[sdiy] tapehead stuff

patchell patchell at silcom.com
Wed Aug 21 16:01:22 CEST 2002

    Well, I am glad you don't have the transistor manual, because it looks like
I will be coming back up to the PNW in a few weeks (to drive a couple of cats
up)....Hmm...there was/is a giant used bookstore in Portland.  I wonder if they
might have a copy.  Does anybody remember the name of this place, or better yet,
if they have a website?

John L Marshall wrote:

> 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,
> John
> ---------------------------------------------------------------------------
> 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
> was
> > the 1964 vintage one.  I might be off by a year or so.  I would kill to
> have one
> > of those manual again. <snip>

* Visit:http://www.silcom.com/~patchell/
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