me relate some of the most effective methods
in my experience:

1. EMI and spike filters at the hiVAC power input - series EMI filter,
  MOVs, etc.
2. EMI/spike filtering on the power supplies - "transient voltage
  suppressor" diodes [eg, Microsemi 1.5KE series] on the P/S input side,
  downstream of the AC transformer, if there is one.
3. Bypass caps, of course, at all the usual points.
4. Of course, diodes across the relay coils and snubbers across relay
  contacts.
  NOTE - some loads produce significantly worse switching transients
  than others, so the same snubber may not be universally effective.
  When looking across the contacts, you will see hi-speed spikes [bad]
  riding on a slower wave [normal] in cases where the snubber is not
  effective enough. You might want to use an isolation xfrmr to do
  this measurement.
  NOTE - one thing you can do is sniff around with a scope probe,
  ungrounded, to measure presence of EMI, and determine what it is
  correlated to.
5. On the low-level signal lines, RC filters and transorbs [transient
  voltage suppressor diodes, which are essentially low-inductance
  zeners] are effective. Note - we ended up putting transorbs on
  practically ever signal line - and regular zeners are too slow here.
6. Layout issues - physically separate hi/low V, and signal/switching
  circuitry. Separate power busses and gnd planes [if possible]. Don't
  run different lines near each other, and don't cross them.
7. Use watch dog timer in uC s.w. Use debounce routines on signal
  measurements.
8. Use digital bus crowbar ckt in cases where chip latchup is an
  especially bad problem. [Note - the watchdog will not fix latchup].

There are probably a few others which I forget.
==============

>
>The whole point of this long-winded explanation is to ask if
>filling the "no trace zone" with a ground plane would do any
>good. If so, should it be earth ground or circuit ground? Is
>there any way to hack a current board (adding foil or
>something) to simulate the ground plane that would give
>meaningful test results before we redo the board? The board
>is two-sided, through hole.
>

Regarding gnds, the digital, analog, switching, and switched
should be as physically and electrically separate as possible,
and should be connected at "one point" as close to the power
entry point of the board as possible. The more current, the larger
the trace/wire.

Regarding hacking the test bd, try using aluminum duct tape
grounded back to the hiV side [looks like relay power in this case].
In essence, you are putting a guard ring around the hiV side which
is intended to contain the internal fields. Likewise, you can
put a gnd guard ring around each other subsystem, connected to
the gnd of that subsystem.

Hope this helps,
- Dan Michaels
Oricom Technologies
http://www.sni.net/~oricom
==========================

2000\05\24@131740 by Chris Eddy

flavicon
face
Ryan;

This subject came up just a few weeks ago.  The relay contacts are
generating EMI with a spark.  You need to use a snubber, just a cap, or
some other means to quench the arc on the contacts.  See the archive.

Chris Eddy

Ryan Miller wrote:

> I have a board that I recently redesigned that contains nine
> T90 relays that switch 110VAC. The board goes in an

2000\05\24@132805 by Dan Michaels

flavicon
face
BTW, a good book on this topic is

"Noise Reduction in Electronic Systems" by Henry Ott

2000\05\24@133156 by Spehro Pefhany

picon face
At 06:16 AM 5/24/00 -0400, you wrote:
>Ryan;
>
>This subject came up just a few weeks ago.  The relay contacts are
>generating EMI with a spark.  You need to use a snubber, just a cap, or
>some other means to quench the arc on the contacts.  See the archive.

He said he has snubbers on there.

Part of the problem is the type of relays used. This is a very complex
subject. The closest thing to a magic bullet is to go multilayer.

Best regards,


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speffEraseMEspam.....interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

2000\05\24@134432 by Dan Michaels

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face
Always the stuff forgotten the first time [or 6]:

One way to tell if a gnd plane will be effective in a particular
situation is to simply place a grounded metal plate close to the
underside of the circuitry in question [insulated from it of
course], and note the effects. Use a short, thick gnd lead directly
to the cktry being shielded. I have used this method to determine
where gnd planes are most effectively added onto 2-sided pcbs.

- Dan Michaels

'[EE][OT] Impedance Matching a Phone Line'
2000\05\24@145247 by Clark, John

flavicon
face
I am trying to connect the output of a D/A signal to an open phone line to
play audio (sort of similar to the "DTMF decoding with a PIC" thread that is
going on, only I need to transmit DTMF and music).  I have been doing quite
a bit of searching for specifications on telco line impedance and so forth,
but I have yet to find a definitive guide.  I am also strongly leaning to
finding a 3rd party product that would accept a standard 47K ohm impedance
signal from an RCA phono plug shielded type of connector.  If anyone has
information, especially on the latter, I would really appreciate it.

Thanks.


John Clark
Indianapolis, IN

'[EE]: Impedance Matching a Phone Line'
2000\05\24@173809 by Brian Hopkins

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face
John:
Telco subscriber loops (twisted pair cable) have a nominal characteristic
impedance (Z) of 900 ohms. That is the classic comprise number used when
designing subscriber side equipment, and why all the CO line simulators
(artificial lines) use that value.
This of course is not the DC loop resistance (R) which will depend on your
distance from the CO and the gauge of cable in your loop makeup.
So..if you design your line drive electronics to have an output impedance of
900 ohms you should have maximum power transfer, and minimize reflections
(echo) for... most.... average...typical ... loops your equipment may
connect to.
I can't find any of my tech college references, but these sites confirm what
I recall was drilled into me.
www.mnm.com.sg/measurement/teltone/tls5.htm
teltone.com/telecom_solutions/test_tools/test_tls-3a_specs.html
http://www.wilcominc.com/t240.htm
http://www.egyed.com/phonework.html

Any references you see to 600 ohms (Z) relate to 'open wire' , used for toll
circuits (open wire carrier) in the pre-microwave days which were the
pre-fibre optic days. The equipment side of the telco was designed to match
that 600 ohms.
Old standards...old history...

Brian Hopkins

{Original Message removed}

'[EE]: 120VAC Traces'
2000\05\24@180514 by frmiller

flavicon
face
Thanks for your reply, Dan. Comments interlaced:

> Dan Michaels wrote:
>
<snip>
>
> That being said, let me relate some of the most effective
methods
> in my experience:
>
> 1. EMI and spike filters at the hiVAC power input
> - series EMI filter, MOVs, etc.

Could you give examples of the EMI filters. I assume you're
talking about something that goes across the contacts of the
relay switching the AC.

> 2. EMI/spike filtering on the power supplies -
> "transient voltage suppressor" diodes [eg, Microsemi 1.5KE
> series] on the P/S input side, downstream of the AC
transformer, if there is one.

Got these.

> 3. Bypass caps, of course, at all the usual points.

Got these, too.

> 4. Of course, diodes across the relay coils and
> snubbers across relay contacts.
>    NOTE - some loads produce significantly worse switching
transients
>    than others, so the same snubber may not be universally
effective.
>    When looking across the contacts, you will see hi-speed
spikes [bad]
>    riding on a slower wave [normal] in cases where the
snubber is not
>    effective enough. You might want to use an isolation
xfrmr to do
>    this measurement.
>    NOTE - one thing you can do is sniff around with a
scope probe,
>    ungrounded, to measure presence of EMI, and determine
what it is
>    correlated to.

Got the diodes and snubbers, though obviously my snubbers
could use a redesign.

> 5. On the low-level signal lines, RC filters and transorbs
[transient
>    voltage suppressor diodes, which are essentially
low-inductance
>    zeners] are effective. Note - we ended up putting
transorbs on
>    practically ever signal line - and regular zeners are
too slow here.

I use TVS's at the power line and at the +5V input to
sensitive chips. Haven't put them on signal lines, except
for RS485 out. I was concerned with the amount of
capacitance.

> 6. Layout issues - physically separate hi/low V,
> and signal/switching circuitry. Separate power busses and
gnd
> planes [if possible]. Don't run different lines near each
other, and don't
> cross them.

This is what I was trying to accomplish by separating the
110VAC. Some of the spikes from the mag starters were
coupled back into the low V circuit either across the gap or
through the relay, which has to physically bridge that gap.
That's why I was asking about the ground plane (guard ring)
in that gap.

> 7. Use watch dog timer in uC s.w. Use debounce routines on
signal measurements.

Watch dog on the pics (2 17C44) as well as cpu supervisors
(MAX706).

> 8. Use digital bus crowbar ckt in cases where chip latchup
is an especially
>  bad problem. [Note - the watchdog will not fix latchup].

I really miswrote. The Mux does not lock up; it resets.
Since it drives the relays, all the relays will drop out
when a spike happens. Not cool. I was actually able to fix
the problem by putting bypass caps on the Chip Enable and
Clear lines of the mux. However, I would like to give myself
some wriggle room by eliminating as much of the coupled
noise as possible. Since I have to redo the board anyway, I
was trying to find other suggestions, like the guard ring.

><snip>

> Regarding hacking the test bd, try using aluminum duct
tape
> grounded back to the hiV side [looks like relay power in
this case].
> In essence, you are putting a guard ring around the hiV
side which
> is intended to contain the internal fields. Likewise, you
can
> put a gnd guard ring around each other subsystem,
connected to
> the gnd of that subsystem.

This is the main info I was looking for. Will this be as
effective for testing purposes as traces on the board? Also,
would it be better to connect this gaurd ring to earth
ground or circuit ground?

Thanks for the info.

Ryan

2000\05\24@180522 by frmiller

flavicon
face
Thanks Chris,

I do have snubbers but they need work. Do you have a good
rule of thumb for design? Most of the books and articles
that I have read really boil down to "keep trying different
values 'til it works".

Ryan


{Quote hidden}

2000\05\24@180525 by frmiller

flavicon
face
Spehro,

Could you expand on this? Is there a problem with the T90
relays?

Ryan

> Spehro Pefhany wrote:
<snip>
>
> Part of the problem is the type of relays used.

'[EE][OT] Impedance Matching a Phone Line'
2000\05\24@190231 by David Huisman

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face
John,

The phone line impedance should be 600 or 900 Ohms.

You can match to this with an opamp.

Use 47k in series with inverting input with a capacitor (where C = 1/
2*PI*47k*F, F = lowest frequency .. say 20Hz).
Now make feedback resistor = Gain Required x 47k. Say gain is 5, then
feedback resistor is 235k (use 220k or maybe a 500k pot if you want to
adjust the level).

The output of the op-amp goes to a 600 Ohm isolation transformer (Farnell
have small PCB mounting versions for Telecom) via a resistor equal to your
line impedance, the other side of the winding goes to +ve.

This now gives you a balanced, isolated drive to the line. You will need to
do a little more on the line side depending on your application (line seize
and hold circuitry etc)

Hope this is useful to you as a starting point.

Regards
David Huisman
Orbit Communications
http://www.orbitcoms.com
NSW
Australia

2000\05\24@202038 by Max Toole

picon face
In a message dated 5/24/00 2:53:21 PM Eastern Daylight Time, EraseMEJohnCspamININ.COM
writes:

> I am trying to connect the output of a D/A signal to an open phone line to
>  play audio (sort of similar to the "DTMF decoding with a PIC" thread that
is
{Quote hidden}

Take a look at the Motorola MC34014P speech circuit for interface to the
phone line.

Hope this helps,

Max

'[EE]: 120VAC Traces'
2000\05\24@204125 by Dan Michaels

flavicon
face
Ryan Miller wrote:
....
>> 1. EMI and spike filters at the hiVAC power input
>> - series EMI filter, MOVs, etc.
>
>Could you give examples of the EMI filters. I assume you're
>talking about something that goes across the contacts of the
>relay switching the AC.
>

Actually, I was referring here to general filtering on the
power input from the AC line - which you may already have - and
which any industrial controller should have. Many commercial
versions are available, usually a C-L-L-C filter across the lines,
[C's across, L's in series in each line] with 2 C's to earth gnd,
plus MOV on downstream end, etc. Among other things, it will
help protect the controller from external noise [lightning, etc],
as  well as spikes generated by the switched loads and which are
conducted into the controller via the AC lines.
==============

{Quote hidden}

As mentioned, directly measuring the transients across the relay
contacts during on/off will help identify ineffective snubbers.
Alternatively, write some test code to exercise the relays
repetitively [at 1/sec or so] and observe which loads cause
problems. Fix those snubbers/etc. Probably use a smaller R.
================

{Quote hidden}

By "signal" lines, I really meant "all" of the low-level lines
in and out of the uC [bad terminology on my part]. It is common
for spikes to be conducted from the switched circuits directly
backwards to uC pins driving the relays. Series R's and RC's
will help here. Also, I don;t recall transorb C values, but I
believe they are small enough to not have to worry about in the
comm lines - specifically regarding the *low* V transorbs.
===============

{Quote hidden}

Here, the best defense is a good offense. First, try to kill
the spikes as dead [ie, make small] as possible. After that,
it's a systems-level, "defense" problem - ie, add preventive
measures so that spike residues have as little effect as possible.

I try to err on the conservative side, and include as many
good design features as possible, rather than just try to
get by with the minimum allowable. I think the extra cost
and effort helps in the long run. The guys I mentioned
consulting for had 10,000-20,000 units in the field and a
significant amount of "warranty" costs - about 2-5% failures
per year - that's of a lot of $$$$. By working on the
protection on the controllers over time, we were able to
greatly reduce the in-field failure rate.
=============

>> 7. Use watch dog timer in uC s.w. Use debounce routines on
>signal measurements.
>
>Watch dog on the pics (2 17C44) as well as cpu supervisors
>(MAX706).
>

Man, you already know/have it all.
===========

{Quote hidden}

Reset vs latchup is, I think, mainly related to the severity
of the garbage picked up. Your's sounds like it's on the lesser
side of real evil. The guard rings might have some small effect,
but will probably not produce magic. 1st attack the source of
the spikes - as above.
===============

{Quote hidden}

From my experiences with actually doing this, I think a good
patch of duct tape is about as effective as a real gnd plane of
the same area/etc. If adding a guard ring will have any significant
effect on the problem at all, I think it will be highly noticeable
with the duct tape jury rig.

Re ground used - try both ways & see what happens. Earth gnd might
be better. Also, it would probably help to keep the uC and relay
gnds separate if possible - if using an ULN2803 type driver or
BJTs/MOSFETs, you could run the gnds separately to the tie point.

best regards,
- Dan Michaels
==============

'[EE] PC board transfer'
2000\05\24@214443 by Brian Kraut

picon face
Has anyone modified an inkjet printer to print on things like circuit boards and
front panels?

"Scott, Gary" wrote:

{Quote hidden}

2000\05\24@214903 by Dale Botkin

flavicon
face
On Sun, 14 May 2000, Brian Kraut wrote:

> Has anyone modified an inkjet printer to print on things like circuit boards and
> front panels?

Not I - my favorite was an HP pen plotter loaded with permanent ink pens,
which also make dandy etch resist.  I don't know if you can get inkjet
cartridges that print with etch-resistant ink (something not water
soluble).

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

2000\05\24@215920 by Mark Willis

flavicon
face
The problem (as I see it) is that many inkjets (all that I own, for
certain!) have water-soluble ink;  I could print with an InkJet then
photocopy onto glossy paper then fuse THAT onto a PCB, but it doesn't
make a lot of sense to put water-soluble ink down as etch "resist" then
dunk in Ferric Chloride.  (Not pretty when I print onto an envelope then
walk it out to the mailbox in the rain, either.)

The other problem I see with inkjets is that their ink's nowhere near as
"thick" and opaque, as laser printer toner.  So would have to mess with
contrast a little when photocopying.

So, even if you made one to go with a straight media path, still have
problems - Laser's go for $25 occasionally around here used, was given
one free the other day, so I'll stick with laser printers.

 Mark

Brian Kraut wrote:
{Quote hidden}

'[EE]: Impedance Matching a Phone Line'
2000\05\24@225848 by Clark, John

flavicon
face
MC34014P

Looks interesting from the few application notes I found, but for whatever
reason I cannot seem to find data sheets on this product...  Could you give
me a direct link?  This looks like it may be worth investigating.

Additionally, is there additional certifications needed for telco
connectivity?  A complete third party product that could save us additional
certifications may be an attractive alternative (depending on unit price).


John Clark
Indianapolis, IN

{Original Message removed}

'[EE]: 120VAC Traces'
2000\05\24@232821 by Robert A. LaBudde

flavicon
face
<x-flowed>At 02:58 PM 5/24/00 -0700, ryan wrote:
>Thanks Chris,
>
>I do have snubbers but they need work. Do you have a good
>rule of thumb for design? Most of the books and articles
>that I have read really boil down to "keep trying different
>values 'til it works".

Typical values are 0.1 uF with series 100 ohm.

================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: RemoveMEralKILLspamspamlcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
824 Timberlake Drive                            Tel: 757-467-0954
Virginia Beach, VA 23464-3239                   Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================

</x-flowed>

'[EE]: Impedance Matching a Phone Line'
2000\05\25@031155 by Brian Hopkins

flavicon
face
John,
It seems what you are looking for is a pre-certified DAA...and ideally
certification that is transferable to your product.
The certifications your are concerned about for North America are FCC Part
68 (USA) and DOT CSA CS-03 Part I (Canada)
Try XECOM
http://www.xecom.com/_PageFiles/about.htm
or Cermetek
http://www.cermetek.com/

Hope this helps
Brian
{Original Message removed}

'[EE] PC board transfer'
2000\05\25@040524 by Alan B Pearce

face picon face
>Has anyone modified an inkjet printer to print on things like circuit boards
and
>front panels?

I have seen people suggest using special pens in flat bed plotters, but I think
you will have a problem with an inkjet printer, as all the inks they use are
water soluble AFAIK.

2000\05\25@090343 by Albert Noah

flavicon
face
Actually, you can get indelible inks to refill your cartridges with. I had
to do this to print labels for packaging in a freezer. Worked great where as
the normal inkjet ink just ran and smeared. I got the ink from a company
called V-Tech.

Hope this helps,

Albert

{Original Message removed}

'[EE]: 120VAC Traces'
2000\05\25@103413 by Dan Michaels

flavicon
face
Robert wrote:
>At 02:58 PM 5/24/00 -0700, ryan wrote:
>>Thanks Chris,
>>
>>I do have snubbers but they need work. Do you have a good
>>rule of thumb for design? Most of the books and articles
>>that I have read really boil down to "keep trying different
>>values 'til it works".
>
>Typical values are 0.1 uF with series 100 ohm.
>

And you probably realize it, but there are *special*
capacitors made particularly for this type of application.
They tend to be rather bulky and take up a lot of board
space. Not any old cap will do.

'[EE]: Re: Step up voltage regulator'
2000\05\25@171526 by Roland Andrag

flavicon
face
There are various voltage doubler chips available.  I think (one of) the
original chip(so) was the ICL7660, now also available from many other
manufacturers e.g.. MAX7660 from Maxim. To volunteer the info that launched
me into electronics properly: If you ever feel like buying a book that
contains this and a thousand other useful pages of info get 'The Art of
Electronics', by Horowitz and Hill. You won't regret it.

Roland



----- Original Message -----
From: Soon Lee <pslnSTOPspamspamspam_OUTCYBERWAY.COM.SG>
To: <spamBeGonePICLISTSTOPspamspamEraseMEMITVMA.MIT.EDU>
Sent: Thursday, May 25, 2000 7:53 AM
Subject: Step up voltage regulator


Hi All

Do anyone have any idea in how to step up voltage
like from 5 volts to 10volt
Is there such things call step up regulators?
if there are may i know the part number thanks
i heard that there is one of such device in picstart that step a 9V to 13 V
any oneknow the part number thanks

'[EE]: 120VAC Traces'
2000\05\26@063333 by Tom Handley

picon face
At 11:18 AM 5/24/00 -0600, Dan Michaels wrote:
>BTW, a good book on this topic is
>
>"Noise Reduction in Electronic Systems" by Henry Ott

  Dan, I also have this book and highly recommend it. For those interested:

     Noise Reduction Techniques in Electronic Systems
     Henry W. Ott
     Wiley-Interscience
     ISBN: 0-471-65726-3

  Another good one is:

     Low-Noise Electronic Design
     C.D. Motchenbacher and F.C. Fitchen
     Wiley-Interscience
     ISBN: 0-471-61950-7

  - Tom


------------------------------------------------------------------------
Tom Handley
New Age Communications
Since '75 before "New Age" and no one around here is waiting for UFOs ;-)

'[EE]: Boosting power of radio modules/Yagi beamwi'
2000\05\26@091349 by Jim P

flavicon
face
Taking a quick look at the Decibel Products catalog
for a 6-element 10 dBd gain UHF band Yagi (-"Uda")
antenna such as the DB436 through DB438 Yagis:

Horz. Beamwidth:  60 deg. (3 dB points)
Vert.  Beamwidth:  44 deg. (3 dB points)

This assumes vertical orientation of the E-plane (elements
placed vertically).

To achieve a substantially tighter vertical pattern (you
mentioned 5 deg. vert. as a 'spec') Yagis can be stacked
vertically to tighten up this pattern while increasing gain
and not affecting the horrizontal pattern.

Two Yagis of the type above would 13 dBd gain, 4 stacked
Yagis would yield 16 dBd ...

Jim P

{Original Message removed}

'[EE]: Re: Step up voltage regulator'
2000\05\26@112756 by Dan Mulally

flavicon
face
A note on the 7660. It does not provide regulation so consider your current
draw to see if the voltage drop is acceptable.

Dan

{Original Message removed}

'[EE] TDA 8822 video modulator'
2000\05\26@123030 by Dan Mulally

flavicon
face
Has anyone used the Philips TDA 8822 video modulator? I'm  trying to set it
with the I2C buss and am having trouble. It seems to be getting some data
because it's operation changes when I load data but I can't get the test
modes or nomal modes to work properly. The P0 port always has a 7.813kHz
signal present (fref/512), I don't get any RF out but the VCO seems to be
working but not locking. My configuration bytes now are: CA, 44, 34, A2, E4.
Any help would be appreciated. Thank you in advance.

Dan Mulally

KILLspamdtconspamBeGonespamrapidnet.com
http://rapidnet.com/~dt2000

'[EE] Re: Boosting power of radio modules[EE]'
2000\05\26@123625 by Dan Mulally

flavicon
face
Mini circuits have several easy to use amplifiers that can boost the output
to up to 30dBm (1Watt) depending on if linearity is desired. Your system is
probably FM so linearity is not needed or desired since linear amps are
inefficient. You need to check the FCC rules.

Dan Mulally

{Original Message removed}

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\26@130144 by Edson Brusque

face
flavicon
face
Hello,

   someone knows if there's a microcontroller with 4 USARTs capable of
working at 31250bps? I need extra 24 I/Os minimum. One USB port would be a
plus. Also, I would need an A/D converter, but I could use an external one.

   Maybe a SCENIX can do 4 USARTs as virtual peripherals???

   Best regards,

   Brusque

2000\05\26@134517 by Chris Eddy

flavicon
face
Edson, I think that you want to check out the Rabbit 2000.  I have seen it
advertised in the likes of Circuit Cellar.

Chris Eddy

Edson Brusque wrote:

{Quote hidden}

'[EE] Re: Boosting power of radio modules[EE]'
2000\05\26@135344 by Harold M Hallikainen

picon face
On Fri, 26 May 2000 10:24:59 -0600 Dan Mulally <EraseMEdtconspamEraseMERAPIDNET.COM>
writes:
> Mini circuits have several easy to use amplifiers that can boost the
> output
> to up to 30dBm (1Watt) depending on if linearity is desired. Your
> system is
> probably FM so linearity is not needed or desired since linear amps
> are
> inefficient. You need to check the FCC rules.
>

       Assuming you are operating this as an FCC part 15 unlicensed intentional
radiator (and not some licensed transmitter, such as amateur), the
appropriate rules are in part 15.
       FCC Rules regarding unlicensed intetional radiators start at section
15.201. The table of contents with links to rules is available at
http://hallikainen.com/cgi-bin/section.pl?section=15 .
       In particular, note that 15.201requires such devices to be
"certificated" with the Commission. Adding power amplifiers, etc. would
violate this certification (the equipment is not the same that was
certificated).
       See also 15.204 which prohibits use of an antenna other than that
supplied with the transmitter on a part 15 intentional radiator.

Harold


FCC Rules Online at http://hallikainen.com/FccRules
Lighting control for theatre and television at http://www.dovesystems.com

________________________________________________________________
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Try it today - there's no risk!  For your FREE software, visit:
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'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\26@141039 by M. Adam Davis

flavicon
face
Perhaps if you give us a little more information we can help you out more.  If
you take an atmel or scenix micro you could fairly easily develop 4 software
UARTs if they are all running at the same speed.  The PIC probably wouldn't run
fast enough unless you are doing very little or no processing of the data.  (I
just mashed a 4800bps full-duplex software UART into a 16c54 running at 4MHz
with a small bit of data processing...  It took a /lot/ of planning...)

It is unlikely that you will find an 8-bit micro with 4 hardware UARTs (as a
hobbyist), so you probably should plan on finding one with one or two UARTs and
build the rest in software.  If I were in your shoes, I would build them all in
software.  If you run a scenix or atmel at 24 MIPs, you'll have exactly 768
instructions (scenix, varies for atmel) per bit time to run the UARTs and your
user process (at the specified 31.25Kbps).  Divide it by four (bit slicing) and
you end up with 192 instructions to read the state of four RX lines, change the
state of four TX lines, and then do some data processing.  It really would not
be too difficult.

-Adam

Edson Brusque wrote:
{Quote hidden}

2000\05\26@142939 by Dan Michaels

flavicon
face
Edson Brusque wrote:
.....
>>     someone knows if there's a microcontroller with 4 USARTs capable of
>> working at 31250bps? I need extra 24 I/Os minimum. One USB port would be a
>> plus. Also, I would need an A/D converter, but I could use an external one.
>>
>>     Maybe a SCENIX can do 4 USARTs as virtual peripherals???
>>

Scenix can easily do this, **BUT** you will have to go to 48 or
52-pin PQFP part - with tiny smt pads - to get 24 additional I/O lines.
No PLCC available. [or possibly do a multiprocessor with 18 & 28
pin parts - not all that hard to build off a single RS-232 host line].

And I suspect with the scenix, you actually could get the weird
31250 rate you indicate here - or any other weird baudrate imaginable.
But whatcha gonna talk to at that speed?
================

Adam Davis wrote:
>Perhaps if you give us a little more information we can help you out more.  If
>you take an atmel or scenix micro you could fairly easily develop 4 software
>UARTs if they are all running at the same speed.  The PIC probably wouldn't run
..........

I believe with the scenix VP route, the separate UARTs do *not* have
to be running at the same bps. The VPs all run off the same basic
timer interrupt, but each uses a different divider to index its
update rate.

cheers,
- Dan Michaels
Oricom Technologies
===================

'[EE] Re: Boosting power of radio modules[EE]'
2000\05\26@144015 by Dan Michaels

flavicon
face
Harold wrote:
.....
>        Assuming you are operating this as an FCC part 15 unlicensed
intentional
{Quote hidden}

....


If I read this correctly, Harold, you are saying that even an
"unlicensed" transmitter still "must" be certified.

<SECRET STUFF>
Shoot - in for a penny, in for a pound. I guess if someone does
this the "wrong" way, they might as well go "all the way" - and
break all the rules - overpowered, illegal antenna, non-certified,
what the heck. [did all you Echelon moles pick this up?].

Maybe we should have an [ECHELON] admin category to make
Echelon's job easier!!
</SECRET STUFF>

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\26@151309 by Andrew Seddon

picon face
There is a VP on the scenix site with I think 8 USART`s running not sure of
the speed but I know it is on a 50mhz SX28. If you were to get a new 100mhz
SX52/48 I am sure you could do pretty much everything in software, not sure
about the USB.

> Hello,
>
>     someone knows if there's a microcontroller with 4 USARTs capable of
> working at 31250bps? I need extra 24 I/Os minimum. One USB port would be a
> plus. Also, I would need an A/D converter, but I could use an external
one.
>
>     Maybe a SCENIX can do 4 USARTs as virtual peripherals???
>
>     Best regards,
>
>     Brusque
>

'[EE] Re: Boosting power of radio modules[EE]'
2000\05\26@153824 by Andrew Seddon

picon face
I don`t think most of this applies to me as I am in the UK. Believe me if I
thought there was any chance of causing disruption to others I wouldn't`t
even consider it. I know the band I am transmitting on is set aside for
short range keyfob transmitters etc. BTW it is actually 418Mhz I am
transmitting on not 433 as I previously said.

> Harold wrote:
> .....
> >        Assuming you are operating this as an FCC part 15 unlicensed
> intentional
> >radiator (and not some licensed transmitter, such as amateur), the
> >appropriate rules are in part 15.
> >        FCC Rules regarding unlicensed intetional radiators start at
section
{Quote hidden}

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\26@161428 by Harold M Hallikainen

picon face
       Another approach is to use Maxim external uarts hung on a serial bus out
of the PIC.

Harold


FCC Rules Online at http://hallikainen.com/FccRules
Lighting control for theatre and television at http://www.dovesystems.com

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
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'[EE] Re: Boosting power of radio modules[EE]'
2000\05\26@161439 by Harold M Hallikainen

picon face
On Fri, 26 May 2000 12:38:23 -0600 Dan Michaels <@spam@oricom@spam@spamspam_OUTLYNX.SNI.NET>
writes:
{Quote hidden}

       Yes, 15.201 pretty much requires that. However, 15.23 allows "home built
devices" as follows...

Sec. 15.23  Home-built devices.

   (a) Equipment authorization is not required for devices that are not
marketed, are not constructed from a kit, and are built in quantities of
five or less for personal use.
   (b) It is recognized that the individual builder of home-built
equipment may not possess the means to perform the measurements for
determining compliance with the regulations. In this case, the builder
is expected to employ good engineering practices to meet the specified
technical standards to the greatest extent practicable. The provisions
of Sec. 15.5 apply to this equipment.



       I don't believe that adding an unauthorized power amplifier or antenna
to a commercial device would make the resulting system "home built." I
believe that this section continues to require that users of home built
equipment comply with all the limits of part 15, but recognizes that a
typical person does not have the means to make the required measurements.


Harold



FCC Rules Online at http://hallikainen.com/FccRules
Lighting control for theatre and television at http://www.dovesystems.com

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
dl.http://www.juno.com/get/tagj.

2000\05\26@161442 by Harold M Hallikainen

picon face
       Actually, I'd expect NONE of the US FCC rules to apply in the UK.
However, most countries have very similar rules on unlicensed
transmitters.

Harold


On Fri, 26 May 2000 08:34:23 +0100 Andrew Seddon <spamBeGoneseddonaspamKILLspamHOTMAIL.COM>
writes:
{Quote hidden}

FCC Rules Online at http://hallikainen.com/FccRules
Lighting control for theatre and television at http://www.dovesystems.com

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
dl.http://www.juno.com/get/tagj.

'[EE]: Re: About serial port scoping'
2000\05\26@163122 by mike

flavicon
picon face
DataScope is a powerful serial communications analyzer
designed as a high performance tool for software and
hardware professionals. Now you can eliminate guesswork
about asynchronous transmissions, connections, character
timing, and serial events without purchasing an expensive
hardware monitor.

I did'nt write the description ;-) and  its only 90k long.

www.simtel.net/pub/simtelnet/msdos/sysutl/scope140.zip
http://www.corn2.freeserve.co.uk/scope140.zip  *** only for a few
days ***


ATB  Mike W

On 25 May 00, at 7:42, pic microcontroller discussio wrote:

> IIRC there was a program from Simtel Archives called DSCOPE
> that achieved this. I might still have it on my tape archive. IF I can
> still read it (big IF) and if anyones interested.
>
> Could this be a project for the PIC testbench mentioned last year?.
>
> Mike W

--
.....mikespam_OUTspamcorn2.freeserve.co.uk

Never underestimate the power of Human stupidity

'[EE]Re: TCP/IP SEIKO STARTER KIT (USING THE PARALL'
2000\05\26@171532 by Andrew Seddon

picon face
> No, i have the Specctra Autoroute 7.1, i did pay for it U$1245,00
>
> Miguel
>

Really how do you find it?? Not that I can really get it on a students
budget. I am currently working through every computer I can find with the 30
day trial on Protel. I have to say my experience is limited but I managed to
layout a pretty complex board and I didn`t find it too much trouble. Also
the autorouter does about a good a job as I think I could do.

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\26@182255 by Edson Brusque

face
flavicon
face
> Perhaps if you give us a little more information we can help you out more.

   As I'm a musician, and my (piano) keyboard controller doesn't makes all
the tricks I would like it to do, I'm thinking in developing a MIDI
black-box that could do everything I want. Maybe I can sell hundreds of
units and make some money :)

> It is unlikely that you will find an 8-bit micro with 4 hardware UARTs (as
a
> hobbyist), so you probably should plan on finding one with one or two
UARTs and
> build the rest in software.  If I were in your shoes, I would build them
all in
> software.  If you run a scenix or atmel at 24 MIPs, you'll have exactly
768
> instructions (scenix, varies for atmel) per bit time to run the UARTs and
your
> user process (at the specified 31.25Kbps).  Divide it by four (bit
slicing) and
> you end up with 192 instructions to read the state of four RX lines,
change the
> state of four TX lines, and then do some data processing.  It really would
not
> be too difficult.

   I think I'll want to put 16 keys on the thing (8 I/Os for that), an LCD
(6 I/Os for that), four MIDI Ins plus four midi Outs (8 I/Os), and I would
like it to communicate with the PC with Paralell or USB. Even Serial at
115.200bps would do the job nicely. Well, this puts 22 I/Os plus PC
communication. A 48 or 52 pin Scenix at 50MHz seens to be a very good option
(I've took a look at SX documentation and it says it can run eight 19.2Kbps
UARTs using 13% of 50MHz). The hard thing will be to make an adaptor to use
it on a proto-board.

   I would also like to put 16 pots on it to control various things (like
volume, pan, reverb, modulation, etc).

   I would preffer to make it with PICs, but I don't think it's possible. I
don't want to expend money on another C compiler, debugger, etc...

   Atmel would also be a good option. What Atmel micros can do 24MIPS?

   Best regards,

   Brusque

2000\05\26@190523 by Andrew Seddon

picon face
>     I would preffer to make it with PICs, but I don't think it's possible.
I
> don't want to expend money on another C compiler, debugger, etc...

Try http://www.geocities.com/SiliconValley/Network/3656/c2c/c.html for a C
and Pascal compiler that will work with the 52/48. Also if you talk to Mr
Newton I am sure he will sort you out with a demo board and socket, I would
send you the layout for mine but it is pretty crappy in comparison.

2000\05\26@191144 by Edson Brusque

face
flavicon
face
Hello Dan,

> Scenix can easily do this, **BUT** you will have to go to 48 or
> 52-pin PQFP part - with tiny smt pads - to get 24 additional I/O lines.
> No PLCC available. [or possibly do a multiprocessor with 18 & 28
> pin parts - not all that hard to build off a single RS-232 host line].
>
> And I suspect with the scenix, you actually could get the weird
> 31250 rate you indicate here - or any other weird baudrate imaginable.
> But whatcha gonna talk to at that speed?

   31250bps isn't weird: 1,000,000 (instructions for second) / 31250 (bps)
= 32 (instructions for serial bit).

   I'm looking at an Atmel datasheet. It says the AT89C55 can do 33MHz, but
how much clocks does it takes to execute one instruction? Why few
manufacturers put this information on the datasheets??? 33Mhz equals to
33MIPS? Or 8,25MPIS? Or 2,75 MIPS???

   Regards,

   Brusque

'[EE]: Re: About serial port scoping'
2000\05\27@014831 by Robert Rolf

picon face
See also

http://www.fte.com/

SerialTest Spy. A windows comm port shim that taps the data going to
and from a serial port. You don't need a separate PC since it
creates a software T connection. Very good software, but you have
to pay the registration fee to get it log more than a couple of kB.

More on Dscope below:

Mike W wrote:
{Quote hidden}

www.ultranet.com/~dtweed/cajindex/ftp_area/areaib41.htm
ftp://ftp.circuitcellar.com/IBMPC/OTHER/DSCOPE.ZIP

> >
> > Could this be a project for the PIC testbench mentioned last year?.
> >
> > Mike W
>
> --
> TakeThisOuTmike.....spamTakeThisOuTcorn2.freeserve.co.uk
>
> Never underestimate the power of Human stupidity

'[EE] Non interacting zero and span. how?'
2000\05\27@021421 by Dan Mulally

flavicon
face
----- Original Message -----
From: "Chris Eddy" <TakeThisOuTceddyKILLspamspamspamNB.NET>
To: <.....PICLISTspamRemoveMEMITVMA.MIT.EDU>
Sent: Saturday, May 20, 2000 5:22 PM
Subject: [EE] Non interacting zero and span. how?


{Quote hidden}

You could use an inverting summing configuration with a fixed resistor in
the feedback loop and 2 rheostats connected to the inverting input. One
rheostat can connect to a DC source and the other to your signal. The output
will be inverted so you may have to use another opamp invertor to get the
correct polarity.

Dan Mulally

'[EE] Re: Boosting power of radio modules[EE]'
2000\05\27@072730 by mike

flavicon
picon face
On 27 May 00, at 0:01, Automatic digest processor wrote:

> Date:    Fri, 26 May 2000 10:51:04 -0700
> From:    Harold M Hallikainen <RemoveMEharoldhallikainenspamspamBeGoneJUNO.COM>
> Subject: Re: [EE] Re:      Boosting power of radio modules[EE]
>
<<snip>>
>
>         Assuming you are operating this as an FCC part 15 unlicensed
> intentional
> radiator (and not some licensed transmitter, such as amateur), the
> appropriate rules are in part 15.
<< 'nother snip>>
>         See also 15.204 which prohibits use of an antenna other than
> that
> supplied with the transmitter on a part 15 intentional radiator.
>
> Harold
>
how do you do a smiley blowing a friendly rasberry?.

'[EE]Re: TCP/IP SEIKO STARTER KIT (USING THE PARALL'
2000\05\27@110532 by WF

flavicon
face
I got it in IVEX in 1998

My board aren't complex...during 7 year i did use the MANUAL OPTION route of
Tango...

When you have a complex layout for route, you have to change the RULES of
routing...othewise, can not route 100%...

My specctra is limited for 4000 holes and 2 layes, but is enough for me...

Miguel

{Original Message removed}

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\27@115818 by Dan Michaels

flavicon
face
Edson wrote:
.........
>> And I suspect with the scenix, you actually could get the weird
>> 31250 rate you indicate here - or any other weird baudrate imaginable.
>> But whatcha gonna talk to at that speed?
>
>    31250bps isn't weird: 1,000,000 (instructions for second) / 31250 (bps)
>= 32 (instructions for serial bit).
>

Only weird viz-a-viz the "usual" baudrates, like 19200, 38400, 57600,
etc. For local networks, anything is a go. But I'm not sure whether
a PC, if used as a host, could accommodate anything like 31250. Depends
upon the internal clocks and USART h.w.

The scenix s.w. VP could probably be massaged to accommodate both 31250
and 38400, for example, if you try hard enough. 50Mhz/38400 = 1302 and
50Mhz/31250 = 1600.

- Dan

2000\05\27@163855 by Sebastian Garcia

flavicon
face
Edson wrote:

| I'm looking at an Atmel datasheet. It says the AT89C55 can do 33MHz,but
|how much clocks does it takes to execute one instruction? Why few
|manufacturers put this information on the datasheets??? 33Mhz equals to
|33MIPS? Or 8,25MPIS? Or 2,75 MIPS???


If it don't say anything more, it may be the classic 8051's: one machine
cycle is formed by twuelve clock cycles, and the instruction cycle
depends on the particular instruction.


If You want more speed enhacement look at Dallas MCS-51 compatible, hi-speed
micros.

Regards,

S.-

2000\05\27@180739 by David VanHorn

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1


>If it don't say anything more, it may be the classic 8051's: one machine
>cycle is formed by twuelve clock cycles, and the instruction cycle
>depends on the particular instruction.
>
>
>If You want more speed enhacement look at Dallas MCS-51 compatible, hi-speed
>micros.


Or the AVR, at one xtal clock per instruction (a few take two). 8 mhz, but
that's 96 to an 8051 apparently.

- --
Are you an ISP?  Tired of spam?
http://www.spamwhack.com  A pre-emptive strike against spam!

Where's Dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

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Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

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ZPWtc4N49sDH1YL4AotBu6qG
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'[EE]Re: TCP/IP SEIKO STARTER KIT (USING THE PARALL'
2000\05\28@031522 by Damon Hopkins

flavicon
face
Andrew Seddon wrote:
>
> > No, i have the Specctra Autoroute 7.1, i did pay for it U$1245,00
> >
> > Miguel
> >
>
> Really how do you find it?? Not that I can really get it on a students
> budget. I am currently working through every computer I can find with the 30
> day trial on Protel. I have to say my experience is limited but I managed to
> layout a pretty complex board and I didn`t find it too much trouble. Also
> the autorouter does about a good a job as I think I could do.

http://mainstream.pcb.cadence.com/specctra/index.asp

'[EE] Flash and EEPROM based file systems'
2000\05\28@041657 by Damon Hopkins

flavicon
face
anyone have any code dealing with implementing a file system on either
FLASH memory or any other type of memory.. I'd like to get a 1 MB flash
chip and put a small filesystem on it but rather than try to design the
thing myself I'd like to sample what's out there.. I haven't turned up
much. I plan on using the Atmel SPI Flash memory chips and figure that
with a 16 bit pointer I could have access to 4 MB I want to make a tiny
file server :)

                       Thanks,

                                       Damon Hopkins

'[EE] Info: Rechargeable Lithium coin cells'
2000\05\28@070258 by Russell McMahon

picon face
I went looking for info on rechargeable Lithium coin cells and found it very
hard to find anything technical.
Here's the best of my slim pickings.

Most of following sites are subset of this one with good source of battery
technical data including tables etc
       http://www.allbatteries.com

Sanyo ML series rechargeable Lithium Manganese coin cells
   http://www.allbatteries.com/sanyo19.htm

Varta MC series Lithium Ion coin cells
   http://www.allbatteries.com/vartrlbc.htm

Varta also do button cells in NiMH which have a much higher max
charge/discharge rate.
   http://www.allbatteries.com/nimhre24.htm

Maxell make them too (and sell them via eg Farnell 3031998 etc) but don't
seem to want to tell you about them on their various sites.
A bit at
   http://www.maxell.co.jp/eng/device/ml_bat/


Std Lithium coin cells - discharge curves. usefulish
   http://www.tbcl.co.jp/TB_e/lb_b_e.htm

`

'[EE] Flash and EEPROM based file systems'
2000\05\28@082709 by Bob Ammerman

picon face
Flash file systems are tricky. You have to worry about load-leveling. It
wouldn't do to continually write, for example, the FAT and have it wear out
before the rest of the space.

Bob Ammerman
RAm Systems
(high function, high performance, low level software)

{Original Message removed}

2000\05\28@103604 by Robert A. LaBudde

flavicon
face
<x-flowed>At 04:14 AM 5/28/00 -0400, you wrote:
>anyone have any code dealing with implementing a file system on either
>FLASH memory or any other type of memory.. I'd like to get a 1 MB flash
>chip and put a small filesystem on it but rather than try to design the
>thing myself I'd like to sample what's out there.. I haven't turned up
>much. I plan on using the Atmel SPI Flash memory chips and figure that
>with a 16 bit pointer I could have access to 4 MB I want to make a tiny
>file server :)

Because of the finite lifetime of eeprom, you might consider one of the
systems used for CD-ROM or CD-RW.

Or, a simple method is the use a linked list directory. When a file gets
replaced more than N times, mark the entry as deleted and replace it with a
new entry the first one is linked to. This results in slower directory
accesses, but predictable write cycling of memory.

Of course, if your data will be write-once and only appended to, you could
use one of the classic simple file systems, such as the CP/M-DOS FAT16
method (well-documented in the IBM Technical Reference Manual for the PC,
or in Dr. Dobbs).

================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: spamBeGoneral@spam@spamspam_OUTlcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
824 Timberlake Drive                            Tel: 757-467-0954
Virginia Beach, VA 23464-3239                   Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================

</x-flowed>

'[EE] Wireless communication...'
2000\05\28@170308 by Jilles Oldenbeuving

flavicon
face
Hi...


For prototypeing purposes we bought a couple of 4 pins 'complete AM radio
transmitters' from R.F. Solutions. Also bought
a couple of matching receivers ofcourse (433 MHz). (http://www.rfsolutions.com).
My problem with them is this: when supplying Vcc (5V) and GND to the
transmitter and connecting a function generator
at the data in, of 2 kHz, 50 % dutycycle (coupled AC or DC) i can't see
anything at the receiving end. I can't measure
if the transmitter is actually oscilating at 433 MHz becouse the fastest
scopes we have is a Philips 200 Mhz scope...

Also the datasheets and the technical support are far beneath appropiate, in
my opinion.

The units were places 20 cm apart and had just a wire of 15 cm as an
antenna. Anybody couped with the same problem?
Anyone have experience with these modules (i mean the AM-RT4-433 transmitter
and the AM-HRR-433 receiver, of RF Solutions)

Jilles

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\28@171749 by Edson Brusque

face
flavicon
face
> >If it don't say anything more, it may be the classic 8051's: one machine
> >cycle is formed by twuelve clock cycles, and the instruction cycle
> >depends on the particular instruction.
> >If You want more speed enhacement look at Dallas MCS-51 compatible,
hi-speed
> >micros.
> Or the AVR, at one xtal clock per instruction (a few take two). 8 mhz, but
> that's 96 to an 8051 apparently.

   Ok, but beside the Scenix, there's no 8-bit microcontroller capable of
doing more than 20 MIPS???

   And what about the 16-bit micros? Can it be a good option for my
project? A US$10-20 microcontroller isn't very expensive to me if it can do
all I need on this project.

   Best regards,

   Brusque

'[EE] Info: Rechargeable Lithium coin cells'
2000\05\28@172841 by Jilles Oldenbeuving

flavicon
face
Have you also stumbled on some charge circuits for secondary cells? If you'd
know some good web-site for it,
please let me know....


Jilles
-----Oorspronkelijk bericht-----
Van: Russell McMahon <TakeThisOuTapptechspamspamCLEAR.NET.NZ>
Aan: PICLISTEraseMEspamMITVMA.MIT.EDU <RemoveMEPICLISTEraseMEspamspam_OUTMITVMA.MIT.EDU>
Datum: zondag 28 mei 2000 13:05
Onderwerp: [EE] Info: Rechargeable Lithium coin cells


>I went looking for info on rechargeable Lithium coin cells and found it
very
{Quote hidden}

'[EE][PIC] How to measure level of liquids and sens'
2000\05\28@174123 by Hugo Jorge Mčller

flavicon
face
Hello

I am beginning to work in the final project of my career of Electronic
Engineering and at the moment, we have decided to make the following work
(with a friend): To automate a plant of Concrete.

The idea is to use a PC for the general control of the plant and to arm a
network (Possibly RS485) with terminals that will be slaves working with
PICs, to complete different tasks, as the following ones:

1) To control the pneumatic servos and read proximity sensores and other.

2) To Sense the weight of the materials with cells of loads, indicate the
value measured in a  7 segments display and to send the measures througt the
network when they are requested or periodically. This partly would be
resolved, but I accept ideas and suggestions in this respect.

3) To Sense the level of water in the main dosificador tank. The tank should
be filled until certain level and then it is pumped to the truck concrete
mixer. I have think in sense the height of the column of liquid with a
sensor of pressure Motorola of the series MPX, I also thought of the
ultrasonic solution  but I don't have idea that resolution i can achieve.
The tank in question has 1100 Liters and a height of about 2 meters. aprox.,
it is cylindrical. I need a precision of about 5 liters. (or better).
Ideas? Comments? Other viable methods?
On the other hand I should dose some aditives, special liquids that
unfortunately they are corrosive and at the moment it is filled a small tank
of about 26 liters by means of a key, for graveness, then they closes this
key (superior) and two keys open up, one in the inferior part that allows
the exit of the preservative toward the MIXER and the other one in the
superior part that injects compressed air at 10 Kg/cm^2 to impel to the
preservative and to pump it without having contact with the same one.
The problem is to measure the level or the quantity of this aditive without
touch it and to be able to pump it too to the mixer.
I thought of measuring it with sensor MPX, but the problem is when opening
the key of compressed air, the sensor doesn't support 10 Kg/cm^2 (although
it could measure in differential form, but I suppose that the transitory one
provoked, it would destroy to the silicon sensor).
Here it is where I request them help that mensuration methods advise me?

Somebody had worked with sensor MPX with PICs ?  What kind of interface/ ADC
use ?

4) Another topic not less difficult of solving it is to be able to measure
the relative humidity that there is in the sand and in the concrete once
blended. Here the only method that I am happened (electronic) it is between
two by means of the mensuration of conductivity electrodes of a material
that is not oxidized, located inside the material to measure, at a certain
distance. That other methods or variantes suggests me?

As for the net RS485, has somebody used them with PICs? That protocols
suggest? Some link with information?

Good, I won't extend more in the detail, I wait their collaboration with
ideas...

Sorry if there are errors in the text, but my language is Spanish  :-)

Thank you from already.

Hugo J. M|ller
H.J.M. Hardware & Software Diseqos Electrsnicos
San Nicolas 683
Tel-Fax : 54-(0)-343-424-5953
(3100) Parana (Entre Rmos) Argentina
Email : hmuller [ANTISPAM-QUITAR-ESTO] @arnet.com.ar
Web Site: http://www.pagina.de/hjm
UIN (ICQ) : 38.605.074

'[EE] Wireless communication...'
2000\05\28@174746 by Jim P

flavicon
face
     "  ...Philips 200 Mhz scope...  "

... should still see something as that is usually the
"3 dB point" for the scope's bandwidth ... I once trouble
shot a Tektronix 454 (150 MHz scope) trigger circuit using
just a 10 MHz bandwidth Tek portable - the trigger circuit
incorporated a tunnel diode that excited a 'tank' circuit that
resonated at several hundred MHz ... the indication was only
a small 'blip' when the tunnel diode was working as seen on
the low bandwidth scope.

Take a look at the xmtr with the Philips scope -  433 MHz
is just over an octave higher frequency - and the scope
should show enough to give a yea/nay indication.

Watch out for the the scope probe though - they often have a
much lower cutoff freq than the scope itself. You may have to
rig a short piece of coax and if the scope has a built-in 50 Ohm
termination switch it it to then couple the xmtr output directly
into the scope.

Zero dBm is about .223 V RMS (.6 V Pk-Pk) less any rolloff
in amplitude the scope shows at 433 MHz.

Jim P

{Original Message removed}

2000\05\28@180453 by Jilles Oldenbeuving

flavicon
face
{Quote hidden}

Hmmm, you're right i guess. But the scope is a digital one. Even when i
measure a
voltage that goes from 0V to 5V it takes approx. 3 seconds to adjust the
screen. What
one will see is this:

0V -----------------------------

('bout 1 sec later:)


5V       .                 .
0V -----  -------------  ------------

again, 1 sec later:


5V   --    ---      ---
0V --   ---    ----   ----

and, finaly after about 3 seconds:


5V -----------


I think this has to do with how the A/D converter works within the scope...
If i measure a point were
i *suspect* to be 433 MHz all i see is something like 3/4 Vcc, wich could be
the avarage voltage?
I want to say that i mustn't have to measure these 'ready to go'-modules! I
mean, they have to work, don't they?
The only thing i could find on the website of RF Solutions was a ****3****
page datasheet. And after asking some
application information, they reffered to book! That application information
had to be in the datasheet in my humble opinion...
(frustrated, you guessed it right :)

Did anyone get these modules to work? I'm interested in how they did it.

Jilles

2000\05\28@190512 by Jim P

flavicon
face
Oh - digiscope ...

Do you have any small signal diodes like types 1N914
or 1N4148 diodes on hand?

If these are 'AFSK'  (AM or amplitude or Pulse modulation) a quickie
"RF detector" can be rigged and the data can be 'demodulated' and
seen with a low freq scope.

A DC voltage will also be produced - verifying the prescence of RF.

ckt:

RF from xmtr to a  50 Ohm  Resistor (load for RF)  to ground ---
--- Anode_diode_Cathode -----  1 K Resistor to gnd --- scope Input


Might also place a 470 pF cap to ground across the 1K R.

Schematically (if this comes through):

RF In---------o ------|< -----o-------o- to scope
                      |                       |           |
                  R 50                 R 1K     470 pF
                      |                       |           |
                     _                      _          _


Hope this helps.

Jim P.





{Original Message removed}

'[EE] LED Challenged'
2000\05\28@200640 by Ed Edmondson

picon face
I guess I am really "LED Challenged" as I can't find a circuit that will dim
an LED used as a backlight.  The LED has a Vf of 3.5 to 4.0 volts @ If of 20
mA.  I want to run it off 5 volts and want to vary the intensity from "Off"
to "On" (less the drop across the Vbe) using a 2N3904?  I figured the LED
limit resistor to be about 45 ohms (5 - .6 - 3.5)/.020) ?  Is this right?

How do I vary the base drive to vary the LED intensity?  A resistive divider
with a pot?  How do I calculate the values for the divider?  The 2N3904 has a
hfe of 100 to 300.  Does anyone care to help me out?

Regards,
Ed

'[EE]:[PIC]: How to measure level of liquids and se'
2000\05\28@201049 by Gennette, Bruce

flavicon
face
       Looks do-able to me.

       Reading proximity sensors, reading load cells and displaying values
on request while regularly logging them is simple PIC stuff.

       Measuring liquid heights can be done several ways, but as you are
already reading proximity switches why not use that method for this task
too?  Use a captive rod in a guide above a float to trip proximity switches
above your tanks (KISS principle).  Also gives a visual indication of the
amount in the tank as the rod rises above the rim.

          ______  _
            ||  <||
            ||x <|| sensors
            ||  <||
          _ || _ ||
       ___| || |_||_________
       |  | || |           |
       |  | || |           |  Use courier font to see diagram
       |    ||             |
       | ___||___          |
       |_|float |__________|
       | |______|          |
       |                   |
       |       liquid      |
       |                   |
       |___________________|

       This should also work for your special additive liquids as long as
you use compatible materials for the float and rod.  For increased accuracy
use tall, thin tanks (large, vertical pipes?).

       Humidity sensors are available in 1-wire devices.  [I assume you
need to know the humidity in several feeds to guess the amount of water
contained in the raw materials (sand and gravel) to calculate the real
amount of material being added and the water to be added]

       Good luck.

       <original message>

       To automate a plant of Concrete.

       The idea is to use a PC for the general control of the plant and to
arm a
       network (Possibly RS485) with terminals that will be slaves working
with
       PICs, to complete different tasks, as the following ones:

       1) To control the pneumatic servos and read proximity sensores and
other.

       2) To Sense the weight of the materials with cells of loads,
indicate the
       value measured in a  7 segments display and to send the measures
througt the
       network when they are requested or periodically. This partly would
be
       resolved, but I accept ideas and suggestions in this respect.

       3) To Sense the level of water in the main dosificador tank.
       <snip>

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\28@202332 by Byron A Jeff

face picon face
On Sun, May 28, 2000 at 06:21:24PM -0300, Edson Brusque wrote:
> > >If it don't say anything more, it may be the classic 8051's: one machine
> > >cycle is formed by twuelve clock cycles, and the instruction cycle
> > >depends on the particular instruction.
> > >If You want more speed enhacement look at Dallas MCS-51 compatible,
> hi-speed
> > >micros.
> > Or the AVR, at one xtal clock per instruction (a few take two). 8 mhz, but
> > that's 96 to an 8051 apparently.
>
>     Ok, but beside the Scenix, there's no 8-bit microcontroller capable of
> doing more than 20 MIPS???
>
>     And what about the 16-bit micros? Can it be a good option for my
> project? A US$10-20 microcontroller isn't very expensive to me if it can do
> all I need on this project.

A piece of advise. Stick to environments you know instead of striking out.
Especially when your striking out for more MIPS because you want them for
something that's easily done in hardware.

I'd advise sticking with PICs. Let me throw out a couple of suggestions.

1) I'm planning on using a Cirrus Logic CL-CD180 octart. Unfortunately Cirrus
Logic has obsoleted the part. In fact they've spun off their communcations line
into Basis Communications. I have a couple of samples and an incomplete
data sheet. If anyone has the pinout I'd really appreciate it. I liked the
part because of the number of serial ports and the fact that it came in a
84 pin PLCC package making it easy to use to hobby work. Basis Comm does have
an updated version the CL-CD1865. But it comes in a 100 pin PQFP. Not real
easy to prototype with.

2) My second choice was to build an intelligent UART out of a PIC. Specifically
for MIDI conversion of the stream into events with timestamps would be
very useful. Also having buffering so that the main processor can dump
events ahead of time and have the intelligent MIDI UART deliver them to the
channel at the appropriate time. Also doing MIDI channel mapping, splits and
volume control in the UART seems interesting. It's also interesting to consider
direct transmission of events from one UART to another bypassing the main
processor.

A single software channel can easily be handled by a 12C509 with a software
UART. Of course developing the UART code, the interface to the main processor,
(probably something I2Clike) would take some effort. But once it's done
any number of channels could be added to the system and the main system
wouldn't have to be uberpowered.


Maxim has an interesting discussion in their MAX3100 intro describing the
issues of software UARTs. You can find it here.

http://dbserv.maxim-ic.com/tarticle/view_article.cfm?article_id=53

The bottom line IMHO is that the traditional approach is better than the
Winmodem approach because you end up having a highly overpowered processor
just so that you can have the MIPS to bit bang UARTS. Just remember that
8 12C509's will give you 8 MIPS just for the UARTS. Think about the
distributed processing solution.

BAJ

'[EE]: Wireless communication...'
2000\05\28@202749 by Jim P

flavicon
face
I visited http://www.rfsolutions.com web page - but could not
find any references to the RF data rcvrs/xmtrs. Looks
like they are 'repping' various other lines of RF products
as well as providing other RF engineering services targetted
for wireless system's operators (cellular, PCS, trunked 2-way,
etc).

I've reviewed Linx Technologies products (link below) in the
past - never bought any of their product (except some of the
900 MHz rubber ducky antennas and samples of their 'patch'
antennas). It looks like they have done their homework - they
basically have three tiers of miniature RF data OEM-level
product, each one offering improved performance/features.

http://www.linxtechnologies.com/f_modules.html

They have detailed technical material of their product in pdf form -

They also offer some ready-made eval boards - hook up RS-232
and go!

http://www.linxtechnologies.com/m_evalkitdata.html

Jim P.

{Original Message removed}

'[EE] LED Challenged'
2000\05\28@214626 by Bob Ammerman

picon face
Use PWM (pulse width modulation).

Assuming you are driving this with a PIC. Some PICs have built in pulse
width modulators.

Alternatively, since you don't need a particularly fast output, you could do
it in software, perhaps driven off a timer interrupt.

Bob Ammerman
RAm Systems
(high function, high performance, low level software)

{Original Message removed}

'[EE] Flash and EEPROM based file systems'
2000\05\28@220119 by Damon Hopkins

flavicon
face
"Robert A. LaBudde" wrote:
{Quote hidden}

I was thinking of a fat16 type of system I'll work of my hand scribbled
notes into an HTML document if anyone would be willing to look at it and
HOPEFULLY give me suggestions or ideas.. the main purpose of the file
system would be to have multiple files that are mainly read. there
should be very little writing.. I'm thinking about this as being used in
a web server type application.

                       maybe I should write it out in HTML anyway just to MAKE myself be
more specific :)

                       Damon Hopkins

'[EE] Info: Rechargeable Lithium coin cells'
2000\05\28@220534 by Damon Hopkins

flavicon
face
Jilles Oldenbeuving wrote:
{Quote hidden}

I have tons of links for rechargeable battery chargers if you want me to
post them let me know..

                       Damon Hopkins

2000\05\28@220744 by Dan Michaels

flavicon
face
Russell McMahon wrote:
>I went looking for info on rechargeable Lithium coin cells and found it very
>hard to find anything technical.
>Here's the best of my slim pickings.
.........

Checkout the following for another portal site to mine:

http://www.ibatteries.com

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\28@221341 by Bob Ammerman

picon face
There are some good ideas here, but you have moved the data movement problem
from SERIAL<->PIC to be PIC<->PIC. You're still going to need some hefty
horsepower to do the PIC<->PIC transfers. Remember, the main processor has
to handle all channels at once. MIDI waits for no man (nor PIC) :-)

Bob Ammerman
RAm Systems
(high function, high performance, low level software)

{Original Message removed}

'[EE] LED Challenged'
2000\05\28@223031 by Robert A. LaBudde

flavicon
face
<x-flowed>At 08:06 PM 5/28/00 -0400, you wrote:
>I guess I am really "LED Challenged" as I can't find a circuit that will dim
>an LED used as a backlight.  The LED has a Vf of 3.5 to 4.0 volts @ If of 20
>mA.  I want to run it off 5 volts and want to vary the intensity from "Off"
>to "On" (less the drop across the Vbe) using a 2N3904?  I figured the LED
>limit resistor to be about 45 ohms (5 - .6 - 3.5)/.020) ?  Is this right?
>
>How do I vary the base drive to vary the LED intensity?  A resistive divider
>with a pot?  How do I calculate the values for the divider?  The 2N3904 has a
>hfe of 100 to 300.  Does anyone care to help me out?

The emitter voltage is the base voltage V(B) minus the diode drop of 0.7 V.
The voltage across the emitter resistor determines the emitter current. The
emitter current is the collector current I(C) (99+%).

So use a voltage divider to generate a voltage V(B) such that

        I(C) = (V(B)-0.7))/R(E)

The maximum current you will be able to get with 5.0 V is

        I(C)max = (5-0.7-3.5)/R(E) = 0.8/R(E)

For this to equal 20 mA, you'll need R(E) = 40 ohm.

However, I believe you've got a mistaken impression on the LED voltage
drop. They usually start about 1.7-2.0 V. In this case

        I(C)max = (5.0-2-0.7)/R(E) = 2.3/R(E)

and you'd need R(E) = 110 ohm.

Also, modern diodes have the same brightness at 5 mA as the original ones
did at 20 mA. You might do better to get by with 0-10 mA instead of 20 mA.

Assuming a 150 ohm resistor for R(E) (to be conservative), then

        I(LED) ~ I(C) ~ (V(B)-0.7)/R(E)

and you set V(B) with a voltage divider. The r(B) will be about beta*150
ohm, or about 20k. You need voltage divider resistors of about 2k to avoid
feedback from the base current.

In summary, use a 2k pot as a voltage divider, backed by 200 ohm resistors
at its ends (unless you want to go fully to saturation and cutoff), use a
150 ohm emitter resistor, and put the LED across the +5 V and collector.

Once you've determined the brightness you want, replace the pot with fixed
resistors.



================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: ralspamBeGonespamlcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
824 Timberlake Drive                            Tel: 757-467-0954
Virginia Beach, VA 23464-3239                   Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================

</x-flowed>

2000\05\28@232516 by Bob Blick

face
flavicon
face
>However, I believe you've got a mistaken impression on the LED voltage
>drop. They usually start about 1.7-2.0 V. In this case

The original poster probably had the drop right.
Backlit LCD displays I've used have a series+parallel string and you have
the equivalent of 2 series LEDs.

Back to the original topic, is it neccessary to have infinite levels? Why
not just 3 levels controlled by two pins, each driving a transistor and
resistor.

If you decide to so software PWM, make it very regular, or you'll notice
pulsing as the PIC does different tasks(especially if you do a timer based
interrupt and sometimes shut off interrupts!).

-Bob

- Every day, computers are making people easier to use -

'[EE]: Wireless communication...'
2000\05\28@232722 by David Huisman

flavicon
face
We also have wireless data link modules.
http://www.orbitcoms.com

regards
David Huisman
Orbit Communications
RemoveMEinfo@spam@spamspamBeGoneorbitcoms.com
NSW
Australia

'[EE] LED Challenged'
2000\05\29@001724 by Spehro Pefhany

picon face
At 08:06 PM 5/28/00 EDT, you wrote:

the base drive to vary the LED intensity?  A resistive divider
>with a pot?  How do I calculate the values for the divider?  The 2N3904 has a
>hfe of 100 to 300.  Does anyone care to help me out?

Assuming you just want to vary the brighness with a pot, not under program
control...

If you intend to use a pot to control the brightness, one easy way would
be to use a 555 to do PWM and also switch the LED.

Have a look at the data sheet for the 555. If you connect the backlight
from +5 , through a series resistor, to pin 3 the 555 will easily drive
20mA (even a CMOS 555 will easily sink the 20mA).

If you use a fixed resistor from +5 to pin 7, perhaps 10K, then use a pot
of, say, 100K with a 1K series resistor from pin 7 to pins 2 & 6,
you can get from 10% to 90% brightness. Use a timing capacitor such as
1n0 that will give a reasonable frequency.

Best regards,

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
.....speff@spam@spamEraseMEinterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

2000\05\29@024918 by Steve Smith

picon face
Consider a different approach.
Dont vary the current but vary the on time!
have the led current set to 25mA via the series resistor and then turn it on
and off with a pic pin the longer the led is on the brighter it will be .
Make the frequency of the "flashing" high enough and it wont be percived as
flashing but as varied intentisy.

Cheers Steve.....

'[EE] Embedded Internet enabling methods: Which?'
2000\05\29@040746 by TOM THERON

flavicon
face
Hi there all,

I am anticipating a design for an embedded system, probably 8031-derivative
based,  that will include internet connectivity. My quetion is: what is the
route to take? there are several ways to do it, of which I found the next 3
as possibilities:

1. Using emWare embedded software package, embedding TCP/IP etc. in software
2. Using SEIKO TCP/IP stack chip
3. Using Dallas TINI board

I currently vote for 1st option, because it does not add hardware cost like
2. and also does allow freedom in hardware design, unlike TINI. Also it
seems TINI still presents a lot of problems if you look at their usergroup
list of confusions.

What is your possible experience with any of these methods, or anything else
I do not know of? I'd like to get some real objective comparison, if
possibly somebody worked with more than one method.

What do you think about Java and the future of  emmedded internet? - (this
is the focus of  TINI, I believe)


Regards
Tom

"Designing a future"
MMS Electronic Systems
Tel +27-(0)12-6645696
Fax. +27-(0)12-6642682
Mobile. 0833109007

2000\05\29@101553 by Michael Damon Hopkins

flavicon
face
TOM THERON wrote:
>
> Hi there all,
>
> I am anticipating a design for an embedded system, probably 8031-derivative
> based,  that will include internet connectivity. My quetion is: what is the
> route to take? there are several ways to do it, of which I found the next 3
> as possibilities:
>
> 1. Using emWare embedded software package, embedding TCP/IP etc. in software
> 2. Using SEIKO TCP/IP stack chip
> 3. Using Dallas TINI board
>
> I currently vote for 1st option, because it does not add hardware cost like

I just wish there was a free full TCP/IP implementation out there for
the PIC :)  I dread having to write my own.

I've looked at the previously mentioned implementations, not with too
much detail but they seem to have certain problems.. such as you
mentioned.. hardware based or limited features. I want an API library
where I can use standard library calls like in unix to program my
application.
I don't want to only be able to use certain ports, or have to connect
via a ppp/slip link.. Let me know if you find anything like this..

                       Damon Hopkins

2000\05\29@102008 by Alok Dubey

flavicon
face
i thnk as long as u can make a follow a b8zs std and fig out the hware.. u
need not put in the tcp controller .. but it makes life easier definately
alok

{Original Message removed}

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\29@102422 by Byron A Jeff

face picon face
On Sun, May 28, 2000 at 09:38:33PM -0400, Bob Ammerman wrote:
> There are some good ideas here, but you have moved the data movement problem
> from SERIAL<->PIC to be PIC<->PIC. You're still going to need some hefty
> horsepower to do the PIC<->PIC transfers. Remember, the main processor has
> to handle all channels at once. MIDI waits for no man (nor PIC) :-)

This is true to a point but you can gain a few advantages:

1) Many of the mid level PICs have hardware support for such transfers. A
16F87X could use its hardware USART or I2C module to do the transfers thus
eliminating the high powered need for software bit banging from the main
PIC. And while the auxillary PICs are stuck with the software bit banging
problem, their function is limited to a single channel. Thus you gain an
advantage because the aux processors are not trying to do everything in the
system for all channels, just limited functionality for a single channel.

2) Intelligent buffering can mitigate quite a few of the tight timing
contraints in the PIC to PIC transfers. In short the main processor can dump
events that it knows is going out to the intelligent UART before the actual
moment the event needs to be played. This happens often in a multichannel
MIDI situation because the primary usage is as a multitrack MIDI recorded
where the sequencer plays some or all of the prerecorded MIDI tracks while
the musician adds the next track to the sequence. The timing sequences of
the prerecorded tracks are known apriori and can be scheduled accordingly.

3) Compression can be utilized in the PIC to PIC transfer whereas with a
straight UART the exact data stream that's required for the end unit must
be sent to the UART. For example each event in the MIDI stream encodes a 4
bit channel number. However if an intelligent UART knows that it's only
going to output 1 channel, or possibly two because of a a keyboard split,
then the channel information isn't required at all in the PIC to PIC
transfer, potentially saving a ton of bits. Another example is that typically
in MIDI streams a NOTE OFF events is generated by sending a NOTE ON event
with a volume of 0, requiring 2 to 3 bytes in the actual MIDI data stream.
However we could easily compress a note off event into a single BIT in the
PIC to PIC stream, having the Intelligent MIDI UART (IMU) do the proper
expansion on output.

4) The potential of direct IMU to IMU communication can potentially alleviate
the latency caused on the real time streams that are being recorded. See
typically the controller generating the real time stream and the one playing
that realtime stream are not on the same IMU. For example I generate my
MIDI events using my Yamaha digital piano, but those events are played on
my Alesis Nanosynth or my old Roland MT32. So the transfer sequence is
Input IMU -> main processor -> Output IMU. This would require a low latency
main processor to turn the events around quickly. However if instead the
transfer can be Input IMU -> main processor and Output IMU, then the Output
IMU would get the event with lower latency and the main processor could
take more time recording the event because it's not obligated to turn the
event around to the IMU.

MIDI streams have structure. This structure can be exploited by an IMU
type system. But it requires something more than a dumb UART. This would be
the exact reason I'd look to a software periperal.

BAJ
>
> Bob Ammerman
> RAm Systems
> (high function, high performance, low level software)
>
> {Original Message removed}

'[EE] LED Challenged'
2000\05\29@103708 by Alok Dubey

flavicon
face
why would anyone want to use a PWM thru a 555 waveform to change the
intensity of an ordinary LED?.....if u req a large sensitivity use a small
FET , or somethg in series with the LED or somethng.. of course u need a god
amt om resistance calulations and make sure no surge current in LED et al.
Alok


{Original Message removed}

2000\05\29@115459 by Spehro Pefhany

picon face
At 08:02 PM 5/29/00 +0530, you wrote:
>why would anyone want to use a PWM thru a 555 waveform to change the
>intensity of an ordinary LED?.....if u req a large sensitivity use a small
>FET , or somethg in series with the LED or somethng.. of course u need a god
>amt om resistance calulations and make sure no surge current in LED et al.
>Alok

Why would anyone what to reduce the brighness of the backlight?

Maybe to save power and extend battery life?  PWM will do that.

Best regards,



=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
.....speffRemoveMEspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

2000\05\29@120331 by Alok Dubey

flavicon
face
u mean using a 555 with all its cap and res and the sudden volatge spikes u
get out of switching the o/p on pin 3 and hence causing some amt of PS droop
, gnd bounce etc is better than using a sort of mosfet whose current i can
control ?
alok


{Original Message removed}

2000\05\29@120742 by Spehro Pefhany

picon face
At 09:28 PM 5/29/00 +0530, you wrote:
>u mean using a 555 with all its cap and res and the sudden volatge spikes u
>get out of switching the o/p on pin 3 and hence causing some amt of PS droop
>, gnd bounce etc is better than using a sort of mosfet whose current i can
>control ?
>alok

Yes, it could well be.

See http://www.ti.com TLC555 for a modern version of the 555.

Best regards,


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
.....speffSTOPspamspam@spam@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

2000\05\29@121817 by Alok Dubey

flavicon
face
okay..
try analog dev site for a list of CMOS ratings
alok

-----Original Message-----
From: Spehro Pefhany [speffEraseMEspam@spam@INTERLOG.COM]
Sent: Monday, May 29, 2000 5:10 PM
To: RemoveMEPICLISTspamspamBeGoneMITVMA.MIT.EDU
Subject: Re: [EE] LED Challenged


At 09:28 PM 5/29/00 +0530, you wrote:
>u mean using a 555 with all its cap and res and the sudden volatge spikes u
>get out of switching the o/p on pin 3 and hence causing some amt of PS
droop
>, gnd bounce etc is better than using a sort of mosfet whose current i can
>control ?
>alok

Yes, it could well be.

See http://www.ti.com TLC555 for a modern version of the 555.

Best regards,


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=
Spehro Pefhany --"it's the network..."            "The Journey is the
reward"
spamBeGonespeffKILLspamspam@spam@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=

'[EE] Flash and EEPROM based file systems'
2000\05\29@122439 by Jilles Oldenbeuving

flavicon
face
>
>I was thinking of a fat16 type of system I'll work of my hand scribbled
>notes into an HTML document if anyone would be willing to look at it and
>HOPEFULLY give me suggestions or ideas.. the main purpose of the file
>system would be to have multiple files that are mainly read. there
>should be very little writing.. I'm thinking about this as being used in
>a web server type application.
>
>                        maybe I should write it out in HTML anyway just to
MAKE myself be
>more specific :)


Maybe you have to go something like this:

Go flash. Then, just make a sort of adapted FAT system. Loose all the
data/time/atrrb information so that you only
retain 8 byte namen 3 byte extention (no dot between them, it just takes up
space), and a pointer to a particular
memory space where the file is located. In the first 2 bytes or so the
length is recorded for the file, so you know
where the file ends. E Voila!
But when you've got to alter the contents of your FLASH-DISK, just flush the
whole thing and write a new adapted file-
table. Ofcourse you will write a VB application or so for that task....


Jilles

'[EE] Embedded Internet enabling methods: Which?'
2000\05\29@130633 by Dan Michaels

flavicon
face
Damon Hopkins wrote
>TOM THERON wrote:
>>
>> Hi there all,
>>
>> I am anticipating a design for an embedded system, probably 8031-derivative
>> based,  that will include internet connectivity. My quetion is: what is the
>> route to take? there are several ways to do it, of which I found the next 3
>> as possibilities:
>>
>> 1. Using emWare embedded software package, embedding TCP/IP etc. in software
>> 2. Using SEIKO TCP/IP stack chip
>> 3. Using Dallas TINI board
>>
>> I currently vote for 1st option, because it does not add hardware cost like
>
>I just wish there was a free full TCP/IP implementation out there for
>the PIC :)  I dread having to write my own.
.......


Check out the PIC Internet Appliance article in the latest June issue
of Poptronics mag. In involves both PIC 16C877 or 12C671, and the
firmware is emWare. The article says s.w. is free-free-free. I ordered
the kit [$80] and received it on Saturday - a bag of parts with **1**
page of documentation, saying only goto the site and download the s.w.

http://www.edtp.com

Looks like an easy/cheap way to enter the embedded internet game.

best regards,
Dan Michaels
Oricom Technologies
http://www.sni.net/~oricom
==========================

2000\05\29@131459 by Spehro Pefhany

picon face
At 10:43 AM 5/29/00 -0600, you wrote:
>
>Check out the PIC Internet Appliance article in the latest June issue
>of Poptronics mag. In involves both PIC 16C877 or 12C671, and the
>firmware is emWare. The article says s.w. is free-free-free. I ordered
>the kit [$80] and received it on Saturday - a bag of parts with **1**
>page of documentation, saying only goto the site and download the s.w.
>
>http://www.edtp.com
>
>Looks like an easy/cheap way to enter the embedded internet game.

Except it isn't really embedded internet, because it requires a
"real" computer to act as a gateway between the LAN and the 'net.

If that works for the application, great, but it's apples and oranges..

Bset regards,


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speffspam_OUTspam@spam@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\29@132333 by andy howard

flavicon
face
> From: "Dan Michaels" <spamBeGoneoricom@spam@spamLYNX.SNI.NET>
> Edson Brusque wrote:
> .....
> >>     someone knows if there's a microcontroller with 4 USARTs
capable of
> >> working at 31250bps? I need extra 24 I/Os minimum. One USB port
would be a
> >> plus. Also, I would need an A/D converter, but I could use an
external one.
> >>     Maybe a SCENIX can do 4 USARTs as virtual peripherals???
> Scenix can easily do this, **BUT** you will have to go to 48 or
> 52-pin PQFP part - with tiny smt pads - to get 24 additional I/O
lines.
> No PLCC available. [or possibly do a multiprocessor with 18 & 28
> pin parts - not all that hard to build off a single RS-232 host line].


> And I suspect with the scenix, you actually could get the weird
> 31250 rate you indicate here - or any other weird baudrate imaginable.
> But whatcha gonna talk to at that speed?

I'm guessing here, how about the world's second most common serial port,
MIDI?

'[EE] Embedded Internet enabling methods: Which?'
2000\05\29@141010 by Damon Hopkins

flavicon
face
Spehro Pefhany wrote:
> Except it isn't really embedded internet, because it requires a
> "real" computer to act as a gateway between the LAN and the 'net.
>
> If that works for the application, great, but it's apples and oranges..
>
> Bset regards,
>
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> Spehro Pefhany --"it's the network..."            "The Journey is the reward"
> RemoveMEspeffEraseMEspamKILLspaminterlog.com             Info for manufacturers: http://www.trexon.com
> Embedded software/hardware/analog  Info for designers:  http://www.speff.com
> Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

see I agree.. if you have to have a computer hooked up to the network
then whats the point of the microcontroller.. I'm trying to do things
without a PC not trying to add stuff to a PC :)

                       Damon Hopkins

2000\05\29@141631 by Dan Michaels

flavicon
face
Spehro Pefhany wrote:
>At 10:43 AM 5/29/00 -0600, you wrote:
>>
>>Check out the PIC Internet Appliance article in the latest June issue
>>of Poptronics mag. In involves both PIC 16C877 or 12C671, and the
>>firmware is emWare. The article says s.w. is free-free-free. I ordered
>>the kit [$80] and received it on Saturday - a bag of parts with **1**
>>page of documentation, saying only goto the site and download the s.w.
>>
>>http://www.edtp.com
>>
>>Looks like an easy/cheap way to enter the embedded internet game.
>
>Except it isn't really embedded internet, because it requires a
>"real" computer to act as a gateway between the LAN and the 'net.
>

Good point. Apparently, you can do the other, but you have to
license that s.w. from emWare. The present path looks like a cheap
way to get started in this area.

'[EE] Re: Boosting power of radio modules[EE]'
2000\05\29@151113 by andy howard

flavicon
face
> From: "Harold M Hallikainen" <spamBeGoneharoldhallikainenspam_OUTspamRemoveMEJUNO.COM>
> Subject: Re: [EE] Re: Boosting power of radio modules[EE]


> Actually, I'd expect NONE of the US FCC rules to apply in the UK.
> However, most countries have very similar rules on unlicensed
> transmitters.


Indeed, the rules are in effect pretty much the same. All devices must
be type-approved though, there's no home hobbyist exemption AFAIK. This
system is due to be scrapped in favour of "self-certification" of
compliance by manufacturers by next April.

I suspect that if Andrew S is fitting his device at the feedpoint of a
small Yagi (probably the best solution), he would not be complying with
the spirit of the type approval - and probably the letter of it too. On
the other hand, it looks like the federales have bigger fish to fry.

The relevant UK authority is the Radiocommunications Agency
http://www.radio.gov.uk/

There's a good detailed paper on "licence exempt" devices too.
http://www.radio.gov.uk/document/ra_info/ra114/ra114.htm  includes
references to all the relevant specification documents, which can be
researched from the front page.

Andy.


----------------------------------------

{Quote hidden}

http://www.dovesystems.com
>
> ________________________________________________________________
> YOU'RE PAYING TOO MUCH FOR THE INTERNET!
> Juno now offers FREE Internet Access!
> Try it today - there's no risk!  For your FREE software, visit:
> dl.http://www.juno.com/get/tagj.
>

'[EE] Embedded Internet enabling methods: Which?'
2000\05\29@162420 by Mark Walsh

flavicon
face
> I am anticipating a design for an embedded system, probably
> 8031-derivative
> based,  that will include internet connectivity. My quetion is:
> what is the
> route to take? there are several ways to do it, of which I found
> the next 3
> as possibilities:
>
> 1. Using emWare embedded software package, embedding TCP/IP etc.
> in software
> 2. Using SEIKO TCP/IP stack chip
> 3. Using Dallas TINI board
>

Since you are familiar with the 8031 may already have tools and code that
can be re-used, you might want to look at the iKit2000 from All-American.
It is a development system with proto-board and software that supports the
new Triscend CSoC (configurable system on chip) 8051 based controller along
with the Seiko S-7600 chip.  I believe the cost is around US$700.  I have an
earlier Triscend development system (without the Seiko chip) and have been
very happy with the time its saved us developing new applications.

http://www.ikit2000.com

Mark Walsh

2000\05\29@163915 by Dan Michaels

flavicon
face
While rooting around the  http://www.linuxdevices.com/
site, I ran across a link to open-source "embedded" webserver:

   New version of available-source embedded webserver -- Bellevue, WA --
   (press release) -- GoAhead Software announced the release of GoAhead
   WebServer 2.1, the latest version of GoAhead's available-source, royalty
   free, standards-based embedded webserver software. WebServer 2.1
   supports embedded Linux applications. According to ...

http://www.goahead.com

Their view, however, appears to mean "embedded" = 32-bit uP running
Linux, Win98, WinCE, etc.

But it is open-source, royalty-free, and written in C. Could probably
be transported to PIC C. Bottom line, as always, is how much can you
stuff into a lowly PIC.

- Dan Michaels
==============

'[EE] Wireless communication...'
2000\05\29@233441 by Ian Hynes

flavicon
face
If you've got a UHF capable sig-generator around the lab somewhere,
maybe try heterodyning the the Tx's output down into the scope's
range?
Just a thought.

Ian

Jilles Oldenbeuving wrote:
>
>  .... i can't see
> anything at the receiving end. I can't measure
> if the transmitter is actually oscilating at 433 MHz becouse the fastest
> scopes we have is a Philips 200 Mhz scope...
>
>
> Jilles

--

2000\05\30@012206 by Jilles Oldenbeuving

flavicon
face
Hmmm... I might try that today.... still, i think it just had to work... :)


Regards,

Jilles Oldenbeuving
jillesspam@spam@rendo.dekooi.nl


>If you've got a UHF capable sig-generator around the lab somewhere,
>maybe try heterodyning the the Tx's output down into the scope's
>range?
>Just a thought.
>
>Ian
>

2000\05\30@022130 by Vasile Surducan

flavicon
face
> Jilles Oldenbeuving wrote:
> >
> >  .... i can't see
> > anything at the receiving end. I can't measure
> > if the transmitter is actually oscilating at 433 MHz becouse the fastest
> > scopes we have is a Philips 200 Mhz scope...

 One poor man method is to modulate the transmitter with low
frequency (let say 1KHz ) and to detect a proportional DC signal
near antenna using a Schottky diode and a 1MHz bandwith
oscilloscope...
*********************************************
Surducan Vasile, engineer
mail: EraseMEvasileRemoveMEspamSTOPspaml30.itim-cj.ro
URL: http://www.geocities.com/vsurducan
*********************************************

2000\05\30@024239 by markwillcox56

picon face
<x-flowed>Jilles
  How much power out is your xmtr?


{Quote hidden}

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

</x-flowed>

'[EE] Embedded Internet enabling methods: Which?'
2000\05\30@030357 by William Chops Westfield

face picon face
   I just wish there was a free full TCP/IP implementation out there for
   the PIC :)  I dread having to write my own.

   I've looked at the previously mentioned implementations, not with too
   much detail but they seem to have certain problems.. such as you
   mentioned.. hardware based or limited features. I want an API library
   where I can use standard library calls like in unix to program my
   application.
   I don't want to only be able to use certain ports, or have to connect
   via a ppp/slip link.. Let me know if you find anything like this..

IMO (not very humble - I've got a fair amount of experience in this area),
this isn't possible.  To start with, the protocols pretty much assume an
environment with "separate" operating system and applications, which will
get you to pretty large code (for the "OS" side, which has to have
"everything") pretty quick.  Implementing Internet connectivity on a small
microcontroller means cheating.  How badly you cheat, and where, and whether
you'll be able to get away with it on a large scale, is dependent on how
much space you're willing to sacrifice to the network code (and it IS
primarilly a space issue, rather than a speed issue.)

Possible approaches with "minimal" cheating:

1) Code-generator type scheme, where your code is carefully analyzed,
  and a "custom Network OS" is generated that implements ONLY those parts
  of the stack that you actually use.

2) an interpretter (basic-stamp-like, I guess) with a very large external
  memory... (here, performance might start to be an issue, of course.  An
  interpretted OS with applications written in assembly.  Weird.)

As a reference or starting point, you might consider NCSA telnet, an "open
source" (but predating that term) application/OS/Internet stack that runs on
DOS.  a 1990 ("pre-bloat but post-64k-frugal") implementation has a
"minitel.exe" program without too much extra stuff (like tektronix terminal
emulators) and is about 93kbytes (for the exe file.)  Other possibilities
include "ka9q" - a similar project targetted (restricted?) to ham radio
applications.

BillW

2000\05\30@055310 by Bob Ammerman

picon face
I have implemented TCP/IP (well actually UDP/IP) from the hardware up on
X86. A moderate complete implementation (in "C") uses about:

Code (16-bit x86): 16KBytes
Data: about 12K minimum

This stack implements ARP, IP, ICMP and UDP, but _not_ TCP, PPP or SLIP (it
runs on ethernet).

Seems a bit large for a PIC.

btw: please don't ask for a copy - I wrote this for hire and can not
distibute it  :-(

Bob Ammerman
RAm Systems
(high function, high performance, low level software)

{Original Message removed}

2000\05\30@055313 by TOM THERON

flavicon
face
----- Original Message -----
From: William Chops Westfield
To: spam_OUTPICLISTspam_OUTspamspam_OUTMITVMA.MIT.EDU
Sent: Tuesday, May 30, 2000 9:03 AM
Subject: Re: [EE] Embedded Internet enabling methods: Which?

IMO (not very humble - I've got a fair amount of experience in this area),
this isn't possible.  To start with, the protocols pretty much assume an
environment with "separate" operating system and applications, which will
get you to pretty large code (for the "OS" side, which has to have
"everything") pretty quick.  Implementing Internet connectivity on a small
microcontroller means cheating.  How badly you cheat, and where, and whether
you'll be able to get away with it on a large scale, is dependent on how
much space you're willing to sacrifice to the network code (and it IS
primarilly a space issue, rather than a speed issue.)

Possible approaches with "minimal" cheating:

1) Code-generator type scheme, where your code is carefully analyzed,
  and a "custom Network OS" is generated that implements ONLY those parts
  of the stack that you actually use.

2) an interpretter (basic-stamp-like, I guess) with a very large external
  memory... (here, performance might start to be an issue, of course.  An
  interpretted OS with applications written in assembly.  Weird.)

As a reference or starting point, you might consider NCSA telnet, an "open
source" (but predating that term) application/OS/Internet stack that runs on
DOS.  a 1990 ("pre-bloat but post-64k-frugal") implementation has a
"minitel.exe" program without too much extra stuff (like tektronix terminal
emulators) and is about 93kbytes (for the exe file.)  Other possibilities
include "ka9q" - a similar project targetted (restricted?) to ham radio
applications.

BillW

I am primarily looking at a 8051 based system, thus DOS would not serve the
purpose, although if nothing else I can possibly move to an 80188 platform.
But it might be something to look at as part of the learning curve.

Tom Theron

2000\05\30@055315 by TOM THERON

flavicon
face
>Except it isn't really embedded internet, because it requires a
>"real" computer to act as a gateway between the LAN and the 'net.
>If that works for the application, great, but it's apples and oranges..

I agree with you, Spehro,  I had a closer look at their web site. All they
had done was to implement a proprietary protocol to a PC and from there
captured the data into the internet environment. For "local" type of
projects, proprietary is OK, but as soon as we speak about international
markets, I shy away.

Lets see what others have to say.

Bset regards,


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=
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'[EE]:Current on a PCB'
2000\05\30@055318 by Andrew Seddon

picon face
Could anybody tell me what the recommended minimum track widths are for
different current values. A general case formula or rule of thumb would be
great but specifically around 0.4-0.5 amps.

Thanks.

'[EE] LED Challenged'
2000\05\30@055934 by Vasile Surducan

flavicon
face
On 29 May 00, at 20:02, Alok Dubey wrote:

> why would anyone want to use a PWM thru a 555 waveform to change the
> intensity of an ordinary LED?...

  If you have a three colour (RGB) LED it's the simplest solution to
achieve any colour you may need from a digital output, else, why
not more complicated as possible...
  Vasile



..if u req a large sensitivity use a small
> FET , or somethg in series with the LED or somethng.. of course u need a god
> amt om resistance calulations and make sure no surge current in LED et al.
> Alok
>
>
> {Original Message removed}

'[EE]:Current on a PCB'
2000\05\30@062430 by Mark Willis

flavicon
face
IIRC on a 2Oz board, 10 mils will do for this;  Aaah.
http://www.aracnet.com/~gpatrick/ (from a post in the archives by Peter
Keller) - 5 mils will do you on a 1Oz board (1 mil = 0.001 inch, FWIW.)

Glenn Golden had, as raw numbers with no PCB copper thickness added,
> 0.010 INCH - 0.8A
> 0.015 INCH - 1.2A
> 0.020 INCH - 1.5A
> 0.025 INCH - 1.7A
> 0.050 INCH - 3.2A
> 0.100 INCH - 4.8A
> 0.150 INCH - 6.0A

Marcelo Puhl had,
{Quote hidden}

I have yet another set of similar numbers in my palmtop that I usually
refer to <G>

Be sure to degrade for middle layers of a 3+ layer PC board, BTW.

I usually go with 10+ mil traces, a little extra current capacity is not
a bad thing...  (When printing on a 300DPI laser, you want at least 3
pixels or so of width in the toner for clean continuous traces.
Probably can get away with 2, BUT, ...  12.5 mil traces on 25 mil
centers gives you about 2A peak, and about 300V insulation between
traces - better than I usually need for small boards.)

 Mark

Andrew Seddon wrote:
> Could anybody tell me what the recommended minimum track widths are for
> different current values. A general case formula or rule of thumb would be
> great but specifically around 0.4-0.5 amps.
>
> Thanks.

2000\05\30@070245 by Alan B Pearce

face picon face
It depends on what voltage drop and temperature rise you can deal with. Others
have posted trace widths which can carry the current without fusing, but you
will need to consider these other items as well. Usually it comes down to a case
of use the widest trace you can in the PCB area you have.

2000\05\30@073844 by David Kott

flavicon
face
> Could anybody tell me what the recommended minimum track widths are for
> different current values. A general case formula or rule of thumb would be
> great but specifically around 0.4-0.5 amps.

I use a nice calculator that UltraCAD corp. has made available.  It will
solve for tracewidth, temperature rise, ampacity, width and thickness of
copper.

http://www.ultracad.com/pcbtemp.zip

-d

'[EE][PIC] How to measure level of liquids and sens'
2000\05\30@092333 by M. Adam Davis

flavicon
face
You are putting this into a concrete plant?  You should really use some sort of
industrial solution.  A number of companies make non contact and contact
distance sensors specifically for liquid level measurement.  The one I am
thinking of now for your application is a non contact laser liquid level sensor,
which you simply point down on the liquid.  Many of these can be used in
corrosive environments (glass, stainless steel, etc) as well.

As far as the water content of sand, the only thing I can think of would be to
take a certian volume of the sand, and weigh it.  The same volume will be
heavier the more damp it is.  I don't think the usual method of electrodes
spaced so far apart will be very accurate (nevermind having to replace them
every month, and recalibrate them daily due to wear) Most dampness/humidity
sensors require contact with the substance you are measuring.  Perhaps you can
tell us more about the properties of wet sand.  Does it reflect a lightsource
differently depending on its dampness?

-Adam

Hugo Jorge M|ller wrote:
{Quote hidden}

'[EE] Embedded Internet enabling methods: Which?'
2000\05\30@102405 by TOM THERON

flavicon
face
I definitely don't intend it for PIC , I'll need at least an 8051 with lots
of external memory, or 80188, or 80386EX or...
Tom
{Original Message removed}

'[EE]:Current on a PCB'
2000\05\30@102414 by TOM THERON

flavicon
face
I did some PCB's  for power applications a while ago, and we handle up to
30A in tracks with 70 micron copper and 10mm MINIMUM width. However, where
possible we fill out areas to act as heatsinks, i.e. some places tracks are
30mm wide.

It is not only the track width that has an impact, but also the length,
since the resistance is a function of the whole track area, and this
influences the actual heat dissipation (IIR).

Tom Theron

'[EE] Embedded Internet enabling methods: Which?'
2000\05\30@103036 by Byron A Jeff

face picon face
{Quote hidden}

You're right on the mark here Bill. The bottom line is that microcontrollers
aren't really designed for that level of networking. And aside from the
"coolness" factor and compatibility with existing protocols, designing
a full TCP/IP implementation for a microcontroller doesn't buy you very much.

All of your typical heavyweight net applications take advantage of the fact
that the underlaying OS implements the full TCP stack. But TCP as a protocol
puts really heavy demands on the OS. Buffering, retransmissions, flow and
congestion control, and the like cost in code size, data memory required, and
computational complexity.

As I've said before in this forum that UDP/IP is the savior for ucontrollers
requiring internetwork capability because the loss of reliable, sequential
flow controlled delivery completely simplifies the stack implementation. The
only minor cost is having to write an application at the client end to
interact with PIC. But the client doesn't have to be a gateway, it can be
located anywhere on the internet.

The bottom line is that applications are way too varied and ucontroller
way to limited to afford sticking a "standard" OS on them. OTOH a UDP/IP
library could have some utility. Let's see how it stacks up against the
original issues:

"... API library ... standard calls:" This isn't a bad idea. A library with
open, send, receive, and close calls for UDP could be useful.

"certain ports:" The API could easily be designed to handle multiple/varied
ports. And a library implementation would have to. It's just easier to
hardcode a port number...

"[only] ppp/slip link:" This is a matter of the hardware. Ethernet is
easily achievabile with chips like the CS8900. Other's have looked at
RealTek chips and NE2000 interfaces. But the hardware implementations for
PPP/SLIP are much more cost/space effective. A standalone serial link can
be built using a single 8 pin DS1275 or a MAX232 whereas the ethernet
implementations requires a bunch of pins.

Just some thoughts.

BAJ

2000\05\30@103242 by Byron A Jeff

face picon face
>
> I definitely don't intend it for PIC , I'll need at least an 8051 with lots
> of external memory, or 80188, or 80386EX or...

Then why not just go with a PC104 type form factor and use a standard PC OS?

BAJ

'[EE]:Current on a PCB'
2000\05\30@112808 by Bob Blick

face
flavicon
face
www.apcircuits.com/html/amperage.html

A big jpeg of a graph that shows temperature rise, current, and trace
width.

Sometimes the more important thing to consider is the voltage loss, or
the integrity of your ground traces(especially if you have any analog
stuff going on).

Cheers,

Bob

'[EE] Embedded Internet enabling methods: Which?'
2000\05\30@121424 by Jilles Oldenbeuving

flavicon
face
I don't get it whit this Internet stuff. Abviously a complete web-browser
will not be viable with
a PIC processor. But as everyone will have seen, (app.notes, circuit
cellular, etc.) one could
implement just SLIP and UDP to send packets to a server wich will receive
these packets
(even appending data to a ping command could be used).

Also, implementing an SLIP/UDP/SMTP protocol implementation will allow your
application
to send it's data by email to you.... wich i think would be very nice!

I don't think for this an x86 processor will be needed... ofcourse if you
want to implement
more web-functionality, more *memory* will be needed. But as mentioned
before, not more MIPS,
becouse i think that one isn't going to connect it's application via an
T1-line to the internet, so
speed should not be an issue.....

Tom, No offence intended to the ones that think an x86 is needed, becouse
you perhaps have
a different idea of the general 'internet application' than i do...



Regards,

Jilles Oldenbeuving
RemoveMEjillesKILLspamspam@spam@rendo.dekooi.nl
-----Oorspronkelijk bericht-----
Van: TOM THERON <mmsesysspamBeGonespam.....ICON.CO.ZA>
Aan: KILLspamPICLISTspam.....MITVMA.MIT.EDU <spam_OUTPICLISTspamKILLspamMITVMA.MIT.EDU>
Datum: dinsdag 30 mei 2000 16:27
Onderwerp: Re: [EE] Embedded Internet enabling methods: Which?


>I definitely don't intend it for PIC , I'll need at least an 8051 with lots
>of external memory, or 80188, or 80386EX or...
>Tom
>{Original Message removed}

'[EE]:Current on a PCB'
2000\05\30@121628 by Jilles Oldenbeuving

flavicon
face
Resistance will determine the heat-dissipation, but not the temperature
rise,.
Becouse how longer the track, the more the heat-dissipation will be
distributed
along the track...


Regards,

Jilles Oldenbeuving
RemoveMEjillesRemoveMEspamEraseMErendo.dekooi.nl
-----Oorspronkelijk bericht-----
Van: TOM THERON <KILLspammmsesysspamspamBeGoneICON.CO.ZA>
Aan: PICLISTspamspamMITVMA.MIT.EDU <RemoveMEPICLISTspamBeGonespamRemoveMEMITVMA.MIT.EDU>
Datum: dinsdag 30 mei 2000 16:27
Onderwerp: Re: [EE]:Current on a PCB


{Quote hidden}

'[EE] Embedded Internet enabling methods: Which?'
2000\05\30@134810 by Dale Botkin

flavicon
face
On Tue, 30 May 2000, Jilles Oldenbeuving wrote:

> I don't get it whit this Internet stuff. Abviously a complete web-browser
> will not be viable with
> a PIC processor. But as everyone will have seen, (app.notes, circuit
> cellular, etc.) one could
> implement just SLIP and UDP to send packets to a server wich will receive
> these packets
> (even appending data to a ping command could be used).
>
> Also, implementing an SLIP/UDP/SMTP protocol implementation will allow your
> application
> to send it's data by email to you.... wich i think would be very nice!

PPP, IP and UDP are not terribly difficult to implement, and are quite
useful.  However, you can't run SMTP or http over UDP, they require TCP.
TCP is more involved if you do it completely.

> I don't think for this an x86 processor will be needed... ofcourse if you
> want to implement
> more web-functionality, more *memory* will be needed. But as mentioned
> before, not more MIPS,
> becouse i think that one isn't going to connect it's application via an
> T1-line to the internet, so
> speed should not be an issue.....

Agreed.  To do fully compliant TCP, you'd need a LOT more memory.  If I
weren't so fond of PICs now I'd be tempted to go back to an 8051 and ang a
big EPROM to do TCP.  Instead, I plan to cheat like hell, use very small
packets and make it *work* like TCP, even if it's not RFC compliant.

It would all be much, much easier with an X86 DOS or Linux platform, maybe
one of those neat little PC104 systems or something.  But none of them
even remotely approach the cost per unit of using a PIC, and the actual
TCP requirements in my project are so rudimentary it would be very
difficult to justfy the extra expense, power, and size.  That's "very
difficult" as in "totally impossible".  Besides - where's the challenge in
making a DOS or Linux box speak TCP?

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

'[EE]:Current on a PCB'
2000\05\30@135440 by Chris Eddy

flavicon
face
Just curious...

Now that we can get heat rise on a trace, which I had some data on before, what
is a safe operating temperature?  If board browning or mask discoloration is the
primary limitation for your design, at what absolute temperature does the mask
begin to be damaged?  If we know the absolute temperature, then we know the
ambient+rise.

Any experience with this?

Chris Eddy

'[EE] Embedded Internet enabling methods: Which?'
2000\05\30@140445 by Jilles Oldenbeuving

flavicon
face
>
>PPP, IP and UDP are not terribly difficult to implement, and are quite
>useful.  However, you can't run SMTP or http over UDP, they require TCP.
>TCP is more involved if you do it completely.


Ooops.... overlooked that one... But you get the point....


{Quote hidden}

That's the spirit! Just do only those things that are required. That AN724
might
be of interest as an starting point... The nice thing about the app note is
that they use a modem, wich drives up the cost but it can be directly
connected
to a telephone network and doesn't  need a host. Also use only those things
that
are absolutly needed... so filling in all the fields of an IP-packet doesn't
have
to be necessary.... one has to expiriment with it to see what's required and
what
not... and i'd program it in assembler, not in C. This with the program
memory
space in mind... (not to start a C vs Assembler threat (thread?) on
this)....

>Dale
>---
>The most exciting phrase to hear in science, the one that heralds new
>discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
>                -- Isaac Asimov
Isaac Asimov isn't that the writer of those science fiction books?
(heck, now i can't find them anymore.....)  I found those books a good joy
on trips etc.!!!

'[EE]:Current on a PCB'
2000\05\30@140846 by Dan Michaels

flavicon
face
........
>
>Now that we can get heat rise on a trace, which I had some data on before, what
>is a safe operating temperature?  If board browning or mask discoloration
is the
>primary limitation for your design, at what absolute temperature does the mask
>begin to be damaged?  If we know the absolute temperature, then we know the
>ambient+rise.
>

The general bent of this thread seems a little strange to me.

As a general rule of thumb in electronics, it seems reasonable to
allow 2-3x safety margin on most critical design decisions - especially
those concerning power dissipation levels. It would seem that even so
much as thinking about driving traces to the point where they are
heating up or glowing or discoloring the pcb might be like flying
too close to the sun on waxed wings.

'[EE] Embedded Internet enabling methods: Which?'
2000\05\30@151547 by Dale Botkin

flavicon
face
On Tue, 30 May 2000, Jilles Oldenbeuving wrote:

> >It would all be much, much easier with an X86 DOS or Linux platform, maybe
> >one of those neat little PC104 systems or something.  But none of them
> >even remotely approach the cost per unit of using a PIC, and the actual
> >TCP requirements in my project are so rudimentary it would be very
> >difficult to justfy the extra expense, power, and size.  That's "very
> >difficult" as in "totally impossible".  Besides - where's the challenge in
> >making a DOS or Linux box speak TCP?
>
>
> That's the spirit! Just do only those things that are required. That AN724
> might
> be of interest as an starting point... The nice thing about the app note is
> that they use a modem, wich drives up the cost but it can be directly

I am starting from there.  I'm sticking with C because it's a lot easier
for me to mentally manage a larger program in C than in assembler.  I've
found that the C compiler produces code that is sometimes worse than mine,
sometimes better, but usually overall it's better.  I've learned a lot
about using assembly by reading the C listings after it compiles, in fact.

I plan to dump the modem (and the dialer code, etc) and connect directly
to a PPP server via RS232 serial, so that saves some code space too.

> >Dale
> >---
> >The most exciting phrase to hear in science, the one that heralds new
> >discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
> >                -- Isaac Asimov
> Isaac Asimov isn't that the writer of those science fiction books?
> (heck, now i can't find them anymore.....)  I found those books a good joy
> on trips etc.!!!
>

The same.  I used to read his work a lot -- long ago -- but the quote, I
think, is one of the best I've heard.

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

'[EE]:Current on a PCB'
2000\05\30@162130 by rottosen

flavicon
face
Dan Michaels wrote:
{Quote hidden}

Obviously, visable signs of damage to the PCB are not wht you use for a
good design goal. So, what *would* you use as the limiting factor(s) for
temperature and power dissipation of the trace?

-- Rich

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\05\30@180234 by Erik Reikes

flavicon
face
Something else to check out is the I2C UART chips from Maxim.  They have a
family of chips that has either 232, 485, or logic level serial on one side
and SPI or I2C on the other.  Very cool part.  I also believe they have a
couple byte buffer to avoid overloading your micro.

You should be able to find them on their site by searching for 'uart'...




At 07:25 PM 5/26/00 -0300, Edson Brusque wrote:
{Quote hidden}

Erik Reikes
Senior Software Engineer
Xsilogy, Inc.

KILLspamereikesspamBeGonespamxsilogy.com
ph : (858) 535-5113
fax : (858) 535-5163
cell : (858) 663-1206

2000\05\30@180241 by Erik Reikes

flavicon
face
Something else to check out is the I2C UART chips from Maxim.  They have a
family of chips that has either 232, 485, or logic level serial on one side
and SPI or I2C on the other.  Very cool part.  I also believe they have a
couple byte buffer to avoid overloading your micro.

You should be able to find them on their site by searching for 'uart'...




At 07:25 PM 5/26/00 -0300, Edson Brusque wrote:
{Quote hidden}

Erik Reikes
Senior Software Engineer
Xsilogy, Inc.

@spam@ereikesSTOPspamspam@spam@xsilogy.com
ph : (858) 535-5113
fax : (858) 535-5163
cell : (858) 663-1206

2000\05\30@181727 by David VanHorn

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

At 02:59 PM 5/30/00 -0700, Erik Reikes wrote:
>Something else to check out is the I2C UART chips from Maxim.  They have a
>family of chips that has either 232, 485, or logic level serial on one side
>and SPI or I2C on the other.  Very cool part.  I also believe they have a
>couple byte buffer to avoid overloading your micro.

Max 3100A with internal 232 buffers?
I'm using four of them, along with the on-chip uart, in an AVR project.
The SPI is a little tricky in that it's 16 bit words, and I can't afford to
hang around and bit-bang, but I worked out a way to do the whole mess
interrupt driven.

The hardest thing to do is to poll them and see which one interrupted you
(without having to receive data), but all you have to do is abort the
transaction, and you can have the uart hold the data while you figure the
rest out.

My four have the ints wire-or, so I have to go look at all four's status
before I know who to start pumping data from.

Why am I so busy? 7200 calculations/sec involving polar-rectangular
conversions, a little DSP, and then rect-polar again. (in addition to
parsing the stat-mux protocol that gives me four external full speed full
duplex 4800 baud ports, plus an internal virtual port, and a control
channel, with the on-chip uart talking to a PC at 115200)

I'm almost 50% busy!

- --
Are you an ISP?  Tired of spam?
http://www.spamwhack.com  A pre-emptive strike against spam!

Where's Dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

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Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

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=tRIC
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'[EE]:Current on a PCB'
2000\05\30@223517 by Dan Michaels

flavicon
face
Richard Ottosen wrote:
....
>>
>> As a general rule of thumb in electronics, it seems reasonable to
>> allow 2-3x safety margin on most critical design decisions - especially
>> those concerning power dissipation levels. It would seem that even so
>> much as thinking about driving traces to the point where they are
>> heating up or glowing or discoloring the pcb might be like flying
>> too close to the sun on waxed wings.
>
>
>Obviously, visable signs of damage to the PCB are not wht you use for a
>good design goal. So, what *would* you use as the limiting factor(s) for
>temperature and power dissipation of the trace?
>

Richard,

Having seen a few pcbs with this type of "indicator" [ie, fried traces],
I have to agree with you. My general approach [which may not be the
best of all possible worlds] is iterative. I figure it takes a couple
of cuts to get it right [others may disagree here].

As I alluded to above, I would measure or estimate the max current
to be conducted by the trace, and look in the table and select a geometry
that would provide "at least" 2-3x safety margin. More if allowable.
This is also how I choose resistor wattages, among other things.

I personally would not design any closer than that to the ragged edge.
Then, build it and see how it goes. Next cut may need adjusting in some
cases. [Is this approach too imprecise?? - I'm sure there are different
tribes of opinion here - things like "safety margin" are opinion
oriented].

best regards,
- Dan Michaels
==============

2000\05\30@223726 by Dmitry Kiryashov

flavicon
face
Hmm... What is heat dissipation ?

I guess it is dissipation of heat in air, right ?
So there is difference in temperatures in copper
and surround air. The higher temperature is around
the less heat can be dissipated for the same time.
As I remember there is also such a parameter as
thermal resistance (please correct me if I wrong,
I don't remember exact english term for that) It is
used in heatsink and so stuff design.

WBR Dmitry.

Jilles Oldenbeuving wrote:
{Quote hidden}

2000\05\30@235827 by Brian Kraut

picon face
There used to be maximum currents for various trace widths on the AP Circuits
web site.  http://www.apcircuits.com

Dan Michaels wrote:

{Quote hidden}

'[EE]: [WKB] Need help with MAX 762 DC-DC converter'
2000\05\31@004129 by William K. Borsum

flavicon
face
<x-flowed>Hi All
I've got a MAX762 step-up converter circuit--straight off Maxim's data
sheet that won't start oscillating under what should be data sheet approved
voltages, parts, etc.

If anyone has direct experience with this part, I'd sure like to hear from
you--off list is fine.
Give me a phone number, and I'll call with the details.

Kelly
--------------------------------------------------------------------------------------------------------
Just Switched to Cable-Net.   If you get duplicate messages, please let me
know asap.

William K. Borsum, P.E. -- OEM Dataloggers and Seismic Instrumentation Systems
<TakeThisOuTborsumspamspamRemoveMEdascor.com> & <http://www.dascor.com>San Diego, California, USA

</x-flowed>

'[EE] Wireless communication...'
2000\05\31@011636 by Robert Rolf

picon face
Or use a cable TV convertor to do the same thing. The video detector
should show you the modulation.  North American cable channel 59 is
433.25Mhz. You'll also see a nice herringbone pattern on a TV screen
from a stable carrier. (sortta like 'sound' in video when the fine
tuning is off).

Ian Hynes wrote:
{Quote hidden}

2000\05\31@014226 by David Huisman

flavicon
face
I suggest that a known working TX/RX pair is a simple, low cost way of
determining that the RF is functional.
Especially if the receiver has RSSI facility and you can monitor the signal
on your scope.

Regards
David Huisman
Orbit Communications
http://www.orbitcoms.com
NSW
Australia

'[EE] Embedded Internet enabling methods: Which?'
2000\05\31@030138 by TOM THERON

flavicon
face
PC104  form factor does not fit the requirement: space, peripherals and cost
.

.----- Original Message -----
From: Byron A Jeff
To: KILLspamPICLISTspamspamspam_OUTMITVMA.MIT.EDU
Sent: Tuesday, May 30, 2000 4:31 PM
Subject: Re: [EE] Embedded Internet enabling methods: Which?


>
> I definitely don't intend it for PIC , I'll need at least an 8051 with
lots
> of external memory, or 80188, or 80386EX or...

Then why not just go with a PC104 type form factor and use a standard PC OS?

BAJ

'[EE][PIC] How to measure level of liquids and sens'
2000\05\31@094056 by Hugo Jorge Mčller

flavicon
face
Adam:
  How work the laser measurement of liquid (water) level ? Do you know
something that sell this sensores ready to use ?

With respect to wet sand properties, i don't have more information that
you.. sorry  I am in the beggining of my project and
recolecting information, I am not a expert on sand and concret ;-)

TIA.

Hugo

{Original Message removed}

2000\05\31@101338 by riest

flavicon
face
Maby I'm jumping in the middle of a discussion but ever thought
about using ultrasonic transducer?
The only thing you have to do is doing some calibration.

Ries

2000\05\31@102419 by Alok Dubey

flavicon
face
yeah they are the best soln.. sonar type thngies//
alok

-----Original Message-----
From: Ries van Twisk [riesRemoveMEspamFRANKSINTL.NL]
Sent: Wednesday, May 31, 2000 3:01 PM
To: EraseMEPICLISTSTOPspamspamRemoveMEMITVMA.MIT.EDU
Subject: Re: [EE][PIC] How to measure level of liquids and sense
relativehumidity?


Maby I'm jumping in the middle of a discussion but ever thought
about using ultrasonic transducer?
The only thing you have to do is doing some calibration.

Ries

2000\05\31@103251 by Robert A. LaBudde

flavicon
face
<x-flowed>The normal method of measuring effective humidity in wood, concrete, sand,
etc., is by conductivity.

Use a 1 kHz square-wave from the PIC through two stainless steel probes
spaced a fixed distance apart. For wood and concrete, use needles.

Measure the conductivity as an unknown resistance in a bridge and read it
with an ADC input.

The method is not a priori specific for water, but it can be calibrated on
materials in a specific environment.

The official method for moisture is to weigh the sand, cook for 4 hrs @ 125
C (=270 F), and weigh again. The weight loss is crude moisture.

Conductivity is also used as a surrogate for other measurements, such as pH
in pool water or plant soil.

Tap water usually has a conductivity of 1-200 uS/cm. The water in the sand
would be probably 100x larger than this, up to 20,000 uS/cm. Therefore the
effective resistance of 1 cm apart probes would be expected to be 50 ohm or
more.


================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: spam_OUTralRemoveMEspamEraseMElcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
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'[EE]:Current on a PCB'
2000\05\31@114306 by Dan Michaels

flavicon
face
Brian Kraut wrote:
>There used to be maximum currents for various trace widths on the AP Circuits
>web site.  http://www.apcircuits.com
>

Looking at those nomographs in a couple of books I have [one being H.
Johnson's "High-Speed Digital Design", p. 214] shows curves for 5degC -
100degC temp rises vs current in trace. Curves are linear on a log-log
plot. Roughly speaking, going from the 5degC curve to the 100degC curve
involves "only" a 3x increase in current. This is roughly the spectrum
from no problem to fusing the trace [or at least boiling water].

Thus, it would seem good practice to determine the worst case situation,
and then allow a good sized safety margin [2-3x min] in trace width
selection. This is fairly easy to do with pcb traces, since situations
requiring large currents generally involve physically large switching
components, like relays and transistors, so there is usually plenty of
room for wide traces. Traces can also be doubled, top and bottom of pcb,
and of course, heavier copper can be used for more severe cases.

best regards,
- Dan Michaels
==============

'[EE][PIC] How to measure level of liquids and sens'
2000\05\31@114707 by Don Hyde

flavicon
face
Some colleagues here took on a liquid-level sensor based on ultrasonic
ranging, and were suprised at what a major project it turned into.

For starters, cost was an important issue.  It turns out that, like with
many things, there are two kinds of ultrasonic transducers -- cheap ones
that aren't very good and very expensive ones that are still only pretty
good.

After spending a lot of time dealing with analog noise, they got down to
difficult problems with ringing in the transducer, multiple reflections, and
the fact that all the transducer's properties varied a whole lot with
temperature.  Then they got to work compensating for the fact that, while
the speed of sound in air and water vapor is fairly well-behaved, the speed
of sound in diesel fuel vapor is not.  It varies a lot, and in a highly
nonlinear fashion, with temperature (and to a lesser extent, from one batch
of fuel to another).

> {Original Message removed}

2000\05\31@115957 by Dan Michaels

flavicon
face
At 10:42 AM 5/31/00 -0500, you wrote:
>Some colleagues here took on a liquid-level sensor based on ultrasonic
>ranging, and were suprised at what a major project it turned into.
>
>For starters, cost was an important issue.  It turns out that, like with
>many things, there are two kinds of ultrasonic transducers -- cheap ones
>that aren't very good and very expensive ones that are still only pretty
>good.
>
>After spending a lot of time dealing with analog noise, they got down to
>difficult problems with ringing in the transducer, multiple reflections, and
>the fact that all the transducer's properties varied a whole lot with
>temperature.  Then they got to work compensating for the fact that, while
>the speed of sound in air and water vapor is fairly well-behaved, the speed
>of sound in diesel fuel vapor is not.  It varies a lot, and in a highly
>nonlinear fashion, with temperature (and to a lesser extent, from one batch
>of fuel to another).
>

For a slightly different viewpoint, I consulted with a company that
used std Polaroid ultrasonic transducers to determine the level of
ice in an icemaker machine. They had 10s of 1000s of unitsin the
field. This device is quite easy to interface, and fairly cheap,
and used just a couple of chips running off a 6805 uC, which provided
control and took measurements.

However, the transducers always had a heavy coating of water
condensate on them, so I was always amazed they didn't have
horrendous reliability problems. Eventually, they gave them up for
a simpler/cheaper solution involving a thermistor in a tube.

best regards,
- Dan Michaels
==============

'[EE] Embedded Internet enabling methods: Which?'
2000\05\31@124013 by Byron A Jeff

face picon face
>
> PC104  form factor does not fit the requirement: space, peripherals and cost

OK. I went back to your original message. It didn't have any specific
requirements in terms of internet connectivity. What are the physical and
internet protocol that you require?

Also I'm not real familiar with the 80386EX. Can you explain how it
compares in cost and form factor to PC104? Also does the 80386EX have the
80386 MMU? If that's the case you could possibly run an embedded copy of
Linux on it with very little problem, completely solving your internet
connectivity problem.

Lastly 8051's don't have any better ability to access "lots" of external
memory than the PIC does. The 17CXX series can access 128K of ram directly
whereas the 8051 family only can access 32K directly IIRC. Beyond that you
get into back switching and then all bets are off, right? So what's the
definition of "lots" of memory?

Then of course is the speed issue. At the top end you have 8051 derivitives
with 24 Mhz clocks and 3 clock cycle instructions giving up to 8 MIPS.
17CXX parts have a top speed of 33 Mhz with 4 clock cycle instructions giving
up to 8.33 MIPS with most non jump instructions running in a single cycle.
Just wondering why you'd switch from an 8051 family part to a 80386 but
dismiss the PIC as a possibilty.

The bottom line is that if you're going the mostly software route then
the capabilities and performance of the part is critical. A cursory comparison
has PICS matching capability and outpacing performance of 8051s at each
stage.

BTW Neither will effectively support a completely implemented TCP/IP stack.

You've never stated if UDP/SLIP, UDP/PPP, or UDP/IP/Ethernet would satisfy
the application's needs? A full UDP stack is doable on a uController while
a full TCP stack will require some help.

I'm interested because I had a couple of my students doing a UDP/SLIP
implementation on a 16F87X part. They succeeded in pinging before the end
of the semester. UDP still to come.

BAJ


{Quote hidden}

2000\05\31@125709 by Andrew Kunz

flavicon
face
WWW.ZFLINUX.COM

Check it out.

Andy

'[EE][PIC] How to measure level of liquids and'
2000\05\31@131201 by M. Adam Davis

flavicon
face
One source has level (and flow) sensors here:
http://www.omega.com/toc_asp/section.asp?book=green&section=K

You might also check out their conductivity and resistivity sensors:
http://www.omega.com/green/index.html#ph

It is not inexpensive, but when you're dealing with industrial work it is often
better to use the appropiate equipment than develop your own if you aren't very
familiar with it.

-Adam

Hugo Jorge M|ller wrote:
{Quote hidden}

> {Original Message removed}

'[EE]:Current on a PCB'
2000\05\31@144411 by Mark Willis

flavicon
face
I do it this way, just in case someone misunderstood me - keep seeing
posts that might indicate that:  I'm a "massive overkill style" sorta
guy <G>

This saves having to make another board when you were in a hurry and
some twerp stole your good test leads and that dang test probe slips and
shorts Vcc and Ground.  (We all heat shrink 90% of the test probes off
our DVM's, or use microclips, I'd bet.  Dingbat DVM manufacturers - who
wants test probes?  Ack.)

You don't get paid for removing copper, you get paid for the final
circuit working <G>

Tightest packing I ever use is 12.5 mil to 15 mil traces on 25+ mil
centers, for SMD CMOS gate to CMOS gate routing.  Usually 25 mil traces
on 100 mil centers (leaving room for a trace between pads where
needed.)  Keep the smaller traces as short as possible i.e. just for 50
mils or less as you go between pads on a DIL I.C., use 10 mils, then
back to wider traces.  Avoid that when you can, as it's a bear to FIX
that *when* that fusible link blows...

I use 35 mil traces at a minimum for Vcc/Ground.  Usually 50+ mils.  Or
just Flood Fill all unused space for a power/ground plane.

(Go 250 mils for a 1.5A power supply, right?  <G>)

If things go wrong, solder a piece (or even several) of wire wrap or #22
phone wire down atop the ground trace, to "enhance it's current carrying
capability somewhat".  It's a pain, almost never have to do that unless
space is really tight - Or, nightmare of nightmares, someone who doesn't
know what they're doing routes a bad PCB.  (Some people think you can
get away with 10 mil ground & Vcc traces that snake all over the board,
and things will work fine.  Well, even when you solder some #32 WW wire
down on that puppy, you still have problems, and the PCB Cad guy's your
worst problem <G>  Educate 'em, gently, on what the consequences are of
that thinking.)

Use despiking caps, large and small, then add more, and add some more
for fun;  Add more on a whim - any whim will do.  Get it working right,
then you can remove some them to lower costs, if the manager wants to
spend the time -  Engineering time costs too, and there's nothing like a
glitch to confuse you in your coding.  For quick prototypes, use SMD
parts when you can, if out you can take a scrap box through-hole part
(one of those with short, cut leads is good <G>), bend the leads and
solder it down SMD style - saves drilling more holes, works well too,
and is fast & cheap.

Put text on the PCB somewhere to remind you what the durn thing's for,
btw.  "Solder" and "Component" side markings (even "S" and "C"!) are
good ideas too, those'll save your sanity.  Also - design the boards so
they're not completely symmetrical, if you can (Ever seen someone turn
the solder side 180 degrees and it FITS?  That can really mess things
up!  Wasn't pretty.  Love learning vicariously on THAT sorta thing.)

Ground rings are good where applicable <G>

I mingle TH and SMD a lot, put LEDs & DE-9 connectors etc. on the edge
of the PCB, for example - it's quicker than drilling and works well;
Learned all that when I didn't have a drill press available for one job,
having just a few pin vices and elbow grease for drilling gets sorta
old.  You don't get extra points for working harder, just for working
smarter and faster.

Finally, cast the spec in quick-setting epoxy and wait for it to cure
before starting work, whenever possible <VBG>  (A spec that isn't set in
stone, is usually a spec that'll run away FAR faster than you can code
and design...)  It's "time to practice and re-train yourself" if they
don't have that set yet, you'll probably have to re-do things (maybe
you'll be lucky & can re-do it all in software, though.)

 Mark

'[EE] Embedded Internet enabling methods: Which?'
2000\05\31@153414 by William Chops Westfield

face picon face
   Also I'm not real familiar with the 80386EX. Can you explain how it
   compares in cost and form factor to PC104?

The 80386EX is a processor chip, not particularly related to PC104.  It's
sort of the 186 (highly integrated) version of a 386, I think.


   You've never stated if UDP/SLIP, UDP/PPP, or UDP/IP/Ethernet would satisfy
   the application's needs? A full UDP stack is doable on a uController while
   a full TCP stack will require some help.

Heh.  PPP is so bloated that a microcontroller would be hard-pressed to
sypport a "full PPP."  (fortunately, this is rarely required.)

BillW

'[EE][PIC] How to measure level of liquids and sens'
2000\05\31@153624 by Mark Willis

flavicon
face
Laser could be aimed at say 30 degrees from vertical onto the waters'
surface, a sensor at 30 degrees the other side of vertical would pick up
specular reflection, BUT:

Water's top surface isn't perfectly flat so you get early "hits",
perhaps want several photodiodes and to think on how to handle the top
surface wave problem there.  If you have a top styrofoam "float" atop
the water, stick a reflective mylar sheet on there and you have specular
reflection again, and reduce the wave problem <G>

There are capacitive sensors used to detect water levels also.

What's wrong with a cheap and easy, hot bead thermistor solution,
though?  Constant current through a thermistor to intentionally
self-heat it to say body temperature or so, when in free air -  then
measure the resulting voltage - when water level rises to where the
thermistor is covered in water, it'll cool the thermistor in a heck of a
hurry, thus voltage change and you know the water's there.  Want the
water to not spray onto the thermistor, of course, placing the
thermistor inside a tube or if needed adding a tank water inlet baffle
will solve that though <G>  Yeah, it's contact sensing, I know.

 Mark

Hugo Jorge M|ller wrote:
{Quote hidden}

<snip>

2000\05\31@155109 by Patrick J

flavicon
face
And how about another even simpler way ?
(which might even prove to work in the real world!)

Just stick a pipe down in the fluid and measure the air pressure that
builds in the pipe when the level rises. There are sensors availfor it.

'[EE]:Current on a PCB'
2000\05\31@155657 by Dan Michaels

flavicon
face
Mark Willis wrote:
.....
(Some people think you can
>get away with 10 mil ground & Vcc traces that snake all over the board,
>and things will work fine.
......

Hard to imagine anyone would do this. Even though the nomograph
indicates you can run 750 mA thru such a trace, and only have a 10degC
temp rise, there are several "other" things to worry about. Trace series
R producing IR drops. Digital noise in this narrow channel. Inductive
effects of narrow trace width at hi speeds. Impedance issues. On and on.

'[EE][PIC] How to measure level of liquids and sens'
2000\05\31@160118 by Dan Michaels

flavicon
face
Mark Willis wrote:
.........
>What's wrong with a cheap and easy, hot bead thermistor solution,
>though?  Constant current through a thermistor to intentionally
>self-heat it to say body temperature or so, when in free air -  then
>measure the resulting voltage - when water level rises to where the
>thermistor is covered in water, it'll cool the thermistor in a heck of a
>hurry, thus voltage change and you know the water's there.  Want the
>water to not spray onto the thermistor, of course, placing the
>thermistor inside a tube or if needed adding a tank water inlet baffle
>will solve that though <G>  Yeah, it's contact sensing, I know.
>

Plus, I suspect you could use 2 or more thermistors arranged
vertically within the tube, plus a little math, to actually
determine the level, not just whether above/below one point.

'[EE]: Re: embedded internet: which'
2000\05\31@160755 by Peter L. Peres

picon face
Hi,

imho, get and read AN724. I do not know if you can use the code as is, as
it is licensed in a particular way (for PICs only), but the background on
negotiation and protocol internals will save you weeks of research.

AN724 is an excellent reference for embedded Internet imho.

hope this helps,

       Peter

'[EE]:Current on a PCB'
2000\05\31@162425 by Mark Willis

flavicon
face
Dan Michaels wrote:
> Mark Willis wrote:
> .....
>  (Some people think you can
> >get away with 10 mil ground & Vcc traces that snake all over the board,
> >and things will work fine.
> ......
>
> Hard to imagine anyone would do this. Even though the nomograph
> indicates you can run 750 mA thru such a trace, and only have a 10degC
> temp rise, there are several "other" things to worry about. Trace series
> R producing IR drops. Digital noise in this narrow channel. Inductive
> effects of narrow trace width at hi speeds. Impedance issues. On and on.

Sure - All those things that total newbies haven't learned about yet -
Ability to use a CAD package does NOT imply exquisite knowledge of all
things electronic <G>

We've all had our "weird" experiences - I've had an argument with an
Honors EE 4th year student who argued that 10-turn panel pots didn't
exist, while sitting there *using* a Textronics 'scope that had several
on it's front panel (with locks);  I've accepted that people don't learn
everything and tried to focus on educating the spots they missed.  Many
colleges teach loads of "Book" knowledge - new EE graduates don't always
know about the real world things that Techs have learned (soldering, for
one <G>)  Happens.  Some of us are good on digital, some on analog, some
stronger or weaker on code or hardware, a little redundancy isn't always
a bad thing on the list <G>

 Mark

--
I re-ship for small US & overseas businesses, world-wide.
(For private individuals at cost; ask.)

'[EE][PIC] How to measure level of liquids and sens'
2000\05\31@163637 by Mark Willis

flavicon
face
Dan Michaels wrote:
> Mark Willis wrote:
> .........
> >What's wrong with a cheap and easy, hot bead thermistor solution,
> >though?  Constant current through a thermistor to intentionally
> >self-heat it to say body temperature or so, when in free air -  then
> >measure the resulting voltage - when water level rises to where the
> >thermistor is covered in water, it'll cool the thermistor in a heck of a
> >hurry, thus voltage change and you know the water's there.  Want the
> >water to not spray onto the thermistor, of course, placing the
> >thermistor inside a tube or if needed adding a tank water inlet baffle
> >will solve that though <G>  Yeah, it's contact sensing, I know.
> >
>
> Plus, I suspect you could use 2 or more thermistors arranged
> vertically within the tube, plus a little math, to actually
> determine the level, not just whether above/below one point.

True on multiple height determination - though (despite my being pretty
good in math) I don't see where the math's needed/applicable.  I thought
with 3 hot beads, you'd know one of 4 states, {"Height < A" || "Height
>= A" || "Height >= B" || "Height >= C"}, don't see how you can determine shades of height between say A and B (putting A lowest, C highest here, to clarify.)  Am I missing something?  Has been a "Bad Brain Day" to some degree <G>  (There's not a big difference for thermistor B in temperature, between temperature for water say 1 foot below it and 1 inch below it, barring splashing, is there?  Has been a while since I last hot-beaded <G>)

 Mark

'[EE]: Current and PCB'
2000\05\31@164309 by Peter L. Peres

picon face
Hi,

In my experience I don't think that a 15 mil trace of any length will be
fine with 0.5A over any length of time. I would use a ~1mm (1/20 ~= 50
mils) trace for short lengths and as wide as possible for longer ones, at
0.5A.

The problem with this is, as others have pointed out already, that the
heat buildup from the traces and the parts sums up to heat the whole
board. Not enough, most analog circuit's power requirements increase with
the temperature, so you can contribute to thermal runaway. In my
experience exceeding 0.3W/cm^2 dissipation for small boards used w/o
forced ventilation in closed enclosures is asking for trouble. The evil
part is, that the failures will only crop up after a while with returns,
and not on the lab desk where the unit is open and rather well ventilated.

A 10 mm length of 15 mils passing 0.5A will be fine. 120 mm of it will
have a significant resistance, inductivity, and more, and may start to
contribute considerable heat to the board if you have a bus of these
running in parallel together. The PCB trace tables do not usually cover
bussing and bunching, so over-engineer copiously if using these.

The only proven way to find hotspots in a board is an infrared photo of
it, especially since it is very hard to simulate partial duty cycles and
other difficult to compute currents. If you can borrow an IR camera or a
35mm SLR loaded with IR film and expose 2-3 positions you will have the
data. By borrowing I mean find someone who uses IR photography all the
time and use his services. Thermal insulation installation firms in cold
weather countries come to my mind. The IR film is too expensive to use for
boards otherwise imho.

Just as an aside, my 233MHz K6 computer runs Linux (which saves a lot of
power at low computing load by HALTing the CPU between scheduler
interrupts), that emits a distinct CRACK due to thermal expansion near the
CPU socket when the load is high for 20-30minutes (CPU power trebles from
idle 5W to over 15W on full computing load), I seem to remember that
someone wrote a simulation program for thermal load in pcb's as a thesis,
this may be useful.

Of course you get to use this information at your own risk.

Peter

'[EE] Flash and EEPROM based file systems'
2000\05\31@165922 by Marc

flavicon
face
> anyone have any code dealing with implementing a file system on either
> FLASH memory or any other type of memory.. I'd like to get a 1 MB flash
> chip and put a small filesystem on it but rather than try to design the
> thing myself I'd like to sample what's out there.. I haven't turned up
> much. I plan on using the Atmel SPI Flash memory chips and figure that
> with a 16 bit pointer I could have access to 4 MB I want to make a tiny
> file server :)

I have plans for the same type of project.  Maybe we (and/or some other
members of the list) should join together and make this reality.

The driver _I_ need has these properties:

- written in ANSI C

- offers ANSI C inspired functions for file access (fopen(), fread() etc)
 but does implement only the basic functionality, no need for 100%
 compatibility.

- optimized for write-once-read-many files (data) and append-write (logfiles).
 With "optimized" I don't mean that other access profiles are forbidden,
 just that those might suffer an impact in speed.

- data, once successfully written, is guaranteed to remain intact. only
 files currently written to might be lost on powerfail/crash.

- as little traffic over the SPI as possible.

- where possible, stick to 64bit boundaries for data fields (for example in
 directory or file list blocks) to support later addition of encryption.  Most
 older crypto algorithms work on 64bit blocks.

Do you see enough convergence for a co-development? Please send me email (list
or private) when you're interested in working on such a file system.  I'm
quite experienced with the technology and limits of flash, and am convinced
that my capabilities cover this project completely..  If only the day had
35 hours..

'[EE]: AT Keyboards --- Not all equal![ADMIN]'
2000\05\31@184425 by jamesnewton

face picon face
Ok Mark, I turned it off, but not until it autoreplied to your reply <EVIL
GRIN>

Lets work up a serious version of a shorter message and try again tomorrow.

I can move most of that to a web page and just include a link.

The point, folks is that if this is going to work, you want to A) put one of
the following at the start of all posts to the list

[PIC]:
[EE]:
[OT]:
[AD]:

and B) turn off your subscription to the other channel that this
autoresponder will clutter up by sending SET PICLIST TOPICS: -Other to
EraseMELISTSERVRemoveMEspamMITVMA.MIT.EDU or, in most email clients, click here:
spamLISTSERV.....spamspamMITVMA.MIT.EDU?body=SET%20PICLIST%20TOPICS:%20-Other

---
James Newton (PICList Admin #3)
jamesnewtonspam_OUTspam@spam@piclist.com 1-619-652-0593
PIC/PICList FAQ: http://www.piclist.com or .org

{Original Message removed}

'[EE]:Current on a PCB'
2000\05\31@190744 by Andrew Seddon

picon face
> Hard to imagine anyone would do this. Even though the nomograph
> indicates you can run 750 mA thru such a trace, and only have a 10degC
> temp rise, there are several "other" things to worry about. Trace series
> R producing IR drops. Digital noise in this narrow channel. Inductive
> effects of narrow trace width at hi speeds. Impedance issues. On and on.

I always thought that it was best to use the least ammount of copper you can
with digital logic, come to think of it I think I made this rule up myself
so any input appreciated. BTW I just got a board back from the shop, it has
8 mil ground and power traces. Seems to be working OK. I dind`t mean to do
it but it was a rush job and I fogot to manually route the power traces.

'[EE][PIC] How to measure level of liquids and sens'
2000\05\31@190953 by Dan Michaels

flavicon
face
Mark  wrote:
....
>>
>> Plus, I suspect you could use 2 or more thermistors arranged
>> vertically within the tube, plus a little math, to actually
>> determine the level, not just whether above/below one point.
>
>True on multiple height determination - though (despite my being pretty
>good in math) I don't see where the math's needed/applicable.  I thought
>with 3 hot beads, you'd know one of 4 states, {"Height < A" || "Height
>>= A" || "Height >= B" || "Height >= C"}, don't see how you can determine
shades of height between say A and B (putting A lowest, C highest here, to
clarify.)  Am I missing something?  Has been a "Bad Brain Day" to some
degree <G>  (There's not a big difference for thermistor B in temperature,
between temperature for water say 1 foot below it and 1 inch below it,
barring splashing, is there?  Has been a while since I last hot-beaded <G>)
>

Not that I've ever tried this, but I figure the temperature variation
would distribute itself along the tube in some manner [to be measured
and calibrated empirically], and the math would be some weighted
averaging routine. Just a thought. The sorta thing you try once, and
immediately get a strong hunch whether it will ever work or not.

- Dan

2000\05\31@194532 by Gennette, Bruce

flavicon
face
Yeah, my washing machine uses this to 'control' the level of water used.
It's not very accurate, but in a washing machine who cares if it's a few
litres out?  But in a concrete plant the amount of water added controls the
workability, setting time and, to a degree, the final strength of the
concrete, so it *MAY* not be accurate enough.

Bye.

       {Original Message removed}

'[EE]: Current on a PCB'
2000\05\31@195146 by Donald L Burdette

picon face
Dan Michaels wrote:

>The general bent of this thread seems a little strange to me.

>As a general rule of thumb in electronics, it seems reasonable to
>allow 2-3x safety margin on most critical design decisions - especially
>those concerning power dissipation levels. It would seem that even so
>much as thinking about driving traces to the point where they are
>heating up or glowing or discoloring the pcb might be like flying
>too close to the sun on waxed wings.

How can you figure where 50% is unless you know what 100% is?  You have
to know where the failure occurs before you can estimate a safety margin.

>My general approach [which may not be the
>best of all possible worlds] is iterative. I figure it takes a couple
>of cuts to get it right [others may disagree here].
<snip>
>Then, build it and see how it goes. Next cut may need adjusting in some
>cases. [Is this approach too imprecise?? - I'm sure there are different
>tribes of opinion here - things like "safety margin" are opinion
>oriented].

This approach is not imprecise if you use your prototype to actually
measure how close you are to the limits.  You could easily build a
prototype that works, but is significantly beyond the safe limits, or
even the limits of what will work at all over the long term or under
extreme conditions.  Limited or short-term testing may not discover these
flaws.

If you guess at the right values and don't measure how close you got,
(which I suspect is rarely true in your case), then you are being
horribly imprecise.  In fact, you could be building a safety and/or
reliability nightmare.

I believe the most reasonable solution (at least for most commercial
applications) is to KNOW the right values.  Then there's no guesswork,
and you can build in "comfortable" safety margins.

Of course, in high-reliability applications (military, medical, space),
you should KNOW and then VERIFY through extensive testing.

I felt that the general bent of this thread was about KNOWing.



NOW - MY CONTRIBUTION

The topic of 'fusing' the traces is actually very different from the
topic of 'reasonable' currents.  The fusing (melting or vaporizing)
currents are at least an order of magnitude higher than what you want to
use.  A trace that will melt at 10 amps will discolor the solder mask and
the substrate, even melt the glue and peel off the board at currents of 1
amp or less.  Fusing normally occurs only if there's a major fault
somewhere.

I think the heart of the question is twofold:

1. What is the max allowable temperature of the trace.  If you know that
and the ambient temperature, you can calculate the allowable temperature
rise (the difference), from which you can calculate the current carrying
capacity of a trace, or conversely, the trace needed to carry a given
current.

2. What is the max allowable voltage drop across the trace.  This is
highly application dependant.

After answering these two questions, you can use the tools mentioned by
previous contributors to make the necessary calculations.

The vast majority of PCB's are made on either phenolic or FR4 fiberglass,
with one of several mask materials.  Does anyone know the max temp of
this stuff?  If nobody knows offhand, I'll call my PCB vendor on Friday
to ask.

Don

2000\05\31@212233 by Mark Willis

flavicon
face
Andrew Seddon wrote:
> > Hard to imagine anyone would do this. Even though the nomograph
> > indicates you can run 750 mA thru such a trace, and only have a 10degC
> > temp rise, there are several "other" things to worry about. Trace series
> > R producing IR drops. Digital noise in this narrow channel. Inductive
> > effects of narrow trace width at hi speeds. Impedance issues. On and on.
>
> I always thought that it was best to use the least ammount of copper you can
> with digital logic, come to think of it I think I made this rule up myself
> so any input appreciated. BTW I just got a board back from the shop, it has
> 8 mil ground and power traces. Seems to be working OK. I dind`t mean to do
> it but it was a rush job and I fogot to manually route the power traces.

You're using enough despiking caps, I take it <G>  You can get away with
a lot on 2Oz boards that won't work on a 1/2 Oz copper clad board, too,
due to 4x the copper thickness.  If it gives you fits, try my wire wrap
wire trick <G>  Bet you didn't route the power/ground wires last, too
<G>

Not much is wrong with using 65 mil traces or so for CMOS logic traces,
IME, it doesn't sour the behavior - 8 mils works fine as well if your
board shop's better than my laser printer works, for short runs
anyways.  Capacitance increases with larger traces, but 1/16" spacing is
fairly large WRT making large caps out of 65 mil traces - Inductance has
a lot to do with clock speed, want to minimize lengths for high speed
circuits, as you know.  Resistance can affect things.

Have to watch out more on 0.020" thick boards (Boeing Surplus sells a
lot of that - Sorta neat stuff, if fragile) as interlayer capacitance
would be lots higher due to 1/3 the plane separation.

One advantage of "fatter" traces for prototyping boards is that it's
easier to break the trace then SMD solder a series resistor in place
when you find you need it on a 40 mil trace than an 8 mil trace <G>
Each of us does a different, Niche market to some extent - you make a
prototype once-off board a little different than you make a production
board (I tend to do things like leaving places where I can drill through
the PCB to solder additional jumpers / components on, WHEN they're
needed due to a design change, on some boards, due to knowing the
designer's habits.  You don't do that on production boards, "usually"
<G>)

I'm no RF PCB expert, most of my board work's been either on fixing
existing boards (re-work is a pain, it does tend to show you what design
flaws people made and what parts blow / break most often -
Electrolytics, power resistors, UJT's / JFets / MOSFET's, occasionally
transistors.  Often CPU's that're attached to a keyboard without
protection networks (diodes or zeners) to protect the I/O pins -
Fortunate we are to be working with PICs <G>) or on new prototypes and
on re-working those - I haven't done a lot of production, 1000+ off
boards, I'm sure for those you do more trying to shrink the board, try
to stay with 1-sided PCB's, or go to truly tiny boards that're
multi-layer, depending, and try to minimize through holes, so not huge
differences as I already do a lot of that but not all <G>  More SMD and
smaller SMD lately, from what I see.  And BGA's, my nemesis <G>

 Mark

'[EE]:,[PIC]: How to measure level of liquids and s'
2000\05\31@213705 by Mark Willis

flavicon
face
Dan Michaels wrote:
{Quote hidden}

Aaah, you're thermally bonding the hot beads to the tube?  Perhaps
that'd work, might want to instead put a heater at the top of a small
rod, bond the thermistors to the rod, use them to measure along the rod,
maybe would work.

Good news is that you can use one larger PIC and run quite a few
thermistors simultaneously to get many data points simultaneously.
Sigma Delta code's not too hard to find <G>

 Mark

'[EE]: AT Keyboards --- Not all equal![ADMIN]'
2000\05\31@221627 by piclist.com

face picon face
You are missing that the list server will happily filter out ALL the noise
of miss tagged posts, and the autoresponder and all that and you will get
ONLY the properly tagged message about [PIC]: or [EE]: or what ever you
want.

All you have to do is send SET PICLIST TOPICS: -Other to
.....LISTSERVspamspam.....MITVMA.MIT.EDU or, in most email clients, click here:
LISTSERVKILLspamspamEraseMEMITVMA.MIT.EDU?body=SET%20PICLIST%20TOPICS:%20-Other> Then the autoresponder and the "Duh.. how do I unsubscribble?" posts all GO
AWAY.

As the autoreply message says. Please help me phrase it more clearly so that
everyone will understand. After you read it. <SAD GRIN>

Or lead a revolt and I will back off and go back to the way it was...
... I'm really not all that interested in continuing this.

James Newton, PICList Admin #3
EraseMEjamesnewton@spam@spam@spam@piclist.com
1-619-652-0593 phone
http://www.piclist.com

----- Original Message -----
From: Jerry Merrill <@spam@jerrymspamspamKILLspamtech-tools.com>
To: <spamBeGonejamesnewtonRemoveMEspamEraseMEpiclist.com>
Sent: Wednesday, May 31, 2000 16:09
Subject: Re: [EE]: AT Keyboards --- Not all equal![ADMIN]


>
> Why should the autoreply go to the list at ALL?  Why should I receive a
> reminder for EVERY message that violates the rules?  Seems to me the
> autoreply will double the noise level (for those of us accepting all
messages).
>
> Am I missing something here?
>
>
> At 05:40 PM 5/31/00, you wrote:
> >Ok Mark, I turned it off, but not until it autoreplied to your reply
<EVIL
> >GRIN>
> >
> >Lets work up a serious version of a shorter message and try again
tomorrow.
> >
> >I can move most of that to a web page and just include a link.
> >
> >The point, folks is that if this is going to work, you want to A) put one
of
{Quote hidden}

> >{Original Message removed}

2000\05\31@225025 by Mark Willis

flavicon
face
IMO the way this would work best is that:

1)  The poster sends their message to the list server.
2)  The autoresponder and those subscribed with "All Topics enabled" or
in index or digest mode, would then get that post.
3)  The autoresponder would notice that the post didn't adhere to the
rules.
4)  The autoresponder would then post to the *sender*.
5)  The sender would then realize their error, fix the message's Subject
line, and re-send with a proper Subject line syntax.

I'm guessing Digest mode is going to get less popular for a week or two,
as we train everyone, BUT once we're all re-trained this should only
happen for new posters to the list, so things will self-repair <G>
Think of it same as changing from Parallax to Microchip assembler - it's
different, you get some assembler errors for a while, then things get
better.

(James, is planned to have autoresponder post to whole list or just the
"one who's flirting with 'the Other side'"?

 Mark

piclist.com wrote:
{Quote hidden}

> > >{Original Message removed}

2000\05\31@233413 by piclist.com

face picon face
Mark, I don't know if you remember, but due to the way Outhouse does email
(remember I'm a Win guy not Linux) I can't make the responder reply to the
person that actually posted the message, only to the list or to the reply to
address set by the poster IF they set one.

So... I just setup a subscription with ONLY the Other topic selected and
told it to respond to all message with that post and the same subject line.

Please keep in mind that the ENTIRE point of this thing is that EVERYBODY
else turns OFF "Other:" once they get used to putting the tags on. No one
but new subscribers has Other on. So when the newbie subscribes, ignores the
welcome message and posts "Hi, How do I unsubscribble" or "please measure
10k degrees heat in combustion chamber" YOU DON'T SEE IT. He gets an instant
response that tells him, again, how to tag posts and how to get off the
list.

I'm totally amazed that I can't get that across.

Again. Once you get the idea of tagging the topics, you turn Other off by
sending
SET PICLIST TOPICS: -Other to spam_OUTLISTSERVspamTakeThisOuTMITVMA.MIT.EDU or, in most email
clients, click here:
.....LISTSERV.....spamRemoveMEMITVMA.MIT.EDU?body=SET%20PICLIST%20TOPICS:%20-Other> Then the autoresponder and the "Duh.. how do I unsubscribble?" posts all GO
AWAY. Only people with Other on see them.

Can someone who is getting this please help explain it to everyone else?
Preferably one of the several hundred who posted a "TOPICS_YES" post to me
when I originally presented the idea and asked if we should try it.

Or if you have a Linux server that can autorespond to untagged posts, using
the buried "on behalf of" email address of the original poster....

Or just put me out of my misery and let me go back to doing it to old way...

James Newton, PICList Admin #?
spam_OUTjamesnewtonTakeThisOuTspamEraseMEpiclist.com
1-619-652-0593 phone
http://www.piclist.com

----- Original Message -----
From: Mark Willis <EraseMEmwillisspamBeGonespamKILLspamFOXINTERNET.NET>
To: <RemoveMEPICLISTspamBeGonespamspamMITVMA.MIT.EDU>
Sent: Wednesday, May 31, 2000 19:48
Subject: Re: [EE]: AT Keyboards --- Not all equal![ADMIN]


{Quote hidden}

noise
> > of miss tagged posts, and the autoresponder and all that and you will
get
> > ONLY the properly tagged message about [PIC]: or [EE]: or what ever you
> > want.
> >
> > All you have to do is send SET PICLIST TOPICS: -Other to
> > @spam@LISTSERVspamspamMITVMA.MIT.EDU or, in most email clients, click here:
> > TakeThisOuTLISTSERVKILLspamspam@spam@MITVMA.MIT.EDU?body=SET%20PICLIST%20TOPICS:%20-Other> > > Then the autoresponder and the "Duh.. how do I unsubscribble?" posts all
GO
> > AWAY.
> >
> > As the autoreply message says. Please help me phrase it more clearly so
that
{Quote hidden}

one
> > of
> > > >the following at the start of all posts to the list
> > > >
> > > >[PIC]:
> > > >[EE]:
> > > >[OT]:
> > > >[AD]:
> > > >
> > > >and B) turn off your subscription to the other channel that this
> > > >autoresponder will clutter up by sending SET PICLIST TOPICS: -Other
to
> > > >RemoveMELISTSERVspamspamSTOPspamMITVMA.MIT.EDU or, in most email clients, click here:
> > > >.....LISTSERVEraseMEspamMITVMA.MIT.EDU?body=SET%20PICLIST%20TOPICS:%20-Other> > > > >
> > > >---
> > > >James Newton (PICList Admin #3)
> > > >
spamBeGonejamesnewtonspamRemoveMEpiclist.com 1-619-652-0593
> > > >PIC/PICList FAQ: http://www.piclist.com or .org
> > > >
> > > >{Original Message removed}

'[EE] Wireless communication...'
2000\05\31@234315 by Ian Hynes

flavicon
face
If you've got a UHF capable sig-generator around the lab somewhere,
maybe try heterodyning the the Tx's output down into the scope's
range?
Just a thought.

Ian

Jilles Oldenbeuving wrote:
>
>  .... i can't see
> anything at the receiving end. I can't measure
> if the transmitter is actually oscilating at 433 MHz becouse the fastest
> scopes we have is a Philips 200 Mhz scope...
>
>
> Jilles

--

'[EE][PIC] How to measure level of liquids and sens'
2000\05\31@235651 by John Orhan

flavicon
face
Hi ,
Where can I find sensors to measure the air pressure. I had exactly the same
idea for a water level meter on a boat, but could not source any sensors to
do the pressure measuring. Please advise.John Orhan
Detection Systems / EDM Engineering Department
Ph: 02 96721233 (ext 219)
Fx: 02 9672 4093
Email: .....jorhanEraseMEspamedm.com.au


{Original Message removed}


'[EE]: Embedded Internet enabling methods: Which?'
2000\06\01@023347 by TOM THERON
flavicon
face
"We're not merely making a living , we are designing a future"
MMS Electronic Systems
Tel +27-(0)12-6645696
Fax. +27-(0)12-6642682
Mobile. 0833109007

{Original Message removed}

'[EE][PIC] How to measure level of liquids and sens'
2000\06\01@024621 by markwillcox56

picon face
<x-flowed>put carbon granuals, powder, or antistatic foam in a plastic pipe,open at
one end for pressure. connect one wie to each end and you have a pressure
sensitive resistor. or mabey use an old carbon mic from a telephone? just
some thoughts..... Mark


{Quote hidden}

>{Original Message removed}

'[EE]: AT Keyboards --- Not all equal![ADMIN]'
2000\06\01@024842 by Mark Willis

flavicon
face
I'm not a Linux guy yet - I do Dos though <G>  It's all LookOut
Express's fault, OK.  I can grok that!  <G>

The problem still exists though.  Obvious from the "Software test end"
over here, unfortunately.

An existing user starts a new thread.  He/She has the '[Other]' topic
turned off, having been on the list for months;  They're having a day
like my yesterday was.  It's NOT pretty.  They forget to put a valid
topic into the Subject line.

All newbies, all admins, all people on Digest mode and Index mode, get
to see the autoresponder's post that complains.  The "offender" doesn't
see anything, though.  An admin has to manually check each posters'
options with "Query Piclist for offenderKILLspamspamspamisp.com" and see if they have
the Other option turned on?  Ack!  Well, we can do that if we have to,
it'd suck though.  Badly.

There has to be a better way.  I can make a Dos app that does this, run
it off a FreeWWWebs.Com account on an old spare 286.  Net-Tamer or
Arachne maybe.  Won't be instant to do that, though.  Does anyone on the
list have a better idea on this one?

James - Guess the one thing to do for now is get that 7k message stuffed
onto piclist.com and pass me a URL and I'll think on this.  I hadn't
considered the evil LookOut Expunger as I don't use that.

Mike, any ideas?

 Mark

piclist.com wrote:
{Quote hidden}

> > > > >{Original Message removed}

'[EE][PIC] How to measure level of liquids and sens'
2000\06\01@025450 by markwillcox56

picon face
<x-flowed>how about a float from a toilet connected to a LVDT or a pot at the fulcrum?


>From: John Orhan <JOrhanTakeThisOuTspamKILLspamEDM.COM.AU>
>Reply-To: pic microcontroller discussion list <RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU>
>To: @spam@PICLISTSTOPspamspamMITVMA.MIT.EDU
>Subject: Re: [EE][PIC] How to measure level of liquids and sense relat ive
>             humidity?
>Date: Thu, 1 Jun 2000 13:57:01 +1000
>
>Hi ,
>Where can I find sensors to measure the air pressure. I had exactly the
>same
>idea for a water level meter on a boat, but could not source any sensors to
>do the pressure measuring. Please advise.John Orhan
>Detection Systems / EDM Engineering Department
>Ph: 02 96721233 (ext 219)
>Fx: 02 9672 4093
>Email: TakeThisOuTjorhanTakeThisOuTspamRemoveMEedm.com.au
>
>
>{Original Message removed}

'[EE] AT Keyboards --- Not all equal!'
2000\06\01@083806 by John Hansen

flavicon
face
<x-flowed>At 10:58 AM 6/1/00 +1000, you wrote:
>At 05:49 PM 5/31/00 -0400, you wrote:
>
>I had the same problem with different keyboards as you describe.
>
>Some keyboards require the CLOCK period to within tight margins. If I
>remember
>correctly this is 40us for a full period.
>
>If the clock period is off some keyboards will not work, others will. When
>I got the clock right all the keyboards worked 100%
>
>-Jim

I'm wondering if you would elaborate, Jim.  The clock is generated by the
keyboard.  As long as I read the data after the falling edge of the clock,
shouldn't I be ok?

Thanks,

John

</x-flowed>

'[EE]: Unfused printouts <-- PC board transfer pap'
2000\06\01@113212 by andy howard

flavicon
face
> From: "Russell McMahon" <spam_OUTapptechspamspam.....CLEAR.NET.NZ>


> Here's a trick which MAY be useful. Like all the best ideas, I
discovered it
> by accident - in this case while trying to print an envelope short
side in.
>
> If you cut a sheet of paper to less than a certain length (the exact
length
> will vary with your printer) and feed it to a laser printer, then the
feed
> rollers after the toner deposition stage will (may?) fail to pick it
up and
> the paper will stop in the midst of the printer without having been
fused.


Be very careful if you're playing with unfused toner.
You really, really don't want to be breathing this stuff in.












.

'[EE]:Current on a PCB'
2000\06\01@115133 by Dan Michaels

flavicon
face
Andrew Seddon wrote:
>> Hard to imagine anyone would do this. Even though the nomograph
>> indicates you can run 750 mA thru such a trace, and only have a 10degC
>> temp rise, there are several "other" things to worry about. Trace series
>> R producing IR drops. Digital noise in this narrow channel. Inductive
>> effects of narrow trace width at hi speeds. Impedance issues. On and on.
>
>I always thought that it was best to use the least ammount of copper you can
>with digital logic, come to think of it I think I made this rule up myself
>so any input appreciated. BTW I just got a board back from the shop, it has
>8 mil ground and power traces. Seems to be working OK. I dind`t mean to do
>it but it was a rush job and I fogot to manually route the power traces.
>

Andy,

Everything I have read indicates you have this exactly backwards. The
problems become more critcal as frequencies been used increase, and when
analog and digital are mixed on the same pcb.

The ideal case would be to have a multilayer board with gnd and power
planes. This gives you minimum possible IR drops in Vcc/Vss lines,
less possibility for heat buildup since planes act like heat sinks,
better overall bypassing since the planes act like distributed caps
[the smaller the vertical spacing between planes the better], smaller
inductive current loops so there is less brodcast EMI [high speed
signals follow the path of least "impedance"], on and on. Tiny traces
are going to be problematical in all of these areas.

I do mostly 2-layer boards, and typically use 70-100 mil traces for
gnd and 30-50 for Vcc. I run them on the upper surface of the pcb in
parallel with each other, directly under the ICs, with feeding from
teh same end of the pcb. The majority of chip interconnections go on
the lower surface. Also, with wide gnd traces, it is easier to run
hi-speed lines, such as clock signals, directly beneath the gnd trace
on the lower pcb surface. This helps to limit EMI generated by the
clock edges/etc.

On and on - this just scratches the surface. Howard Johnson's book
"High-Speed Digital Design A handbook of Black Magic" has lots more.
Expensive, but well worth the price.

best regards,
- Dan Michaels
Oricom Technologies
===================

'[EE]:,[PIC]: How to measure level of liquids and s'
2000\06\01@115140 by Dan Michaels

flavicon
face
Mark  wrote:
.....
>> Not that I've ever tried this, but I figure the temperature variation
>> would distribute itself along the tube in some manner [to be measured
>> and calibrated empirically], and the math would be some weighted
>> averaging routine. Just a thought. The sorta thing you try once, and
>> immediately get a strong hunch whether it will ever work or not.
>>
>> - Dan
>
>Aaah, you're thermally bonding the hot beads to the tube?  Perhaps
>that'd work, might want to instead put a heater at the top of a small
>rod, bond the thermistors to the rod, use them to measure along the rod,
>maybe would work.
>

Yeah, that's pretty much what I had in mind. Although I am not a
thermal engineer, it seems to me there will generally be a temperature
difference between the fluid, now matter what it is, and the air
above it - due to thermal inertia - so a heater may not be required.
I'd have to try this to see how it would work. It might work with
3 thermistors this way - one at the bottom [in the fluid], one at the
top [out of the fluid], both of which act as references, and one in
between to do the actual weighted measurement - all bonded to the same
long tube.
=============

>Good news is that you can use one larger PIC and run quite a few
>thermistors simultaneously to get many data points simultaneously.
>Sigma Delta code's not too hard to find <G>
>

For production stuff, I think most companies would want to go with
as few parts as they could get away with --> costs, plus reliability
issues.

- Dan

'[EE]: Current on a PCB'
2000\06\01@115144 by Dan Michaels

flavicon
face
Don Burdette wrote:
>Dan Michaels wrote:
.....
>This approach is not imprecise if you use your prototype to actually
>measure how close you are to the limits.  You could easily build a
>prototype that works, but is significantly beyond the safe limits, or
>even the limits of what will work at all over the long term or under
>extreme conditions.  Limited or short-term testing may not discover these
>flaws.
>
>If you guess at the right values and don't measure how close you got,
>(which I suspect is rarely true in your case), then you are being
>horribly imprecise.  In fact, you could be building a safety and/or
>reliability nightmare.
>
>I believe the most reasonable solution (at least for most commercial
>applications) is to KNOW the right values.  Then there's no guesswork,
>and you can build in "comfortable" safety margins.
>

Don, hopefully my designs are a little more precise than my
explanations!

Yes, I always calculate everything I can - general and "worst
case" - during the design phase, add in a substantial safety
margin on things like power dissipation, always use the widest
possible traces for power/gnd as a matter of course, cook it up,
and then test/measure the resulting hardware. There are always a
few things that take a 2nd cut to get right, but most things are
pretty good on the 1st go.

After I sent that last memo, I realized it sounded a lot like I
just totally wing everything. Not quite. <:-)).
===============

>
>The topic of 'fusing' the traces is actually very different from the
>topic of 'reasonable' currents.  The fusing (melting or vaporizing)
>currents are at least an order of magnitude higher than what you want to
>use.  A trace that will melt at 10 amps will discolor the solder mask and
>the substrate, even melt the glue and peel off the board at currents of 1
>amp or less.  Fusing normally occurs only if there's a major fault
>somewhere.
>

As I pointed out last time, I was especially struck by the fact
that the nomographs show that it takes "only" a 3x increase in current
to go from the 5degC to the 100degC temp rise curve. That's an
enormous effect for not so enourmous a change in current. Essentially
no effect at all to blistering your finger/whatever.

I would not want my pcbs to be designed anywhere close to the point
where this could occur. I would calculate the worst case currents as
best as possible, find the trace width that produces say a conservative
10degC rise at that current, and then try to allow a substantial
safety margin over **that**.

10degC rise for a 100mil 1oz cooper trace is ~4A, so I would think
that operation at currents <= 1A will "never" be a problem here,
since it would take ~12A to get 100degC rise. At currents much beyond
1A, I think I would go with heavier copper, 2-3oz, from the start.

Looking at the nomographs, and thinking about the physical size of
relays and switches required to handle large currents, it seems you
pretty much have enough room to widen/thicken the traces so heating
should rarely be an issue. Eg, for a 10A design, a 300mil 1oz trace
gives about 10degC rise - there should be plenty of room for parallel
150mil traces top and bottom - and it would handle 30A before you get
to 100deg rise. Plus, there is probably room here to widen the traces
further. 3oz copper would be much better.
===============

>The vast majority of PCB's are made on either phenolic or FR4 fiberglass,
>with one of several mask materials.  Does anyone know the max temp of
>this stuff?  If nobody knows offhand, I'll call my PCB vendor on Friday
>to ask.

I could not find this in Johnson's book, "High-Speed Digital Design",
but as indicated above, I think one can generally design so that you
shouldn't have to worry about it.

best regards,
- Dan Michaels
==============

'[EE]:,[PIC]: How to measure level of liquids and s'
2000\06\01@125948 by Mark Willis

flavicon
face
Dan Michaels wrote:
{Quote hidden}

It'd depend on situation, around here on a cold day that wouldn't work
well though - if the temp's 55F and the water pours in at 55F, you would
need to rethink - in hotter climes, 55F vs. 80F, easy to see the
difference.  Worth a try some time when you have "spare time", that
elusive thing we never have enough of <G>  I wouldn't expect
self-heating from the thermistors to work in this situation, bet you
don't either;  power resistors are cheap and plentiful though <G>  (Bond
a 5W or so resistor inside the top of the tube, use polyurethane power
cable out the top, seal the ends with PVC cement goop after scratching
the cable to give you good bonding and then using that purple MEK stuff
to prep the cable?  Seems to work pretty well in past, IME.  Run say
1-2W into the resistor so it won't be over stressed.)

> >Good news is that you can use one larger PIC and run quite a few
> >thermistors simultaneously to get many data points simultaneously.
> >Sigma Delta code's not too hard to find <G>
> >
>
> For production stuff, I think most companies would want to go with
> as few parts as they could get away with --> costs, plus reliability
> issues.

Sure - So long as it works <G>

> - Dan

--
I re-ship for small US & overseas businesses, world-wide.
(For private individuals at cost; ask.)

'[EE] Microcontroller with 4 USARTs and 40 pins'
2000\06\01@153955 by Keith Causey

flavicon
face
I like that part too (MAX3100 family) and have used it and its cousins on
several projects. The buffer is advertised to hold 8 bytes but I have never
been able to use it sucesfully. I don't think that a normal read is clearing
the buffer. It seems to assert it's contents to me twice.

> Something else to check out is the I2C UART chips from Maxim.  They have a
> family of chips that has either 232, 485, or logic level serial on one
side
> and SPI or I2C on the other.  Very cool part.  I also believe they have a
> couple byte buffer to avoid overloading your micro.
>
> You should be able to find them on their site by searching for 'uart'...
>
>
>
>
> At 07:25 PM 5/26/00 -0300, Edson Brusque wrote:
> >> Perhaps if you give us a little more information we can help you out
more.
> >
> >    As I'm a musician, and my (piano) keyboard controller doesn't makes
all
> >the tricks I would like it to do, I'm thinking in developing a MIDI
> >black-box that could do everything I want. Maybe I can sell hundreds of
> >units and make some money :)
> >
> >> It is unlikely that you will find an 8-bit micro with 4 hardware UARTs
(as
> >a
> >> hobbyist), so you probably should plan on finding one with one or two
> >UARTs and
> >> build the rest in software.  If I were in your shoes, I would build
them
> >all in
> >> software.  If you run a scenix or atmel at 24 MIPs, you'll have exactly
> >768
> >> instructions (scenix, varies for atmel) per bit time to run the UARTs
and
> >your
> >> user process (at the specified 31.25Kbps).  Divide it by four (bit
> >slicing) and
> >> you end up with 192 instructions to read the state of four RX lines,
> >change the
> >> state of four TX lines, and then do some data processing.  It really
would
> >not
> >> be too difficult.
> >
> >    I think I'll want to put 16 keys on the thing (8 I/Os for that), an
LCD
> >(6 I/Os for that), four MIDI Ins plus four midi Outs (8 I/Os), and I
would
> >like it to communicate with the PC with Paralell or USB. Even Serial at
> >115.200bps would do the job nicely. Well, this puts 22 I/Os plus PC
> >communication. A 48 or 52 pin Scenix at 50MHz seens to be a very good
option
> >(I've took a look at SX documentation and it says it can run eight
19.2Kbps
> >UARTs using 13% of 50MHz). The hard thing will be to make an adaptor to
use
> >it on a proto-board.
> >
> >    I would also like to put 16 pots on it to control various things
(like
> >volume, pan, reverb, modulation, etc).
> >
> >    I would preffer to make it with PICs, but I don't think it's
possible. I
{Quote hidden}

'[EE]: Micrphone Noise Detection'
2000\06\01@163921 by Andre Abelian

picon face
part 0 1035 bytes
For TTL input you  need at list 3 volts to make it logic 1. In my project I
started with
picmaster every thing was fine when I tried real part it didn't work
later I found that picmaster is uses FET parts logic 1 is 1,5 volt. any way
I just
drew a schematic that it should work for you. you may need to amplify more
to get what you need
all deepens how high is your noise level. If you are using CMOS level input
then all you
need is 1,5 volts.

Andre Abelian




{Quote hidden}

Attachment converted: creation:noise.PDF (PDF /CARO) (00016028)

'[EE] AT Keyboards --- Not all equal!'
2000\06\01@204935 by Jim Robertson

flavicon
face
At 08:36 AM 6/1/00 -0400, you wrote:

Hi John,

Yes you are right. I was in fact making a "keyboard wedge" and not something
that read the keyboard. This is where I found the timing problem and it
was not with different keyboards, as I first said, rather with different PCs.

Sorry for the bum steer, it was some years ago and I sort of lost the
details in my head.

-Jim



{Quote hidden}

Regards,

Jim Robertson
NEWFOUND ELECTRONICS
________________________________________
Email: EraseMEnewfound.....spampipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.
________________________________________

'[EE] IIR filter design'
2000\06\01@212714 by Plunkett, Dennis

flavicon
face
       Hey anyone got "FREE" IIR filter design software that shows me the
coeffs? and alows denormalisation and all that sort of stuff?


       Dennis

'[EE]:wave file to an pic'
2000\06\02@003940 by rdo Lopes De Souza Junior

flavicon
face
Hi PIClisters,

   I need some help.
   I'm looking for description of "*.wav" files.  I've been searching all the
net for description of this kind of file, but I haven't found yet.
   First I create a file in *.wav than I'd like to get the 8bit sequence,
without it's overhead, put it on a look-up table and generate a sound with a
8bit R/2R network.
   So, how can I reconize that overhead and cut it off  from the useful
information? Somebody could sugest any link to put me right the way?

Best Regards
Eduardo.

2000\06\02@005715 by Ravi Pailoor

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face
part 0 1939 bytes content-type:text/x-vcard; charset=us-ascii; (decoded 7bit)

Pailoor

Eduardo Lopes De Souza Junior wrote:
{Quote hidden}

--
********************************************************************
* e-CHIP INFOTEK (P) LTD.                                          *
* Microchip Consultant                                             *
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* Tel 91 80 2202172, Fax 91 80 2258103, Mobile 98440 81538         *
*------------------------------------------------------------------*
* We design the future with PICmicro                               *
* http://echipinfotek.com                                          *
*------------------------------------------------------------------*
* All attachments will be listed above. If you find any additional *
* attachment, it could be a virus, please delete it and inform me. *
*                                                                  *
* Thanks                                                           *
********************************************************************
Content-Type: text/x-vcard; charset=us-ascii;
name="chiptech.vcf"
Content-Transfer-Encoding: 7bit
Content-Description: Card for Ravi Pailoor
Content-Disposition: attachment;
filename="chiptech.vcf"

Attachment converted: creation:chiptech.vcf 1 (TEXT/CSOm) (00016045)

2000\06\02@010134 by Andrew

flavicon
face
Hi,

try...

http://home.sprynet.com/~cbagwell/AudioFormats-11.html#ss11.6


Andrew

Eduardo Lopes De Souza Junior wrote:

{Quote hidden}

--
Andrew Thoms
    Software Engineer
    Fac Engineering
    University of Technology, Sydney
    No 1 Broadway, Broadway 2007
    NSW, Australia

'[EE]: [PIC]: How to measure level of liquids and s'
2000\06\02@061225 by Peter L. Peres

picon face
> Not that I've ever tried this, but I figure the temperature variation
> would distribute itself along the tube in some manner [to be measured
> and calibrated empirically], and the math would be some weighted
> averaging routine. Just a thought. The sorta thing you try once, and
> immediately get a strong hunch whether it will ever work or not.

The way to do this is with 2 thermistors buried in a full cylinder such that
their sizes are negligible wrt to the cylinder diameter and whose
(cylinder's) heat conductivity approximates that of the liquid. The relation
that governs the output is so hard to match to reality that a lookup table
must be used. The output depends on the heat conductivity of the liquid and
the thermistors must be run very hot to get decent results. At the same time
the liquid must not boil or convect on the cylinder. If the liquid moves
(pump, drain, convection) without level change then the readout changes (the
conductivity changes).

However, there is a similar method, that is used, and works well. It is the
one with the thermistor wire that is partially immersed. This is what
measures the fuel level in your car's tank probably. The sensors are
available in lengths of up to 10 ft (can you say marine diesel tank ?).
Check out a National catalog for chips that interface to these, although you
can roll your own. Note that most sensors are 'bare' wires but there are
such sensors with teflon or ceramic clad wire which can go into evil liquids.
These are expensive and fragile. The fun part is, that this method is
imprevious to sloshing as it integrates the 'waves' away ;-)

bye,

       Peter

2000\06\02@061235 by Peter L. Peres

picon face
Hi,

the method that uses an air column raised by the liquid is actually VERY
accurate. The output value (air pressure in tube wrt atmosphere above free
surface of liquid) will practically depend only on the liquid density (rho)
and the height. Since 10 meters of water column ~= 1 at you can use a
differential pressure gauge for atmospheric use to read the height in most
usual tanks, and it will be accurate to within the height of the measuring
tube inlet (i.e. the vertical size of the tube opening under the liquid
surface). The readings will be off if the liquid is moving (flowing river =
Bernoulli suction on the tube inlet). Keeping the plumbing clean is a pain
however. Overflowed washing machine anyone ? <g>

Afaik, the humidity of construction materials (such as sand) is indeed taken
by weighing, cooking, and weighing, on a probe taken by a worker. They also
determine the density of the material after cooking. The measuring recipient
is a small round cylindrical pot with a hemispherical bottom which is to be
filled to the upper rim and evened. With a kid's sand tools ;-). They use a
sieve to make the input even and they push it in to remove air pockets. The
vessel I say holds about 2 liters of water (~ 5-7 kg of dry sand). The
density can be very important when working with large quantities (ever run
out of some ingredient with 95% of the concrete poured ? <g>). For materials
that cannot be heated (coffee, tobacco, more) the water is removed by using
vacuum at room temperature (0.3 at will dry it in a few hours). The rest is
the same as above. The recipient is also the same afaik. Another thing they
determine for concrete is the Ph of the input materials. This is done on the
wet material. Having a bad Ph in concrete input materials can really ruin
your day afaik.

Peter

'[EE]:Current on a PCB'
2000\06\02@081424 by paulb

flavicon
face
Hello Andrew.

 Your date is a bit off!
--
 Cheers,
       Paul B.

'[EE]: 5V Logic Bypass caps - SMD value/phy size re'
2000\06\02@113553 by Jim P

flavicon
face
Hello all experienced circuit designers:

Given the plethora of suitable:

A) bybass cap values and
B) SMT physical sizes (not to mention various temp. stability options)

listed in the Digikey catalog -

Has anyone found/experimented with the optimum size capacitance
value and/or physical size for use in/around a microprocessor?

I've got a 100 pin QFP device that I'm laying out and would like
to score on (or slightly near the mark) the first time around ...

I've got access to the under side of the board - and that's where
I had intended on placing the SMD bypass caps.

The first few boards will be hand-built prototypes (of course!) - so
am I better off with the larger size (1210 etc) SMD caps?

This is my first real exposure into the world of SMD - having done more
RF projects (most of those devices are 'Surface Mount' in practice!) in
the past than digital/micro circuits using conventional TH or wire wrap
technology.

Jim P

2000\06\02@115640 by James Paul

flavicon
face
Jim P,

In my experience, I have found that a 20 uF or so electrolytic,
usually Tantalum, and a .1 or .01 uF to be sufficient.  I haven't
tried to find an optimum value because these values always worked
for me in the past.  As far as package size goes, the 20 uF is
usually in the 1210 package and the .1 or .01 is either the 0805 or
0603 package.  Which package size I use depends on the size of the
IC I'm bypassing, the size of the board I have to work with, and the
number of components I have to mount.   Regarding the hand built
status, most of the boards I work with are hand built (stuffed)
because the volume is so small.   But I have no difficulty in
soldering packages as small as the 0603.  With some difficulty, I
can solder smaller packages, but them my soldering tip size becomes
a major hurdle.  I've also tried solder paste with some success.
Bottom line, the 1210, 0805 and 0603 packages work for me.  They
probably will for you too.  And that brings up my last point.  If
these boards are to be manufactured after the prototypes have been
proven and/or perfected, check with the manufacturing facility and
ask them their preferences and/or limitations on component size.
It would be a shame to design a circuit, get it perfected with 0603
components, and then find out that the manufacturing facility can
only handle down to 0805 size components.   Also, make sure you
leave enough space between components so that the Pick and Place
machines can get into posotion to place the component where it
belongs.  I'm sure you know most of these points, but I figured I'd
mention them just in case you didn't.

                                            Regards,

                                              Jim







On Fri, 02 June 2000, Jim P wrote:

{Quote hidden}

spamjimKILLspamspam@spam@jpes.com

2000\06\02@115650 by James Paul

flavicon
face
Jim P,

In my experience, I have found that a 20 uF or so electrolytic,
usually Tantalum, and a .1 or .01 uF to be sufficient.  I haven't
tried to find an optimum value because these values always worked
for me in the past.  As far as package size goes, the 20 uF is
usually in the 1210 package and the .1 or .01 is either the 0805 or
0603 package.  Which package size I use depends on the size of the
IC I'm bypassing, the size of the board I have to work with, and the
number of components I have to mount.   Regarding the hand built
status, most of the boards I work with are hand built (stuffed)
because the volume is so small.   But I have no difficulty in
soldering packages as small as the 0603.  With some difficulty, I
can solder smaller packages, but them my soldering tip size becomes
a major hurdle.  I've also tried solder paste with some success.
Bottom line, the 1210, 0805 and 0603 packages work for me.  They
probably will for you too.  And that brings up my last point.  If
these boards are to be manufactured after the prototypes have been
proven and/or perfected, check with the manufacturing facility and
ask them their preferences and/or limitations on component size.
It would be a shame to design a circuit, get it perfected with 0603
components, and then find out that the manufacturing facility can
only handle down to 0805 size components.   Also, make sure you
leave enough space between components so that the Pick and Place
machines can get into posotion to place the component where it
belongs.  I'm sure you know most of these points, but I figured I'd
mention them just in case you didn't.

                                            Regards,

                                              Jim







On Fri, 02 June 2000, Jim P wrote:

{Quote hidden}

jimspamspamTakeThisOuTjpes.com

2000\06\02@120508 by David VanHorn

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

At 10:35 AM 6/2/00 -0500, Jim P wrote:
{Quote hidden}

You want the caps to absorb well at the third harmonic of the clock.
0.1uF does well at 3 MHz, 0.01 at 30. 0.001 at 300.
It's a broad response, so dont think that there's one specific value.
However, if you use 0.1uF on a 20 MHz part, you won't get the supression
that you could if you used 0.047uF.


>I've got access to the under side of the board - and that's where
>I had intended on placing the SMD bypass caps.

Place the cap at the ground pin, and route power to the cap first, and from
there to the chip. Otherwise, you compromise the bypass.
Murata and panasonic make through-hole 3 leaded caps which help eliminate
this by having ground, in and out leads (I and O are reversible)

>The first few boards will be hand-built prototypes (of course!) - so
>am I better off with the larger size (1210 etc) SMD caps?

I do tons of work with 1206 and smaller with no special tools, though 0402
is pretty difficult.

- --
Are you an ISP?  Tired of spam?
http://www.spamwhack.com  A pre-emptive strike against spam!

Where's Dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

iQA/AwUBOTfzsoFlGDz1l6VWEQKJhACgjSJ2x/JUsB/S7mWWBH+siwVhrh4AoJg5
UJbF1YRbEvE2Q4V1qBxfWH01
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'[EE]: [PIC]: How to measure level of liquids and s'
2000\06\02@121935 by Dan Michaels

flavicon
face
Peter L. Peres wrote:
....
>However, there is a similar method, that is used, and works well. It is the
>one with the thermistor wire that is partially immersed. This is what
>measures the fuel level in your car's tank probably. The sensors are
>available in lengths of up to 10 ft (can you say marine diesel tank ?).
>Check out a National catalog for chips that interface to these, although you
>can roll your own. Note that most sensors are 'bare' wires but there are
>such sensors with teflon or ceramic clad wire which can go into evil liquids.
>These are expensive and fragile. The fun part is, that this method is
>imprevious to sloshing as it integrates the 'waves' away ;-)
>

Peter, can you more fully describe the makeup of this 10' length
of sensor? I thought a thermistor was basically a resistive bead with
copper wires attached. Are you referring here to some kind of distributed
thermo-resistive element? Confusing.

- Dan Michaels

2000\06\02@225249 by Ian Wilkinson

flavicon
face
On Thu, 01 Jun 2000 in "Re: [EE]: [PIC]: How to measure level of liquids and sense", you wrote:
I don't know if this has been mentioned before as I've not been following this
until I noticed a system that uses two metal rods that are placed into the
liquid.  The resistance is measured and as the liquid rises the resistence
drops.  Now this will probably only work for water based liquids, but does look
to be a very quick solution...

Ian.
--
Hofstadter's Law:
The time and effort required to complete a project are always more than
you expect, even when you take into account Hofstadter's Law.

Uptime at  3:28am  up 1 day, 11:20,  4 users,

'[EE] Embedded Internet enabling methods: Which?'
2000\06\03@032633 by picxpert

picon face
With emWare, you need to hook it up to a PC running emGateway. This PC
connects to the 'net.

-Randy Glenn
RemoveMEPICxpertANTISPAMRemoveMEspamtechie.com (remove ANTISPAM)
http://i.am/PICxpert

"My Finder has died of fits, chokin',
My Finder has quite ceased to be.
OS X's new Finder looks broken,
Please bring back my Finder to me!" - A concerned Mac user

{Original Message removed}

'[EE]: [PIC]: How to measure level of liquids and s'
2000\06\03@150830 by Peter L. Peres

picon face
>Peter, can you more fully describe the makeup of this 10' length
>of sensor? I thought a thermistor was basically a resistive bead with
>copper wires attached. Are you referring here to some kind of distributed
>thermo-resistive element? Confusing.

Dan,

normally thermistors are indeed bead-type using discoidal or cylindrical
active elements, but the original [tm] - ca. 1800's ? - way to do this, is
thermistor wire. Which comes on reels and is spec'd in ohms/meter. This is
different than resistor wire, as the latter has a near-zero temperature
coefficient, whereas the thermistor wire has a positive (and very linear vs.
other methods) coefficient. Tungsten wire comes to my mind as an inexpensive
<grin> candidate (note: tungsten wire: not tungsten steel. Chemical symbol
W, aka Wolfram in other parts of the world). This is what incandescent bulb
filaments are made of usually. In real life, complex and proprietary alloys
are used for the wire. The W wire is very fragile (it shatters like a
ferrite) so it has very limited uses. The tempco (for certain W alloys) is
about +0.03-0.05 ohms/K at around room temperature. You should really get
hold of a National Data Book that features the relevant chips, they go into
some depth with this (Automotive Section).

The wire is spanned in a frame (or a tube with openings), and immersed
vertically in the liquid. The liquid wets a part of the wire, and this part
will be cooled very efficiently. The part that sticks out heats up due to
the current passed through and this is what you measure. The wires used in
automotive apps. have a very high tempco (can't run them hot). The accuracy
depends directly on the temperature of the exposed wire and on the tempco of
the wire (both as high as possible to make it more accurate).

Peter

'[EE]: Fbus and M2bus related (again) [OT]'
2000\06\04@014445 by :-=jug=-:

picon face
Hi!

Is there anybody can share or give me a circuits for Fbus or M2bus for Nokia
51xx,32xx and 61xx which is not using MAX232?

Thanks in advance...

Best regards,

-=jug=-

/ /                         Homepage:
 (  ,),)             http://juggernut.cjb.net
(  +++)                  Email:
 >   <              TakeThisOuTjuggernutz@spam@spam@spam@yahoo.com
/^      ^\            TakeThisOuTjuggernutspamspamcrosswinds.net
^      ^             KILLspamimceceKILLspamspamspamBeGonecrosswinds.net
just hoping that your okey!!!


__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com

'[EE]:The best way of remote PIC and host PIC samp'
2000\06\04@014648 by -=jugggernut=-

picon face
Hi to all!

Is there anybody can share me a program snips to handle a serial
asynchronous communication protocol that will communicate the two PICs
(16F84) using two wires?

Help will be highly appreciated...
Best regards,

-=jug=-

/ /                         Homepage:
 (  ,),)             http://juggernut.cjb.net
(  +++)                  Email:
 >   <              spamBeGonejuggernutzKILLspamspamyahoo.com
/^      ^\            juggernut@spam@spamKILLspamcrosswinds.net
^      ^             EraseMEimceceRemoveMEspam@spam@crosswinds.net
just hoping that your okey!!!


__________________________________________________
Do You Yahoo!?
Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com

'[EE]: Fbus and M2bus related (again) [OT]'
2000\06\04@055643 by Mircea Ciocan

flavicon
face
M2BUS (Fbus also but with MAX232):
http://www.yegen.ee/~pepper/ps/cables/Nokia%201610%202010%202110%203110%208110.html

Here is another colection of diagrams where you can see that MAX232 is
just a level shifter with an integrated voltage generator:

http://free.polbox.pl/d/drmott/cables.html

http://home.wtal.de/thomasbecker/nokia/nokia-e-datacable.html

http://www.gsm-cables.com/nokia/cables.html

http://www.hut.fi/~ptuomine/nokia/cables/index.htm

Maxim will offer you FREE MAX 232 and 2322 here:

http://dbserv.maxim-ic.com/sl_requests2.cfm

Here you can find the data sheet:

http://dbserv.maxim-ic.com/quick_view2.cfm?pdf_num=1798

       And after all that you are still not able to hack a dual voltage power
supply and some level switchers you relly shouldnt be in that
electronics job.

       And BTW, using http://google.com all that took me almost 5 minutes !!!!

                       HTH

                       Mircea C.


:-=jug=-: wrote:
{Quote hidden}

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\04@161902 by Sean Breheny

face picon face
Hi all,

For a project that I am working on, I need to detect the output of a few IR
leds at about 300 feet (abt. 100 meters) away. The output is pulsed, to
help distinguish it from background light.

I have succeeded in doing this out to about 100 feet, but am having
difficulty beyond that because of noise. I have found appnotes which
explain photodiode noise to some extent, but nothing on phototransistor
noise. Could someone point me to a good reference for both?

Also, does light emitted by an incandescant bulb have a significant noise
due to the discrete nature of the photons (like shot noise in electric
current)? How would one go about calculating the approximate amount of
noise from such a source? I have been using flashlights to simulate intense
background light (like the receiver is trying to pick out the source with
the sun as a backdrop) and the amount of noise I have been seeing is much
larger than I would expect due to electrical effects. I was wondering if I
am seeing real fluctuations in the light intensity.

Thanks,

Sean

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
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'[EE][PIC] How to measure level of liquids and sens'
2000\06\04@182854 by Hugo Jorge Mčller

flavicon
face
John:
  search en http://www.motorola.com for MPX sensor line of sensor or search
Databook DL200/D ( Sensor device data/handbook) in the literature section of
web site.

Good luck.

Thanks to all that contribute to my original question " [EE][PIC] How to
measure level of liquids and sense relat ive humidity?"

Hugo J. M|ller
H.J.M. Hardware & Software Diseqos Electrsnicos
San Nicolas 683
Tel-Fax : 54-(0)-343-424-5953
(3100) Parana (Entre Rmos) Argentina
Email : hmuller [ANTISPAM-QUITAR-ESTO] @arnet.com.ar
Web Site: http://www.pagina.de/hjm
UIN (ICQ) : 38.605.074

----- Original Message -----
From: John Orhan <STOPspamJOrhan.....spamEDM.COM.AU>
To: <spamBeGonePICLISTRemoveMEspamRemoveMEmitvma.mit.edu>
Sent: Thursday, June 01, 2000 12:57 AM
Subject: Re: [EE][PIC] How to measure level of liquids and sense relat ive
humidity?


> Hi ,
> Where can I find sensors to measure the air pressure. I had exactly the
same
> idea for a water level meter on a boat, but could not source any sensors
to
> do the pressure measuring. Please advise.John Orhan
> Detection Systems / EDM Engineering Department
> Ph: 02 96721233 (ext 219)
> Fx: 02 9672 4093
> Email: @spam@jorhanspamBeGonespamedm.com.au
>
>
> {Original Message removed}

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\04@191043 by rottosen

flavicon
face
Sean Breheny wrote:
>
> Hi all,
>
> For a project that I am working on, I need to detect the output of a few IR
> leds at about 300 feet (abt. 100 meters) away. The output is pulsed, to
> help distinguish it from background light.


What is your pulse rate and what is the receiver bandwidth? Of course,
the narrower the bandwidth the better for noise.


>
> I have succeeded in doing this out to about 100 feet, but am having
> difficulty beyond that because of noise. I have found appnotes which
> explain photodiode noise to some extent, but nothing on phototransistor
> noise. Could someone point me to a good reference for both?


I have no references at hand but I suspect that a phototransistor is
noisier than the combination of a photodiode and a low noise transistor.
This would be because of the difficulty of optimizing both photo-gain
and noise in one device in the case of the phototransistor.

You may want to try making your own photodiode/transistor device for
comparison purposes. I think you would want to choose a transistor that
has good noise characteristics at very low currents. A 2N5089 is a part
that comes to mind. I expect that there are better ones.


{Quote hidden}

Again for comparison purposes, maybe try an LED light source to simulate
the background light. Maybe a whole bunch of white LED's ???


-- Rich


{Quote hidden}

'[EE]:PC Power Supply'
2000\06\04@221859 by Mitchell D. Miller

picon face
Mark,

>
> Hint:  This isn't a "low-noise" power supply.  You may want to use R-L-C
> filtering if you need cleaner power - don't know your needs.  For PIC
> projects I just down-regulate from 9V, works.  (7809 inside that panel.)
>

Is the noise enough to cause oscillatior problems on a simple SX project?
I've been trying to use the SX with the Murara resonator that Parallax
sells, but can't seem to make it oscillate.  Project works fine when
Parallax's SX Key is providing the clock.

Why do you choose to regulate down from 9v (which I presume comes from the
+12), instead of directly using the +5 the p.s. provides?  Noise?

-- Mitch

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\04@231406 by Jamie VanderWier

flavicon
face
I think that sunlight will have a much larger IR content then a flash light
would, so using a flash light bulb will likely not simulate intense background
light.
You could also try using optical filters to filter out light from your receiver
that is outside of the IR diode spectrum.

{Quote hidden}

2000\06\04@233529 by Sean Breheny

face picon face
Hi Richard,

Thanks for the response. Please see my answers below:

At 05:09 PM 6/4/00 -0600, Richard Ottosen wrote:
>What is your pulse rate and what is the receiver bandwidth? Of course,
>the narrower the bandwidth the better for noise.

The pulse rate can be whatever I want(I was trying 2kHz because that was
high enough to get away from the 1/f noise of op-amps and low enough so
that op-amps still have significant gain). The bandwidth need only be about
10-20Hz.

>I have no references at hand but I suspect that a phototransistor is
>noisier than the combination of a photodiode and a low noise transistor.
>This would be because of the difficulty of optimizing both photo-gain
>and noise in one device in the case of the phototransistor.
>
>You may want to try making your own photodiode/transistor device for
>comparison purposes. I think you would want to choose a transistor that
>has good noise characteristics at very low currents. A 2N5089 is a part
>that comes to mind. I expect that there are better ones.

That makes lots of sense. When I was able to get to 100 feet, I used a
photodiode combined with a transimpedance amp made from half of a LMC6482,
which has a noise of about 30nV/root Hz around 1kHz. I was actually using a
600Hz pulse freq, so it would probably be a bit easier at 2kHz. I wonder if
it is feasible to do better with a discrete transistor?

>Again for comparison purposes, maybe try an LED light source to simulate
>the background light. Maybe a whole bunch of white LED's ???

Well, yes, you may be correct that an LED would have less noise (no
filament vibrations, etc.), but my question wasn't very clear. What I meant
was: is there some fundamental noise which is inherent in ALL noncoherent
(or perhaps even coherent, for that matter) light sources, simply due to
the fact that the light is emitted as discrete photons which come out at
random times? I think there is, and that it is a similar effect (possibly
different probability distribution) to shot noise in an electric current
(noise which exists in an electric current because it consists of discrete
charges).

>
>
>-- Rich
>
>

Thanks!

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
spamshb7spamspamspamcornell.edu ICQ #: 3329174
_____________________________________________
NetZero - Defenders of the Free World
Click here for FREE Internet Access and Email
http://www.netzero.net/download/index.html

2000\06\04@233729 by Sean Breheny

face picon face
Hi Jamie,

Thanks for the reply. Well, both have significant IR content, but you may
be correct that the sun would have more. I was simply trying to explain why
I get so much noise when I shine a flashlight into it.

The phototransistor I am currently using has a built-in IR filter.

Sean

At 11:03 PM 6/4/00 -0400, you wrote:
>I think that sunlight will have a much larger IR content then a flash light
>would, so using a flash light bulb will likely not simulate intense
background
>light.
>You could also try using optical filters to filter out light from your
receiver
>that is outside of the IR diode spectrum.
>

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
spamBeGoneshb7KILLspamspamKILLspamcornell.edu ICQ #: 3329174
_____________________________________________
NetZero - Defenders of the Free World
Click here for FREE Internet Access and Email
http://www.netzero.net/download/index.html

'[EE]:PC Power Supply'
2000\06\05@042901 by Mark Willis

flavicon
face
Mitchell D. Miller wrote:
> Mark,
> >
> > Hint:  This isn't a "low-noise" power supply.  You may want to use R-L-C
> > filtering if you need cleaner power - don't know your needs.  For PIC
> > projects I just down-regulate from 9V, works.  (7809 inside that panel.)
> >
>
> Is the noise enough to cause oscillatior problems on a simple SX project?
> I've been trying to use the SX with the Murara resonator that Parallax
> sells, but can't seem to make it oscillate.  Project works fine when
> Parallax's SX Key is providing the clock.
>
> Why do you choose to regulate down from 9v (which I presume comes from the
> +12), instead of directly using the +5 the p.s. provides?  Noise?
>
> -- Mitch

I wouldn't expect noisy 5V to cause a resonator to fail to work - more
like to cause brownout problems and crash the SX Key (or repeated
resets?)  Scope Vcc and see what you see - per usual it's late before I
get back to e-mail <G>  Noise tends to CAUSE oscillations (at least when
inside the feedback loop) so I'd think something else is wrong?
(Haven't gotten SX's to the top of my dolist yet - Some day.)

Several reasons why I don't use the 5V directly - I figured the fastest
way to current limit this monster was to put a (2A fused) 7809 behind
the cover plate, that should protect things.  Then let out 9V at 1.5A
max, I used a regular PC style power connector (recycled a HDD connector
IIRC) to feed power to that PC board the 7809 lives on;  I didn't have
any PolySwitches and (at the time) my workbench suffered occasional
Severe Attack Of The Electronics-Eating Cat Incursions, thus fuse
popping was a distinct probability;  No problems yet.  (Have a small
resistor in series there - 0.1 Ohm, 1/2W IIRC - after the fuse & before
the cap across the In side of the 7809, not sure it was *needed* but I
figured it was a good de-coupling idea.  Don't remember if I 'scoped
across it or not!)  I hand-picked a 7809 with lowish Dropout Voltage
(under 3V, obviously!).  Debated using a 7808 with a diode in the base
lead but HAD a 7809 that worked <G>  (It might be some other reg., I
should go look!  Too darn busy here.  It's been a high-interruption
day!  ... life!  <G>)

A lower dropout regulator would be a better design;  I'd suggest at
least some good current limiting inside the PC's case - I like the idea
of using a blank panel as an interface, since it's PORTABLE, easy to
transfer *when* your PC power supply dies, & right there up front where
you need it to be;  Use what works for you.

Been too long since I scoped a PC power supply;  Take a look, it's noisy
in there.  My current O-Scope is a piece of crummy junk, saving to get a
better one.  Now I find it probably should be battery-powered, so much
for the 'scope I had been thinking of!

 Mark

'[EE]:Current on a PCB'
2000\06\05@063732 by Mike Witherden

flavicon
face
Hi I must say that one of the ways around this problem is to use Current Shunts
soldered or bolted (or both) to the track. These Current Shunts may be copper
wire, copper rods or copper bars (square or rectangular.) My favorite are the
copper common and earth bars used in mains DBs.  
Some of these have holes drilled at regular intervals giving you an ideal way
of connecting large cables to your PCB.
This enables hundreds of amps to effectively flow on your PCB with no overheating problems.

Another, not so neat, Current Shunt is old solder wick!

(These Current Shunts also act as great Heat Shunts)

{Quote hidden}

MikeW

'[EE]:[PIC]: How to measure level of liquids and'
2000\06\05@063938 by Mike Witherden

flavicon
face
1 ¸ c worth:  

Dual band Infra Red transducers would also work and can be calibrated very accurately.
The absorption and reflection of Infra Red by a substance is greatly affected by the
substances water content. Using 2 bands of Infra Red improves the effect.

MikeW


.......
The normal method of measuring effective humidity in wood, concrete, sand,
etc., is by conductivity.
......

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\05@074451 by Andrew Kunz

flavicon
face
Sean,

I'd recommend using a Sony or Sanyo IR detector with a 38KHz-type modulation.

They are usually sold for TV IR-type applications, but with the right
transmitter diodes work great outdoors over long ranges.

You DO have lenses on the transmitters, right?

Andy

'[EE][PIC] How to measure level of liquids and sens'
2000\06\05@074905 by Mike Witherden

flavicon
face
The most accurate maturement of liquid level I have dealt with in the Petro
Chemical Industry is the long wire float method, where a float is guided on
one or two vertical wires which run from the top to the bottom of the tank.

The float then either has a flexible wire of some sort  which runs from the
float up to a spool on the top of the tank so the height of the liquid is converted
into a rotational position which can be read using a potentiometer. (some
gearing may be used.) (This can also be done digitally.)

The top of the float may also be used as a reflector and a simple beam of
light or Infra Red or laser etc can be reflected of the top of the float giving a
very accurate reading once the height of the float above the liquid is subtracted.

If the whole thing is put into a 'still tube' the effect of liquid sloshing around is eliminated.

This method enables you to very accurately read liquid levels in tanks tens of
meters high containing just about anything.

MikeW



2000\06\05@110510 by Robert A. LaBudde

flavicon
face
<x-flowed>At 09:48 PM 5/31/00 +0200, you wrote:
>And how about another even simpler way ?
>(which might even prove to work in the real world!)
>
>Just stick a pipe down in the fluid and measure the air pressure that
>builds in the pipe when the level rises. There are sensors availfor it.

Put a float in the pipe and measure its position optically or magnetically,
or use it to mechanically throw a lever.


================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: TakeThisOuTralspamspamlcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
824 Timberlake Drive                            Tel: 757-467-0954
Virginia Beach, VA 23464-3239                   Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================

</x-flowed>

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\05@115255 by Bill Colville

flavicon
face
Sean,

A good reference book for noise reduction in photodiode amplifiers
is:  Photodiode Amplifiers, Jerald Graeme.  McGraw-Hill.
ISBN 0-07-024247-X.

I have found it very useful.

Cheers,
Bill

'[EE]:[PIC]: How to measure level of liquids and'
2000\06\05@120729 by Mike Witherden

flavicon
face
1 ¸ c worth:  

Dual band Infra Red transducers would also work and can be calibrated very accurately.
The absorption and reflection of Infra Red by a substance is greatly affected by the
substances water content. Using 2 bands of Infra Red improves the effect.

MikeW


.......
The normal method of measuring effective humidity in wood, concrete, sand,
etc., is by conductivity.
......

'[EE]:Current on a PCB'
2000\06\05@120733 by Mike Witherden

flavicon
face
Hi I must say that one of the ways around this problem is to use Current Shunts
soldered or bolted (or both) to the track. These Current Shunts may be copper
wire, copper rods or copper bars (square or rectangular.) My favorite are the
copper common and earth bars used in mains DBs.  
Some of these have holes drilled at regular intervals giving you an ideal way
of connecting large cables to your PCB.
This enables hundreds of amps to effectively flow on your PCB with no overheating problems.

Another, not so neat, Current Shunt is old solder wick!

(These Current Shunts also act as great Heat Shunts)

{Quote hidden}

MikeW

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\05@121347 by Andrew Kunz

flavicon
face
Sean,

I'd recommend using a Sony or Sanyo IR detector with a 38KHz-type modulation.

They are usually sold for TV IR-type applications, but with the right
transmitter diodes work great outdoors over long ranges.

You DO have lenses on the transmitters, right?

Andy

'[EE][PIC] How to measure level of liquids and sens'
2000\06\05@121350 by Mike Witherden

flavicon
face
The most accurate maturement of liquid level I have dealt with in the Petro
Chemical Industry is the long wire float method, where a float is guided on
one or two vertical wires which run from the top to the bottom of the tank.

The float then either has a flexible wire of some sort  which runs from the
float up to a spool on the top of the tank so the height of the liquid is converted
into a rotational position which can be read using a potentiometer. (some
gearing may be used.) (This can also be done digitally.)

The top of the float may also be used as a reflector and a simple beam of
light or Infra Red or laser etc can be reflected of the top of the float giving a
very accurate reading once the height of the float above the liquid is subtracted.

If the whole thing is put into a 'still tube' the effect of liquid sloshing around is eliminated.

This method enables you to very accurately read liquid levels in tanks tens of
meters high containing just about anything.

MikeW



'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\05@132159 by Thomas McGahee

flavicon
face
Sean,

To maximize the distance, consider the following:

1) Maximize radiated power.

  A) Power IR LEDs with narrow pulses and LARGE instantaneous
     currents. This will make best use of the super-luminant
     effect. To aid in getting these large currents delivered,
     use fets or transistors that can handle the current pulses.
     Drive them HARD, with clean, fast rise and fall times.
     If you do not drive the FET/TRANSISTOR hard and fast enough,
     then it will spend too much time in the linear region
     and overheat.

     Keep all wiring between LED and local power source SHORT
     and eliminate inductance as much as you can. Use a LOCAL
     current source such as a low ESR capacitor close by the
     fet/LED combination. Use at least one local storage cap
     for each series string of LEDs. Cap must be fully charged
     during the LED "off" time. By "fully charged" I mean to about
     90% of the nominal power supply voltage.

     For best results use IR LEDs that come in metal casings,
     and mount the IR LEDs in snug holes drilled through
     a bar of aluminum such that the lens of the IR LED
     just barely sticks out. Using a heat sink lets you
     push the LEDs just a bit more.

  B) Use multiple IR LEDs. One very useful technique is to
     run several IR LEDs in series. This greatly reduces
     average current drain and minimizes wasted current,
     since you can now use a smaller resistor value for the
     current limiting resistor. More LEDs not only increases
     the average amount of light generated, it also widens
     the field of view of the light source.

  C) Use a condensing lens arrangement to collimate the light
     from the LED(s) so that the light is aimed in the direction
     of interest.

2) Detect signal and minimize interference

  A) Use an IR filter at the receiving end. Do NOT use any
     filter at the transmitting end. The narrower the bandwidth
     of the filter, and the closer it is matched to the IR
     bandwidth of the LED(s), the better.

  B) If operating in low light environments, it is sometimes
     useful to use a local IR LED to flood the IR sensors with
     a very weak DC IR beam that just barely gets the sensor
     to operate in its active region.

  C) Use a modulated IR beam. You get this for free if you are
     pulsing the LEDs. Keep the pulse width ratio LOW. Something
     around 5% works well in most cases.

  D) An optical lens can help gather light from a larger
     area and concentrate it. Large lenses can also help
     increase the useable viewing angle.

  E) Once the signal has been detected, AC couple the modulated
     frequency to a High Q Narrow BandPass Filter. This
     helps you differentiate between noise and signal,
     and rejects anything outside the band of interest.
     I have found LC networks to have the best characteristics
     for the bandpass elements. A parallel LC arrangement
     in the feedback section of an inverting opamp circuit
     works very well.

Fr. Tom McGahee

{Original Message removed}

'[EE]: Paralell port powered little device.'
2000\06\05@132545 by Edson Brusque

face
flavicon
face
Hello,

   I'm doing a little device to be attached to the paralell output of a PC.
I want to take the power to the device (5V, about 40mA max) from the
paralell port.

   I'm looking at some datas and it says the four control pins are
open-collector. This means I cannot take +5V from it... :(

   Anyone have already made something like this? How can I do that?

   Best regards,

   Brusque

2000\06\05@133210 by Tim Hamel

picon face
Brusque,

I do not think you'll be able to suck that much current from the parallel
port without frying it. The max you'll get from maybe the data pins is (I
think, don't quote me on this) 1-2mA per pin. The newer port controller chips
often have IEEE-1284 Level 2 outputs, which can source 12 milliamps at 2.5V,
so maybe you can use a step-up chip?

Regards,

Tim Hamel

In a message dated 6/5/00 10:26:25 AM Pacific Daylight Time,
spamBeGonebrusquespamFLYNET.COM.BR writes:

> Hello,
>
>      I'm doing a little device to be attached to the paralell output of a
PC.
{Quote hidden}

2000\06\05@134217 by Dan Michaels

flavicon
face
Brusque wrote:
>Hello,
>
>    I'm doing a little device to be attached to the paralell output of a PC.
>I want to take the power to the device (5V, about 40mA max) from the
>paralell port.
>
>    I'm looking at some datas and it says the four control pins are
>open-collector. This means I cannot take +5V from it... :(
>
>    Anyone have already made something like this? How can I do that?
>

40 mA, good luck!! Drawing more than a couple of mA off an
Rs-232 or parallel port is usually more than can be hoped for.
Especially if you want the thing to work off more than just
the computer you initially used.

Open-collector means it "sinks" power, does not source it. It
wants/needs "your" juice.

Sometimes, however, you can get away with wiring several "source"
lines of the **same** voltage in parallel, with each connected thru
a small [eg, 10 ohm] resistor, for some minimal isolation. MAybe can
get a few mA from each, adding up to something usable.

- Dan Michaels
==============

2000\06\05@140912 by Arthur Brown

flavicon
face
Why not take the power from the keyboard conecter or a games port
40Ma from the printerPort is not easy to do, as some motherboards use open
collecter outputs if you reduce your Ma request you could take a small
voltage from unused datapins at the lower ttl high voltage.
Art
{Original Message removed}

'[EE]: [PIC]: How to measure level of liquids and s'
2000\06\05@141742 by Craig Lee

flavicon
face
I use a conductivity system with two probes referenced to a common probe
for sensing and controlling liquid levels.  The system is designed using
AC voltage to limit mineral plating to the electrodes.  I wouldn't want
to use it in a flamable liquid! It acts as kind of a Schmitt Trigger.
An output relay is turned on once the top electrode is emersed, and the
output is turned off once the lower electrode is out of the liquid.

Is this of interest to anyone?

{Original Message removed}

2000\06\05@143702 by Craig Lee

flavicon
face
Why not just use a float in a tube connected to an indexed rotary
encoder.  Counterbalance the float to a spring on the shaft of the
encoder, so that the float will extend the length of the tube unless
liquid is present.  Or instead of a spring, just counterbalance with
another weight.

Then just read the gray code.  Some of them even come with their own
counter and SPI interface, making it even easier to connect to a pic.
I'm using a unit that has 4096 transitions per revolution and there
are standard models that do 16384, so resolution certainly shouldn't
be an issue.

See http://www.opticalencoder.com for rotaries that might work for ya.

No Bernoulli issues, no ADC noise problems, no lookup tables, no calcs,
no plating, or liquid specific issues....


Craig


{Original Message removed}

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\05@143857 by Peter L. Peres

picon face
Hi Sean,

DC fed bulbs have been used in cinematography and other applications for
many years. These applications are noise-sensitive and there never were
bulb-related problems. The detector and the amplifier were the culprits in
evey case. The best approximation of an incandescent bulb run within
parameters is a black body radiator of the same temperature ;-) Assume
light is corpuscular and calculate the number of photons that reach your
detector from the solid angle of view. From this work out the shot noise.

I suspect that all other things being equal a LED may be quieter than a
blackbody (on account of bandwidth) and a laser even quieter (for the same
reason).

Note that over-volted small bulbs and certain halogen bulbs are not quiet.
This is because the filament is physically boiling (evaporating metal into
the gas filling) and because of strong convection currents in the gas
filling.

Once upon a time IR remote receivers were discrete-built and one way was
to feed a parallel LC tank directly from a PIN photodiode. I once made a
test circuit using a ZN414 and a 60 kHz tape bias tank pulled down to 40
kHz. It worked but the ZN414 is hard to come by. You could try a
monolithic AM radio IC using its IF section only. You can achieve gains of
60 dB easily like this and noise will be low even with a single tank.

I think that the extra noise you saw when shining the flashlight into the
detector is due to the changed input impedance of the circuit when the
photodetector is overloaded. This may change the way your filter works and
inject or amplify noise.

hope this helps,

       Peter

PS: If anyone knows where ZN414s can be had, or their equivalents, please
say so. I have a few ideas that would greatly benefit from this chip. Why
did they stop making it ?!

PS2: My postings are becoming longish. If anyone is bothered by this then
please say so.

'[EE]: 5V Logic Bypass caps - SMD value/phy size'
2000\06\05@164743 by Robert A. LaBudde

flavicon
face
part 0 1140 bytes
This suggests that lower capacitance a priori works better at higher speeds.

My understanding of the specifications suggests the opposite: for any make
of capacitor, higher capacitance always works better at any frequency.

What might be true is that certain types of capacitors are only available
in small denominations, and these types have lower ESR and ESI so they work
better at higher frequencies.

What's important is that the impedance of the capacitor be only 1 ohm or so
at the frequency of interest to reduce ripple at the current draw required.

</x-flowed>
Attachment converted: creation:capacitor impedance vs freq.gif (GIFf/JVWR) (00016199)
<x-flowed>================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: EraseMEralEraseMEspamlcfltd.com
Least Cost Formulations, Ltd.                   URL: http://lcfltd.com/
824 Timberlake Drive                            Tel: 757-467-0954
Virginia Beach, VA 23464-3239                   Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================
</x-flowed>

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\05@164750 by rottosen

flavicon
face
Peter:
Gateway Electronics (in the U.S.) has some surplus parts at their Denver
store. They have maybe 50 to 100 of them. Their main store in St. Louis
sometimes has more stock.

You can try

http://www.gatewayelex.com/

-- or --  the Denver store at 303-458-5444

They do mail order.


-- Rich




"Peter L. Peres" wrote:
{Quote hidden}

'[EE][PIC] Fast Serial Data'
2000\06\05@164949 by Martin McCormick

flavicon
face
       I recently have posted about building an audio delay
line using a PIC and the delay part plus a scheme to use a P.C.
to store  several minutes of audio looks possible.  Now for the
one awful problem.  I need to receive the digital audio from the
CODEC I am using  in order to be able to store it and send it
back out.  It is a 2-wire interface in which there is a
64-kilobit/sec clock and a data stream that synchronizes to each
clock cycle.  Should the USART on a 17C43 be able to clock in
those data and then deliver an interrupt every 8 bits received?
I hate to try to interrupt the PIC 64,000 times per second at
16.384 MHZ because that only leaves about 31 operations between
interrupts and I see nothing but trouble ahead.

       If one could handle the data as bytes, that would make
everything lots easier.

       In case anybody else is interested in particulars, the
CODEC is a MX-com.com MX639 which is relatively new.  If the
USART can't be used in this way, I will probably use a 16C64
instead due to the number of I/O lines for other parts of the
project.  So, it boils down to the best way to handle the 64,000
bit/S pounding that is going on all the time.

       I also have, on hand, some 4-bit shift registers and
CD4017 decade counters that could be made to reset after the 8TH
bit if everything else fails.  The CD4017 would trigger an
interrupt to tell the PIC to handle a new byte.

       If you want to read about the CODEC, goto

http://www.mxcom.com/

To read about how it works,

http://www.mxcom.com/app_notes/apcvsdr2.pdf

       None of this info will help in answering my question, but
I figured I would try to provide some useful information to
others while asking for some, myself.  Thank you all.

Martin McCormick

'[EE]: RESPONSE: 5V Logic Bypass caps - SMD valu'
2000\06\05@175206 by James Paul

flavicon
face
All,

Capacitors exhibit reactance when excited by alternating current.
This reactance opposes changes in voltage.   If the capacitance
value remains constant, and frequency is increased, the amount of
this reactance goes down.   Likewise, the opposite is true, that
if the capacitance remains constant, and frequency is decreased,
reactance goes up.   This shows that Capacitive Reactance is
Inversely Proportional to Frequency.   Now, lets say we have chosen
our capacitor value to give us a specific reactance value at a given
frequency.  And this frequency is the lowest we have to deal with.
In this case, as frequency goes up, reactance goes down, and the
impedance gets lower.  In bypassing, this means that as frequency
goes up, the capacitor acts as more of a short than at lower
frequencies.

So, the statement

"This suggests that lower capacitance a priori works better at
 higher speeds."

is somewhat correct.  What it really means is that you need less
capacitance at higher frequencies to get the same value of reactance
that you get with a larger capacitor at lower frequencies.


The statement:

My understanding of the specifications suggests the opposite: for
any make of capacitor, higher capacitance always works better at
any frequency.

also is somewhat true.  From a capacitive reactance point of view,
the higher the frequency, the less the capacitive reactance of any
capacitor.   Therefore the above statement is true.  But, there are
other losses that are also frequency dependent.  The most obvious is
INDUCTANCE.  This is directly proportional to frequency, and opposes
a change in current.  So, at some point, what you gain in lower
capacitive reactance will be offset some by an increase in Inductive
reactance.   Therefore, you have the potential for any degree of
inefficiency.  So in this respect, the above statement is not true.

The statement:

What might be true is that certain types of capacitors are only
available in small denominations, and these types have lower ESR
and ESI so they work better at higher frequencies.

Is basically true.  ESR and ESI have the most effect on Q, which
translates to effeciency. Of course this means overall effeciency,
not just at a given frequency or range of frequencies.  It reduces
the amount of heat generated inside tha cap which means that less
energy is consumed by the cap and transformed into heat, which
indicates higher effeciency.

Just my 2 cents worth.   Sorry for butting in uninvited.


                                       Regards,

                                         Jim







On Mon, 05 June 2000, "Robert A. LaBudde" wrote:

{Quote hidden}

spamBeGonejimspam_OUTspam.....jpes.com

2000\06\05@175209 by James Paul

flavicon
face
All,

Capacitors exhibit reactance when excited by alternating current.
This reactance opposes changes in voltage.   If the capacitance
value remains constant, and frequency is increased, the amount of
this reactance goes down.   Likewise, the opposite is true, that
if the capacitance remains constant, and frequency is decreased,
reactance goes up.   This shows that Capacitive Reactance is
Inversely Proportional to Frequency.   Now, lets say we have chosen
our capacitor value to give us a specific reactance value at a given
frequency.  And this frequency is the lowest we have to deal with.
In this case, as frequency goes up, reactance goes down, and the
impedance gets lower.  In bypassing, this means that as frequency
goes up, the capacitor acts as more of a short than at lower
frequencies.

So, the statement

"This suggests that lower capacitance a priori works better at
 higher speeds."

is somewhat correct.  What it really means is that you need less
capacitance at higher frequencies to get the same value of reactance
that you get with a larger capacitor at lower frequencies.


The statement:

My understanding of the specifications suggests the opposite: for
any make of capacitor, higher capacitance always works better at
any frequency.

also is somewhat true.  From a capacitive reactance point of view,
the higher the frequency, the less the capacitive reactance of any
capacitor.   Therefore the above statement is true.  But, there are
other losses that are also frequency dependent.  The most obvious is
INDUCTANCE.  This is directly proportional to frequency, and opposes
a change in current.  So, at some point, what you gain in lower
capacitive reactance will be offset some by an increase in Inductive
reactance.   Therefore, you have the potential for any degree of
inefficiency.  So in this respect, the above statement is not true.

The statement:

What might be true is that certain types of capacitors are only
available in small denominations, and these types have lower ESR
and ESI so they work better at higher frequencies.

Is basically true.  ESR and ESI have the most effect on Q, which
translates to effeciency. Of course this means overall effeciency,
not just at a given frequency or range of frequencies.  It reduces
the amount of heat generated inside tha cap which means that less
energy is consumed by the cap and transformed into heat, which
indicates higher effeciency.

Just my 2 cents worth.   Sorry for butting in uninvited.


                                       Regards,

                                         Jim







On Mon, 05 June 2000, "Robert A. LaBudde" wrote:

{Quote hidden}

spamjimspamjpes.com

'[EE]: 5V Logic Bypass caps - SMD value/phy size'
2000\06\05@181949 by David VanHorn

flavicon
face
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1


>This suggests that lower capacitance a priori works better at higher speeds.
>
>My understanding of the specifications suggests the opposite: for any make
>of capacitor, higher capacitance always works better at any frequency.

That would be true if they didn't have internal inductance that is
proportional to the capacitance.


>What might be true is that certain types of capacitors are only available
>in small denominations, and these types have lower ESR and ESI so they work
>better at higher frequencies.

Smaller values of C have smaller internal inductance, in any given package.

>What's important is that the impedance of the capacitor be only 1 ohm or so
>at the frequency of interest to reduce ripple at the current draw required.

More properly, as low as possible.
A cap with a Z of 1 ohm won't do a lot in a circuit with comparable impedance.

My measurements were made in a 50 ohm system, (stripline on G-10 PCB)
Thinner tracks will be higher impedance, and a given cap will perform
better with higher track impedances. (provided of course proper layout!)




- --
Are you an ISP?  Tired of spam?
http://www.spamwhack.com  A pre-emptive strike against spam!

Where's Dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 6.5.2 for non-commercial use <http://www.pgp.com>

iQA/AwUBOTwuX4FlGDz1l6VWEQIPTwCgzEADRcyP8C1eqBuDk5XTSUVItkMAn2/d
K2s8iHnukYHW+IXXXIIeN/Zn
=F570
-----END PGP SIGNATURE-----

2000\06\05@182604 by rottosen

flavicon
face
Robert:
If you look at the curves that you included you will see that the 0.1uf
capacitor has lower impedance at 10000 KHz then the 1uf capacitor. This
is because the inductance of larger value capacitors is larger than
smaller value capacitors.

Also I think that the value of 1 ohm is somewhat arbitrary and does not
apply well in many cases, especially high gain or high power circuits.

-- Rich


"Robert A. LaBudde" wrote:
{Quote hidden}

'[EE]: Paralell port powered little device.'
2000\06\05@184523 by Bob Ammerman

picon face
Dongles manage to scrape up a usable amount of current out of a parallel
port!

My handy-dandy PC tech ref identifies pin 35 on a standard 36 pin centronic
printer cable as +5V via 3K3 ohms. This pin does not appear on the DB25 at
the PC end though.

Bob Ammerman
RAm Systems
(high performance, high function, low-level software)

2000\06\05@190218 by Edson Brusque

face
flavicon
face
Hello all,

Arthur Brown wrote:
>Why not take the power from the keyboard conecter or a games port
>40Ma from the printerPort is not easy to do, as some motherboards use open
>collecter outputs if you reduce your Ma request you could take a small
>voltage from unused datapins at the lower ttl high voltage.

   Take power from the keyboard connector seens to be the option. I could
make an adapter using a pair of din connectors and take the signals from pin
4 (GND) and pin 5 (+5VDC/VCC) to power my little gadget. What about using a
pair of resistors (say, 47R)in series with the GND and VCC to limit the
current in case of short-circuit?

   Best regards,

   Brusque

'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\05@193141 by Arthur Brown

flavicon
face
Try putting tx & rx in a tube so as to shade from sunlight make sure you use
lens with the right focal lenth.
Firm I worked for used this over 250ft.

Regards Art

{Original Message removed}

'[EE]: Paralell port powered little device.'
2000\06\05@195846 by Mark Willis

flavicon
face
I have seen more than one Parallel Port card modified such that the DB25
connector's pin 18 is re-defined as +5V (even one re-wired to have +12V
on there IIRC.)  IF you do that, document it WELL, hang a notice tag off
the card and off the printer cable, and still expect to some day have
problems (Fuse the +V line going into DB25 pin 18, ok?)

Try to cut down from 40mA, definitely, if you want to power off the
parallel port.  And check for patents on this (I know one local company
(?IQ Technologies?) had patented this same trick on Serial Ports.)  I'd
bet Parallel Technologies might have a patent here, if IQ Tech doesn't?
(Worked with both places somewhat.)  Not a problem for personal
non-profit use, though.  (It's been a while since then!)

Tricks here:  Have your PC-based code intentionally drive all of these
data lines high, as much as possible.  Siphon power off each of these
pins with a Schottky.  Cap right off those to supply power to the
device.  Obviously you have to do this intelligently...

With 8 pins, you can probably get ~4.6V while drawing 16-20 mA (as an
estimated upper limit.)  Use a plug-in Parallel Port card for this in
case you blow the card up.  Obviously, your protocol has to have room in
it for some of the data lines to be pulled up most of the time from the
PC side - Think "Pull all 8 lines high when in Idle state."  If you can
get by with less current, obviously you only need to pull the lines you
have diodes on, high.

Earlier PC ParPort's Data Out pins: 74LS374 octal latch, sources 2.6 mA
MAX, damaged if pulled low too hard.  Don't want to use a 10,000uF cap
on the other side of those Schottky's, 1uF or so is about it IIRC.  (it
HAS been a while.)

 2   D0          Data Bit 0
 3   D1          Data Bit 1
 4   D2          Data Bit 2
 5   D3          Data Bit 3
 6   D4          Data Bit 4
 7   D5          Data Bit 5
 8   D6          Data Bit 6
 9   D7          Data Bit 7

You cannot do too much with these, as they're OC Outputs (7405's
originally.)
 1  /STROBE      Strobe
14  /AUTOFD      Autofeed
16  /INIT        Initialize
17  /SELIN       Select In

I'll second Arthur's idea - Joystick port will source quite a lot of
current (Ahem, it's NOT fused inside the PC, usually, and the smell of
smoking ribbon cable's NOT very nice, so be careful you wire it right.)

Keyboard port's also do-able (I'm about to put a laptop on my tech
bench, with an adapter inline with the keyboard cable.)  Buy a
polyswitch to replace the (usually 2A) keyboard picofuse WHEN you blow
it, ask if I can help you fix your laptop.  And I can find those fuses
if you cannot <G>

For information:
http://home.rmi.net/~hisys/parport.html
http://www.senet.com.au/~cpeacock/  has MOVED to
http://www.beyondlogic.org/ - that's Craig Peacock's pages, GOOD info,
take a look as it's better IMO than before
http://ftp.sunet.se/hwb/ for pinouts on most everything else, BTW <G>

 Mark

Edson Brusque wrote:
{Quote hidden}

--
I re-ship for small US & overseas businesses, world-wide.
(For private individuals at cost; ask.)

2000\06\05@203020 by Mark Willis

flavicon
face
Edson Brusque wrote:
> Hello all,
>
> Arthur Brown wrote:
> >Why not take the power from the keyboard conecter or a games port
> >40Ma from the printerPort is not easy to do, as some motherboards use open
> >collecter outputs if you reduce your Ma request you could take a small
> >voltage from unused datapins at the lower ttl high voltage.
>
>     Take power from the keyboard connector seens to be the option. I could
> make an adapter using a pair of din connectors and take the signals from pin
> 4 (GND) and pin 5 (+5VDC/VCC) to power my little gadget. What about using a
> pair of resistors (say, 47R)in series with the GND and VCC to limit the
> current in case of short-circuit?
>
>     Best regards,
>
>     Brusque

Why 2 resistors?  And why 47R (1.88V drop at 40mA - Apiece!)

I'd suggest perhaps 10R instead, 0.4V drop at 40mA, but then your Isc is
0.5A and your keyboard fuse probably will be safe.

 Mark

2000\06\05@204932 by Bob Ammerman

picon face
----- Original Message -----
From: Mark Willis <EraseMEmwillisspamBeGonespamspamFOXINTERNET.NET>
To: <KILLspamPICLISTspamMITVMA.MIT.EDU>
Sent: Monday, June 05, 2000 8:28 PM
Subject: Re: [EE]: Paralell port powered little device.


> Edson Brusque wrote:
> > Hello all,
> >
> > Arthur Brown wrote:
> > >Why not take the power from the keyboard conecter or a games port
> > >40Ma from the printerPort is not easy to do, as some motherboards use
open
> > >collecter outputs if you reduce your Ma request you could take a small
> > >voltage from unused datapins at the lower ttl high voltage.
> >
> >     Take power from the keyboard connector seens to be the option. I
could
> > make an adapter using a pair of din connectors and take the signals from
pin
> > 4 (GND) and pin 5 (+5VDC/VCC) to power my little gadget. What about
using a
{Quote hidden}

Of course, at 0.5A, your 10R resistor will end up dissipating 2.5W, which is
quite enough to turn a 1/4W (and probably even a 1/2W) resistor into a fuse!
You might be better off with an actual low-current fuse or polyswitch
device.

Bob Ammerman
RAm Systems
(high performance, high function, low-level software)
[And occasionally a little (digital) hardware :-) ]


>   Mark

2000\06\05@211456 by Dale Botkin

flavicon
face
On Mon, 5 Jun 2000, Edson Brusque wrote:

>     Take power from the keyboard connector seens to be the option. I could
> make an adapter using a pair of din connectors and take the signals from pin
> 4 (GND) and pin 5 (+5VDC/VCC) to power my little gadget. What about using a
> pair of resistors (say, 47R)in series with the GND and VCC to limit the
> current in case of short-circuit?

You definitely do want to limit the current.  Most system boards have a
picofuse on the keyboard Vcc line.  If you draw too much, you blow the
fuse -- which results in what appears to the consumer as a dead
motherboard.  Not a nice thing for anyone concerned.  Yeah, a techie can
find & replace the fuse, but not Joe Average.

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

2000\06\05@213411 by rottosen

flavicon
face
I have posted an example of a minimal PIC circuit I built a long time
ago that draws a fraction of a milliamp from the parallel port.

See   http://www.idcomm.com/personal/ottosen/  under the Stupid PIC
Tricks heading for the "Printer Tester".

Good luck getting more than a milliamp or so. Designing the circuit for
operation using a low voltage version of the PIC and other circuits
should help some though.

-- Rich



Dan Michaels wrote:
{Quote hidden}

2000\06\05@222045 by William Chops Westfield

face picon face
Nowdays, you could consider getting power from the USB ports, I think...

BillW

2000\06\05@223521 by Bob Ammerman

picon face
USB guarantees 100ma on each port!

(500ma for 'high power devices, but you need a real USB device to request
the power and not all environments actually support the higher power).

Bob Ammerman
RAm Systems
(high performance, high function, low level software)


----- Original Message -----
From: William Chops Westfield <billwspam_OUTspamspamCISCO.COM>
To: <PICLISTspamspam@spam@MITVMA.MIT.EDU>
Sent: Monday, June 05, 2000 10:18 PM
Subject: Re: [EE]: Paralell port powered little device.


> Nowdays, you could consider getting power from the USB ports, I think...
>
> BillW

'[EE]: RESPONSE: 5V Logic Bypass caps - SMD valu'
2000\06\06@042146 by Russell McMahon

picon face
>> At 10:49 AM 6/2/00 -0700, Dave wrote:
>> > >Has anyone found/experimented with the optimum size capacitance
>> > >value and/or physical size for use in/around a microprocessor?
>> >
>> >You want the caps to absorb well at the third harmonic of the clock.
>> >0.1uF does well at 3 MHz, 0.01 at 30. 0.001 at 300.
>> >It's a broad response, so dont think that there's one specific value.
>> >However, if you use 0.1uF on a 20 MHz part, you won't get the supression
>> >that you could if you used 0.047uF.
>>
>> This suggests that lower capacitance a priori works better at higher
speeds.
>>
>> My understanding of the specifications suggests the opposite: for any
make
>> of capacitor, higher capacitance always works better at any frequency.
>>
>> What might be true is that certain types of capacitors are only available
>> in small denominations, and these types have lower ESR and ESI so they
work
>> better at higher frequencies.
>>
>> What's important is that the impedance of the capacitor be only 1 ohm or
so
>> at the frequency of interest to reduce ripple at the current draw
required.


Practical capacitors are unfortunately not purely capacitive nature.
They also have inductive and resistive components.
Larger value capacitors generally have higher internal inductance and lead
inductance than smaller valued capacitors of the same type.
Consequently the impedance of a given capacitor will generally have a a
minimum at a certain frequency and the impedance will be higher and both
lower and higher frequencies. The rule of thumb that was mentioned above is
in the order of correct for ceramic capacitors.
ie The "correct" value with short leads for decoupling in the MHz plus
region is around 0.1uF. As the frequency rises a smaller capacitor will be
optimum.
The excessively enthused can even specify capacitors based on the series
resonant combination of lead lengths and capacitance.
ARRL handbook gives these figures for series resonance (optimum bypassing)
for disk ceramics with total lead lengths of 0.5 inch.

Cap uF     Freq MHz

0.01            15
.0047          22
.002            38
.001            55
.0005          80
.0001        165

Sounds like we should be using 100 pF decoupling with 100 MHz Scenix's ! :-)

RF practice (and serious microprocessor practice in some cases) is to group
several capacitors of different values together to combine the
characteristics of each = effectively a rather broad bandpass filter. Use of
small ceramics and larger valued distributed electrolytics (tantalum for the
brave, solid aluminium for the wise, wet electrolytic for the adventurous)
can be useful.



RM

'[EE]: Filter Capacitors'
2000\06\06@090115 by Mark Peterson

flavicon
face
In many products, I see a large electrolytic capacitor in parallel with a
small disc or dipped capacitor.  Why is that done?  Obviously, the pair
does not act as a single large capacitor, or aonly a single one would be
used.  Just how does that arrangement work?

Mark P

2000\06\06@091810 by Arthur Brown

flavicon
face
hi Paul
The same way as multiple capacitors on a circuit board. Interference can be
from one chip to the next via the supply, so you put a capacitor across the
supply pins of each chip as close to the chip as possible.
The large capacitor can remove some ripple from the supply while the smaller
capacitor deals with spikes the value and where placed play apart in this.
As does the path of tracks around the board.
Regards Art

----- Original Message -----
From: Mark Peterson <spamBeGonemarkp.....spamCANNONTECH.COM>
To: <.....PICLIST@spam@spamMITVMA.MIT.EDU>
Sent: Tuesday, June 06, 2000 5:58 AM
Subject: [EE]: Filter Capacitors


> In many products, I see a large electrolytic capacitor in parallel with a
> small disc or dipped capacitor.  Why is that done?  Obviously, the pair
> does not act as a single large capacitor, or aonly a single one would be
> used.  Just how does that arrangement work?
>
> Mark P

2000\06\06@092403 by Peter Betts

picon face
Simply, Low frequency noise or fluctuations on the power supplies are
smoothed over as the LARGE capacitor sources extra current into the circuit
or sinks extra current keeping the supply to the ciruit more or less
constant.
It acts as a big reservoir of power.

High frequency noise is filtered out by adding a smaller capacitor which
dumps the excess noise onto the ground (0V)

There's probably some equation for it but I basically always put a 100uF cap
on for the low freq's and a 100nF for the high frequecies. It's worked on
all my projects so far.

Pete

> {Original Message removed}

2000\06\06@095322 by M. Adam Davis

flavicon
face
The smaller cap generally has different characteristics than the large.  For
instance, you will rarely (if ever) see two ceramic caps in parallel, or two
electrolytics in parallel (unless the designer wanted a weird value, or space
considerations dictated such a design) for electrical reasons.  What you may see
is an electrolytic (higher internal resistance, can't react very fast to
small/short transients) in parallel with a ceramic (low capacitance, low
resistance, can't handle large/long transients).

-Adam

Mark Peterson wrote:
>
> In many products, I see a large electrolytic capacitor in parallel with a
> small disc or dipped capacitor.  Why is that done?  Obviously, the pair
> does not act as a single large capacitor, or aonly a single one would be
> used.  Just how does that arrangement work?
>
> Mark P

2000\06\06@103719 by Mike Witherden

flavicon
face
Hi,

Put simply: The large electrolytic capacitor acts as a short for low frequencies.
and the small disc or dipped capacitor acts as a short for high frequencies.

In other words the Impedance/Frequency  characteristics of the two
types of caps are vastly different.

MikeW


>>> @spam@markpspamCANNONTECH.COM 06/06/00 02:58PM >>>
In many products, I see a large electrolytic capacitor in parallel with a
small disc or dipped capacitor.  Why is that done?  Obviously, the pair
does not act as a single large capacitor, or aonly a single one would be
used.  Just how does that arrangement work?

Mark P

2000\06\06@110207 by Spehro Pefhany

picon face
At 07:58 AM 6/6/00 -0500, you wrote:
>In many products, I see a large electrolytic capacitor in parallel with a
>small disc or dipped capacitor.  Why is that done?  Obviously, the pair
>does not act as a single large capacitor, or aonly a single one would be
>used.  Just how does that arrangement work?
>
>Mark P

It does act as a single large capacitor. Have you ever (deliberately or
inadvertently) ;-)  taken an electrolytic capacitor apart? The plates are
coiled together. This construction has a significant amount of
inductance, which is like a series inductor (and there is a series
resistance as well) in series with an ideal capacitor.

So, at low frequencies the added impedance of the series inductance is
negligible, the e-cap acts pretty much like an ideal capacitor (
just some series resistance). At very high frequencies
the impedance of the e-cap may start to rise significantly because of the
inductance, and the ceramic capacitor shunting it may begin to dominate the
parallel impedance. Some e-caps are better than others, this is not
always necessary.




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speffRemoveMEspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
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2000\06\06@112332 by riest

flavicon
face
Large capacitors are to 'slow' to handle fast transients.
So often you see a small (10uF) next to a large one.
Just filtering spices and all other high freqentcy crap out of
the power supply that the large one can't handle.

Ries

'[EE]: RESPONSE: 5V Logic Bypass caps - SMD valu'
2000\06\06@115450 by David VanHorn

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{Quote hidden}

I'm not sure where the ARRL got this data, it more-or-less follows my
measurements, but I would have said 30 at 0.01.  Maybe they were thinking
of second harmonic?

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'[EE]: Filter Capacitors'
2000\06\06@115838 by David VanHorn

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At 07:58 AM 6/6/00 -0500, Mark Peterson wrote:
>In many products, I see a large electrolytic capacitor in parallel with a
>small disc or dipped capacitor.  Why is that done?  Obviously, the pair
>does not act as a single large capacitor, or aonly a single one would be
>used.  Just how does that arrangement work?

They are telling you that they expect to draw large current pulses
(probably driving something connected to the I/O pins) in addition to the
switching currents for the uP.
The large cap is good at providing a lot of current over a relatively long
time, but it's internal impedance is too high to provide a lot of current
over very short time intervals, so they add the small cap.

Warning: Bypassing is very often done wrong, so don't take what you see as
gospel.
Believe instead, what you measure, or read Art of Electronics :)

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2000\06\06@121729 by Harold M Hallikainen

picon face
       The equivalent series resistance and inductance on the electrolytics are
fairly high, making them not do much for high frequencies. The ceramic
capacitor presents a low impedance for high frequencies while the
electrolytic presents a low impedance for low frequencies.

Harold

On Tue, 6 Jun 2000 07:58:32 -0500 Mark Peterson <spammarkpspamCANNONTECH.COM>
writes:
> In many products, I see a large electrolytic capacitor in parallel
> with a
> small disc or dipped capacitor.  Why is that done?  Obviously, the
> pair
> does not act as a single large capacitor, or aonly a single one
> would be
> used.  Just how does that arrangement work?
>
> Mark P

FCC Rules Online at http://hallikainen.com/FccRules
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'[EE]: Paralell port powered little device.'
2000\06\06@121732 by Harold M Hallikainen

picon face
       Has anyone seen these keyboard power splitters available commercially?
I've seen them packaged with some products, but have not seen them on
their own. Also, the ones I've seen have been for the old "big DIN"
connector, not the new "little DIN". Do they exist for the little DIN?
Finally, you can use a PTC thermistor for overcurrent protection without
getting as much voltage drop as with the suggested resistor.

Harold



On Mon, 5 Jun 2000 19:29:36 -0300 Edson Brusque <brusquespam_OUTspamTakeThisOuTFLYNET.COM.BR>
writes:
{Quote hidden}

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'[EE]: Filter Capacitors'
2000\06\06@133323 by Mitchell D. Miller

picon face
Dave,

> Warning: Bypassing is very often done wrong, so don't take what you see as
> gospel.

Can you describe what you see very often that's wrong?

-- Mitch

2000\06\06@135522 by Peter Schultz

flavicon
face
What he is trying to say about a rule of thumb. Common practice is a few
extra capacitor does not hurt.
Most of the cases filtering is over done and try to compensate for bad
layout, grounding systems....
Nice example is a high-end audio preamplifier, takes about 50 ma current
from the power supply, which was filtered by 22000 uF capacitors....
Peter



-----Original Message-----
From: Mitchell D. Miller [spam_OUTmdmiller2@spam@spamRemoveMEHOME.COM]
Sent: Tuesday, June 06, 2000 10:30 AM
To: spamPICLISTspamspamMITVMA.MIT.EDU
Subject: Re: [EE]: Filter Capacitors


Dave,

> Warning: Bypassing is very often done wrong, so don't take what you see as
> gospel.

Can you describe what you see very often that's wrong?

-- Mitch

2000\06\06@140809 by David VanHorn

flavicon
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>Can you describe what you see very often that's wrong?

Well...

Bypasses should be located at the chip's ground pin.
Power should be routed to the cap, and then to the chip from the cap.
Anything else compromises the bypass.

Sockets with caps in them are marginally better than nothing at all (see
above), but it's even worse, because you've provided a path past the cap on
the ground side as well.

It's hard to show this without pictures, but a cap with tracks or leads out
to power and ground tracks, especially thick ones, is much less than
optimum.  You really want the current to be forced to walk across that cap.
Ideally, three-leaded caps (from murata or panasonic) with the center lead
as ground, and the other two treated as "in" and "out".

In many systems, you'll see a pair of tracks between rows of chips, with
caps across the tracks, and one track supplying VCC to row 2 while the
other supplies gnd to row 1.
While this system looks nice at first glance, it really is very noisy.
(look at where the current flows when a given chip needs a pulse of current)

The common practice of putting a 0.1uF on everything is probably better
than not bypassing anything, but it's far from ideal. The size of bypass
caps is related to what frequencies you want them to be low impedance for.
You need to tailor the bypassing for each "consumer".

Adding large value tantalums without a specific need is mostly a waste of
money.

Using fat power tracks can be bad.  Narrow tracks are higher impedance to
high frequencies, but are the same DC resistance (close anyway).  I use a
wide track from the chip to it's bypass cap(s) and a narrow track from
there back to system power. This is because in the high frequency domain, I
want the current to come from the bypass cap, not from the system buss.


The ground return is just as important as the power. You need to make sure
that the chip not only has a low Z ground, that ground needs to get
directly back to where VCC came from.  If for example, you have a chip
bypassed perfectly, but it has a long path to get back to the sourcing cap
at the regulator, you will have a noisy system.  The noise current will
flow around the system, and find it's way back to the reg cap eventually.
If you have a system that is noisy, and it gets worse with cables plugged
in, or with long leads attached to "ground" pads, this is usually why.  If
you have a chip driven by fast signals from another chip, then there needs
to be a low Z ground between them as well. It becomes clear when you think
of cmos inputs as capacitors (which they are) driven by switches on the
other end of the line. That charging current coming out of the destination
chip's ground has got to return to the source chip somehow!  Wouldn't you
rather pick the path?

Microprocessor crystal caps should be connected by an isolated track to the
uP's ground pin. Not to anywhere else.  The current in that oscillator can
make a nice transmitter, especially if it's coupled into a nice low
impedance ground track an inch or so away.  I've seen systems fail part 15
for that alone, when the ground track happened to be a resonant length on
some harmonic of the xtal.


I may have missed a couple, but that's a pretty good "rouge's gallery" of
bypassing mistakes.


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2000\06\06@141627 by David VanHorn

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At 10:53 AM 6/6/00 -0700, Peter Schultz wrote:
>What he is trying to say about a rule of thumb. Common practice is a few
>extra capacitor does not hurt.
>Most of the cases filtering is over done and try to compensate for bad
>layout, grounding systems....

Extra caps will not save a bad layout. It's like bigger engines on the
titanic.
Occasionally, accidentally, you may hit something that makes the problem
look better by shifting it somewhere else.

>Nice example is a high-end audio preamplifier, takes about 50 ma current
>from the power supply, which was filtered by 22000 uF capacitors....

Great example of bad bypassing.
If these large caps were perfect, then this would be a good idea.
It would be very interesting to sweep them, and see where they are really
acting as low impedance capacitors. I suspect they are very effective at
60-120 hz, (of course good regulation would do far more to eliminate PS hum
than large caps)  but up at 10-40kHz, they may not be any more effective
than maybe 100uF (not sure here, I haven't made the measurement on such
large caps, and it would be pretty specific to type)


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2000\06\06@143933 by Peter Schultz

flavicon
face
Dave,
You absolutely right, it will not save a bad layout, but that is what people
think.
We have oscillation on this board, let put more filtering, isn't that sounds
familiar ?
Peter


{Original Message removed}

2000\06\06@145620 by David VanHorn

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At 11:38 AM 6/6/00 -0700, Peter Schultz wrote:
>Dave,
>You absolutely right, it will not save a bad layout, but that is what people
>think.
>We have oscillation on this board, let put more filtering, isn't that sounds
>familiar ?
>Peter


Oh yeah!!

Worst is where I see them added!  Like putting a cap to ground (some
arbitrary point in the ground system) from a signal line, to "smooth it
out"... Grrr. Now the driver needs much more current on each transition,
and the problem is worse.

Resistance in series solves this problem, but it's not so convenient to
implement usually. (Tip: high speed clock lines should always have a
resistor at the source. Even if later you choose the value to be zero,
though likely 100 ohms will be better)



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'[EE]:AT Keyboard Problem Solved!'
2000\06\06@153538 by mike

flavicon
picon face
On 6 Jun 00, at 0:07, Automatic digest processor wrote:

> Date:    Mon, 5 Jun 2000 22:12:49 -0400
> From:    John Hansen <@spam@johnspam_OUTspamHANSEN.NET>
> Subject: AT Keyboard Problem Solved!
>
> Thanks to everyone who offered suggestions about how to help me solve
> the
> problem of hooking up an AT keyboard to a PIC.  I have found the problem
> and I thought that I would report the results back

Ah.. Umm  yes, I thought it might be ;-)  Is'nt it annoying when
something as simple as this causes such confusion... Thanks
for the feedback John

'[EE]: Filter Capacitors'
2000\06\06@162421 by Harold M Hallikainen

picon face
       I seem to recall reading of the development of the first disk drives at
IBM inSan Jose. Rather than look at control system theory and stable
feedback loops, someone figured that a vibrating head positioner could be
fixed by putting a capacitor across the actuator. After the "fix", it
shoved the head through the side of the drive.

Harold

On Tue, 6 Jun 2000 11:38:08 -0700 Peter Schultz <.....PeterSspam.....MINIMED.COM>
writes:
{Quote hidden}

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2000\06\06@165306 by David VanHorn

flavicon
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At 12:40 PM 6/6/00 -0700, Harold M Hallikainen wrote:
>        I seem to recall reading of the development of the first disk
drives at
>IBM inSan Jose. Rather than look at control system theory and stable
>feedback loops, someone figured that a vibrating head positioner could be
>fixed by putting a capacitor across the actuator. After the "fix", it
>shoved the head through the side of the drive.

ROTFLMAO!!


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2000\06\06@170007 by Severson, Rob

flavicon
face
>         I seem to recall reading of the development of the
> first disk drives at
> IBM inSan Jose. Rather than look at control system theory and stable
> feedback loops, someone figured that a vibrating head
> positioner could be
> fixed by putting a capacitor across the actuator. After the "fix", it
> shoved the head through the side of the drive.

Am I correct in understanding, then, that this fixed the vibration problem?

<smirk>

2000\06\06@170811 by David VanHorn

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>Am I correct in understanding, then, that this fixed the vibration problem?
>
><smirk>

This could indeed be seen as a specification problem, rather than a design
problem.
I'm sure that after the application of the "fix" vibration was no longer a
problem.


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'[EE]: Noise in phototransistors/photodiodes/light'
2000\06\06@181513 by Sean Breheny

face picon face
Thanks to all who responded to this question. As usual, I didn't make
myself clear enough, so many of the proposed solutions are not applicable
in this case. Let me explain.

I am a model rocket enthusiast (as are many fellow piclisters, as I have
seen in previous threads), and for a long time I have wanted to try a
project where some kind of control was added to a model rocket. The most
obvious thing (of any significant challenge level) is to try to get the
rocket to hit or pass near to a target suspended in the air (by several
helium balloons).

So, what I have decided to do is to make the target consist of an array of
IR leds, pulsed any way we want (however is best). A four-channel receiver
goes into the rocket's nose and by placing light baffels in the right
positions, the onboard PIC (yes, it involves a PIC ;-) can get a rough idea
of its angle relative to the target by seeing which of the four receivers
is receiving light from the target. Two micro servos would then operate
control fins in an attempt to guide it to the target.

Because of the large number of variables, I can't guarantee the orientation
of the rocket with respect to the target, so I can't collimate the beam
from the target or put all the LEDs pointing in the same direction, etc. In
addition, because of size constraints in the rocket(four receivers have to
fit in a 1.8 inch diameter tube), I don't think it is feasible to use
lenses on the receiver photodiodes/phototransistors.

As I said before, I was able to get the receiver to detect the target at
about 100 feet (perhaps a bit more), so I don't need a really huge
improvement (about a factor of 8 or so in signal to noise ratio should
probably do it).

So, as you can see, this is not a communications system, and I can't put
the receiver and transmitter in tubes with lenses ;-)

I haven't exhausted all my own ideas on this yet, but I thought I would ask
to save myself the trouble if someone had a really good idea. Please do
give me any suggestions you have.

By the way, I have been working on this for quite some time, but I
hesitated to post it for fear that people would think I was trying to work
on a real guided missile. Rest assured, it carries no explosive, has a
ceiling of about 300 feet, and it's guidance system is not practical for
military applications.

Sean

At 12:30 AM 6/6/00 -0700, Arthur Brown wrote:
>Try putting tx & rx in a tube so as to shade from sunlight make sure you use
>lens with the right focal lenth.
>Firm I worked for used this over 250ft.
>
>Regards Art
>

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
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'[EE]: Filter Capacitors'
2000\06\06@183348 by Erik Reikes

flavicon
face
FYI This has to do with the ESR of the caps.  For an ideal capacitor model,
a large cap would work even better for high freq. than a small cap.  In
practice there is an internal resistance that makes large electrolytics
good for damping low freq. (near DC) noise, and small ceramic caps better
for getting rid of high frequency noise.





At 02:16 PM 6/6/00 -0700, you wrote:
>hi Paul
>The same way as multiple capacitors on a circuit board. Interference can be
>from one chip to the next via the supply, so you put a capacitor across the
>supply pins of each chip as close to the chip as possible.
>The large capacitor can remove some ripple from the supply while the smaller
>capacitor deals with spikes the value and where placed play apart in this.
>As does the path of tracks around the board.
>Regards Art
>
>{Original Message removed}

2000\06\06@222730 by Dan Michaels

flavicon
face
David VanHorn wrote:
....
>Sockets with caps in them are marginally better than nothing at all (see
>above), but it's even worse, because you've provided a path past the cap on
>the ground side as well.
>

I've read that the long tiny leads on the caps in this case
represent such a large inductance that this kind of socket is
quite useless at higher frequencies.
==============

>It's hard to show this without pictures, but a cap with tracks or leads out
>to power and ground tracks, especially thick ones, is much less than
>optimum.
......
>Using fat power tracks can be bad.  Narrow tracks are higher impedance to
>high frequencies, but are the same DC resistance (close anyway).  I use a
>wide track from the chip to it's bypass cap(s) and a narrow track from
>there back to system power. This is because in the high frequency domain, I
>want the current to come from the bypass cap, not from the system buss.
>

Interesting observations here. But this makes it sound like going to
"ground planes" would be the worst thing imaginable. I've read in the books
that narrow buss traces might cause a problem regarding "return currents"
for the "signals" routed from one chip to the next. Narrow traces -->
larger inductive loops --> more EMI/noise transmission.

Can you comment on this ??? [also see next]
================

{Quote hidden}

This kinda sounds opposite to what you said in the previous paragraph.

Solution --> narrow Vcc, but wide gnd leads ????? Can you illuminate??

Cheers,
- Dan Michaels
Oricom Technologies
===================

2000\06\06@222740 by Dan Michaels

flavicon
face
Harold wrote:
>        I seem to recall reading of the development of the first disk drives at
>IBM inSan Jose. Rather than look at control system theory and stable
>feedback loops, someone figured that a vibrating head positioner could be
>fixed by putting a capacitor across the actuator. After the "fix", it
>shoved the head through the side of the drive.
>

Without seeing the ckt, this sounds like they re-discovered the
integrator. You;d think even back in 1953 or whatever, IBM would know
you need a "zero-switch" to discharge the cap on an integrator.
Easily done here. Mount the switch on the head. When the head bangs
into the side of the drive, the switch engages and resets the
integrator, which re-centers the head. Wal-la. Shoot I learned about
integrators as a sophomore. <:-)).

Cheers,
- Dan Michaels
==============

2000\06\06@224027 by David VanHorn

flavicon
face
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>I've read that the long tiny leads on the caps in this case
>represent such a large inductance that this kind of socket is
>quite useless at higher frequencies.

Yes.


>Interesting observations here. But this makes it sound like going to
>"ground planes" would be the worst thing imaginable. I've read in the books
>that narrow buss traces might cause a problem regarding "return currents"
>for the "signals" routed from one chip to the next. Narrow traces -->
>larger inductive loops --> more EMI/noise transmission.

You're forgetting the bypass. You want the ground fat, and from the chip to
the cap fat, but track from the cap to the rest of the system thinner. The
loop in this case is very small.

{Quote hidden}

Narrow VCC, up to the bypass. Fat from bypass to chip, fat, and
interconnected ground.

Watch interconnection, it can bite too.  I had a thermal printer that took
pulses of 19A 300uS wide. I did NOT let it's ground return run through my
processor logic in a plane.
Can you guess why? :)   I ran separate co-planar power and ground tracks,
200 mils wide to the head. The ground track was isolated from the plane
until the point where it hit the supply caps for the printhead power.

The PH designer had a clue too, they provided power ground and logic ground
on separate pins.

It's a science, but there's some art in it too :)

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2000\06\07@005840 by Dale Botkin

flavicon
face
On Tue, 6 Jun 2000, Dan Michaels wrote:

> Without seeing the ckt, this sounds like they re-discovered the
> integrator. You;d think even back in 1953 or whatever, IBM would know

They didn't even discover the voice-coil actuator until the late 70's, if
I recall correectly...

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

'[EE]: PC Power Supply... revisited'
2000\06\07@023259 by Sebastian Garcia

flavicon
face
Hi all,

Just wanna know if anyone can send me a schematic of the typical switching
mode power supply of the AT PC, or point me to a web link where I can find
it.

Got one of these ( "Achieve ML200C" ) with a problem...don't starts (either
with load) . It seems that one of the MJE13005 's at the input is dead. Any
hint will be welcome !

TIA,

S.-

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