Does the optocoupler input need a power supply

The main purpose of an optocoupler interface is to completely isolate the input circuit from the output circuit, which normally means there will be two completely separate power supplies, one for the input circuit and one for the output. An optocoupler (or opto-isolator) is a component that transfer signals between circuits using light. 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. What is necessary is to ensure that R1 creates an appropriate current level from the input circuit to correctly drive the LED side of the optocoupler, and that R2 creates appropriate voltage and current levels to supply the output circuit via the inverter. To work well, they need to be correctly connected and used in the feedback loop.