Optoisolators - Triac, SCR OutputOptoisolators with triac or SCR (silicon controlled rectifier) output are electronic devices that use an optocoupler to isolate a triac or SCR output circuit from the input circuit. Optoisolators are commonly used in electrical and electronic systems to prevent the flow of electric current between circuits, or to prevent the transmission of electromagnetic interference (EMI) between systems. An optoisolator with triac or SCR output typically consists of an LED (light emitting diode) and a phototriac or phototransistor, which are optically coupled together. The LED is driven by the input circuit, and the phototriac or phototransistor is used to control the triac or SCR in the output circuit. Optoisolators with triac or SCR output are commonly used in AC switching applications, such as dimming control or motor speed control, where the triac or SCR is used to control the flow of current in the load circuit.