The optocoupler is extensively utilized in computer terminals, thyristor control devices, measuring instruments, copiers, automatic ticketing systems, and household appliances like fans and heaters for transmitting signals between circuits. In this guide, you'll learn how they work and how you can use one in your own projects. It provides complete isolation between the input and the. Optocouplers become specifically useful where an electrical signal is required to be sent across two circuit stages, but with an extreme degree of electrical isolation across the stages.