Electronic – Opto coupler schematic

opto-isolatorschematics

I am analyzing following circuit, but I am not getting its flow.

In the following schematic SW1 is coming from controller and connected to opto coupler ( cathode of LED ) and J4B is connected to heater.

Please explain me its operation and when Mosfet will conduct?enter image description here

Best Answer

its simple, the controller generate a square wave in S1, (probably its at VCC level at the beginning) your circuit U9 (Optocoupler) will work when the diode inside it is conductive at low level, so the transistor Q1 is operational (ON) and you can enable the heater.
The LED D11 is conductive when the transistor Q1 is ON.