Suggested by General Electric in a 1965 publication this circuit uses a light bulb. Can be changed to use LED and capacitor can be 22 uF.
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...