Triac based lamp dimmer

  • Rajkumar Sharma
  • 28171
  • easy
  • Tested


Triac based Indecent lamp dimmer is a simple circuit and it doesn’’t requires additional power supply, works directly with 110V AC or 230V AC.


It is a low cost dimmer circuit for adjusting the light brightness of incandescent, Halogen Lamp, Light Bulb load up to 250 W.


– Input supply: 230 VAC or 110 VAC
– Output: 250 W
– Triac controlled
– On board Potentiometer for adjusting level
– Power Battery Terminal (PBT) for easy input / output connection
– Four mounting holes of 3.2 mm each
– PCB dimensions 40 mm x 34 mm



Circuit description

This kit consists of BT 136 Triac, resistors and capacitor.  CN1 connector is for Load connections and CN2 connector for power supply connections.

BT136: It is a sensitive gate Triac, used in general purpose bidirectional switching and phase control applications where high sensitivity is required.

DB3: It is a DIAC that functions as a trigger diode with a fixed voltage reference.  It can be used in conjunction with Triac for simplified gate control circuits or as a starting element in fluorescent lamp ballasts.

Working principle

This kit is used as a Light dimmer kit.  It is used to adjust the brightness of the Halogen Lamp, Light Bulb up to 250 W.  A power supply of 230 or 110 VAC is supplied to the kit at CN 2 connector and a light bulb is connected at the CN 1 connector.  Using the POT we can adjust the brightness of the bulb.


It is used to adjust the brightness of incandescent, halogen lamp, light bulb up to 250 W.

Parts List





  • Rey Hidrógeno

    Great Article! =D

    3 years ago
    • Rey Hidrógeno

      Rajkumar Sharma, forgot place your name! 😉

      3 years ago
  • FTG

    Tested the circuit, not working. Its a piece of…of not working electronics.

    2 years ago
    • Adrian Andrei

      What you should test first is your electronics knowledge and skills. Next time try something simpler, maybe involving less than 5 electronic parts…

      And now, seriously, take care about the P1 (470k pot.). Must have at least 0.25W power dissipation.

      2 years ago

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