[sdiy] Fairchild uA726

[Carsten Tönsmann]

The old Formant VCOs did.

Carsten

----- Original Message ----- 
From: "David G. Dixon" <dixon at interchange.ubc.ca>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, September 23, 2009 7:50 PM
Subject: [sdiy] Fairchild uA726


>I was flipping through a fantastic (albeit very old: 1976) book I found
> languishing in the stacks of the UBC library, the "Handbook of Operational
> Amplifier Circuit Design" by Stout and Kaufman.  I was studying the
> schematic for "a differential-input logarithmic amplifier with adjustable
> gain and logarithm base" in Fig. 17.1 on page 17-2, when I came upon this
> passage:
>
> "Several other design tricks will keep this circuit from drifting with
> temperature.  Transistors Q1 and Q2 should be a matched pair of devices on
> one chip.  Ideally they should be gain-regulated such as the uA726
> temperature-controlled differential pair (Fairchild).  This device has
> active temperature-regulating circuitry on the same chip as the matched 
> pair
> so that external temperature sources have no effect on transistor
> parameters."
>
> This sounds like the ideal device for building expo converters.  However, 
> I
> could find no reference to it on Google, and no datasheet in the
> datasheetcatalog.com database.  Does anyone here know of this chip?  Is
> anything similar still being manufactured?  Did any vintage synths use it?
>
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