The optocoupler can be used in many different applications as an interface between low voltage digital, such as 3. 3V logic, or 24V control circuits and large mains power electronic devices. Thus protecting sensitive circuits (e. In this guide, you'll learn how they work and how you can use one in your own projects. Optocouplers are very useful when you need to isolate different sections of a circuit, for example in power. An optocoupler, also known as photocoupler or opto-isolator, is a device which can transfer an electrical signal across two galvanically-isolated circuits by way of optical coupling. It typically consists of an LED (light-emitting diode) and a photodetector, such as a phototransistor, housed within a single package.