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. They use light to pass signals between circuits. 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 is an electronic device that uses light as its means of transmission. This article provides a thorough exploration of optocouplers (Optoisolator / Photocoupler), including their construction, working principles, advantages. Photocouplers (also known as optocouplers) generate light by using a light-emitting diode (LED) to generate a current which is conducted through a phototransistor. Internal Equivalence Circuit Here, we will describe how a general-purpose photocoupler with this basic structure is used.