The PC817 is a compact optocoupler (optoisolator) designed to provide electrical isolation between low-voltage control circuits and higher-voltage or noisy signal lines. It uses an internal infrared LED and phototransistor to transfer signals optically without direct electrical connection. This isolation protects sensitive microcontrollers and logic circuits from voltage spikes, noise, and ground loops. With a high isolation voltage of 5000Vrms, the PC817 is widely used in power supplies, switching circuits, PLC interfaces, and microcontroller isolation systems.
