The RCA integrated circuit used in this control is uncommon today. The circuit is from an Electronics Now from July 1995. The sensor determines the value of the adjustment potentiometer.
This circuit is from a 1978 French magazine Electronique Pratique. The magazine no longer exists, but...
The difference in this circuit, found in documentation from the 90s, is the use of a single...
We find this simple tone modulated signal generator in a 1987 publication. It uses common...