[sdiy] tapehead stuff

John L Marshall john.l.marshall at gte.net
Wed Aug 21 15:39:27 CEST 2002

Jim & Arun,

Since you will *kill* to have the GE Transistor Manual, I don't have one.
But, on page 274 is a tape recording amplifier. The driver is a single
2N508A PNP operating class A. The supply voltage is -27 volts and the
resistor from the collector to supply is 10 k ohms. Hmm. A general purpose
opamp could do the job. But wait, there is more, equalization L and C in the
output circuit and more equalization L and C in the emitter circuit. Finally
a bias circuit is required. The recommended operating frequency is 76 kHz.
The circuit is a pair of cross coupled 2N3404's driving a transformer.

I just found the key sentence in the GE Transistor Manual that I definitely
do not have: "The approximate reference level 1 kc record signal current for
the Nortronics B2Q4R is 0.05 ma and the bias currentis 0.70 ma."

Take care,
Pacific Northwest DIY Synthesizer meeting, July 20, 2002
See: www.sound-photo.com

----- Original Message -----
From: "patchell" <patchell at silcom.com>
To: "Arun Bohm" <arun_bohm at hotmail.com>
Cc: <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, August 20, 2002 10:00 PM
Subject: Re: [sdiy] tapehead stuff

>     If you can find one, the old GE transistor manual has circuits in it
for the
> recording circuits.  I can't remember exactly which year, but, I think it
> the 1964 vintage one.  I might be off by a year or so.  I would kill to
have one
> of those manual again. <snip>

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