Found in Popular Electronics from the 90s, this circuit consists of a timer that turns off the power of a circuit after a time determined by C1, saving the battery.
This circuit was found in a Mullard transistor manual from 1960. Note the symmetrical power...
With the shadow over the sensor, it is possible to interrupt the sound of your amplifier using this...
This circuit puts the battery in the circuit when the voltage of a source is cut, preventing it...