This is a two-input audio switching circuit. The operational can be of any type and more entries can be added. The power supply must be symmetrical.
This fast-acting circuit uses any phototransistor as a sensor. The circuit drives a 30 V relay, but...
This circuit is from 1995 documentation. Integrated circuits are used which can still be found...
This circuit was found in a Popular Electronics from the 90s. The circuit uses common components...