6 Simple dimmer circuit (220V)

Using this simple circuit, you can adjust the brightness or light intensity of your incandescent or filament bulb.  By varying the resistance of potentiometer R2, you can adjust the bulb power consumption from maximum down to zero.
220V Dimmer circuit
Triac pinout (BT139)
Part List:
R1 - 5 kilo ohms 1W
R2 - 100 kilo ohms potentiometer
R3 - 120 kilo ohms 1/2W
C - 100nF rated 300V or higher
Bulb - filament or incandescent type
Triac - BT136, BT139 or similar triac

Note: The circuit is powered directly to 220V main, thus avoid touching any parts of the circuit if not insulated. Do not attempt to build the circuit if you have little or no background in electrical engineering. Be reminded always that this circuit can cause electrocution if not handled properly. Use incandescent bulb only.
You can modify the circuit above by adding a diac to the Triac's gate and add some filter to minimize harmonics (see modified dimmer circuit on how it is done).


  1. it's safe to use bt139? or it must be use diac for gate triac??

  2. bt139 is ok. You can add diac in series to the gate of bt139 if you want.

  3. For your own safety, don't try building the circuit if you don't have or little idea in electrical engineering. Voltage involve in this project is fatal.

  4. Is the 'R3 - 100 kilo ohms potentiometer' also 1 watt, or can you use every 100k variable resistor?

  5. any 100k potentiometer will do.

  6. I've tried to build this circuit, but the light won't increase of dim when I change the variable resistor.
    I've tries chanching the poles at the triac, replacing the components, adding a stronger light.
    Do you have any idea what can be wrong at my circuit?
    (I suspect that I do something wrong, but I can't find out what it is)