This circuit is from Philips' 60s documentation. The circuit can be applied to modern operational amplifiers. The power supply must be symmetrical.
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...