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How do two layer voice coils work?

  1. Aug 21, 2012 #1
    I understand how single layer/wound voice coils work, where the positive lead is at one end of the coil and the negative is at the other, but how do double wound coils work where both leads terminate at the top? See photos below for what I mean by double and single wound. On the double wound, wouldn't the electrical charge take the shortest route and not even charge the layers below the two leads since it would just go straight to the negative lead? What am I missing/not understanding?

    Single wound:

    Double wound:
    Last edited: Aug 21, 2012
  2. jcsd
  3. Aug 21, 2012 #2


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    Unless I completely musinderstood the question, you seem to be missing the fact that the wire is insulated. The insulation is a thin coat of material sprayed onto the wire which gives ithe shiry appearance. For this sort of application, you don't need thick flexible plastic insulation to protect the wire against mechanical damage and withstand repeated bending without cracking, whcih you see in most housefold electrical wiring.
  4. Aug 21, 2012 #3
    Well gee, now I feel like a dunce. :wink: I wasn't aware that there was insulation on it! I thought copper wire was just that, copper wire. Now it makes sense. Thanks for clearing that up! :)
  5. Aug 21, 2012 #4


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    dont feel too bad... its all a learning process :)

    but also think about your reasoned comment .... if it was bare copper, even just a single layer would short out as well ;)

    but note, bare copper wire is a very different colour, the colour you are seeing there, a dark, brownish colour is the enamel insulation on the wire.
    then they dip the whole lot in lacquer to keep the turns of wire held in place
    This form of insulation is used on most coils, be they transformers, plain inductors, voice coils as you have shown.
    It is also common to see an almost transparent enamel used on more modern coils where the colour of the copper is somewhat more obvious

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