Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Generating Electricity

  1. Aug 19, 2004 #1

    Can anyone explain to me how I can generate a current (to say, light a lightbulb) by wind power?

    I have a fan which is spinning and I know it has something to do with a wire and a magnetic field but I don't know how to set the circuit up at all.

    Maybe a simple diagram if anyone has a minute spare?


  2. jcsd
  3. Aug 19, 2004 #2


    User Avatar
    Science Advisor

    So. You are wanting to make a wind mill generator? Are you intending on using the fan for the wind source, or will this be an outside device?

    If the latter, are you intending to use the fan to generate the power?

    That could work I suppose, however, it might be tricky to setup. Is it a typical box fan?

    Basically, you can get electrical current by either rotation a conductor (the wire) inside a magnet field, or rotation the magnetic field inside of a conductor.

    Chances are, your fan has natural magnets on the shaft of the fan blade. When power is turned on, coils of wire become electrically charged, creating an EM field, which repels the natural magnets. Spinning the fan blade should induce some current inside the coils, however it will probably not be that effiecent.

    I watched an episode of "Escape from invention(i think) Island" on discovery. They had to build electric rope cars, and transport themselves across a valley.

    Anyhow, part of the challenge was building a water wheel to turn an alternator, which would charge the battery. They provide alternators which were regulated at 12v dc, however, you can get alternators which do not.

    I would start out by perhaps using an old fan blade, although it was more designed to push air, as opposed to being pushed by air. Find a way to mount a pulley on it, and get yourself an alternator. Hook a belt from the fan pulley to the alternator, find a windy area, and you've got power.

    You might find a multimeter usefull, so you can measure the power being produced. Also, while I recomend the buying an alternator, it is not impossible to build your own, just more difficult.

    This site will probably help you a bit

  4. Aug 20, 2004 #3

    Where could I get an alternator that small?
  5. Aug 23, 2004 #4


    User Avatar
    Science Advisor

    Its "Escape from Experiment Island" on the Science and Discovery channel (and DHC or others in their little network of channels). :)

    Any DC motor can generate electricity as well. With permanent magnets, its very simple as you just need to spin it to generate electricity.

    An alternator needs electricity to generate electricity. And you need not worry about size, there is a regulator that controls how much electricity it makes. An alternator is constructed with a spinning coil and a stationary coil. It needs electricity because you use this electricity to turn the spinning coil into a magnet. The spining magnet then causes electricity to flow in the stationary coil of wire.

    If you were lighting just a small light bulb like an automotive dome light, you could take the small DC electric motor from a radio controlled car and add a fan blade to that. From there you could adjust the sizes of the components to get the desired results, most likely a larger fan blade than you would have thought necessary.

    Wind isn't typically a steady source of power. The units for sale are generally hooked to a battery charger so it can store the energy in rechargeable batteries.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook