We obtained this circuit in a technical documentation from the 90's. The circuit has its sensitivity adjustment in the potentiometer. The supply voltage can be reduced with a 1k resistor change.
This circuit with transistors was found in an old Japanese publication, translation of an American...
This 8 W amplifier with germanium transistors was found in a Japanese documentation from 1967. The...
This circuit of the 80's makes use of components of the time. The circuit is from an American...