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From: Paul Burridge
Subject: Re: Class B amplifiers: what are the large low-value resistors for?
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Date: Tue, 19 Nov 2002 14:53:19 +0000
NNTP-Posting-Date: Tue, 19 Nov 2002 16:22:10 GMT
Organization: Virgin Net Usenet Service
On Tue, 19 Nov 2002 23:47:40 +1100, "Phil Allison"
> ** Three bias diodes sounds like a quasi complementary design - ie both
>outputs are NPN and the drivers are NPN and PNP - is that the case ?
You mean as in a Sziklai connection? Nope. The output transistors are
definitely PNP and NPN. and they are single devices and not
'sub-driven' in any kind of Darlington arrangement. The driving stage
just uses one NPN whose collector feeds both bases of the output pair.
> ** This is sounding weird - with even one diode shorted there is no
Correct. At least in theory. Sadly not in this experimental circuit.
> ** The schematic has to be revealed and the type numbers too.
Its actually a *very* simple final stage indeed. I personally can't
see where all this forward bias is coming from.
"I was going to help him up, but then I thumped him."
Michael Head's plea in mitigation to Weybridge Magistrates, Sept. 1975
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