Triac and SCR output photocoupler can be used with both DC and AC signals with optocouplers utilizing a SCR (thyristor) or triac as the photo-detecting device are primarily designed for AC power-control applications. They are semiconductor devices that combine the functionality of an opto-triac or an opto-SCR with a power triac. They provide electrical isolation between a low voltage input and a high voltage output, being able to switch the high voltage output. This type of optocoupler configuration forms the basis of a very simple solid state relay application which can be used to control any AC mains powered load such as lamps and motors.
