The below shown diagram illustrates the interfacing diagram of an opto-coupler with TTL circuits. Here we can see that IRED of the optocoupler is connected across the +5V and the TTL gate output, instead of the usual way which is between the TTL output and ground. 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. It provides complete isolation between the input and the. An Optocoupler Circuit Operation (optoelectronic coupler) is essentially a photo-transistor and an LED combined in one package. Optocouplers become an effective replacement for relays, and. Optocouplers, also known as opto-isolators, uses infrared light to transfer electrical signals between two electrically isolated circuits and are commonly classified by their photosensitive output device What is an Optocoupler? An optocoupler (also called an opto-isolator, photo-coupler, or optical. 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. Unlike transformers or capacitors, which can only transfer AC signals across the isolation barrier, optocouplers can.