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Potentiometer recommendation

Discussion in 'General Electronics Discussion' started by Michael_H, Dec 19, 2020.

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  1. Michael_H


    Dec 19, 2020
    Hello everyone, I'm new to the forum (registered today) and in need of a recommendation for a potentiometer.

    I have an old 8mm projector that uses a 8v 50w bulb. The bulb works off a simple on/off switch. I would like to insert a potentiometer inline between the transformer and bulb to vary the intensity of light the bulb generates. I have been looking at the Digi-Key website however simply dumbfounded by all the options.

    My knowledge of electronics is enough for simple solder/repair (eg, replacing capictors on circuit boards), however out of my depth trying to figure out what part to use when there is no old part to use as a reference. I would sincerely appreciate any suggestions anyone can offer.
  2. Bluejets


    Oct 5, 2014
    Any device used to lower the power to the lamp would need sufficiently high enough power rating.
    Pot as such generally are rather low, perhaps 1/4w and not suitable.
    You do not say whether ac or dc and no other voltages are quoted so impossible to say.
    If dc, then it may be possible to dim the lamp with pwm but not easy given your knowledge level.
    If ac, then some form of thyristor phase angle control.

    As it stands, many projectors have inbuilt current surge and start up current limiting to the lamp to prolong lamp life.

    One would naturally have to say "why do you need to do this".??
  3. ColKlonk


    Dec 22, 2020
    Rather use a proper electronic dimmer module, any pot used will burn out at the lower resistance settings.
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