Electrical – Triac not getting switched by optoisolator

acdimmeropto-isolatortriac

I made this dimmer circuit:

schematic

simulate this circuit – Schematic created using CircuitLab

And it does not work (no light). I have looked up other circuits that serve the same purpose and they seem to be different on a few points:

  • There's a capacitor C1 (can't really tell its purpose)
  • They use another TRIAC (BT136)
  • The resistance at the optocoupler is less than 1kOhm

moc3021 opto isolator triac circuit

Another thing I could think of is that I wired the TRIAC wrong: I connected the optoisolator to T1 and G of the BTA16 800B

EDIT:

Several suggestions have been given in the answers. I removed the red LED, changed R2 to 500Ohm and I rewired the TRIAC. I tested the circuit with a 3.3V battery. It work, can't tell which part was the crucial solution.

Best Answer

Your Opto-Triac needs to be connected between G and A2.

More likely the reason your lamp does not light is you are placing two LEDs in series on a DIO pin that only provides 3.3 V.

Run the two LEDs in parallel with separate resistors fed by the DIO pin.

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