Optocouplers, or photocouplers, are semiconductor devices that transfer electrical signals via light. They house a light – emitting component (like an LED) and a light – receiving part (such as a photodiode or phototransistor) in one package. When an input electrical signal activates the light – emitter, the light – receiver converts the light into an output electrical signal, achieving electrical isolation and signal transfer.
These devices are crucial for electrical isolation. They separate high – and low – voltage circuits, like in switch power supplies, and isolate digital circuits in industrial controls. For signal transmission, they handle both analog signals, as in audio amplifiers, and digital signals in communication interfaces. Optocouplers also convert different logic levels, enabling communication between TTL and CMOS circuits. Moreover, they protect circuits from over – voltage and short – circuit situations, safeguarding sensitive components.