AC Opto-Isolator – No Current Flow Issue


I am just testing this component MOC3021 optoisolator, its datasheet can be found here.

This is my circuit in Proteus:
opto-isolator circuit

Please forgive me for my ignorance of electronics, I have my background in computer science.

I tried the whole day yesterday trying to make out what's written about it in the datasheet, the point of connections was easy to understand, rest I don't know much. However, I did learn a lot and welcome to accept more.

However as you can see the LED didn't glow, now for one thing I know it's an AC optoisolator but shouldn't current flow from one of the diodes of the DIAC?

Thanks a lot 🙂

Update : Problem Solved

Thanks a lot, all of you it's a great community here ( especially for noobs like me ).
This is the final working circuit.

Final Image


All answers were correct but I could only choose one, sorry others 😐

Best Answer

You've got three problems.

1: no current limit on the MOC3021 LED. With 5V there the LED inside the MOC3021 will not last long, so add 220 ohms in series with the input.

2: not enough voltage on the output. The output is is a phototriac which has a forwards voltage drop of 1 to 1.5V - to light the blue LED you want 3V or so and a resistor to limit current, 9V with a 470 ohm resistor in series would be a good starting point.

3: the output is a triac: once triggered on, it will continue to conduct until something else stops the current - using an AC supply to power the output side circuit would help here.