From: "Lukas Louw"
References: <firstname.lastname@example.org> <email@example.com>
Subject: Re: Transistors circuits by the thousands
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
NNTP-Posting-Date: Sun, 05 Jan 2003 00:54:54 GMT
Organization: AT&T Worldnet
Date: Sun, 05 Jan 2003 00:54:54 GMT
If you must use these, why not use two of them connected as a Darlington,
and you should be more than OK as far as gain is concerned. Sometimes this
will make sense for small/medium production runs to reduce number of
different part types you need to buy, and get a better price break on those
However, if your'e having these products made in the far east, they have
access to many more devices than what we can get easily in the US. Assuming
that you're using a good size OEM, they typically have so much buying power
with the part manufacturers that it becomes a moot point to just spec a
better device.Also remember that the 2N3904 CBE pinout, if used for the PCB
layout will make it difficult for the factory to substitute a better part,
as most of the small trannies over there use BCE pinouts............
If I were you, I'd contact the factory and ask them who their preferred semi
manufacturers are, and get them to send you some databooks or online
datasheet URLs, and pick the right part for the job.
Just Google for Mospec, Sanken and KEC for starters, and have a look at what
you can expect your factory to have access to. Don't bother with the North
American distributor for Sanken, Allegro. They have their heads up their
*sses. The other two don't have distribution here anyway.
> In my design, the 3904 was "preferred", not because of the optimal
> characteristics, but because of the fact that it was already used in
> other area's in the existing circuit.