[sdiy] uA726, heated pairs...

[Grant Richter]

> There is the little known National Semiconductor app note AN-299 (1986?),
> where an LM3046 transistor array is used to provide a heated pair for a VCO.
> 
> I've tried it, but it seems to me that there was a change in chip manufacture,
> and it doesn't work as advertised. The substrate pin is the problem.
> 

Just a couple stray thoughts...

The ap note doesn't specify the pin out on the CA3046. You could probably
get it to work by trying different combinations of heater and sensor
transistor.

Also, the substrate connects to the most negative voltage used, in this
case, it looks like ground and not -15V.

For a working example, see the Moog "Source" service manual which used a
thermostated CA3046 for the expo-converter. The Serge NTO and PCO also use a
heated CA3046.