From: John Woodgate
Subject: Re: Limitations of the BC337
Date: Fri, 10 Jan 2003 20:44:24 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Sat, 11 Jan 2003 08:41:32 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Paul Burridge
wrote (in ) about 'Limitations of the BC337', on Fri, 10 Jan 2003:
>On Thu, 9 Jan 2003 21:19:39 -0000, "John Jardine"
> opined thusly:
>>That 200kHz will be due to, too high a gain, capacitive loading effects,
>>high source resistance...
>[comprehensive discourse snipped]
>Well, you've obviously amassed a formidable expertise in RF circuit
>behavior judging by that posting! I'm grateful for the tips from you
>and others who've contributed here. One point arises, however: is the
>chief determining parameter of the maximum frequency a transistor can
>handle its base/collector capacitance (both intrinsic and external)?
>I mean, could one get a good idea of how fast an RF tranny is just by
>the manufacturer's figure for intrinsic b/c capacitance? I'm assuming
>such a figure is also a SPICE parameter?
A lot of the stuff you've been told is more applicable to operation at
20 MHz than 200 kHz. I still say that if you want the correct solution,
you should give more information, preferably a schematic.
Ccb of a small-signal silicon bipolar is NOT a factor at 200 kHz. Unless
you have a 1 Mohm source, of course, and/or a voltage gain of 100.
That's why we need more data.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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