Found in a 1965 Electronic Design the purpose of this circuit is to control the gain of a stage by applying an external voltage. The circuit operates at high voltages.
The integrated circuit used is not common today. The circuit is from the SGS linear integrated circuits...
The basis of this project is an integrated 566 (not to be confused with a 556 which is a double...
This circuit was found in a Popular Electronics of the 90s. The resistor R4 determines the load...