Voltage Controlled Amplifier

This Voltage Controlled Amplifier circuit is simply an op amp having an additional input at pin 5. A current ILsc is inserted into this input which controls the gain of the device linerly. Thus by inserting an audio signal(±10 mV) within pin 2 and 3 and with controlling the current on pin 5, the amount of the signal output (pin 6) is controlled.

Parts list :
R1,R2,R5:10 K
R3 100K
R4 : 1K ( Variable resistor)
D1 : 1N4148
Q1 : 2N3905
IC1, IC2 : CA 3080