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Quick question about DC Motors

  1. Apr 21, 2015 #1
    I'm doing research for my science project. I chose Wind energy and I need to learn a few things about DC Motors,

    Who is a good manufacturer for 6-9V .5 amps DC motor/generators?

    What happens if the generator goes over the recommended RPMs?

    How do you keep the RPMs between the minimum and maximum requirements Is there something that will slow down if the wind blows to fast?

    Can anyone answer or point me in the right direction? Thank you
  2. jcsd
  3. Apr 21, 2015 #2

    Simon Bridge

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    Anyone who manufactures them cheap enough you can afford them.

    It goes faster. It may break sooner.

    You build a governor or have a mechanism to disconnect the motor if it goes too fast or you fiddle the blade profile.
  4. Apr 21, 2015 #3


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    Sounds like you planning to use a small DC motor as a wind generator?

    Small wind turbines typically operate in the range 10-1000 rpm depending on the size. Small ones can safely go faster than large ones but deliver less power.

    Suppose you want around 12V output at say 200rpm then you would need a generator with a constant of around 200/12 = 16 rpm/volt. However most small DC motors have much higher motor constants - perhaps 500-2000 rpm/volt being more typical of those used in toys. You could consider a gearbox but step up gearboxes aren't very efficient. I would suggest looking for a motor with a low motor constant first. You may have to do a lot of experimenting to get it right so I would recommend googling to find a design that someone has already got working. Copy that and then experiment.
  5. Apr 21, 2015 #4


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    I forgot..

    One of the largest manufacturers of small cheap motors is Mabuchi. Many other companies make motors based on the physical form factors "standardised" by Mabuchi.
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