[sdiy] Fairchild uA726

[David G. Dixon]

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?