TRIAC Light Dimmer


This little circuit can be used to dim lights up to about 350 watts. It uses a simple, standard TRIAC circuit that, in my expirience, generates very little heat. Please note that this circuit cannot be used with fluorescent lights.

Circuit diagram

TRIAC Light Dimmer-Circuit diagram


  • R1 50K Pot
  • R2 15K 1/2W Resistor
  • C1, C2 0.068 250V Capacitor
  • L1 Lamp To Be Controlled (up to 350 watts)
  • L2 Neon Lamp
  • TR1 40502 TRIAC
  • MISC Case, Knob, Heatsink For TR1, Wire, Socket For L1


  • This circuit is for 117VAC only. 220 or 240 V will burn up the circuit. L1 can be a maximum of 350 watts.
  • The circuit must be installed and used in a case.