Simple Lamp Dimmer/ Fan Regulator

A Lamp Dimmer/Fan Regulator Circuit

We have modified this circuit: – Take a lookModified Lamp Dimmer

Description .

This is the circuit diagram of the simplest lamp dimmer or fan regulator.The circuit is based on the principle of power control using a Triac.The circuit works by varying the firing angle of the Triac . Resistors R1 ,R2 and capacitor C2 are associated with this. The firing angle can be varied by varying the value of any of these components. Here R1 is selected as the variable element . By varying the value of R1 the firing angle of Triac changes (in simple words, how much time should Triac conduct) changes. This directly varies the load power, since load is driven by Triac. The firing pulses are given to the gate of Triac T1 using Diac D1.


Assemble the circuit on a good quality PCB or common board.The load whether lamp ,fan or any thing ,should be less than 200 Watts. To connect higher loads replace the Triac BT 136 with a higher Watt capacity Triac . All parts of the circuit are active with potential shock hazard.So be careful.

I advice to test the circuit with a low voltage supply (say 12V or 24V AC) and a small load (a same volt bulb) ,before connecting the circuit to mains.

Parts List

R1 1o K 1 Watt Resistor

R2 1o0 K Potentiometer (Variable Resistance)

C1 0.1 uF (500V or above ) Polyester Capacitor

T1 BT 136 Triac

D1 DB2 Diac

Fan Regulator Circuit Diagram

Fan speed regulator circuit and lamp or light dimmer circuit

BT 136Triac Necessary Data.

BT 136 Data sheet,Pin out diagram and specifications

BT 136 Specifications

We have more Power Control circuits in our website that may interest you:

1. Temperature Controlled Fan Regulator

2. Simple DC Power Delay Circuit

3. Temperature Controlled DC Fan

4. PWM Motor Speed Control

5. Fuse With Status Indicator

Show Comments

33 thoughts on “Simple Lamp Dimmer/ Fan Regulator

  1. nalaka

    dera sir ,
    i have use BT 136 for operate 10uf 400v capacitor but after five time tric if burned , pl give solution

  2. soham

    sir please can u send me the total documentation of the temperature controlled fan using triac thermistor. Please send me totally as early as posiible

  3. eng. mohamed

    please help me to control the speed of AC 220v motor 1HP, can i use this circuit with just changing the triac with higher one?

  4. kareemulla

    Hello sir please can u send me the total documentation of the temperature controlled fan using triac, diac, thermistor. Please send me totally as early as posiible. I will be waiting for your reply.

  5. Seetharaman

    Hi Nohammed Saad The same circuit can be used if it is mains operated LED appeared on Circuits today. If it is DC operated then you can use a variable current source using LM317 or MOSFET.

  6. ppadhma

    i want to design light dimmer circuit.lamp brightness will be controlled based on already existing brightness in room.give information about sensor i have to use.

  7. Pingback: Types of Thyristors-SCR-Diac-Triac-Ujt | Free Electronics Projects-Electronics circuits and hobby designs diagrams

  8. Awadhesh Kumar

    I m a 4th year student of EEE department and i m looking 4 project based on automatic temperature controlled circuit. So i choose automatic temperature controlled fan regulator. I need of details about this circuit………..

  9. faruk

    how to modify this “simple lamp dimmer/ fan regulator” circuit to dark controlled on off switch by using LDR

  10. Arie

    This is sure way to have noise on your power lines in your home it will work but coils filtering make a real world circuit


  11. pabitra mukherjee

    I would like to connect higher load like 3000watt filament lamp,pls. recommend me the appropriate triac with proper circuit to avoid potential shock hazards.


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