Homebrew PCBs

Hello everyone,

I am designing a PCB following a schematic designed by someone living 
in Europe, and while he supplied a nice schematic and partlist, I am 
having trouble finding certain parts in America with the same 
specifications.  The part list has part numbers for a supplier called 
Elfa (www.elfa.se).  I have been able to convert most of the parts 
listed in Elfa to parts here in the US.  But some I can't find...

This is making it difficult to design a board design using parts I 
can't purchase here.  In fact, there are a couple parts which are not 
available at all to consumers (I have found some military and OEM 
suppliers who are willing to take a RFQ, but I only need one piece).

How do those of you who live in America deal with designs from other 
countries which have different part suppliers?  

I have tried digikey, jameco, allecetronics, newarkinone, and 
others.  Does anyone know of parts in America that match the ones 
described below?  

http://www.elfa.se/pdf/71/07104979.pdf
bc337b - Philips general purpose transistor
elfa #71-072-46
$0.21 EU

http://www.vishay.com/docs/88501/1500z.pdf
b40c1500r - 1.5a bridge rectifier
elfa#70-050-93
$1.08 EU

I would be most appreciative if someone could find parts that match 
the specs.  As this is for a power source, the specs can't be "close 
enough" (I've found plenty of parts that are close but not quite).

I would even entertain the idea of sending funds via paypal for 
someone in europe to snail mail over these two items (cost of items 
and postage).  Elfa wants 18-70 EU ($21 - 83USD) for delivery outside 
of the EU.  That's more than the project costs for the rest of the 
parts!

Any good ideas?

--- In Homebrew_PCBs@yahoogroups.com, "Greg Codori" <greg_codori@h...>
wrote:
... 
> http://www.elfa.se/pdf/71/07104979.pdf
> bc337b - Philips general purpose transistor
> elfa #71-072-46
> $0.21 EU

mouser lists it for $.06 (yes, 6 cents) but doesn't stock.  I'd sub
with a 2n2222A or 2N4401

> 
> http://www.vishay.com/docs/88501/1500z.pdf
> b40c1500r - 1.5a bridge rectifier
> elfa#70-050-93
> $1.08 EU

mouser carries three direct cross refs for this, $.27, $.52 and $.57.
But, any 1.5A or higher bridge rect will do.  

> 
> I would be most appreciative if someone could find parts that match 
> the specs.  As this is for a power source, the specs can't be "close 
> enough" (I've found plenty of parts that are close but not quite).

With out seeing the schematic, its hard to say to 100% but I seriously
doubt you'll have a problem with those substitutions.  The transistors
have a slightly lower absolute max current rating but better Hfe and
the same power dissipation ratings (same package).  I'd believe the
power rating before the absolute max current - the designer should
have stay well away from the max numbers.  And rectifiers are a
commodity. Look at it this way, since the cost of shipping more than
the rest of the parts combined, what's the cost of blowing up ALL the
components (which you wont)?  Personally, I would sub them in a heartbeat.

Phil

On Fri, 08 Jul 2005 00:30:06 +0200, Greg Codori <greg_codori@...>  
wrote:

>
> http://www.elfa.se/pdf/71/07104979.pdf
> bc337b - Philips general purpose transistor
> elfa #71-072-46
> $0.21 EU
> http://www.vishay.com/docs/88501/1500z.pdf
> b40c1500r - 1.5a bridge rectifier
> elfa#70-050-93
> $1.08 EU


Those are standard parts, you will have no troble finding a US equiv.

The BC337 should be available in the US as is, but a close match will do  
fine. look at the cct. if there are any extraordinary requirements, but i  
say about half of the transistors you can buy will work ;-)


A bridge rectifier is also a standard part, look for the right footprint  
if you have a PCB and use the same or more current and voltage rating.


I would be prepared to send you parts in exchange for paypal, if they  
really were anything you couldn't get or substitute, but it isn't required  
in this case.


ST

> Those are standard parts, you will have no troble finding a US equiv.
> 
> The BC337 should be available in the US as is, but a close match will do
> fine. look at the cct. if there are any extraordinary requirements, but i
> say about half of the transistors you can buy will work ;-)

I use findchips.com to find stuff.

It reports several places that have BC337 in stock (including DigiKey).

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/

he did ask for a 337B but, interestingly, the 337 vs 337B specs
(fairchild) appear to be identical.  wonder what the difference is? 
I'd definitely sub the 337 for the 337B.

$.06 at mouser... 

Phil

--- In Homebrew_PCBs@yahoogroups.com, Dave Hylands <dhylands@g...> wrote:
> > Those are standard parts, you will have no troble finding a US equiv.
> > 
> > The BC337 should be available in the US as is, but a close match
will do
> > fine. look at the cct. if there are any extraordinary
requirements, but i

> > say about half of the transistors you can buy will work ;-)
> 
> I use findchips.com to find stuff.
> 
> It reports several places that have BC337 in stock (including DigiKey).
> 
> -- 
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/

On Thursday 07 July 2005 06:30 pm, Greg Codori wrote:
> Hello everyone,
>
> I am designing a PCB following a schematic designed by someone living
> in Europe, and while he supplied a nice schematic and partlist, I am
> having trouble finding certain parts in America with the same
> specifications.  The part list has part numbers for a supplier called
> Elfa (www.elfa.se).  I have been able to convert most of the parts
> listed in Elfa to parts here in the US.  But some I can't find...

This is why I tend to try and stick with the most generic parts possible when 
I'm designing or building something.  Going to the more specialized stuff 
makes more sense for a manufacturer where shaving a few pennies off here and 
there can make a lot of difference,  but for the likes of us hobbyists the 
shipping costs will be more than the difference in price most times.

> This is making it difficult to design a board design using parts I
> can't purchase here.  In fact, there are a couple parts which are not
> available at all to consumers (I have found some military and OEM
> suppliers who are willing to take a RFQ, but I only need one piece).

I've bumped into those web sites from time to time and as soon as I realize 
that's what I'm looking at I go elsewhere,  those sites are okay for a mfr. 
but not for hobby use.

> How do those of you who live in America deal with designs from other
> countries which have different part suppliers?

Take a look at http://yourpage.blazenet.net/rtellason/parts.html and maybe 
download the pages for reference,  and you'll get an idea.  :-)

> I have tried digikey, jameco, allecetronics, newarkinone, and
> others.  Does anyone know of parts in America that match the ones
> described below?
>
> http://www.elfa.se/pdf/71/07104979.pdf
> bc337b - Philips general purpose transistor
> elfa #71-072-46
> $0.21 EU

I show that as being an NPN Silicon transistor with a Vce of 45V,  an Ic(max) 
of 800mA,  a power rating of 625mW,  and a beta range of 160-400 for the 
generic BC337.  The way those numbers work is that the letter on the end is 
indicative of different segments of that beta range,  so a "c" there would 
tend toward the higher end.  Without looking at the schematic you're working 
from I'm not sure what would be a good substitute -- a 2N2222A has that kind 
of current capability but I don't think it has as much gain.  Whether this 
will matter or not I can't say.

> http://www.vishay.com/docs/88501/1500z.pdf
> b40c1500r - 1.5a bridge rectifier
> elfa#70-050-93
> $1.08 EU

Bridge rectifiers are fairly generic parts.  If I was looking for one for a 
repair then beside the specs I'd be looking at what kind of a package it was 
in.  Some have all four wires in line,  some have them arranged in a square,  
and if nothing else you could always make one up using four individual 
diodes.  I use 1N4000 series parts for anything with 1A or less of a 
requirement (and that *might* work for what you're doing but again it depends 
on the circuit),  1N5408 for heavier-duty (3A) stuff.  You also used to be 
able to find a fair selection of them at radio shack of all places,  though I 
haven't looked lately.

> I would be most appreciative if someone could find parts that match
> the specs.  As this is for a power source, the specs can't be "close
> enough" (I've found plenty of parts that are close but not quite).

You can always exceed the specs in some ways,  particularly with the bridge 
rectifier.  How critical the transistor is I can't say without looking at a 
schematic.

> I would even entertain the idea of sending funds via paypal for
> someone in europe to snail mail over these two items (cost of items
> and postage).  Elfa wants 18-70 EU ($21 - 83USD) for delivery outside
> of the EU.  That's more than the project costs for the rest of the
> parts!
>
> Any good ideas?

See above.  And feel free to point me at a schematic someplace (if it's 
online) or shoot me a copy in email (if it's not) and we'll take it from 
there.

I've found quite a few NPN parts, but most of them are substituting a 
400v part for a 100v part...pretty broad range for a replacement part.
> 
> I show that as being an NPN Silicon transistor with a Vce of 45V,  
an Ic(max) 
> of 800mA,  a power rating of 625mW,  and a beta range of 160-400 
(((SNIP)))
> > http://www.vishay.com/docs/88501/1500z.pdf
> > b40c1500r - 1.5a bridge rectifier
> > elfa#70-050-93
> > $1.08 EU
> 
>
((SNIP))> 
> See above.  And feel free to point me at a schematic someplace (if 
it's 
> online) or shoot me a copy in email (if it's not) and we'll take it 
from 
> there.

Here is the schematic
http://home.no.net/paolsen/mj/dnl/Schematic.pdf

here is the partlist
http://home.no.net/paolsen/mj/slncmst_p10.html

Parts BR1 and Q1.

This schematic is a control station with a built in power supply.  
This control station generates electronic pulses through model RR 
tracks which are decoded by chips within individual locomotives 
(model RR has an electronics part of the hobby, by the way).

I'm trying to rebuild the schematic into a board design through 
Eagle.  There are PDF files of the board as designed, but I can't 
convert PDF files into eagle files.
They are located at 
http://home.no.net/paolsen/mj/dnl/SLNCMST11_layout.zip

Anyone know how to convert pdf's into eagle board files?

Thanks again!

On Fri, 08 Jul 2005 19:43:09 +0200, Phil <phil1960us@...> wrote:

> he did ask for a 337B but, interestingly, the 337 vs 337B specs
> (fairchild) appear to be identical.  wonder what the difference is?
> I'd definitely sub the 337 for the 337B.
> $.06 at mouser...
> Phil


the ABC is usually sorted for hFE with A beeing lowest and C highest.

ST

On Fri, 08 Jul 2005 20:27:58 +0200, Greg Codori <greg_codori@...>  
wrote:

> I've found quite a few NPN parts, but most of them are substituting a
> 400v part for a 100v part...pretty broad range for a replacement part.


That part is only going to see 5V or whatever loconet uses.

What you need to look out for is the current rating in this case, same or  
more to be safe.
hFE and voltage seems non-critical.

ST

> That part is only going to see 5V or whatever loconet uses.
> 
> What you need to look out for is the current rating in this case, 
same or  
> more to be safe.
> hFE and voltage seems non-critical.
> 
> ST

It's nice to see someone who's familiar with loconet...

The BR1 (part BR1) does not feed loconet directly, it's part of the 
power source (it's connected to the fuse and power jack).  

Have you seen the schematic link I posted?  Could I just start with 
another power wall wart current (instead of 15v/20va) and feed 
directly into part U6 and U3?  Part U6 is outputting 15v and U3 is  
outputting 5v.  I would assume that U6 amd U3 both have the same 
input voltage (35v per digikey specs?).  Then I could just have the 
power jack and fuse without the bridged rectifier.

Greg

On Fri, 08 Jul 2005 21:46:38 +0200, Greg Codori <greg_codori@...>  
wrote:

>
> It's nice to see someone who's familiar with loconet...
> The BR1 (part BR1) does not feed loconet directly, it's part of the
> power source (it's connected to the fuse and power jack).
> Have you seen the schematic link I posted?  Could I just start with
> another power wall wart current (instead of 15v/20va) and feed
> directly into part U6 and U3?  Part U6 is outputting 15v and U3 is
> outputting 5v.  I would assume that U6 amd U3 both have the same
> input voltage (35v per digikey specs?).  Then I could just have the
> power jack and fuse without the bridged rectifier.
> Greg


Yea i have seen the schem. and you can feed it with a wall-wart.
You need about 17V or more of DC on the 7815 input for it to work  
properly, how you get that doesn't matter.
In case you get a wall-wart with regulated output of 15V you can hook the  
7805 to that and connect without the 7815 to 15V.

You know this is getting pretty off topic, there is another group,  
Electronics_101@yahoogroups.com, where most of the people here are also  
around and where it is much more on topic.

ST

> Yea i have seen the schem. and you can feed it with a wall-wart.
> You need about 17V or more of DC on the 7815 input for it to work  
> properly, how you get that doesn't matter.
> In case you get a wall-wart with regulated output of 15V you can 
hook the  
> 7805 to that and connect without the 7815 to 15V.
> 
> You know this is getting pretty off topic, there is another group,  
> Electronics_101@yahoogroups.com, where most of the people here are 
also  
> around and where it is much more on topic.
> 
> ST

Thanks for the info, I'll check that group out for more technical 
questions.  To get back on the topic of board design...

In my previous post, I listed the link for the PDF board files (in 
addition to the schem).  Is there an easy way to convert this to an 
eagle file?  This was the reason I first posted, as I have to redraw 
the schematic to a board and couldn't find american versions of the 
two listed parts.  If I could convert the pdf to a board, half of my 
problem would be solved.  Then I could ask the other forum about 
electronic part suggestions.

GC

On Fri, 08 Jul 2005 22:21:23 +0200, Greg Codori <greg_codori@...>  
wrote:

>
> Thanks for the info, I'll check that group out for more technical
> questions.  To get back on the topic of board design...
> In my previous post, I listed the link for the PDF board files (in
> addition to the schem).  Is there an easy way to convert this to an
> eagle file?  This was the reason I first posted, as I have to redraw
> the schematic to a board and couldn't find american versions of the
> two listed parts.  If I could convert the pdf to a board, half of my
> problem would be solved.  Then I could ask the other forum about
> electronic part suggestions.
> GC


There is no way to just "import" a pdf (which is basically a picture) into  
a layout software.
The information about connections, components, ... , while obvious to us  
is very hard to automatically find with software and i'm not aware of any  
software that can do it.

You need to either make the PCB as is (maybe with small changes in a image  
editing software), or you need to re-draw the board in a layout software.
If you don't want to redesign it completely it might help to import that  
picture into your software as picture, and work "over" it laying the new  
components and tracks over the picture. I do that sometimes but i dunno if  
eagle can import pictures.

A quick look at the pdf shows me the layout is not unreasonable, but would  
require small changes (bigger pads in some places) if you want to homebrew  
the PCB (It is very, very hard to plate the holes at home so you need  
larger pads or you can't solder to them). This could be done in a graphics  
software.

ST

On Friday 08 July 2005 02:27 pm, Greg Codori wrote:
> I've found quite a few NPN parts, but most of them are substituting a
> 400v part for a 100v part...pretty broad range for a replacement part.

I wouldn't go up there unless I had to.  As you go to higher collector 
breakdown voltage ratings you sacrifice either gain, frequency response, or 
both.  And I have a fair amount of that stuff kicking around,  mostly 
salavaged horizontal output devices.

> > I show that as being an NPN Silicon transistor with a Vce of 45V,
> > an Ic(max) of 800mA,  a power rating of 625mW,  and a beta range of
> > 160-400
>
> (((SNIP)))
>
> > > http://www.vishay.com/docs/88501/1500z.pdf
> > > b40c1500r - 1.5a bridge rectifier
> > > elfa#70-050-93
> > > $1.08 EU
>
> ((SNIP))>
>
> > See above.  And feel free to point me at a schematic someplace (if
> > it's online) or shoot me a copy in email (if it's not) and we'll take it
> > from there.
>
> Here is the schematic
> http://home.no.net/paolsen/mj/dnl/Schematic.pdf
>
> here is the partlist
> http://home.no.net/paolsen/mj/slncmst_p10.html
>
> Parts BR1 and Q1.

Ok.  As far as the bridge rectifier goes,  I'd worry about form factor when I 
was doing repairs,  otherwise just use whatever you can find that'll meet or 
exceed those ratings.  I did a lot of "1541" disk drives (for the c64) and 
they used 1A (!) bridges in there which would succumb to the heat after a 
while.  I found an identically-packaged unit at Radio Shack rated at 4A that 
fit right into the same holes,  an all-pins-in-line configuration.  Also 
salvaged a 4A bridge out of a printer board in the past couple of days that 
happened to be rated at 4A,  so it's whatever's convenient and cheap for you.  
And there's plenty of stuff out there.

For the transistor I can see where they're switching low-level signals (from 
the use of the +5 supply) though I'm not sure at what rate they're going 
since that whole thing is fed from the output pin of that PIC or whatever it 
is.  *Real* non-critical,  and just about any NPN transistor will work in 
there,  as well as darn near any PNP transistor for Q2 -- I'd use 2N3904 and 
2N3906 for those if I was building this.

> This schematic is a control station with a built in power supply.
> This control station generates electronic pulses through model RR
> tracks which are decoded by chips within individual locomotives
> (model RR has an electronics part of the hobby, by the way).

Yeah,  I'd like to get more info on that stuff.  Are you familiar with Rob 
Paisley's pages?  He has a whole mess of good info out there.  Please feel 
free to pass along any links that you might have to other useful electronics 
stuff in this context.

> I'm trying to rebuild the schematic into a board design through
> Eagle.  There are PDF files of the board as designed, but I can't
> convert PDF files into eagle files.

One of these days I'm going to figure out some way to get info out of PDF 
files,  other than by printing the damn things out and then scanning them 
into some other format...

> They are located at
> http://home.no.net/paolsen/mj/dnl/SLNCMST11_layout.zip
>
> Anyone know how to convert pdf's into eagle board files?

The trouble with trying to get info into Eagle or any other schematic capture 
program is that you have an image,  and the program wants to deal with a set 
of objects with defined relationships,  which is not at all the same thing.  
I guess we need something like OCR for images,  or at least for schematics,  
and I'm not the person to write _that_ program!  :-)

On Friday 08 July 2005 03:46 pm, Greg Codori wrote:

> Have you seen the schematic link I posted?  Could I just start with
> another power wall wart current (instead of 15v/20va) and feed
> directly into part U6 and U3?  Part U6 is outputting 15v and U3 is
> outputting 5v.  I would assume that U6 amd U3 both have the same
> input voltage (35v per digikey specs?).  Then I could just have the
> power jack and fuse without the bridged rectifier.

Actually the 35v limit is only for the 5v regulator,  the other one will 
handle up to 40v in,  but then you need to consider how much power each of 
those will have to dissipate to regulate things properly.  For example if 
you're putting 20v on the input then the 5v regulator is going to be dropping 
15v -- at an output current of (say) 1A,  that's 15W of power being wasted.  
It'll also need a pretty good heatsink to keep working.

But if current is fairly small,  this shouldn't be a problem.

Yes,  you can do that,  leaving out the bridge and just feeding some DC right 
into those regulators.  Better still would be feeding in two levels of DC,  
closer to what the regulators want to see as a minimum,  but that's not a 
problem if the load currents are small.

On Sat, 09 Jul 2005 00:34:20 +0200, Roy J. Tellason  
<rtellason@...> wrote:

>
> One of these days I'm going to figure out some way to get info out of PDF
> files,  other than by printing the damn things out and then scanning them
> into some other format...


What about using acrobat reader / select text or select image and then  
copy / paste?

ST

On Friday 08 July 2005 04:21 pm, Greg Codori wrote:
> > Yea i have seen the schem. and you can feed it with a wall-wart.
> > You need about 17V or more of DC on the 7815 input for it to work
> > properly, how you get that doesn't matter.
> > In case you get a wall-wart with regulated output of 15V you can
> > hook the 7805 to that and connect without the 7815 to 15V.
> >
> > You know this is getting pretty off topic, there is another group,
> > Electronics_101@yahoogroups.com, where most of the people here are
> > also around and where it is much more on topic.
> >
> > ST
>
> Thanks for the info, I'll check that group out for more technical
> questions.

And you'll find me _much_ more active in there than in here.  :-)

On Friday 08 July 2005 06:42 pm, Stefan Trethan wrote:
> On Sat, 09 Jul 2005 00:34:20 +0200, Roy J. Tellason
>
> <rtellason@...> wrote:
> > One of these days I'm going to figure out some way to get info out of PDF
> > files,  other than by printing the damn things out and then scanning them
> > into some other format...
>
> What about using acrobat reader / select text or select image and then
> copy / paste?

I don't use it here,  though maybe I should give it a try some time.  I use 
GhostView,  under linux.

Perhaps a screen capture sort of software would do the trick...

I was actually thinking of bypassing that whole portion of the 
schematic and just hard-wiring two wall warts into the schematic at the 
right voltage (15v and 5v).  Just not sure if the diode served some 
other purpose (like adjusting the amps?).

Do you have any recommendations for the two parts from elfa I listed?  
After looking at the schematic, and seeing what the power portion does, 
are there parts you would substitute?

GC

> 
> Yes,  you can do that,  leaving out the bridge and just feeding some 
DC right 
> into those regulators.  Better still would be feeding in two levels 
of DC,  
> closer to what the regulators want to see as a minimum,  but that's 
not a 
> problem if the load currents are small.

On Sat, 09 Jul 2005 00:51:41 +0200, Roy J. Tellason  
<rtellason@...> wrote:

>
> I don't use it here,  though maybe I should give it a try some time.  I  
> use
> GhostView,  under linux.
> Perhaps a screen capture sort of software would do the trick...


shouldn't ghostview be able to put out post script?

If all else falis install a postscript printer and divert it to file.

That's why i don't use linux any more - everything 2 clicks away in  
windows ends up beeing a major pita.



ST

On Saturday 09 July 2005 01:51 am, Stefan Trethan wrote:
> On Sat, 09 Jul 2005 00:51:41 +0200, Roy J. Tellason
>
> <rtellason@...> wrote:
> > I don't use it here,  though maybe I should give it a try some time.  I
> > use GhostView,  under linux.
> > Perhaps a screen capture sort of software would do the trick...
>
> shouldn't ghostview be able to put out post script?

Possibly,  I haven't tried it.  What use would postscript be?

> If all else falis install a postscript printer and divert it to file.

I have a postscript printer,  it just isn't in use at the present time.

On Sat, 09 Jul 2005 18:45:44 +0200, Roy J. Tellason  
<rtellason@...> wrote:

>
> Possibly,  I haven't tried it.  What use would postscript be?
>

well, you can open it with other graphics software, sometimes ;-)
maybe gimp.

>> If all else falis install a postscript printer and divert it to file.
> I have a postscript printer,  it just isn't in use at the present time.

You don't need the physical printer, you just tell the PC you got one and  
divert the output not to lpt1 or so but a file instead. I don't remember  
how this is done with unix but i remember it is fairly easy. Under windows  
you just click print to file. But it only gives you a postscript file  
again.
Still much better than scanned.


Is there still no better PDF reader for unix? the acrobat reader has the  
select text/image function for ages.


ST

On Saturday 09 July 2005 01:24 pm, Stefan Trethan wrote:
> On Sat, 09 Jul 2005 18:45:44 +0200, Roy J. Tellason
>
> <rtellason@...> wrote:
> > Possibly,  I haven't tried it.  What use would postscript be?
>
> well, you can open it with other graphics software, sometimes ;-)
> maybe gimp.

Hmm.  I never thought about using that program to open postscript files,  but 
it works...

> >> If all else falis install a postscript printer and divert it to file.
> >
> > I have a postscript printer,  it just isn't in use at the present time.
>
> You don't need the physical printer, you just tell the PC you got one and
> divert the output not to lpt1 or so but a file instead. I don't remember
> how this is done with unix but i remember it is fairly easy. Under windows
> you just click print to file. But it only gives you a postscript file again.
> Still much better than scanned.

Probably would work,  yeah.

> Is there still no better PDF reader for unix? the acrobat reader has the
> select text/image function for ages.

There are a couple of them here,  and I did get the adobe product but haven't 
installed it yet,  figuring that most of what I've got worked fine.  There 
are a small number of datasheets that the current software won't open,  so 
maybe one of these days I'll get around to installing that and seeing if it 
deals with them or assume that if it won't the files really are corrupted...

Hi,

I've just uploaded a schematic of a 40V 3A circuit that I put together.
I've thrown in every security measure I could find in the DigiKey manual as
an exercise.  The file is in FILES / Power supplies.  This link may (or may
not) work:
<http://f1.grp.yahoofs.com/v1/MHDRQjmKCjHN8hORzw6Lxapg3rQLHR9sg4BZ8ePemrCIKl
pX6E8d2Q1QnZ52WUfAGgpe1uV08UyZCt9sgF5IHEcaLLyziJI/Power%20supply/Drilling%20
station%2040V%203A%20steppers.JPG>

Please let me know if I have design flaws, is the fuse rating high enough,
components in series instead of parallel or vice versa, suggestions for
additional security measures, improvements in filtering, etc.

This is my first power supply and I don't want to have problems with it in
the future.  I also want to make it as robust as possible.  A separate 5V
circuit will power the logic circuitry, this is exclusively for the
steppers.

Robert
:)


Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

On Sun, 10 Jul 2005 21:16:38 +0200, Robert Hedan  
<robert.hedan@...> wrote:

> Hi,
> I've just uploaded a schematic of a 40V 3A circuit that I put together.
> I've thrown in every security measure I could find in the DigiKey manual  
> as
> an exercise.  The file is in FILES / Power supplies.  This link may (or  
> may
> not) work:
> <http://f1.grp.yahoofs.com/v1/MHDRQjmKCjHN8hORzw6Lxapg3rQLHR9sg4BZ8ePemrCIKl
> pX6E8d2Q1QnZ52WUfAGgpe1uV08UyZCt9sgF5IHEcaLLyziJI/Power%20supply/Drilling%20
> station%2040V%203A%20steppers.JPG>
> Please let me know if I have design flaws, is the fuse rating high  
> enough,
> components in series instead of parallel or vice versa, suggestions for
> additional security measures, improvements in filtering, etc.
> This is my first power supply and I don't want to have problems with it  
> in
> the future.  I also want to make it as robust as possible.  A separate 5V
> circuit will power the logic circuitry, this is exclusively for the
> steppers.
> Robert
>


You certainly have a few surplus parts in there ;-)

What's the inductor L1 for?

U2/3/4/5 are a mystery to me.

What is the EMI coil, what is the input? mains?

Putting caps in parallel to lower ESR is a nice idea, but usually you'd  
only put one electrolytic and one ceramic. If you want to use several  
electrolytic parallel instead that is a good thing, but usually you'd use  
the same size. A very small electrolytic parallel with a big one is just  
not changing anything, esp. if you have a ceramic cap too.

I dunno about your fuses, you certainly have a great many. I wouldn't want  
to predict which one will trip first. Also, i wouldn't see the need.

What i would have done if i had to use a transformer supply and not a SMPS:

hot->fuse->(NTC)->primary1->primary2->neutral.
(ntc in case of toroid transformer)

sec->bridge rect. at least 20A->electrolytic cap 6800-10000u->voltage  
regulator->cap 220u or more parallel 100n to 470n->polyfuse->out.


ST

Hi Robert,

The schematic is not very clear, not enough resolution. But of what I can
see, these points I noticed:
- I think that you should move the fuse to the AC part of the circuit
- The LT1085 is rated for 3A and you want a power supply for 3A. Don't you
think it's to close? What if there's an overload? Even without overload, if
you use a motor with this, or any other inductive or capacitive load, it's
starting up will not be an easy one. My advise is that you use a higher
current regulator, like the LT1084 or LT1083. 
	Same thing with the power supply diodes. Higher amperage rating is
better.

http://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1040,C1055,P128
3

- These regulators are adjustable ones. This means that they can be set to
supply a voltage from 1.25V up to whatever you choose with the resistors in
the adjustment pin. If you want 40V you cannot connect it to ground
directly.

If you whish, I can send you a better schematic of an 40V, 3A power supply,
with the LT's regulators or others. Or, you can send me the schematic with
much better resolution and I can help you to solve its problems.

P.S. use my private E_mail: nuno_t@..., this subject doesn't fit in this
group, OK?

Best,

Nuno Tavares

> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Robert Hedan
> Sent: domingo, 10 de Julho de 2005 20:17
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Drilling station 40V 3A power supply
> 
> Hi,
> 
> I've just uploaded a schematic of a 40V 3A circuit that I put together.
> I've thrown in every security measure I could find in the DigiKey manual
> as
> an exercise.  The file is in FILES / Power supplies.  This link may (or
> may
> not) work:
> <http://f1.grp.yahoofs.com/v1/MHDRQjmKCjHN8hORzw6Lxapg3rQLHR9sg4BZ8ePemrCI
> Kl
> pX6E8d2Q1QnZ52WUfAGgpe1uV08UyZCt9sgF5IHEcaLLyziJI/Power%20supply/Drilling%
> 20
> station%2040V%203A%20steppers.JPG>
> 
> Please let me know if I have design flaws, is the fuse rating high enough,
> components in series instead of parallel or vice versa, suggestions for
> additional security measures, improvements in filtering, etc.
> 
> This is my first power supply and I don't want to have problems with it in
> the future.  I also want to make it as robust as possible.  A separate 5V
> circuit will power the logic circuitry, this is exclusively for the
> steppers.
> 
> Robert
> :)
> 
> 
> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
> 
> 
> 
>

On Sun, 10 Jul 2005 22:25:18 +0200, Nuno Tavares <nuno-t@...> wrote:

> Hi Robert,
> The schematic is not very clear, not enough resolution.

That's 'cause it's a jpg instead of a gif. jpg is not suitable for line  
art, only photos. use gif or png, it will also use much less space.

Very good point with the regulator, i didn't catch that one.

ST

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> On Fri, 08 Jul 2005 19:43:09 +0200, Phil <phil1960us@y...> wrote:
> 
> > he did ask for a 337B but, interestingly, the 337 vs 337B specs
> > (fairchild) appear to be identical.  wonder what the difference is?
> > I'd definitely sub the 337 for the 337B.
> > $.06 at mouser...
> > Phil
> 
> 
> the ABC is usually sorted for hFE with A beeing lowest and C highest.
> 
> ST

Except in this case the datasheets claim the same Hfe numbers for
both.   Wonder if they are really both Bs. It wouldn't be the first
time a manufacturer labled higher spec parts as lower.

On Sun, 10 Jul 2005 23:26:59 +0200, Phil <phil1960us@...> wrote:

>
> Except in this case the datasheets claim the same Hfe numbers for
> both.   Wonder if they are really both Bs. It wouldn't be the first
> time a manufacturer labled higher spec parts as lower.


The abc is not always the same for different manufacturers (all the specs  
can be different).
Also, some have numbers like -10 -15 -20 and so on instead of the letters.
Luckily few circits are really gain-sensitive, or we would be in real  
trouble ;-)

ST

--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
> On Sun, 10 Jul 2005 23:26:59 +0200, Phil <phil1960us@y...> wrote:
> 
> >
> > Except in this case the datasheets claim the same Hfe numbers for
> > both.   Wonder if they are really both Bs. It wouldn't be the first
> > time a manufacturer labled higher spec parts as lower.
> 
> 
> The abc is not always the same for different manufacturers (all the
specs  
> can be different).
> Also, some have numbers like -10 -15 -20 and so on instead of the
letters.
> Luckily few circits are really gain-sensitive, or we would be in real  
> trouble ;-)
> 
> ST

Yes, in fact H&H explicitly talk about avoiding that in their section
on trasistors.

"What's the inductor L1 for?"

- Absolutely no idea, I was hoping you'd clear that up, hence the schematic
request.  I saw that somewhere, can't remember.


"U2/3/4/5 are a mystery to me."

- Sorry, I wanted to explain the acronyms and forgot.
- PolySwitch, a resettable device to protect against excessive current,
voltage and temperature (more in DigiKey catalog).
- ICL, incurrent rush limitted.
- ZOV, zinc oxide varistor.


"What is the EMI coil, what is the input? mains?"

Input is the secondary coils via a terminal block, 24V, 24V 48VCT.  An
electro-magnetic interference coil, supposed to remove common waveforms
across all signals.  I read somewhere it is a good idea to place these when
cables enter a PCB, to remove interference they pick up.


"A very small electrolytic parallel with a big one is just not changing
anything, esp. if you have a ceramic cap too."

- I didn't know much about the filter caps, even less when more than 1A is
involved.  I thought electrolytic caps acted like ceramic caps, the large
ones filling in larger gaps in the waveform, the smaller ones filling in
some more of the remaining gap.


"I dunno about your fuses, you certainly have a great many. I wouldn't want
to predict which one will trip first. Also, i wouldn't see the need."

- I only have one fuse on each stepper.  I don't want to have one general
fuse and then have to figure which circuit is the problem.
- The ZNRs and MOVs are there to act as crowbars in case of a short further
down the line.  They don't have the same speeds, so I put one of each model.
- If I place the fuse on the 115V line, the crowbar devices are kinda far
removed.
- I do note that the ZOV has a clamp rating, I assume that makes it a
crowbar-type device.  I have that device in series instead of parallel, not
gonna do much that way.  Technically, I should also have a fuse at that
point also.
- Determining which fuse will be blown is not a problem.  The fuses will be
mounted on the front panel along with an indicator lamp.
- Since the ZOV has clamping capability, I am considering placing one on the
primary side of the transformer along with 2 more ICL and a fuse.  That
would give me an immediate indication of where the problem is; primary,
secondary or post-voltreg DC signal.


"What i would have done if i had to use a transformer supply and not a
SMPS:"
hot->fuse->(NTC)->primary1->primary2->neutral.
(ntc in case of toroid transformer)

- I have no idea what NTC is.  I don't understand the coil configuration
either, I've only dealt with single 115V primaries so far.


I could increase cap size as you recommend.  As I said, I don't have any
sample to work with, nor do I know how to calculate required caps.

Robert
:)



-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Stefan Trethan
Envoyé : juillet 10 2005 16:21
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: [Homebrew_PCBs] Drilling station 40V 3A power supply


You certainly have a few surplus parts in there ;-)

ST



Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

Hi Nuno,

"The schematic is not very clear, not enough resolution."

- Don't browse it via Internet Explorer, save it and browse it using
PaintBrush; you'll get a much better view.
- I've just sent a BMP of the pic to you.  You can improve that one, or send
me another schematic and I'll compare.

"I think that you should move the fuse to the AC part of the circuit"

- As I told Stefan, I think the fuse should be close to the ZNR and MOV
crowbar devices.  But I am going to add another fuse on the AC side, I have
lots of spare holders.  :D


"The LT1085 is rated for 3A and you want a power supply for 3A. Don't you
think it's to close?"

- Yes I do, I thought of that earlier today.  I'm going to move up to the
LT1084 at least, same thing with the diodes.
- I also noticed I totally forgot the adjustment circuitry for the voltage
regulator.


"this subject doesn't fit in this group, OK?"

- several people in this group are building a PCB drilling station, hence
the title.  We've been given permission to discuss stuff related with this
project here.


Robert
:)



-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Nuno Tavares
Envoyé : juillet 10 2005 16:25
À : Homebrew_PCBs@yahoogroups.com
Objet : RE: [Homebrew_PCBs] Drilling station 40V 3A power supply


Hi Robert,

The schematic is not very clear, not enough resolution. But of what I can
see, these points I noticed:
- I think that you should move the fuse to the AC part of the circuit
- The LT1085 is rated for 3A and you want a power supply for 3A. Don't you
think it's to close? What if there's an overload? Even without overload, if
you use a motor with this, or any other inductive or capacitive load, it's
starting up will not be an easy one. My advise is that you use a higher
current regulator, like the LT1084 or LT1083. 
	Same thing with the power supply diodes. Higher amperage rating is
better.

http://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1040,C1055,P128
3

- These regulators are adjustable ones. This means that they can be set to
supply a voltage from 1.25V up to whatever you choose with the resistors in
the adjustment pin. If you want 40V you cannot connect it to ground
directly.

If you whish, I can send you a better schematic of an 40V, 3A power supply,
with the LT's regulators or others. Or, you can send me the schematic with
much better resolution and I can help you to solve its problems.

P.S. use my private E_mail: nuno_t@..., this subject doesn't fit in this
group, OK?

Best,

Nuno Tavares


> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com 
> [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Robert Hedan
> Sent: domingo, 10 de Julho de 2005 20:17
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Drilling station 40V 3A power supply
> 
> Hi,
> 
> I've just uploaded a schematic of a 40V 3A circuit that I put 
> together. I've thrown in every security measure I could find in the 
> DigiKey manual as an exercise.  The file is in FILES / Power supplies.  
> This link may (or may
> not) work:
> <http://f1.grp.yahoofs.com/v1/MHDRQjmKCjHN8hORzw6Lxapg3rQLHR9sg4BZ8ePemrCI
> Kl
> pX6E8d2Q1QnZ52WUfAGgpe1uV08UyZCt9sgF5IHEcaLLyziJI/Power%20supply/Drilling%
> 20
> station%2040V%203A%20steppers.JPG>
> 
> Please let me know if I have design flaws, is the fuse rating high 
> enough, components in series instead of parallel or vice versa, 
> suggestions for additional security measures, improvements in 
> filtering, etc.
> 
> This is my first power supply and I don't want to have problems with 
> it in the future.  I also want to make it as robust as possible.  A 
> separate 5V circuit will power the logic circuitry, this is 
> exclusively for the steppers.
> 
> Robert
> :)
> 
> 
> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here: 
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here: 
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
> 
> 
> 
> 




Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

"That's 'cause it's a jpg instead of a gif. jpg is not suitable for line
art, only photos. use gif or png, it will also use much less space."

- Ok,  I'll upload a GIF instead.  I draw in BMP, so I have to convert into
something to save space on the group site.

Robert
:)


-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Stefan Trethan
Envoyé : juillet 10 2005 16:41
À : Homebrew_PCBs@yahoogroups.com
Objet : Re: [Homebrew_PCBs] Drilling station 40V 3A power supply


On Sun, 10 Jul 2005 22:25:18 +0200, Nuno Tavares <nuno-t@netc.pt> wrote:

> Hi Robert,
> The schematic is not very clear, not enough resolution.

That's 'cause it's a jpg instead of a gif. jpg is not suitable for line  
art, only photos. use gif or png, it will also use much less space.

Very good point with the regulator, i didn't catch that one.

ST




Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

"What's the inductor L1 for? -ST"

As it turns out, absolutely nothing in a linear power supply.  I must have
looked at a schematic that had components from both a linear and SMPS power
supply design.

I like this explanation of linear versus SMPS power supplies; very clear for
newbs like me:
http://www.answers.com/topic/switched-mode-power-supply

Robert
:)





Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

This thread looks like it should be on Electronics_101.

Steve Greenfield

Steve,

This is the exactly why I had started a separate group to discuss a PCB
drilling station.  I knew that there will be all sorts of discussions on
'peripheral' circuitry, technology, components and what-not.  So as to not
disturb those that are not interested in this project, I always start my
threads with the mention Drilling Station so it can be ignored.  You had
asked us to keep the discussion here and not move to a separate group.  So
that's why I kept the threads here; to do exactly as you said 'so that we do
not partition the information'.

So which is it going to be?  When I think about it, I guess you've already
answered that question by saying this discussion is out of line.

You see, several of us have very little knowledge on what we are doing.
This group is our source of information on this PCB drilling station.  But
now you've changed your mind and decided that we have to post 'some'
discussions elsewhere.

Sorry, but you can't decide on the fly what aspect of this project is
relevant and what is not.  Either the whole project is acceptable here, or
it is not.  You can't start picking away at components and judging each
thing individually.  The E-101 group is fine, the people are nice, but we
are not going to be allowed to discuss PCB/CNC/automation/bearings/etc over
there either.

So, please make a final decision now, one way or another, I don't care.  But
I'm not going to start second-guessing myself on every thread wondering if I
am out of bounds.

Robert





-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de Steve
Envoyé : juillet 11 2005 01:01
À : Homebrew_PCBs@yahoogroups.com
Objet : [Homebrew_PCBs] Re: Drilling station 40V 3A power supply


This thread looks like it should be on Electronics_101.

Steve Greenfield




Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

> Steve,
>
> This is the exactly why I had started a separate group to discuss a PCB
> drilling station.  I knew that there will be all sorts of discussions on
> 'peripheral' circuitry, technology, components and what-not.  So as to not


Try the DIY-CNC group instead.  All that & more.  They even had a thread
on a DIY pick-n-place machine a while back.

Before you do that, have a quick look at http://www.crankorgan.com, he
sells plans for a PCB drilling/milling machine.  There are a few similar
sites, like http://www.hobbycnc.com etc.

Tony

On Mon, 11 Jul 2005 03:28:47 +0200, Robert Hedan  
<robert.hedan@...> wrote:

> "What's the inductor L1 for? -ST"
> As it turns out, absolutely nothing in a linear power supply.  I must  
> have
> looked at a schematic that had components from both a linear and SMPS  
> power
> supply design.
> I like this explanation of linear versus SMPS power supplies; very clear  
> for
> newbs like me:
> http://www.answers.com/topic/switched-mode-power-supply
> Robert
>


I see ;-)
I personally would convert a PC PSU to the higher voltage, but i dunno if  
you are yet up to that task, linear is definitely easier.


Steve is right tho, this would fit much better in e_101.

ST

On Sunday 10 July 2005 03:16 pm, Robert Hedan wrote:
> Hi,
>
> I've just uploaded a schematic of a 40V 3A circuit that I put together.
> I've thrown in every security measure I could find in the DigiKey manual as
> an exercise.  The file is in FILES / Power supplies.  This link may (or may
> not) work:
> <http://f1.grp.yahoofs.com/v1/MHDRQjmKCjHN8hORzw6Lxapg3rQLHR9sg4BZ8ePemrCIK
>l
> pX6E8d2Q1QnZ52WUfAGgpe1uV08UyZCt9sgF5IHEcaLLyziJI/Power%20supply/Drilling%2
>0 station%2040V%203A%20steppers.JPG>

The link does not work.  Yahoo uses some kind of dynamic setup where they move 
things around,  and links that look like this often don't work for long -- if 
I load a page listing files in one of the groups it often doesn't work after 
a while.

> Please let me know if I have design flaws, is the fuse rating high enough,
> components in series instead of parallel or vice versa, suggestions for
> additional security measures, improvements in filtering, etc.

The only thing I'd do differently is to move D2 so it's right at the output of 
the regulator,  which I'm assuming it's in there to protect.

> This is my first power supply and I don't want to have problems with it in
> the future.  I also want to make it as robust as possible.  A separate 5V
> circuit will power the logic circuitry, this is exclusively for the
> steppers.

I'm not familiar with that regulator,  and will see if I can snag a datasheet.

On Sunday 10 July 2005 04:21 pm, Stefan Trethan wrote:
> On Sun, 10 Jul 2005 21:16:38 +0200, Robert Hedan
>
> <robert.hedan@...> wrote:
> > Hi,
> > I've just uploaded a schematic of a 40V 3A circuit that I put together.
> > I've thrown in every security measure I could find in the DigiKey manual
> > as
> > an exercise.  The file is in FILES / Power supplies.  This link may (or
> > may
> > not) work:
> > <http://f1.grp.yahoofs.com/v1/MHDRQjmKCjHN8hORzw6Lxapg3rQLHR9sg4BZ8ePemrC
> >IKl
> > pX6E8d2Q1QnZ52WUfAGgpe1uV08UyZCt9sgF5IHEcaLLyziJI/Power%20supply/Drilling
> >%20 station%2040V%203A%20steppers.JPG>
> > Please let me know if I have design flaws, is the fuse rating high
> > enough,
> > components in series instead of parallel or vice versa, suggestions for
> > additional security measures, improvements in filtering, etc.
> > This is my first power supply and I don't want to have problems with it
> > in
> > the future.  I also want to make it as robust as possible.  A separate 5V
> > circuit will power the logic circuitry, this is exclusively for the
> > steppers.
> > Robert
>
> You certainly have a few surplus parts in there ;-)
>
> What's the inductor L1 for?

I was wondering about that myself.

> U2/3/4/5 are a mystery to me.
>
> What is the EMI coil, what is the input? mains?

Presumably coming out of a transformer?

> Putting caps in parallel to lower ESR is a nice idea, but usually you'd
> only put one electrolytic and one ceramic.

To the contrary,  data sheets from some regulators do recommend a tantalum cap 
there.  I've done it that way myself on more than one occasion.

> If you want to use several electrolytic parallel instead that is a good
> thing, but usually you'd use the same size. A very small electrolytic
> parallel with a big one is just not changing anything, esp. if you have a
> ceramic cap too.

It _will_ have somewhat better response at higher frequencies,  but a tantalum 
cap will have much more of an improvement.

> I dunno about your fuses, you certainly have a great many. I wouldn't want
> to predict which one will trip first. Also, i wouldn't see the need.

Two isn't what I'd call "a great many",  the first one protects the 
transformer from a shorted rectifier,  the second one protects the regulator?

> What i would have done if i had to use a transformer supply and not a SMPS:
>
> hot->fuse->(NTC)->primary1->primary2->neutral.
> (ntc in case of toroid transformer)
>
> sec->bridge rect. at least 20A->electrolytic cap 6800-10000u->voltage
> regulator->cap 220u or more parallel 100n to 470n->polyfuse->out.

I too tend to over-spec rectifiers.  The difference in price for hobby 
quantities is just not significant,  particularly when you add shipping 
charges into the picture.  I don't know if I'd go as far as 20A, but it sure 
wouldn't hurt anything.  I also notice a couple of 1N5401 diodes in there, 
presumably to protect the regulator.  I wouldn't bother with anything less 
than 1N5408 -- same series,  ten times the breakdown voltage rating,  and 
probably a minimal difference in the cost.  They'll be useful for other 
things as well.

On Sunday 10 July 2005 04:25 pm, Nuno Tavares wrote:
> Hi Robert,
>
> The schematic is not very clear, not enough resolution.

That depends on your software.  :-)

I use the firefox browser here,  and once loaded all I had to do was click on 
the image and the resolution on my screen doubled...

> But of what I can see, these points I noticed:
> - I think that you should move the fuse to the AC part of the circuit

There is one there.

> - The LT1085 is rated for 3A and you want a power supply for 3A. Don't you
> think it's to close?

I am not familiar with those parts or I would have commented on this as well. 
That is indeed too close,  and for a 3A load I'd want a regulator capable of 
handling at least 5A...

> What if there's an overload? Even without overload, if you use a motor with
> this, or any other inductive or capacitive load, it's starting up will not
> be an easy one. My advise is that you use a higher current regulator, like
> the LT1084 or LT1083.

I think I'm going to have to dig out some datasheets for these parts.  :-)

> 	Same thing with the power supply diodes. Higher amperage rating is
> better.

Yes.

On Sunday 10 July 2005 07:18 pm, Robert Hedan wrote:
> "What's the inductor L1 for?"
>
> - Absolutely no idea, I was hoping you'd clear that up, hence the schematic
> request.  I saw that somewhere, can't remember.

I wouldn't bother with it,  then.  Inductor-input power supply filters are 
something that I haven't seen used since the days of vacuum tubes.

<...>

> "What is the EMI coil, what is the input? mains?"
>
> Input is the secondary coils via a terminal block, 24V, 24V 48VCT.  An
> electro-magnetic interference coil, supposed to remove common waveforms
> across all signals.  I read somewhere it is a good idea to place these when
> cables enter a PCB, to remove interference they pick up.

I've seen those used that way,  and also in the transformer primary circuit,  
but if you do that make sure you select a part rated for that use.  Often 
capacitors (also specially rated and often called "safety" capacitors) are 
placed across the line at each end of the coil.  This can also have some 
effect on interference getting out into the line from the equipment,  as 
well.

> "A very small electrolytic parallel with a big one is just not changing
> anything, esp. if you have a ceramic cap too."
>
> - I didn't know much about the filter caps, even less when more than 1A is
> involved.  I thought electrolytic caps acted like ceramic caps, the large
> ones filling in larger gaps in the waveform, the smaller ones filling in
> some more of the remaining gap.

It's not a bad thing,  and doesn't cost all that much or take up that much 
board space.  I note that the datasheet for the regulators that I'm looking 
at compare a 22uF tantalum with a 150uF electrolytic...

<...>

> - The ZNRs and MOVs are there to act as crowbars in case of a short further
> down the line.  They don't have the same speeds, so I put one of each
> model. - If I place the fuse on the 115V line, the crowbar devices are
> kinda far removed.
> - I do note that the ZOV has a clamp rating, I assume that makes it a
> crowbar-type device.  I have that device in series instead of parallel, not
> gonna do much that way.  Technically, I should also have a fuse at that
> point also.

You should know that MOVs have a limited lifetime when it comes to absorbing 
transients,  which is why _all_ surge-protected outlet strips that use them 
include either a fuse or a circuit breaker.  When they do fail they often 
fail _shorted_.

> - Determining which fuse will be blown is not a problem.  The fuses will be
> mounted on the front panel along with an indicator lamp.
> - Since the ZOV has clamping capability, I am considering placing one on
> the primary side of the transformer along with 2 more ICL and a fuse.  That
> would give me an immediate indication of where the problem is; primary,
> secondary or post-voltreg DC signal.

One arrangement that I've seen done with MOVs is to put three in the primary 
circuit,  one from line to neutral,  one from line to ground,  and one from 
neutral to ground.  I don't know that this would be necessary though unless 
you had a lot of really bad lightning surges or some really delicate 
electronics to protect.  This was done in an article in Byte magazine way 
back when they still had hardware construction articles.

> "What i would have done if i had to use a transformer supply and not a
> SMPS:"
> hot->fuse->(NTC)->primary1->primary2->neutral.
> (ntc in case of toroid transformer)
>
> - I have no idea what NTC is.

"Negative Temperature Coefficient" -- a thermistor.  Used in some power 
supplies to limit inrush current when you first turn it on and the filter 
capacitors are completely discharged.  I wouldn't worry about it unless you 
want to under-rate your rectifiers.

> I don't understand the coil configuration either, I've only dealt with
> single 115V primaries so far.

I think he's referring to the two ends of the primary winding there.

> I could increase cap size as you recommend.  As I said, I don't have any
> sample to work with, nor do I know how to calculate required caps.

I wouldn't worry about that.

On Mon, 11 Jul 2005 17:12:24 +0200, Roy J. Tellason  
<rtellason@...> wrote:

>   An
>> electro-magnetic interference coil, supposed to remove common waveforms
>> across all signals.  I read somewhere it is a good idea to place these  
>> when
>> cables enter a PCB, to remove interference they pick up.
> I've seen those used that way,  and also in the transformer primary  
> circuit,
> but if you do that make sure you select a part rated for that use.  Often
> capacitors (also specially rated and often called "safety" capacitors)  
> are
> placed across the line at each end of the coil.  This can also have some
> effect on interference getting out into the line from the equipment,  as
> well.


You can get mains filters as complete module, really cheap, sometime  
combined with the power plug.
Also, they can often be found in various equipment like PC supplies and  
other stuff.

I don't think they are needed for a transformer supply however.

ST

Cripes, I made a suggestion and I get this. Talk about football. Talk 
about cars, beer, whatever. Who gives a crap, right? You'd be hard 
pressed to find anyone here who thinks I am a control freak about the 
list. Let's just open it up to anything Robert feels like, because 
it's all about Robert.

I get people complaining that anything not specifically about making a 
PCB at home is off topic. I get people complaining because I stop 
threads that wander off into personal topics. The first I can handle, 
the 2nd type just want everything for their personal convenience, and 
screw everyone else. I get all kinds of wierd accusations and demands.

Oh, yeah, you're welcome. I should be grateful for the paycheck I 
(don't) get for running the list. I'm sure you're one of those guys 
who screams at cops directing traffic when you don't get waved through 
when you think you should.

And you are -supposed- to be second guessing yourself before you post 
a topic on anything but a general chat list. Just because you put 
"drilling station" in the subject line doesn't make it on topic here. 
You are obviously a beginner designing a rudimentary power supply. 
Just the thing for Electronics_101 list. Just because you buy some 
transistors on eBay doesn't make eBay discussions on topic.

Nothing like baiting the listowner.

Steve, listowner

--- In Homebrew_PCBs@yahoogroups.com, Robert Hedan <robert.hedan@v...> 
wrote:
> Steve,
> 
> This is the exactly why I had started a separate group to discuss a 
PCB
> drilling station.  I knew that there will be all sorts of 
discussions on
> 'peripheral' circuitry, technology, components and what-not.  So as 
to not
> disturb those that are not interested in this project, I always 
start my
> threads with the mention Drilling Station so it can be ignored.  You 
had
> asked us to keep the discussion here and not move to a separate 
group.  So
> that's why I kept the threads here; to do exactly as you said 'so 
that we do
> not partition the information'.
> 
> So which is it going to be?  When I think about it, I guess you've 
already
> answered that question by saying this discussion is out of line.
> 
> You see, several of us have very little knowledge on what we are 
doing.
> This group is our source of information on this PCB drilling 
station.  But
> now you've changed your mind and decided that we have to post 'some'
> discussions elsewhere.
> 
> Sorry, but you can't decide on the fly what aspect of this project 
is
> relevant and what is not.  Either the whole project is acceptable 
here, or
> it is not.  You can't start picking away at components and judging 
each
> thing individually.  The E-101 group is fine, the people are nice, 
but we
> are not going to be allowed to discuss PCB/CNC/automation/bearings/
etc over
> there either.
> 
> So, please make a final decision now, one way or another, I don't 
care.  But
> I'm not going to start second-guessing myself on every thread 
wondering if I
> am out of bounds.
> 
> Robert
> 
> 
> 
> 
> 
> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com [mailto:
Homebrew_PCBs@yahoogroups.com] De
> la part de Steve
> Envoyé : juillet 11 2005 01:01
> À : Homebrew_PCBs@yahoogroups.com
> Objet : [Homebrew_PCBs] Re: Drilling station 40V 3A power supply
> 
> 
> This thread looks like it should be on Electronics_101.
> 
> Steve Greenfield
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, and 
Photos:

> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links

"Let's just open it up to anything Robert feels like, because it's all about
Robert."

- You have absolutely no idea how far from the truth you are.  I do not care
about owning a list, all I care about is being able to discuss a PCB
drilling station.


"I get all kinds of wierd accusations and demands."

- I believe that.  But I'm not making any accusations nor am I making a
demand.  I'm asking if you permit discussing all aspects of a DIY PCB
drilling station and not just select topics.


"Oh, yeah, you're welcome. I should be grateful for the paycheck I (don't)
get for running the list."

- We all volunteer in one form or another and none of us expect any thanks
or renumeration for our work (pics, tutorials, schematics, etc).


"Just because you put "drilling station" in the subject line doesn't make it
on topic here."

- It is since you gave us permission to discuss it and the post is about a
part of a drilling station.


"You are obviously a beginner designing a rudimentary power supply."

- I'm pretty sure I said that already.


"Just the thing for Electronics_101 list."

- Yes, but YOU are the one that asked that we keep information on this
project in one central place.  What happens when we will discuss the tool
changer?  What group will you send us for that?  What about those that will
want to use component pick and place mechanisms?


"Nothing like baiting the listowner."

- You obviously haven't read anything of what I said.  None of it was
provocation, it was a request for clarification.  Can we or can't we,
nothing more.


I'm not here to have a pissing contest with you.  All I ask (not demand) was
for consistency when it comes to the station.  As I said, there will be all
sorts of peripheral devices that will be added on this project. None of them
directly related with making PCBs, but they will still be an important
feature.

Now if you are going to say that this device may only drill holes, then
that's a different story.  But I personally have a lot of plans for my
machine and I believe several others do too.  I don't have money for several
tools, so I try to incorporate as many features as I can into what I build.
My machine will be built for prototyping and small production runs.

I intend to have some sort of track pin installation mechanism; most likely
a wire fed through a hole, bent and cut by automated pliers.  I also want a
camera to monitor progress and quality; there will be all sorts of specific
problems there.  I also want to apply solder paste for track pins and common
SMD parts like resistors and capacitors.  Then I'd like the machine to be
able to place the SMD components for me so I can then transfer the PCB into
an oven for soldering.  I also want to be able to route my traces directly
on the PCB eliminating the chemical etching process.  This requires more
precision and strength that a Dremel can handle.  It will undoubtedly
generate discussions on all sorts of board-holding devices (clamps, vacuum,
etc), so as to keep the PCB perfectly flat and remove only copper and barely
any FR4.

All these different features are ALL related to fabricating a printed
circuit board.  None of the few features I've listed are extravagant either,
and I'm sure others will have even more things they want to do.  I want my
machine to do the most it can do; not to show off my grand invention, but
because I am not in perfect health nor do I know if I will lose some more
motor control.  The more it can do for me the better.  I want to build it so
that even my non-technical wife will be able to operate it given a checklist
of things to do.


"I'm sure you're one of those guys who screams at cops directing traffic
when you don't get waved through when you think you should."

- Nope, I'm a volunteer fireman, I stop and help all the time.  It's my
responsibility, even if I don't get paid for what I do.  And no, I'm not a
'paid' volunteer fireman either.


Robert



Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

In article <dakade+mb9c@...>,
   Greg Codori <greg_codori@...> wrote:
> Hello everyone,

> I am designing a PCB following a schematic designed by someone living 
> in Europe, and while he supplied a nice schematic and partlist, I am 
> having trouble finding certain parts in America with the same 
> specifications.  The part list has part numbers for a supplier called 
> Elfa (www.elfa.se).  I have been able to convert most of the parts 
> listed in Elfa to parts here in the US.  But some I can't find...

We have the same problem the other way round :-)

And sometimes with other european countries. I for one would be happy to
help anyone to source parts available in the UK. Perhaps you US and
Canadian guys would reciporacate