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Stero Speaker magnets

Discussion in 'Home Power and Microgeneration' started by Johnny, Feb 24, 2006.

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  1. Johnny

    Johnny Guest

    Are stereo speakers a good source of magnets to use in building generators?
  2. Generally, No but speakers vary so much it's anyones guess.

  3. Johnny

    Johnny Guest

    Their size and weight seem like they would be good candidates.
    Strength is also a consideration.
    If I knew the formulae I could determine this for myself.
    Anyone know the formula to determine how much induced current/voltage can be
    obtained from a given magnet?
    I imagine speed of rotation matters somewhat.
  4. Pop

    Pop Guest

    I don't know anything about the formulae, but I do know two
    things that might be indicative. Or not <g>. Of something <g>.

    The higher the "efficiency" rating on a speaker, the stronger the
    mangetics. The better the speaker, the stronger the magnets.
    Assuming of course, that the speaker uses mangets: Most do, but
    some use electromagnetics in their design so it takes current to
    create the magnetism.

    Most speakers are also designed such that, to get the intended
    power of the magnet, you have to have either the "ring" that
    comes with it, or something that will achieve the same objective
    for the shape of the generator location.
    The ring is used to concentrate the flux pattern so that it's
    strongest in the place where it's needed. Without it, they're
    often pretty weak. Maybe someone here can fill in some holes on
    this one. Actually, you might want to try an audio or hobby
    group for more detailed information.

    I've used a couple of high efficiency 6 inch mid-ranges to make
    magnetic floor sweepers with. They work great, but if anything
    gets directly onto the magnet itself, it can be a job to pull
    Haven't found a good use for it yet, but I pulled apart a
    drowned 15" woofer awhile back that you will -not- pull anything
    off it with your fingers. Only prying with a sliding motion can
    get anything bigger than a nail off it! it's surprising just HOW
    powerful they can be, but, like I said, a lot of that strength is
    the flux conduction design, not the magnet itself. Pull off the
    flux conductor and that same magnet can't even hold its own
    weight to a steel shelf. Interesting stuff.
    I think I'd want to take some courses if I were going to try
    to use them for a generator of some kind. But hey, that's just
    me! ;-}

  5. Johnny

    Johnny Guest

    Nice info.
  6. Hard Disk Drive positioners have very string magments in them.
  7. JoeSP

    JoeSP Guest

    What's the point? There are lots of better ways to do it without magnets.
    If you just want to see it work, efficiency isn't important. If you want
    efficiency, there are lots of cheap alternatives in the junkyards and
    surplus stores.
  8. Bob Adkins

    Bob Adkins Guest

    HDD magnets are so powerful and so much fun, it's surprising they aren't
    illegal. :)
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