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What's the function of capacitors in dynamos?

  1. Apr 29, 2014 #1
    what is the function of the cap 104, why is it there? what's the function of this cap in the dynamo.. i know caps are used in motors for P.F correction, but what about the dynamos in toys??

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  3. Apr 29, 2014 #2

    jim hardy

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    probably to 'absorb'(or suppress) the electrical noise from sparking at the motor's brushes.
    Observe it's been placed as close to the noise source as physically possible which is good practice.
  4. Apr 29, 2014 #3


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    I agree.
    That looks more like a DC motor than a dynamo. The worm gear confirms it.
    The 104 capacitor is 10 0000 pF = 100nF and is there to prevent radiation of RF noise from the sparking at the brushes.
  5. Apr 29, 2014 #4
    Dynamo in the US is an outdated term that used to mean generator and/or alternator not sure which. I was wondering if dynamo might just be Aussie for motor in the US?
  6. Apr 30, 2014 #5

    jim hardy

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    in 1890's it referred to a DC machine which of course can both generate and motor.

    As late as 1963 Austin-Healey 3000 labelled its dashboard ammeter with word "Dynamo"
    but here the term is quaint.

    I once used a small motor like the one pictured and controlled it with a 555 IC. Need for bypass capacitor at motor was immediately obvious.
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