Modified lamp dimmer circuit


This is a modification of the circuit Simple Lamp Dimmer/Fan Regulator  previously  posted here. The working of the circuit is same as that of the previous, but in addition a snubber circuit consisting of resistor R4 and capacitor C3  is included to improve the performance of the triac T1. A fuse is also included for better safety. I think this is the better circuit to try .

Circuit diagram with Parts list .



  • No matter how  what ever may be the load lamp,fan , heater or anything it should be rated less than 200 Watts.
  • No matter how  what ever may be the load lamp,fan , heater or anything it should be rated less than 200 Watts.
  • Assemble the circuit on a good quality PCB or common board .
  • Almost all parts of the circuit are live with potential shock hazard.Be careful.
Show Comments

15 thoughts on “Modified lamp dimmer circuit

  1. Mehrdad

    Thanks! but would you please explain more about R4 and C3 i wanna know that how them improve the TRIAC performance?

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  3. Rami

    Thanks for the schematic, I tried this one and it worked just great, I tried adding 2 more diacs in series with the first one to be able to control the entire range 0% to 100% of the power on the output, does changing the pot’s value give the same result?

  4. Max

    This looks like a good circuit.
    I need to use it for a 570W 2.6A 220-240Vac drill, as well as a 60W soldering iron for the same voltage. The frequency is 50Hz.

    How can I increase the power handling capacity of this circuit t 1KW?

    Why is there no choke? Is it because there is a snubber circuit?


  5. Seetharaman

    If C3 is rated for 1kV it is not be the problem. raise R1 value to 100K and try. If 330K 1watt pot is available replace 100k with that. it will have more control range.

  6. sandeep

    i have tried this circuit but the light is continuously glowing without any deduction in the intensity please give a suggestion to solve my problem.i have used 0.1uf ceramic capacitor instead of 0.1uf polyester on the snubber circuit.does this have any effect on my circuit.plz hlp me

    • Rami

      Hi, I’ve just tried this circuit and I noticed that putting another Diac in series with the first one will increase the control range, 1Diac: 220 to 180 volts, 2Diacs: 220 to 80 volts, 3Diacs: 220 to 0 volts.
      I used a 60 Watt lamp as a load, so I had the previous results, changing the pot’s range maybe another solution, but I’m telling the one I’ve tried.
      Anyway, I’m planning to do an Arabic walk-through with the circuit I’ve made, make sure to visit my linked blog (just click my name).
      wish you luck :)

  7. Hicham

    Could you please give a method of calculating the values of components such a R1, because i have a welding transformer with dimmer placed into the primary, and this R1 was burn and i can not know the most correct value, i have also tested many Resistance in serial with pot 47K even i changed with 100K but it doesn’t work, could you please help me.
    Best Regards


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