This circuit was found in a 1965’s General Electric documentation. It is intended for low voltage brush motors. The SCR must be according to the engine controlled.
Suggested by a 1966 publication, this circuit applies a 60 Hz signal to a transistor to test its...
This circuit is indicated to operation with piezoeletric transdicers or other with high impedance...
Two operational amplifiers are used in this source obtained in an American documentation...