Electronic Lamp Dimmer Circuit

dimmer switchThis electronic lighting dimmer circuit is used to control the lamp for arbitrary brightness. This electronic lamp dimmer circuit work for incandescent lamp, not a fluorescent one. The dimmer circuit here work for both 110V and 220V AC.

The dimmer circuit is wired in series with the lamp, you can say the dimmer circuits is installed in series with the lamp. Be careful that the circuit is not isolated from high voltage, so the potentiometer should be installed with plastic knob. Don’t touch the circuit or you’ll be shocked by the electricity.

The lighting dimmer control is done by the potentiometer, you need to turn right or left to adjust the lamp’s brightness.
The lamp dimmer has no switch, you can see only a fuse for safety. You can add a switch in series with the fuse, or just insert this dimmer circuit between the existing swith and the lamp.

Lamp dimmer circuit diagram

dimmer circuit

For more lighting dimmer circuits check the related links bellow.
Capacitor C4 is charged via resistors R3, R4, P1, and R5. After a certain time, dependant on the potentiometer, the charge contained in C4 is large enough for diac D to start conducting, so that a firing pulse is applied to the gate of the triac. Consequently the triac conducts and power is transferred to the lamp.

Lighting dimmer precautions

Be aware that dimmer switches can only handle a specific amount of light load. You can typically purchase dimmers that are rated for 600 or up to 1,000 watts of lighting. Light bulbs are usually clearly marked as to their wattage. Determine the total wattage of the bulbs that are being controlled by any one dimmer.

This lamp dimmer switch has not been tested.


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  • ferenc-lengyelgmail-com


    I need to modify the dimmer to control the light intensity through transistor opto-coupler.
    I tried to replace the P1 resistor by a pair of NPN and PNP transistors with connected collector and emitter and with both base driven by a separate opto-coupled transistor. But it does not work very well, does anybody have any experience with this?

    My goal is to control intensity with analog input 0-10V.


    How can i will use EL Lamp

  • Gamini Tilak.

    This is a reply to Darren;
    When you pass an AC current through a diode it removes one half of the sine wave. Although it is removed power of that half is not lost. A process similar to that is taking place in the Triac too.

  • Hernando Restrepo

    Sorry: I forgot to mention. Could anyone tell me who or where can I obtain information about this item.


  • Hernando Restrepo

    I am in need of a light dimmer capable of handling a 1000 total watt continuos lighting (tungsten photographing bulb)


    thanks for the electronic informatios. i like to control three no’s of electromagnetic vibrators with a dimmer. load current on each vibrator is 3.4A maximum. can you send me a well tested circuit

    thanking you.

  • darren

    sir is this different to saving energy device?coz once u dimmed d light,means decreasing voltage,but heat dissipated only at the ckt mostly at triac point?
    is this will apply to the omhs law?that when voltage decreases also current decreases,difinitely saving energy??tnx

  • s.k chhoker

    i want my exhaust fan auto start after every 30 minute for 5-10 minute. please suggest me timer brand and model ( Direct operate without starter )

    my mail

  • kishore kumar koneru

    very good whatever the concepts we need all those available in this circuits we are saying greatfull thanq’s to this site

  • toni

    thanks for information….

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