[sdiy] CA3096 Temperature Controlled Question

[patchell]

Grant Richter wrote:

> Hello,
>
> I have tried this approach. I noticed the PNP transistors in the CA3096 have
> a rather high Rbe and you may need quite a lot of compensation for the log
> converter. Assume you will need to use a Rossum compensation, a De Franco
> scheme will require up to 10K in series with the timing cap.
>

    This is not surprising.  The PNP transistors in the CA3096 are lateral (as
opposed to vertical) PNP's.  This is a very poor way to make a transistor, but,
that was all they could do back then with the standard diffusion issolated
process.  The THAT140 (no longer availiable :-(  ) used dialectric isolation, so
the PNP's in that part were vertical.

>
> The typical temperature for thermo stabilized dies is just above the highest
> ambient temperature expected. 130-140 degrees F is typical, watch out for
> oscillation in the thermal loop which will show up as pitch cycles. If the
> loop will not stabilize, use different transistors for heater and sensor.
>
> > From: "M. Falconi" <thermen at libero.it>
> > Reply-To: owner-synth-diy at dropmix.xs4all.nl
> > Date: Fri, 04 Jan 2002 01:23:56 +0100
> > To: synth-diy at dropmix.xs4all.nl
> > Subject: [sdiy] CA3096 Temperature Controlled Question
> >
> > I Built  temperature control as in National semic. AN-299 modified by
> > Rick Jansen.
> > I used a CA 3096 instead CA 3046, i need of two PNP/Matched transistor
> > for my log converter.
> > The circuit work well ! I test at 35 C° on the chip for many hours , all
> > ok.
> >
> > But i have a question: What is the correct temperature I will have work
> > the chips , for work my converter well and no burn the ic?
> >
> > Excuse me for my english
> >
> > Thank you
> >
> > Maurizio
> >
> > ----------------------------------------------------------------------------
> >
> > Thank you for visit my Theremin / Analog Synth amateur site
> >
> > ----   " OFFICINA ANALOGICA"  ----
> >
> > http://homepage.mac.com/mauriziofalconi/
> >
> > WELCOME!
> >
> > Maurizio Falconi - Siena - ITALY
> >
> >
> >

--
 -Jim
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