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Easy question / confirmation...

Discussion in 'General Electronics Discussion' started by cjdelphi, Jul 27, 2015.

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  1. cjdelphi

    cjdelphi

    1,096
    104
    Oct 26, 2011
    if these ebay pots are 0.1w (see attached)

    then...

    0.1v x 1amp is 0.1watt ?


    So i should be able to use a 10k pot inplace of the resistor to a 1amp load, or have i gone incredibly stupid after writing so much code lol
     

    Attached Files:

  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,025
    2,138
    Nov 17, 2011
    Right, but: 1A*10kΩ=10kV, not 0.1V, therefore P=10kV*1A=10kW!
    You have several option for calculating the power through a resistor (aka potentiometer in this case):
    P=V*I
    P=I²*R (becasue V=I*R)
    P=V²/R (because I=V/R)
    Depending on which variables you know.

    For direct control of power by a potentiometer you will need a high power pot (typically wire wound) with only a small resistance.
    It is usually more convenient to use the potentiometer to control a suitable power circuit, e.g. a PWM dimmer as in your 2nd attachment.
     
  3. cjdelphi

    cjdelphi

    1,096
    104
    Oct 26, 2011
    ah, yes of course via pwm to dim it, i'll stick with the resistor :)

    thanks!
     
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