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Dimming a 12V 24W Incandescent Bulb

Discussion in 'LEDs and Optoelectronics' started by caferacer, Dec 18, 2013.

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  1. caferacer


    Aug 11, 2013
    Hi All,

    I want to be able to vary the output of a 12V 24W incandescent bulb by approx 50% can be more, but it certainly doesn't need to be completely extinguished.

    I have a 12V 2A output power supply (APD model WA-24E12), which I was intending on using, but not sure what device would be best, i.e. a potentiometer, rheostat etc..

    What is the simplest way of doing this, without lots of components.

  2. BobK


    Jan 5, 2010
    A potentiometer or rheostat would dissipate a large amount of power in that application. You would be better off using PWM (Pulse Width Modulation), which basically turns the current on and off rapidly and the brightness will depend on what percent of the time it is on. You can buy PWM controllers already built.

    This one for instance would do what you need:

  3. Arouse1973

    Arouse1973 Adam

    Dec 18, 2013
    I agree with Bob, 50-50 DC would give you 50% of the current.
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Or put two bulbs in series. It will not give you exactly 50% but is easy to do.

    Otherwise I agree with the prior posters that PWM is the best way to do it. Plus you get variable brightness by changing the duty cycle of the PWM.
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