This is a battery powered 3W power amplifier using germanium transistors. The circuit is from an English documentation from 1967. The transistors are from the time.
A complete test for opto-couplers can be made using the circuit Bellow. The function generator...
The 50 kHz signal generated by this circuit is applied to a low impedance inductive transducer. A...
This circuit was found in a 1980s documentation. The operational amplifier is of a common type at the...