PC817 optoisolator/optocoupler

A Optocoupler also called a photocoupler, optical isolator or opto-isolator is a small chip that transfers signals between two isolated circuits using light. A basic optocoupler uses a led and a phototransistor, the brighter the led the more current is allowed to pass through the phototransistor. For more info on how optocouplers work check out this link ( OPTOCOUPLER )…

An optocoupler is analogous to a relay which isolates two circuits magnetically. They differ with relays in the sense that they are smaller in size and allow fast operation. 4N35s are commonly used in interfacing an electronic circuit with the parallel port of a computer.

 PC817.pdf