Post by thread:[EE]

'[EE]'

Hi all,

first post.

I am trying to use a CA3140E op-amp as a comparator.

The two inputs are chemical sensors. The difference voltage between them

can range between 400mV, to 50mV (100% concentration to 0% concentration).

I remember reading somewhere in a text book, that if V1-V2 is greater than

(I think) 100uV the op-amp will go into saturation.

Can anyone a) clarify this for me, or b)suggest a better way to measure

the difference voltage.

Component count is a factor, as is power consumption. (I want my cake and

eat it too!)

TIA

--

rgrds,

Bernard

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University*P:01.7005273*L:N117*W:frank.physics.dcu.ie/~bty

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> I am trying to use a CA3140E op-amp as a comparator.

> The two inputs are chemical sensors. The difference voltage between them

> can range between 400mV, to 50mV (100% concentration to 0% concentration).

>

> I remember reading somewhere in a text book, that if V1-V2 is greater than

> (I think) 100uV the op-amp will go into saturation.

>

> Can anyone a) clarify this for me, or b)suggest a better way to measure

> the difference voltage.

An opamp used as a comparator typically would go into saturation, especially

since you probably want to add a little hysterisis.  A saturated opamp may

take a little longer to respond to different input signals, but that should

still be much faster than your chemical concentration can change.

********************************************************************

Olin Lathrop, embedded systems consultant in Littleton Massachusetts

(978) 742-9014, spam_OUTolinTakeThisOuTembedinc.com, http://www.embedinc.com

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        Is it possible that the statement meant "if 100uV is applied between

the inverting and non-inverting terminals, the op-amp will go into

saturation"?

        If that was the question, then someone needs to explain negative

feedback :) Certainly, it's possible to use an op-amp to amplify a

differential signal between 50mV and 400mV. Just don't apply that difference

directly to the op-amp terminals.

        Perhaps the problem needs to be explained a little more. Is the

difference between two sensors being measured? or are there two sensors,

whose ouput varies between 50mV and 400mV? What is the amplified output

connected to? what range does the output voltage need to be in?

> {Original Message removed}
I started building an observatory with a roll off roof about 3 years ago.

The structure itself is finished.  The roof probably weighs about 2000 lbs

and rolls on steel wheels and while it can be pushed by hand, it takes a far

amount of force.  Not being fond of being cold, I constructed the mechanics

to roll the roof back using a couple of 24v dc motors.  The controller box

uses a 16F877 as the brains.  I am using (trying to at least) to use the PWM

to control the motors with.  The output of the PWM goes to a 220 ohm

resistor and then to the gate of an IRLZ44 (N-channel 60v 50A FET) which

between the motors and ground.  There are a pair of relays that reverse the

leads of the motors to change direction.  I am aware of back EMF and the

need for a blocking diode.  I have a blocking on each relay coil and another

diode between the +24v and the FET.  The FET works the first time, ramping

the motors up in speed, but after the relays switch the first time, the FET

becomes a dead short.  At first I thought the motors were drawing too much

current, so I tried two of the IRLZ44 paralleled - same result.  Anyone got

any suggestions?  I would really like to get this finished.

If the word pictured is not clear enough, I can place the schematic on my

web site.

Thanks to all,

David V. Fansler

.....DFanslerKILLspam@spam@MindSpring.com

http://www.DV-Fansler.com

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> I started building an observatory ..

If you want a better response, try stop annoying people by:

1  -  Net setting a hard reply address so that a default reply goes to the

list instead of just you.

2  -  Put a meaningful phrase in the subject line.

*****************************************************************

Embed Inc, embedded system specialists in Littleton Massachusetts

(978) 742-9014, http://www.embedinc.com

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Olin Lathrop a écrit :

> > I started building an observatory ..

>

> If you want a better response, try stop annoying people by:

>

> 1  -  Net setting a hard reply address so that a default reply goes to the

> list instead of just you.

>

> 2  -  Put a meaningful phrase in the subject line.

Trimming is find but too much trimming is bad.

Olin, from the above how are we suppose to know who annoys you so much?

Gaston

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A bit off-topic, but I'll ask anyhow: I have been asked to come up with

a vehicle 'mini-UPS' design, something that takes 12v (car DC) in and

produces 12v @3amp and 5V @6amp out. The PSU must be able to maintain

power for a few seconds when the vehicle is started, and the battery may

dip to say, 8v.

I guess I'll end up with some switcher design & and small NIMH / NICAD

battery pack able to provide a few amps to the PSU input for a minute or

so, but wonder if the listers have any thoughts on this problem? Any

great IC / regulator chips out there that solve this problem?

Thanks, Peter Moreton

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Hi Peter,

I think I'd solve the 12V dip with a NiMH. Remember that normally the car

runs at 13.8V or higher, so you could always keep a 12V NiMH pack topped

off except during starting. Since the differential is so small, I'd charge

the Pak in pulse mode, i.e. directly off the raw 13.8v using HV MOSFET

switches. For a 5V supply, there are several choices, but for ruggedness, I

like National's stepdown switchers LM2576. They are efficient and run very

cool at 3A each (I'd split the supply into 2 legs with large Schottky diodes).

Make the NiMH pak easily to replace; even with its small duty cycle, it

will need to be user-replaceable in a year or two.

Just my suggestions.

--Bob

At 10:29 AM 7/18/2003 +0100, you wrote:

{Quote hidden}>A bit off-topic, but I'll ask anyhow: I have been asked to come up with

>a vehicle 'mini-UPS' design, something that takes 12v (car DC) in and

>produces 12v @3amp and 5V @6amp out. The PSU must be able to maintain

>power for a few seconds when the vehicle is started, and the battery may

>dip to say, 8v.

>

>I guess I'll end up with some switcher design & and small NIMH / NICAD

>battery pack able to provide a few amps to the PSU input for a minute or

>so, but wonder if the listers have any thoughts on this problem? Any

>great IC / regulator chips out there that solve this problem?

>

>Thanks, Peter Moreton

>

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Peter Moreton said:

> A bit off-topic, but I'll ask anyhow: I have been asked to come up with

> a vehicle 'mini-UPS' design, something that takes 12v (car DC) in and

> produces 12v @3amp and 5V @6amp out. The PSU must be able to maintain

> power for a few seconds when the vehicle is started, and the battery may

> dip to say, 8v.

Sounds like a PC power supply meant for a car. Have you seen this:

http://www.bobblick.com/techref/projects/yammp3/yammp3.html

It does more than your requirements, but you can reduce it to what you

need. It'll run at 8 volts in.

Cheers,

Bob

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Rather than a battery backup, why not just build a flyback or SEPIC dc-dc converter that will work from 8 to say 14V?

Cheers,

-Neil.

On Friday 18 July 2003 04:29, Peter Moreton scribbled:

{Quote hidden}> A bit off-topic, but I'll ask anyhow: I have been asked to come up with

> a vehicle 'mini-UPS' design, something that takes 12v (car DC) in and

> produces 12v @3amp and 5V @6amp out. The PSU must be able to maintain

> power for a few seconds when the vehicle is started, and the battery may

> dip to say, 8v.

>

> I guess I'll end up with some switcher design & and small NIMH / NICAD

> battery pack able to provide a few amps to the PSU input for a minute or

> so, but wonder if the listers have any thoughts on this problem? Any

> great IC / regulator chips out there that solve this problem?

>

> Thanks, Peter Moreton

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Yes, I suppose you are right. So long as the PSU can run OK from 8v, and

produce 12v, it should withstand the sag when the vehicle is started. I

guess I need to breadboard a design and see what works.

> {Original Message removed}

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On Sat, 16 Oct 2004, junos (nickname) wrote:

> ------------------------------

>

I said no, and I meant no.

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Someone asked about single supply operation of OP AMPS a while back.  If there is still an interest in a technical review, the link below is a good one.

http://focus.ti.com/lit/an/sboa059/sboa059.pdf

___________________________________________
What would be the chip-of-choice to driver a bunch (4 or 8) N-Mosfets

from PIC output pins? The Mosfets are of course not 5V-types, they need

>10V at their gates.

Wouter van Ooijen

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

Van Ooijen Technische Informatica: http://www.voti.nl

consultancy, development, PICmicro products

docent Hogeschool van Utrecht: http://www.voti.nl/hvu

Russell McMahon posted a message in reply to a question about this 

yesterday or the day before, a discrete solution (2 transistors and a 

diode I believe)

For an IC solution I like the ON semiconductor drivers such as the MC33152.

Micrel has a 12A MOSFET driver in  TO-220-5 package that looks interesting.

You didn't mention what the gate charge would be or what switching 

frequency is required so it is hard to give a better recommendation.

-- 

Martin K

http://wwia.org/

Wouter van Ooijen wrote:

> What would be the chip-of-choice to driver a bunch (4 or 8) N-Mosfets

> from PIC output pins? The Mosfets are of course not 5V-types, they need

> 

>>10V at their gates.

> 

> 

> Wouter van Ooijen

On 6/2/05, Wouter van Ooijen <wouterspam_OUTvoti.nl> wrote:

> What would be the chip-of-choice to driver a bunch (4 or 8) N-Mosfets

> from PIC output pins? The Mosfets are of course not 5V-types, they need

> >10V at their gates.

Wouter, I suggest you an european solution: CD40107 open drain circuit

and there is also an open source but I don't remember the name, both

have two gates in a DIP8 or SO8 package, high current, high voltage

drive, with low voltage input.

Vasile

> 

> Wouter van Ooijen

> 

> -- -------------------------------------------

> Van Ooijen Technische Informatica: http://www.voti.nl

> consultancy, development, PICmicro products

> docent Hogeschool van Utrecht: http://www.voti.nl/hvu

> 

> 

> -
part 1 820 bytes content-type:text/plain; (decoded 7bit)

TC426 or DS0026?

But Russell has taught me a good trick with two transistors.

Is working good with ~18Khz with 2N3904s.

The gif is made from Jinx Library(TM).:)

Dennis 

vasile surducan <@spam@vsurducanKILLspamgmail.com> wrote:

{Quote hidden}> On 6/2/05, Wouter van Ooijen <KILLspamwouterKILLspamvoti.nl> wrote:

>> What would be the chip-of-choice to driver a bunch (4 or 8) N-Mosfets

>> from PIC output pins? The Mosfets are of course not 5V-types, they

>> need 

>>> 10V at their gates.

> 

> Wouter, I suggest you an european solution: CD40107 open drain circuit

> and there is also an open source but I don't remember the name, both

> have two gates in a DIP8 or SO8 package, high current, high voltage

> drive, with low voltage input.

> 

> Vasile

> 

part 2 2398 bytes content-type:application/octet-stream; (decode)

part 3 35 bytes content-type:text/plain; charset="us-ascii"
 (decoded 7bit)

> TC426 or DS0026?

> But Russell has taught me a good trick with two transistors.

> Is working good with ~18Khz with 2N3904s.

> The gif is made from Jinx Library(TM).:)

It's a good circuit. But for safety it is a very good idea to also 

place a zener diode from FET gate to ground (cathode to gate). 

Physically mount it as reasonably close to the FET as possible. This 

shunts stops capacitively coupled transients which are injected into 

the gate from the drain via the Miller capacitance. It also helps 

stops gate ringing -  a whole black art in its own right. I have seen 

circuits that run forever with this zener in place but die in minutes 

without it. Zener voltage is slightly higher than the V+ gate drive 

voltage.

For faster switching place a small capacitor in series with the base 

drive resistor on the left hand transistor (not shown in your 

diagram).

        Russell McMahon

On Fri, 2005-06-03 at 08:58 -0300, Dennis Crawley wrote:

> TC426 or DS0026?

> 

> But Russell has taught me a good trick with two transistors.

> Is working good with ~18Khz with 2N3904s.

> The gif is made from Jinx Library(TM).:)

> 

> Dennis 

Very neat circuit.

Anyone have a similar circuit that could be used for the high side

driver in an H-Bridge running at say 200V? PMOS and NMOS high side

versions?

Thanks, TTYL

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

Herbert's PIC Stuff:

http://repatch.dyndns.org:8383/pic_stuff/

On 6/3/05, Russell McMahon <RemoveMEapptechTakeThisOuTparadise.net.nz> wrote:

> > TC426 or DS0026?

> 

> > But Russell has taught me a good trick with two transistors.

> > Is working good with ~18Khz with 2N3904s.

> > The gif is made from Jinx Library(TM).:)

> 

> It's a good circuit. But for safety it is a very good idea to also

> place a zener diode from FET gate to ground (cathode to gate).

> Physically mount it as reasonably close to the FET as possible. This

> shunts stops capacitively coupled transients which are injected into

> the gate from the drain via the Miller capacitance. It also helps

> stops gate ringing -  a whole black art in its own right. I have seen

> circuits that run forever with this zener in place but die in minutes

> without it. Zener voltage is slightly higher than the V+ gate drive

> voltage.

   But also then then the 10 ohm resistor must be increased or the V+

voltage must be very carefully chosen. BTW, why such a small resistor

when the gate ON current is quite small ? How large is the gate-source

parasitic capacitance of this FET ?

Vasile

> 

> For faster switching place a small capacitor in series with the base

> drive resistor on the left hand transistor (not shown in your

> diagram).

> 

> 

> 

>        Russell McMahon

> 

> -

Microsoft Robotics development kit!

http://www.pcmag.com/article2/0,1895,1978578,00.asp

http://www.microsoft.com/downloads/details.aspx?FamilyID=66d1363e-36a4-46be-ad36-01bcfbfb4969&DisplayLang=en

-- 

Feel the power of the dark side!  Atmel AVR

On Tue, 20 Jun 2006, David VanHorn wrote:

> Microsoft Robotics development kit!

>

> http://www.pcmag.com/article2/0,1895,1978578,00.asp

>

> http://www.microsoft.com/downloads/details.aspx?FamilyID=66d1363e-36a4-46be-ad36-01bcfbfb4969&DisplayLang=en

Oh s**t. Now they embraced and extended Asimov's 3 principles of 

(human-friendly) robotics.

Peter

Hi all,

a friend of mine is looking for two pieces of CYPRESS CY7C64513.

Anyone having two he/she want to sell (or know where to search for

them)?

Regards

/Ake

Does anyone know how to create the footprint for an electrolitic

capacitor?? Or is there some footprint standarized included in any

library I  do not know?

I really appreaciate your help and any tips you can give.

Regards,

             Carito.

On 6/10/07, Carolina Dieguez <spamBeGonecaro.dieguezspamBeGonegmail.com> wrote:

> Does anyone know how to create the footprint for an electrolitic

> capacitor?? Or is there some footprint standarized included in any

> library I  do not know?

It would probably help if you gave some idea of what cad package you are using.

I'm  sorry, I'm using PROTEL...

On 6/10/07, David VanHorn <TakeThisOuTmicrobrixEraseMEspam_OUTgmail.com> wrote:

> On 6/10/07, Carolina Dieguez <RemoveMEcaro.dieguezTakeThisOuTgmail.com> wrote:

> > Does anyone know how to create the footprint for an electrolitic

> > capacitor?? Or is there some footprint standarized included in any

> > library I  do not know?

>

> It would probably help if you gave some idea of what cad package you are using.

> -
The comment requesting the CAD package is important.  Usually, in any CAD 

package you can pick a similar part and edit the part to make one with the 

footprint you need.  Also, you can look at the manufacturer's packaging 

specifications and dimensions and use the drawing tools to draw it and save 

the file by the name you choose.

{Original Message removed}
I'm experimenting with analog switches/muxes ('4051 and '4066)--my first

time. When selected, the resistance of all switches is as expected, <150

ohms, but when control signal is low R varies from 20-50K among channels,

always way lower than spec. If power removed, all channels' resistance is in

spec.

My first thought was my meter, a garden-variety $20 job, but it seems to be

working fine.

Thanks all,

Don

===============

Don Rahmlow

Ramfish Golf

http://www.ramfish.com

===============

Don,

What is the input impedance of your meter?  If it is less than 20

megohms or so, you'll load the FET down,

And you'll get less than expected resistance.   

Regards,

Jim 

{Original Message removed}
I recently junked a Brother inkjet printer(MFC3320C), it yielded several

interesting parts. One part I like is the LCD display, a really neat and

small unit. I was hoping to use it for something else, but I can't figure

out the connections. It has wires connected to it. It has some kind of

controller chip glued on the glass, but no markings. The unite carries a

part number B53K680-1, but this seems to be a Brother part number. If I

search Google, I actually get a parts manual for the printer, but is no good

for identification.

I was wondering if anyone might have some idea what the connections might

be. I hate to chuck it.....

Bill van Dijk

Could any one reccomend a C compiler that doesn't resort

to the Command prompt to run what ever you write.  I'm writing simple C programs and editors are easy to find but

compilers all seem to use the Command Prompt to run the

results. Thanks in advance to anyone who can help ! ! !

CR
Assuming you are working in Windows:

Visual Studio 2010 C++ Express

could be a very good (and free!) choice.

-- Bob Ammerman

RAm Systems

{Original Message removed}
> Could any one reccomend a C compiler that doesn't resort

> to the Command prompt to run what ever you write.  I'm

> writing simple C programs and editors are easy to find but

> compilers all seem to use the Command Prompt to run the

> results. Thanks in advance to anyone who can help ! ! !

DevCpp has a setting to develop windows applications. No experience with it, I always use it to generate commandline applications (which you for some reason seem to hate).

I am not sure what you mean by 'use the command prompt', the IDEs I know use a button to launch the application.

-- 

Wouter van Ooijen

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

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consultancy, development, PICmicro products

docent Hogeschool van Utrecht: http://www.voti.nl/hvu
On Mon, 23 May 2011 20:54 -0500, "Charles Rogers" wrote:

> Could any one reccomend a C compiler that doesn't resort

> to the Command prompt to run what ever you write.  I'm 

> writing simple C programs and editors are easy to find but

> compilers all seem to use the Command Prompt to run the

> results. Thanks in advance to anyone who can help ! ! !

Are you talking about compilers for the PC or for the PIC?

Bob

-- http://www.fastmail.fm - Send your email first class
On 24/05/2011 02:54, Charles Rogers wrote:

> Could any one reccomend a C compiler that doesn't resort

> to the Command prompt to run what ever you write.  I'm

> writing simple C programs and editors are easy to find but

> compilers all seem to use the Command Prompt to run the

> results. Thanks in advance to anyone who can help ! ! !

>

> CR

>

Do you mean you want to create a GUI app in plain C?

If so check out Win API, Win SDK (comes with Visual Studio or can be downloaded seperately), GTK. The compiler doesn't create the GUI, it's the code you pass to it (e.g. using Windows API - CreateWindowEx() and suchlike)

Charles Petzold wrote a good book "Programming Windows" that covers the Windows API quite well IIRC.

> On Mon, 23 May 2011 20:54 -0500, "Charles Rogers" wrote:

> > Could any one reccomend a C compiler that doesn't resort

> > to the Command prompt to run what ever you write.  I'm 

> > writing simple C programs and editors are easy to find but

> > compilers all seem to use the Command Prompt to run the

> > results. Thanks in advance to anyone who can help ! ! !

> 

> Are you talking about compilers for the PC or for the PIC?

> 

To the OP: It is not quite clear what you mean. Can you give us an example of what the compilers does and what you want it to do instead?

What do you mean by "run the results"?

Are you talking about the compiling process (writing your program) or about running your compiled program (using your program)?

/Ruben

==============================

Ruben Jönsson

AB Liros Electronic

Box 9124, 200 39 Malmö, Sweden

TEL INT +46 40142078

FAX INT +46 40947388

rubenEraseME.....pp.sbbs.se

==============================
What do you mean by "run the results"? Run the compiled code? Most modern

IDE can run the compiled code by clicking on a button -- and then you can

get the output in a window if you like.

Or if you need a window based application (GUI as opposed to TUI/CLI), then

you also need to learn a bit of the windowing frameworks, such as MFC or

Windows Forms or VxWorks or GTK or Cocoa -- depends on your

taste, licensing policy, your base platform and whenever you need to

cross-compile your code to other platforms, and of course available tools.

Generally speaking basic stuff such as displaying a string in a text box or

handling an event like a button pressed is relatively easy in all

frameworks. However, each works differently so you cannot easily swap in

between.

Tamas

On Tue, May 24, 2011 at 2:54 AM, Charles Rogers <EraseMEcrogerstotelcsi.com>wrote:

> Could any one reccomend a C compiler that doesn't resort

> to the Command prompt to run what ever you write.  I'm

> writing simple C programs and editors are easy to find but

> compilers all seem to use the Command Prompt to run the

> results. Thanks in advance to anyone who can help ! ! !

>

> CR

>

>
CCS.

PerL

----- Original Message ----- From: "Charles Rogers" <RemoveMEcrogersEraseMEEraseMEtotelcsi.com>

To: "Microcontroller discussion list - Public." <RemoveMEpiclistspam_OUTKILLspammit.edu>

Sent: Tuesday, May 24, 2011 3:54 AM

Subject: [EE]

> Could any one reccomend a C compiler that doesn't resort

> to the Command prompt to run what ever you write.  I'm 

> writing simple C programs and editors are easy to find but

> compilers all seem to use the Command Prompt to run the

> results. Thanks in advance to anyone who can help ! ! !

> 

> CR

> 

> -
Can anyone help me?

I'm looking for a source of desktop universal input SMPSs that will do

at least 2.7A at 24V.

Those are easy to find, but the next bit isn't.

In case of overcurrent, I need the supply to shut down until the plug is pulled.

Everything I have found has "Hiccup mode" or "Auto-Restart" which is

unacceptable.

A supply that operates in this mode could cause a disastrous fire.

There are connector and ratings requirements also, but I will discuss

that with the vendor.

Surplus onesies would be interesting in that they would point me to

the proper vendor to get them from in bulk.

VERY interesting reading:

http://www.kodiakconsulting.com/page19/assets/Low%20Voltage_The%20Incompetent%20Ignition%20Source_Final.pdf

Thanks
An interesting article.

I particularly liked the statement "There exists a sobering truth

about today’s electronic assemblies. 100% of today’s

consumer electronics are made without rosin flux (moisture

resistance), use fluxes that do not

“require” cleaning (leaves contamination behind more readily), use

solders that contain no lead

(creates more difficult soldering processes), and use boards that

contain no halides to prevent the

board from burning if a shorting or corrosions event were to occur."

Regarding the original posters problem - how about adding a crowbar

circuit + fuse. Pretty easy to implement on any type of power supply.

RP

On 9 October 2012 04:54, David VanHorn <RemoveMEmicrobrixTakeThisOuTspamgmail.com> wrote:

{Quote hidden}> Can anyone help me?

>

> I'm looking for a source of desktop universal input SMPSs that will do

> at least 2.7A at 24V.

> Those are easy to find, but the next bit isn't.

>

> In case of overcurrent, I need the supply to shut down until the plug is pulled.

> Everything I have found has "Hiccup mode" or "Auto-Restart" which is

> unacceptable.

> A supply that operates in this mode could cause a disastrous fire.

>

> There are connector and ratings requirements also, but I will discuss

> that with the vendor.

> Surplus onesies would be interesting in that they would point me to

> the proper vendor to get them from in bulk.

>

> VERY interesting reading:

> http://www.kodiakconsulting.com/page19/assets/Low%20Voltage_The%20Incompetent%20Ignition%20Source_Final.pdf

>

> Thanks!

>
On 10/08/2012 11:54 AM, David VanHorn wrote:

> Can anyone help me?

>

> I'm looking for a source of desktop universal input SMPSs that will do

> at least 2.7A at 24V.

> Those are easy to find, but the next bit isn't.

>

> In case of overcurrent, I need the supply to shut down until the plug is pulled.

> Everything I have found has "Hiccup mode" or "Auto-Restart" which is

> unacceptable.

> A supply that operates in this mode could cause a disastrous fire.

>

> There are connector and ratings requirements also, but I will discuss

> that with the vendor.

> Surplus onesies would be interesting in that they would point me to

> the proper vendor to get them from in bulk.

>

> VERY interesting reading:

> http://www.kodiakconsulting.com/page19/assets/Low%20Voltage_The%20Incompetent%20Ignition%20Source_Final.pdf

>

> Thanks!

Why not add a SCR that fires when it reaches a certain current limit...It would "lock"/crowbar the output until the power supply has been unplugged and the SCR's gate releases. Reading the voltage developed across a low value (.5ohm) high wattage  (5~10W) resistor in series with the 24v leg and firing the gate of the SCR when it reaches your current limit... A few components and a standard (available) 24v SMPS power supply. You would need to handle the turn on surge also.

Dav
All good suggestions, IF I could modify the existing circuits.

What I need, is a power supply brick, to replace the existing power

supply brick, that won't keep hammering a failed circuit