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Why isn't my homemade DC motor working?

  1. May 7, 2014 #1
    I am building a two coil DC motor as a project. I have two neodymium magnets, an aluminium split ring, and alligator clips acting as brushes, connected to a 9v battery. For some reason it is not working and I cannot figure out why. Can anyone think of something I may be doing wrong. I can post photos if needed. Thank you!
  2. jcsd
  3. May 7, 2014 #2


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    There are lots of reasons a motor might not work.

    The magnets have to be of opposite polarity. Are they? Get a compass and check them or note which way the magnets attract each other.

    The coils have to produce magnetic fields that are strong enough and of opposite polarity.
    This means you have to have a lot of turns or a lot of current. A 9v battery is unlikely to give much current.

    Coils with a soft iron core can generate stronger fields than coils without cores.

    You may have a poor connection to the aluminium commutator. Connecting copper wire to aluminium is difficult.

    The rotor needs to have as much mass as needed to keep the rotor turning when it isn't getting power.
    Simple motors only get power in brief pulses.
  4. May 7, 2014 #3


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    some photos of your setup may help us to see where the problems are

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