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From: Robert Baer
X-Mailer: Mozilla 4.75 [en] (Win98; U)
Subject: Re: Transistors circuits by the thousands
Date: Fri, 03 Jan 2003 00:49:32 GMT
NNTP-Posting-Date: Thu, 02 Jan 2003 16:49:32 PST
Organization: EarthLink Inc. -- http://www.EarthLink.net
> Hi Guru's
> I'm looking at the datasheets for a 2n3904. It specifies an hfe of at
> least 20 at ic=.1ma. The "typical" performance curve show a gain of
> I need the hfe to be at least 50.
> If I was designing a circuit to be manufactured by the thousands, how
> risky would it be if I do not use worst case values? Am I really
> likely to end up with a batch of transistors that stray far from the
> "typical" values.
> My alternative is to use another transistor (more cost, higher parts
> Does anyone have experience with this? Do you always use worst case
> values for high volume designs? I've looked at designs from far east
> manufacturers and they often seem to get away with simply using
> "typical" specs.
> Your comments would be appreciated.
There are hundreds of similar transistor types that would work, just
pick those with minimum beta that you want.
Most small signal parts have similar quantity prices, but it is
relatively easy to find a part that matches or exceeds your specs.
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