In fact, it is a night light system that automatically turns on the outside lights when it gets dark and turns them off at dawn. The circuit only applies to incandescent lamps.
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...