How Optocouplers work - opto-isolator solid state relays phototransistor

Optocoupler. In this video we learn how optocouplers work and also look at some simple electron circuits you can make yourself to understand how an optocoupler, opto-isolator, phototransistor, photocoupler works. Photo transistor
Correction 13:21 Upper text "220Ω" resistor should say "22Ω" calculation in lower screen is correct