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'[EE]:What is the purpose of the circuit'
2004\11\21@023333 by Hopkins

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part 1 486 bytes content-type:text/plain; (decoded 7bit)


Have attached an Eagle file with a simple transistor circuit and
I think the purpose is current limiting - is this correct?

If so how do I work out the current limit?
_______________________________________
Roy
Tauranga
New Zealand
_______________________________________


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____________________________________________

2004\11\21@091529 by olin_piclist

face picon face
Hopkins wrote:
> Have attached an Eagle file

This is a bad idea.  Many people don't have Eagle.  You should have
converted the schematic to a PDF or small GIF file.

By the way, why are you using WIREs for schematic connections instead of
NETs?  Note the lack of dots where two "wires" meet.  This means Eagle
doesn't understand them as connections.  You are probably going to run into
trouble when exporting the netlist or doing the layout.  I don't know for
sure since I've never tried to abuse Eagle in this manner.

> with a simple transistor circuit and
> I think the purpose is current limiting - is this correct?

It's impossible to tell purpose without additional documentation.  We can
only tell you what this circuit will do.  Q1 will come on when the +5V
supply is above about 900mV.  Once that happens, the collector of Q1 will
track the +5V rail minus its CE drop, which I'm declaring 200mV as a rough
guess.  At 5V there will be about 4.3mA drawn from the supply, plus whatever
is drawn from the collector of Q1.

I'm having a hard time thinking of a useful purpose this circuit serves.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________

2004\11\21@102013 by Herbert Graf

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On Sun, 2004-11-21 at 20:33 +1300, Hopkins wrote:
> Have attached an Eagle file with a simple transistor circuit and
> I think the purpose is current limiting - is this correct?
>
> If so how do I work out the current limit?

Unfortunately not everyone here HAS Eagle installed, and likely won't
install it just to view your message.

It's a FAR better idea to include an image of the schematic, a screen
capture is more then enough if the circuit is small. TTYL

____________________________________________

2004\11\21@114903 by Ake Hedman

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Olin Lathrop wrote:

>Hopkins wrote:
>  
>
>>Have attached an Eagle file
>>    
>>
>
>This is a bad idea.  Many people don't have Eagle.  You should have
>converted the schematic to a PDF or small GIF file.
>
>By the way, why are you using WIREs for schematic connections instead of
>NETs?  Note the lack of dots where two "wires" meet.  This means Eagle
>doesn't understand them as connections.  You are probably going to run into
>trouble when exporting the netlist or doing the layout.  I don't know for
>sure since I've never tried to abuse Eagle in this manner.
>
>  
>
To use wires instead of nets is no problem in eagle. Just a matter of choice.  Probably have to add the dots at the interconnections manually though...

Regards
/Ake

--  ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
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___________________________________________

2004\11\21@120555 by Gaston Gagnon

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Ake Hedman wrote:
{Quote hidden}

As far as I can see, this schematic is normal and everything is
connected and NO dot are required.
If you make a layout out of this schematic, everything is there and
connected.

As far as I am concerned, those dots only clutter the schematic. So I
use them only when there is an ambiguity like where two lines cross but
are in fact connected. With no dot they are generally assumed "not
connected".

Gaston

____________________________________________

2004\11\21@124515 by Wouter van Ooijen

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> To use wires instead of nets is no problem in eagle. Just a matter of
> choice.

If you care only for the graphic result you are right, but a wire is not
considered an electrical connection, so when you export your wires to
the PCB editor you won't see any ratasnest (connections to be made) at
all. And the electrical check on your cicruit won't recognise the wires
either.

At least, this was the case when I first learned eagle (the hard way).

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


____________________________________________

2004\11\21@125535 by Hopkins

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part 1 745 bytes content-type:text/plain; (decoded 7bit)

Ok guys - thanks for the tip on using net command instead of wires, did
not appreciate the difference until now.

Have attached a small jpg file this time.

This was some one else's circuit and looked to be a current limiter on
the output of a 78L05 regulator to the VCC pins on several chips.
Yes I know the 78L05 already limits current to 100ma but I wanted to
know why someone thought they had to add this circuit as well.
_______________________________________
Roy
Tauranga
New Zealand
_______________________________________



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part 3 79 bytes content-type:text/plain; charset="us-ascii"
(decoded 7bit)

____________________________________________

2004\11\21@132008 by Roy E. Burrage

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Roy,

Like that first name...

I don't see any sensing element for this circuit to be a current
limiter.  It could, however, be used to remove Vcc from the rest of the
circuit by taking the base of the 2N2222 low.  Other than that, as Olin
stated, it appears to serve no useful purpose.

REB

Hopkins wrote:

{Quote hidden}

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____________________________________________

2004\11\21@133521 by Ake Hedman

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Wouter van Ooijen wrote:

>>To use wires instead of nets is no problem in eagle. Just a matter of
>>choice.
>>    
>>
>
>If you care only for the graphic result you are right, but a wire is not
>considered an electrical connection, so when you export your wires to
>the PCB editor you won't see any ratasnest (connections to be made) at
>all. And the electrical check on your cicruit won't recognise the wires
>either.
>
>
>  
>

Its OK also in that respect. Its perfectly fine to use wires and then transfer the result to the PCB. No problem!

Regards
/Ake


--  ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
Company home: http://www.eurosource.se      Kryddor/Te/Kaffe: http://www.brattberg.com
Personal homepage: http://www.eurosource.se/akhe
Automated home: http://www.vscp.org


___________________________________________

2004\11\21@140838 by Dave Tweed

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"Hopkins" <spam_OUTrdhopkinsTakeThisOuTspamihug.co.nz> wrote:
> Yes I know the 78L05 already limits current to 100ma but I wanted to
> know why someone thought they had to add this circuit as well.

No, it doesn't. The 78L05 is *rated* at 100 mA, but the only internal
limiting is on the die temperature. If it gets too hot, it will shut
down until it cools off again.

The external circuit isn't a current limiter, either, as others have
noted. It's just a simple switch -- always on, unless there's a way
to ground the base of the NPN.

-- Dave Tweed
____________________________________________

2004\11\21@140928 by res0qrqr

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If that's *really* all there is to this circuit
(are you sure there's no other control signal
coming into the base of the 2N2222?), then I might
speculate that it has something to do with the
power-up or power-down performance.  It will impose
a deadband of sorts when the incoming power is
between zero and one Vbe, which may have some effect
on reset behavior elsewhere in the circuit.
Or not.

Brian Aase

{Quote hidden}

____________________________________________

2004\11\21@140945 by Gaston Gagnon

face
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Wouter van Ooijen wrote:

>>To use wires instead of nets is no problem in eagle. Just a matter of
>>choice.
>
>
> If you care only for the graphic result you are right, but a wire is not
> considered an electrical connection, so when you export your wires to
> the PCB editor you won't see any ratasnest (connections to be made) at
> all. And the electrical check on your cicruit won't recognise the wires
> either.
>
> At least, this was the case when I first learned eagle (the hard way).

This Wire vs Net in schematic is a recurrent question for Eagle users.

The following is Richard Hammerl's answer to the question "What's the
difference between NET and WIRE?" in one of the Cadsoft's news group:

"The NET command is determined to draw an electrical connection between
two pins in the schematic. It is automatically drawn in the nets layer.
A wire is simply a line (for symbols, frames...) and can be used in all
layers of the schematic. Used in the nets layer and drawn from one pin
to another it also works like NET.
But as a rule: Draw nets (electrical connections) with the NET command
not with WIRE."

Gaston

____________________________________________

2004\11\21@141859 by steve

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> This was some one else's circuit and looked to be a current limiter on
> the output of a 78L05 regulator to the VCC pins on several chips. Yes
> I know the 78L05 already limits current to 100ma but I wanted to know
> why someone thought they had to add this circuit as well.

It looks to me like someone changed their mind.
If R1 was connected to a micro pin, it could switch the circuit/load on
and off. Tying it to Vcc is a safe way to hold the circuit in a (almost)
benign state.
There are numerous reasons why you might want to do something like
that and if the volumes are low and/or the load is unknown at design-
time, it may be reasonable to put the components in the circuit for easy
implementation later if needed.
It may also be used as an indicator of an unauthorized person just
copying the circuit.

Steve.





____________________________________________

2004\11\21@142913 by Martin K

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Gaston Gagnon wrote:

{Quote hidden}

I have had problems with connections not exporting correctly to the PCB
when I just used the wire command. I will use the net command from now on.

--
Martin K
____________________________________________

2004\11\21@143127 by Brent Brown

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On 22 Nov 2004 at 6:55, Hopkins wrote:

> This was some one else's circuit and looked to be a current limiter on
> the output of a 78L05 regulator to the VCC pins on several chips.
> Yes I know the 78L05 already limits current to 100ma but I wanted to
> know why someone thought they had to add this circuit as well.

So everyone agrees it just turns Vcc on when power is on and off when
power is off. What if you think of it like a diode with very low forward voltage
drop? Could that be a reason for it being there in the circuit?

--
Brent Brown, Electronic Design Solutions
16 English Street, Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile/txt: 025 334 069
eMail:  .....brent.brownKILLspamspam@spam@clear.net.nz


____________________________________________

2004\11\21@144753 by Wouter van Ooijen

face picon face
> Its OK also in that respect. Its perfectly fine to use wires and then
> transfer the result to the PCB. No problem!

Confirmed. But this was definitely different in some previous version of
Eagle. Great imrovement, although removing the wire/net distinction
would have been even better. Or is there any usefull distinction?

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


____________________________________________

2004\11\21@151411 by Ake Hedman

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Wouter van Ooijen wrote:

>>Its OK also in that respect. Its perfectly fine to use wires and then
>>transfer the result to the PCB. No problem!
>>    
>>
>
>Confirmed. But this was definitely different in some previous version of
>Eagle. Great imrovement, although removing the wire/net distinction
>would have been even better. Or is there any usefull distinction?
>
>Wouter van Ooijen
>
>  
>

>although removing the wire/net distinction
Agree.

Regards
/Ake


--  ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
Company home: http://www.eurosource.se      Kryddor/Te/Kaffe: http://www.brattberg.com
Personal homepage: http://www.eurosource.se/akhe
Automated home: http://www.vscp.org


___________________________________________

2004\11\21@151605 by Peter van Hoof

picon face
I threw it in electronics workbench and it simulates as an ideal diode in
series with approximately 85 ohms resistance

Peter
> So everyone agrees it just turns Vcc on when power is on and off when
> power is off. What if you think of it like a diode with very low forward
> voltage
> drop? Could that be a reason for it being there in the circuit?


____________________________________________

2004\11\21@151625 by Dwayne Reid

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At 10:55 AM 11/21/2004, Hopkins wrote:

>This was some one else's circuit and looked to be a current limiter on
>the output of a 78L05 regulator to the VCC pins on several chips.

It looks to be a Vcc disconnect circuit.  I can think of a couple of
reasons for including it:

1) remove power from chips if Vcc at illegal level (many PICs lock up if
Vdd drops to around 0.6 - 0.7V, then increases back to normal)

2) power supply sequencing - ensure that part of the circuit gets power
applied first.

For what its worth, I use a variety of circuits that performs a similar
function to all of our products using low end PICs - Vdd is held off until
it exceeds 2V or so.

dwayne

--
Dwayne Reid   <dwaynerspamKILLspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
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____________________________________________

2004\11\21@165634 by Gaston Gagnon

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Martin K wrote:
>
>
> Gaston Gagnon wrote:
>
>> "The NET command is determined to draw an electrical connection between
>> two pins in the schematic. It is automatically drawn in the nets layer.
>> A wire is simply a line (for symbols, frames...) and can be used in all
>> layers of the schematic. Used in the nets layer and drawn from one pin
>> to another it also works like NET.
>> But as a rule: Draw nets (electrical connections) with the NET command
>> not with WIRE."
>>
>> Gaston
>>
>
> I have had problems with connections not exporting correctly to the PCB
> when I just used the wire command. I will use the net command from now on.

This problem is not related to wire vs net. It is because the connexion
was not fully registered by eagle.
You can check this with the SHOW command (the eye icon). If you click on
a connexion with SHOW  both the pin and the wire should highlight. If
either one does not highlight, grab the part on its origin and move it a
little, the wire should move along with the pin. Then bring the part
back to its place. Now SHOW should highlight both of them now. And as
expected the airwire will be in the board.

As mentioned previously, it does not matter which one of wire or net you
use if it is drawn on the net layer.

Gaston
____________________________________________

2004\11\21@174801 by Dennis Crawley

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Hopkins wrote:
> Have attached an Eagle file with a simple transistor circuit and
> I think the purpose is current limiting - is this correct?
> If so how do I work out the current limit?
> _______________________________________
> Roy
> Tauranga
> New Zealand

Hi,
To me, it looks like a polarity protection.
Some times the source capacitor is to big and can make the current runs
in an opposite way, when is discharged. The best way to do this is with a
mosfet, which was commented many times in this list.

Regards,
Dennis Crawley

____________________________________________

2004\11\21@184649 by olin_piclist

face picon face
Roy E. Burrage wrote:
> I don't see any sensing element for this circuit to be a current
> limiter.  It could, however, be used to remove Vcc from the rest of
> the circuit by taking the base of the 2N2222 low.  Other than that,
> as Olin stated, it appears to serve no useful purpose.

I'm thinking that maybe there is a resistor missing from the base of T1 to
ground.  That resistor would form a voltage divider with R1 so that T1 would
not turn on until the +5V net got to some minimum voltage.  This is using
the BE junction of T1 as the voltage reference.  In that case, this circuit
could be useful when power could rise slower than allowed by some devices.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________

2004\11\21@184928 by Russell McMahon

face
flavicon
face
> It looks to be a Vcc disconnect circuit.  I can think of a couple of
> reasons for including it:
>
> 1) remove power from chips if Vcc at illegal level (many PICs lock up if
> Vdd drops to around 0.6 - 0.7V, then increases back to normal)
>
> 2) power supply sequencing - ensure that part of the circuit gets power
> applied first.
>
> For what its worth, I use a variety of circuits that performs a similar
> function to all of our products using low end PICs - Vdd is held off until
> it exceeds 2V or so.

I agree that this seems to be the most probable intended use.
Adding a resistor from the NPN base to ground would allow a higher turn on /
off voltage to be set.
The 1k resistor is unnecessarily low for any reasonably conceivable
application, unless it is intended to load the +5V supply as well as drive
the transistor.

As Dwayne says, a number of IC's perform badly or fatally if Vdd is taken
low and then high again under certain circumstances. This circuit
disconnects the output from the effects of large electrolytics etc on the
+5V rail and allows it to drop from a few tenths of a volt to a true 0v in
much less time than it otherwise might. It is however a rather unusual
circuit and the fine points of its intended use are not clear. It would not
be of general applicability and I'm guessing that the designer had a very
specific problem they were addressing. As Dwayne says, dropping the supply
rapidly from a much higher voltage usually makes more sense.

I have a product which is causing problems at the moment because a new batch
of processors has just such a problem as noted above (this is out of spec
but the supplier doesn't seem to care). I have added a supply disconnector
to solve this as alternative parts are not available quickly enough. In my
case I disconnect the input to the 5v regulator and add a large enough
output load to get adequate shutdown times.



       Russell McMahon




____________________________________________

2004\11\21@184950 by olin_piclist

face picon face
Ake Hedman wrote:
> Its OK also in that respect. Its perfectly fine to use wires and then
> transfer the result to the PCB. No problem!

That's kind of like globally turning off type checking in a compiler.  Yes,
you can make a program that works, but it's really not a smart idea.  I
don't understand the drawback to using NET to draw connections.  It's no
harder to use than WIRE.  Eagle then puts the little connection dots in
there automatically, which is nice visual confirmation that it knows there
is a connection.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________

2004\11\21@190050 by Roy J. Gromlich

picon face
Yes, I also like that first name. (grin)

Anyway, the 1K base resistor on the 2N2222 virtually guarantees it is
in saturation, while the 22K base resistor on the 2N2907 would likely
put it right at the edge of saturation. Although the circuit could current
limit, the value would vary from transistor to transistor, and could also
be very temperature sensitive.  

Unless there are other connections to that circuit, it appears to serve
no useful purpose.

Roy J. Gromlich

{Original Message removed}

2004\11\21@200007 by Russell McMahon

face
flavicon
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> As far as I am concerned, those dots only clutter the schematic. So I use
> them only when there is an ambiguity like where two lines cross but are in
> fact connected. With no dot they are generally assumed "not connected".

This is a key issue when drawing circuit diagrams which must be understood
by people.
IF you want the result not to be ambiguous the following two rules are
highly recommended.

   A line crossing another line NEVER joins.

   A line intersecting another line at a "T" ALWAYS joins.

Dots at T's are optional and dots at crossings are, of course, never
appropriate.

There is no good reason for not doing this and very good reasons for doing
it. Although the first rule sometimes leads to a slightly less tidy visual
result than you might otherwise be able to achieve, it will assist you
greatly over time. It is impossible to mistake the intention on the circuit.
Dots need not be relied on.




       Russell McMahon


____________________________________________

2004\11\21@202713 by Bob Barr

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On Mon, 22 Nov 2004 06:55:24 +1300, "Hopkins" wrote:

FWIW, I just ran a Spice sim on the circuit and got the following
results:

Rload___Iout(mA)__Vout
1k______4.90_____4.90
500_____9.75_____4.67
250____18.50_____4.64
125____18.67_____2.33
62.5____18.73_____1.17

(I hope the spacing on this shows up OK.)

Regards, Bob

{Quote hidden}

____________________________________________

2004\11\21@232951 by Hopkins

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Thanks guys for all the advice - was not to worried about it and now
understand it could be a low voltage disconnect.

As for Eagle - yes I agree that using the NET connection is better than
a wire command as it does automatic joins, name each net and then layout
the PCB by each net name.

_______________________________________
Roy
Tauranga
New Zealand
_______________________________________


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____________________________________________

2004\11\22@030240 by Ake Hedman

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Olin Lathrop wrote:

>Ake Hedman wrote:
>  
>
>>Its OK also in that respect. Its perfectly fine to use wires and then
>>transfer the result to the PCB. No problem!
>>    
>>
>
>That's kind of like globally turning off type checking in a compiler.  Yes,
>you can make a program that works, but it's really not a smart idea.  I
>don't understand the drawback to using NET to draw connections.  It's no
>harder to use than WIRE.  Eagle then puts the little connection dots in
>there automatically, which is nice visual confirmation that it knows there
>is a connection.
>
>  
>
My point is that its just a matter of preference which method you like to use. Its not a *wrong way* in using any of them. But as you state NET have some advantages, no question about that..
Regards
/Ake

--  ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
Company home: http://www.eurosource.se      Kryddor/Te/Kaffe: http://www.brattberg.com
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___________________________________________

2004\11\22@032800 by Wouter van Ooijen

face picon face
> No, it doesn't. The 78L05 is *rated* at 100 mA, but the only internal
> limiting is on the die temperature.

It does have a current limit, check the circuit for R11/Q12 in
http://cache.national.com/ds/LM/LM78L05.pdf. But while that limit
current is guaranteed to be at least 100 mA, on quick scan I only found
a typical max current of 140 mA.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


____________________________________________

2004\11\22@034507 by Wouter van Ooijen

face picon face
> My point is that its just a matter of preference which method
> you like
> to use. Its not a *wrong way* in using any of them. But as
> you state NET
> have some advantages, no question about that..

I teach programming. A lot of my time is spend explaining that even
though a program made by the student works (in some cases even exactly
according to the specs) I might still turn it down because it is done in
a bad way.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


____________________________________________

2004\11\22@043459 by Ake Hedman

flavicon
face
Wouter van Ooijen wrote:

>>My point is that its just a matter of preference which method
>>you like
>>to use. Its not a *wrong way* in using any of them. But as
>>you state NET
>>have some advantages, no question about that..
>>    
>>
>
>I teach programming. A lot of my time is spend explaining that even
>though a program made by the student works (in some cases even exactly
>according to the specs) I might still turn it down because it is done in
>a bad way.
>
>Wouter van Ooijen
>
>  
>
At the university I went to (Uppsala, Sweden) they have a sign that says something like

"To think freely is good, to think right is better"   (sort of)...

I never liked that sign....
There are may ways to do things and we are all different. For me the result matters more then how we reach it. If the code I write is bad looking in the eyes of someone but I produce more and more stable code I can't see how it can be a problem. This is typical for Indian programmers for instance. Rock solid work. Good productivity. Hard to read. (my opinion!)

I know what Olin meant and he is correct and it was a good suggestion he gave but the other guy was still not *wrong* because he did it in another way. And as you state above it is of course fine to suggest other ways to do things espacilially in a tutor student relationship. But I still think that we should use all colors of the spectra instead of reverting to the news reporting black & white style of looking at the world.

Back to electrionics....

Regards
/Ake

--  ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
Company home: http://www.eurosource.se      Kryddor/Te/Kaffe: http://www.brattberg.com
Personal homepage: http://www.eurosource.se/akhe
Automated home: http://www.vscp.org


___________________________________________

2004\11\22@044402 by hael Rigby-Jones

picon face


>-----Original Message-----
>From: .....piclist-bouncesKILLspamspam.....mit.edu [EraseMEpiclist-bouncesspam_OUTspamTakeThisOuTmit.edu]
>On Behalf Of Hopkins
>Sent: 21 November 2004 17:55
>To: 'Microcontroller discussion list - Public.'
>Subject: RE: [EE]:What is the purpose of the circuit
>
>
>Ok guys - thanks for the tip on using net command instead of
>wires, did not appreciate the difference until now.
>
>Have attached a small jpg file this time.
>
>This was some one else's circuit and looked to be a current
>limiter on the output of a 78L05 regulator to the VCC pins on
>several chips.
>Yes I know the 78L05 already limits current to 100ma but I
>wanted to know why someone thought they had to add this
>circuit as well.

I'm wondering if R3 was meant to be connected to the base of T1 rather than
the emitter?  This would provide positive feedback and result an SCR-like
action.  This could be used to ensure a fast rise time of the output voltage
when the output of the regulator raised above a certain amount.

As it stands it really doesn't seem to do anything very usefull part from
waste some current

Regards

Mike

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____________________________________________

2004\11\22@053811 by Wouter van Ooijen

face picon face
> Rock solid work. Good productivity. Hard to
> read. (my opinion!)

Readability by other persons is an important quality aspect. The
original author will likely not be around when the code has to be
modified. And if he/she is around he/she will probably have a hard time
understanding code that is unreadable for others. I agree that there are
is no single right way to do things, but there are certainly a lot of
well-kown bad ways.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


____________________________________________

2004\11\22@054853 by Russell McMahon

face
flavicon
face
> ... If the code I write is bad looking in the eyes of someone but I
> produce more and more stable code I can't see how it can be a problem.

Point taken, but to be maintainable in a company environment code must be
understandable by others. Even when writing for one's own use code needs to
be able to be well understood retrospectively. When looking for bugs a
week/month/year/decade later the understandability of the code can go a long
way towards helping - especially as the fact that a bug exists means that
the programmer wasn't as good as they had hoped they were. And bugs always
exist.

Just to tease:

   Very creative programmers should be invited to recant.

   Extremely creative programmers should be fired at the earliest possible
opportunity

:-)



       RM


____________________________________________

2004\11\22@074942 by Ake Hedman

flavicon
face
Wouter van Ooijen wrote:

>>Rock solid work. Good productivity. Hard to
>>read. (my opinion!)
>>    
>>
>
>Readability by other persons is an important quality aspect. The
>original author will likely not be around when the code has to be
>modified. And if he/she is around he/she will probably have a hard time
>understanding code that is unreadable for others. I agree that there are
>is no single right way to do things, but there are certainly a lot of
>well-kown bad ways.
>
>Wouter van Ooijen
>
>-- -------------------------------------------
>Van Ooijen Technische Informatica: http://www.voti.nl
>consultancy, development, PICmicro products
>docent Hogeschool van Utrecht: http://www.voti.nl/hvu
>
>
>____________________________________________

2004\11\22@075122 by Ake Hedman

flavicon
face
Russell McMahon wrote:

{Quote hidden}

>____________________________________________

2004\11\22@075628 by olin_piclist

face picon face
Ake Hedman wrote:
> My point is that its just a matter of preference which method you like
> to use. Its not a *wrong way* in using any of them. But as you state NET
> have some advantages, no question about that..

But does WIRE have any advantages at all over NET?  I can't think of any.

*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________

2004\11\22@081239 by Ake Hedman

flavicon
face
Olin Lathrop wrote:

>Ake Hedman wrote:
>  
>
>>My point is that its just a matter of preference which method you like
>>to use. Its not a *wrong way* in using any of them. But as you state NET
>>have some advantages, no question about that..
>>    
>>
>
>But does WIRE have any advantages at all over NET?  I can't think of any.
>
>  
>
No non. You are absolute right!

Regards
/Ake

--  ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
Company home: http://www.eurosource.se      Kryddor/Te/Kaffe: http://www.brattberg.com
Personal homepage: http://www.eurosource.se/akhe
Automated home: http://www.vscp.org


___________________________________________

2004\11\22@091906 by Gaston Gagnon

face
flavicon
face
Olin Lathrop wrote:
> Ake Hedman wrote:
>
>>My point is that its just a matter of preference which method you like
>>to use. Its not a *wrong way* in using any of them. But as you state NET
>>have some advantages, no question about that..
>
>
> But does WIRE have any advantages at all over NET?  I can't think of any.

As far as I understand it, the Net is a very convenient special case of
Wire that draws obligatory on the net layer. Wire can be used on any layer.
When Wire is used on the net layer, the result is indistinguishable from
a Net. At least I don't see any differences. Do you see any?

How did you know wires was used in the first place?

Gaston
____________________________________________

2004\11\22@130419 by olin_piclist

face picon face
Gaston Gagnon wrote:
> How did you know wires was used in the first place?

Because the connection dots were missing.  I use this feedback from Eagle
all the time as verification that my nets really are connected where I think
they are.  I occasionally make an error where I have to do something at
higher than .1 inch resolution (like aligning special symbols or annotation
text), then forget to put the grid back.  This can make two things look like
they touch on the screen, but in fact do not touch.  lack of dot symbols is
a clue that I specifically look for.  You get other clues when editing the
nets, like things don't drag as expected.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
____________________________________________

2004\11\22@131311 by Russell McMahon

face
flavicon
face
>>Just to tease:
>>
>>    Very creative programmers should be invited to recant.
>>
>>    Extremely creative programmers should be fired at the earliest
>> possible opportunity

> ;-)   mmmmmm.... Glad I'm self employed... :-)

You may have to fire yourself if a major project needs major changes a few
years after you've written it and you find the task far far harder than you
expected due to impenetrable coding. "How hard can it be to understand my
own code ? " :-)



       RM


____________________________________________

2004\11\22@141301 by Ake Hedman

flavicon
face
Russell McMahon wrote:

{Quote hidden}

To be honest I never remember much about my own code if its older than a year or so. So to start up an old project again always needs a "phase in" just as if I took over some other programmers code. Much the same as if you have to start using some maths learned in school many years ago. People have paid me to do programming for them for a bit over twenty years now so I comment code and explain difficult parts in my code and know I have to do so not because customers tell me to (most never care) but because I need it . Sometimes customers have special coding templates I have to adopt to and that is all fine.

But I believe strongly in programing as a creative engineering art and that every software development team needs at least one "extremely creative programmers" to be successfully. And my experience says that is also looks that way on all successful software departments. The "extremely creative programmers" maybe slack for 90% of the project time (assimilate the project ;-) )  and then delivers the hard parts on time. The less creative programmers  do a lot of the foundation work and fill in the stuff that is left out by the "super programmer". End effect is good code delivered on time. But Less creativity is never better! Less creativity is to me more dead.....

Regards
/Ake

--  ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergavägen 17, 820 50 LOS, Sweden
Phone: (46) 657 413430 Cellular: (46) 73 84 84 102
Company home: http://www.eurosource.se      Kryddor/Te/Kaffe: http://www.brattberg.com
Personal homepage: http://www.eurosource.se/akhe
Automated home: http://www.vscp.org


___________________________________________

2004\11\22@171900 by Gaston Gagnon

face
flavicon
face
Olin Lathrop wrote:
> Gaston Gagnon wrote:
>
>>How did you know wires was used in the first place?
>
>
> Because the connection dots were missing.  I use this feedback from Eagle
> all the time as verification that my nets really are connected where I think
> they are.  I occasionally make an error where I have to do something at
> higher than .1 inch resolution (like aligning special symbols or annotation
> text), then forget to put the grid back.  This can make two things look like
> they touch on the screen, but in fact do not touch.  lack of dot symbols is
> a clue that I specifically look for.  You get other clues when editing the
> nets, like things don't drag as expected.
>

I see that you use Eagle with the option "Auto set Junction" On.

We do not know but the original OP, Roy Hopkins could have used Net with
 the option "Auto set Junction" Off or, as you suppose, use Wire and
the end result would be indistinguishable and perfectly acceptable for
eagle.

For myself I always have "Auto Set Junction" Off and use Show to check
connectivity for both wire joining and parts connexion at once.

A side note for people using dots, be careful if you erase a dot at a T
junction, although the wire still look connected they are not anymore.
Removing the dot change the names of joining wires.

Gaston




____________________________________________

2004\11\22@190043 by William Chops Westfield

face picon face

On Nov 22, 2004, at 11:12 AM, Ake Hedman wrote:

> every software development team needs at least one "extremely creative
> programmers" to be successful

"creative" code need not be synonymous with "unreadable", any more than
"art" has to be modern and abstract...

BillW

____________________________________________

2004\11\23@040057 by Peter L. Peres

picon face

On Mon, 22 Nov 2004, Olin Lathrop wrote:

> Ake Hedman wrote:
>> My point is that its just a matter of preference which method you like
>> to use. Its not a *wrong way* in using any of them. But as you state NET
>> have some advantages, no question about that..
>
> But does WIRE have any advantages at all over NET?  I can't think of any.

The only 'advantage' I can see is, that you can make an enclosure drawing
on the schematic and it will be faithfully routed for you if you start it
at the wrong place (on a real wire) (since you shouldn't get a warning
about joining nets like this).

Peter
____________________________________________

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