I've spend days debugging this circuit and have exhausted all possible solutions. I'm trying to use an Arduino PWM pin to light a 120V AC lightbulb. In order to do this I'm using a MOC3010 opto-isolator and a BT136 Triac. The goal is to be able to fade up and down a 120v light.
Below is my circuit (Vcc is 5v arduino pin):
I'm certain I soldered everything correctly. I'm certain the components are working (tested with multimeter). The issue is getting the photocell within the opto-isolator to trigger the gate of the Triac. Currently when I plug this circuit in – the light doesn't turn on.
One weird thing is that when I touch the line between pin 4 and the gate with a multimeter- sometimes the light flickers. I'm thinking that the voltage difference isn't correct and that my probe is inducing a difference that allows the gate to be triggered for a very very brief moment.
Has anyone been able to make this circuit work before? Is the 180 ohm resistor too small/big for my appllication?
This simple circuit has now become the hardest circuit I've ever worked on… Please help!
Best Answer
Connect a 470 ohm resistor as shown, and the problem of flickering when pin 4 is touched will be solved: