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Electric Motor

  1. Jun 19, 2008 #1
    I'm trying to build a motor like the one in this video.

    I can't seem to figure out how the split ring works. From what I can tell, only one solenoid would be powered at a time, but wouldn't that be inefficient? Also if only one is powered, would it be necessary to have 2 permanent magnets?

    Maybe I'm missing something (which is very probable).

  2. jcsd
  3. Jun 19, 2008 #2
    Basically my question is should I go ahead with the design in the video, or is there a better way to build this motor than that offered in the video?

    (Sorry about the second post, but I can't figure out how to edit my original post)
  4. Jun 19, 2008 #3


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    I'm reasonably sure that just one coil is energized, but I might be wrong. To energize more coils might require another pair of brushes and commutators, which could be cumbersome.

    Having two magnets provides twice the force than having one magnet. Also, the force is more evenly distributed during the "power stroke" by having two magnets. With only one magnet, the force would be weaker when the energized coil has rotated farther away from the single magnet.

    The split ring seems to be 3 pieces of some kind of sheet metal. Probably sections from a metal tube of some sort, so they are already curved.

    I don't know if a better or easier design is out there, give this forum a day or two and see what kind of responses you get here. I think if I built one like in that video, I'd try having the magnets closer to the coils.

    Good luck!

  5. Jun 19, 2008 #4


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    IIRC you only need three sections on the commutator (split ring).
    The "start" wire of one coil is hooked to the "end" wire of the next coil and to one of the commutator segments in sequence.
    So you need to make sure you wind all the coils in the same direction.
    Also the angle at which the brush wires touch the commutator is important.
  6. Jun 19, 2008 #5
    Anyone remember the old HO scale slot cars with an armature with 3 poles? They also had a 3 section commutator. The ones I recall had a verticle shaft and then gears on a plate out to the back wheels. They were wired as NoTime described. It is entirely possible that some or all of the newer cars that have an armature with a horizontal shaft also have 3 poles.
  7. Jun 20, 2008 #6


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  8. Jun 20, 2008 #7
    I think this was my problem, I had each coil hooking up to 2 of the commutator segments, and not to any of the other coils.

    Does it matter which commutator segment I hook it up to?

  9. Jun 20, 2008 #8
    I think you can tell in the video which is hooked to which and yes it does matter.
  10. Jun 20, 2008 #9
    Do you think you can enlighten me as to which is hooked to which, as I cannot seem to figure it out.

  11. Jun 20, 2008 #10


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    Near as I can tell, each coil is directly adjacent to one of the 3 commutators, and is wired to the other two.

    Then a coil would be energized when it is near the bottom of the rotation.
  12. Jun 21, 2008 #11
    Thanks for that site russ, brings back alot of memories. The original cars I had were the magna-traction. They didn't hold the track that well compared to the newer cars. I recall getting newer cars that stuck to the track like glue. You couldn't have a wreck if you tried. We got bored with them and went back to the old magna traction which required some skill to drive. Eventually some of the car bodies got so worn on their mounts that they would rock back and forth on the chassis as the car went down the track. Fun times...
  13. Jun 22, 2008 #12


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    "They didn't hold the track that well compared to the newer cars."

    Yes. You could make the fly.
  14. Jun 22, 2008 #13
    And believe me we did!
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