[sdiy] Fairchild uA726

[Tim Parkhurst]

Hi Dave,

Yup, that chip was used in some Minimoogs, amongst others. It works
well from what I've heard, but it hasn't been in production for
several years now and is quickly becoming unobtainium. Prolly best to
avoid it for any new designs.

Tim (old design) Servo


On Wed, Sep 23, 2009 at 10:50 AM, David G. Dixon
<dixon at interchange.ubc.ca> wrote:
> 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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