This amplifier with gain control was obtained in a documentation from Signetics of the 80's. Transistors are of power and operational amplifiers are not common nowadays.
The presented circuit is a sinusoidal oscillator for 1 kHz that makes use of the four amplifiers...
This circuit was found in a 1967 Electronics World. Transistor Q1 can be a TIP321 and Q2 can be a...
Currents up to 1.5 A can be regulated with this circuit. The resistor R that determines the...