Homebrew PCBs

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.