[sdiy] Bernie Hutchins CA3080 VCA

[Scott Juskiw]

>  > Is this similar to the technique used by W. Jung (see Journal of Audio
>>  Engineering Society, April 1975, Vol.23, No.3)? The normal PNP + op amp
>>  current source is not used here - instead, the OTA is put in the
>>  feedback loop of an op amp. Positive control voltages feed a resistor
>>  connected to op amp (-) input, op amp output connects to OTA Vcc- (pin
>>  4), while OTA Iabc (pin 5) is connected to op amp (-) input. This forces
>>  a current linearly proportional to the control voltage into the Iabc
>  > pin. A diode clamp is used for reverse polarity protection.

This same circuit is given on page 5c(8) of Hutchins' Musical 
Engineer's Handbook, and there he refers to Jung's JAES article of 
April 1975 V23 #3. So the short answer is "yes".