Wiring And Schematic

Consist of an LED (usually Infra-red) and a phototransistor close-coupled in a DIL IC package. Commonly used to isolate two sections of a circuit for safety reasons. An example where you want to swap your case power or drive activity LED for something with a bit more bling, without endangering the motherboard. The optoisolator diode is connected in place of the case LED.