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scratch built wind generator

Discussion in 'Home Power and Microgeneration' started by FrankG, Dec 23, 2005.

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  1. FrankG

    FrankG Guest

  2. Bughunter

    Bughunter Guest

    I love this kind of engineering. "From trash to treasure".
    With today's emphasis on the environment and recycling, it
    is actually very hip. Nicely done website. Both entertaining and

    It reminds me that "what is important is the journey and not the
  3. Outstanding job!!! I love making things from old industrial stuff, but
    this is very advanced project.


  4. wmbjk

    wmbjk Guest

    Nice job Frank.

  5. phatty mo

    phatty mo Guest

    I once started work on a similar project..
    I used the HDD platters,and spindle motor,and glued the magnets to that
    with JB-weld (careful,it's magnetic.)
    I never got around to finishing it..still need to wind some coils.. :)
  6. Steve Spence

    Steve Spence Guest

    This is the one we are starting on:
  7. FrankG

    FrankG Guest

    I don't know that my ambitions run that high quite yet... in the short term
    I certainly would like to hit 100 to 250 watts by the spring...

    Though ultimately I would be satisified with 3 towers each flying a 500Watt
    for providing power for the shop.

  8. daestrom

    daestrom Guest

    I don't mean to discourage you, but having worked in a motor/generator
    repair shop, you still have a problem with your magnet/coil layout.

    As I understand your design, you have 24 magnetic poles, and 8 coils. And
    from your description, the magnets are arranged on one disk, and the coils
    on another that is to be mounted very close to the magnet disk. And there
    will be a steel/iron plate behind the coils? That part I can't tell for

    Looking at how the magnets are arranged, N pole of one next to the S pole of
    the next, I'm not clear how the magnetic flux will pass from the pole of
    one, across a coil side, into the steel backing and return across another
    coil side back to the S pole of the neighboring magnet. It seems the flux
    would have an easier path to just jump from one magnet's N pole to the next
    magnet's S pole and only a fringe of flux would pass up wards from the disk
    to where the coil is spinning.

    Instead of breaking the magnets in half, you might try mounting them so the
    N pole of one is next to the N pole of the next. Followed by it's S pole
    next to the S pole of the third, and so on. Then the flux from both N poles
    would be opposing, and would have to rise up out of the disk, to where you
    have the coils spinning. This would be hard to first hold in place since
    the magnets would naturally repel one another, but I think you'll get more
    voltage for a given coil setup/speed.

    Another thought is that ideally the number of coils should equal the number
    of poles in a single phase machine. With the odd ratio of 3 poles per coil,
    however you connect the coils together, there will be times when the voltage
    developed in one will be opposing that of another. Mind, I understand that
    winding 24 coils to fit in the same circumference would seem to be a
    challenge. But it is done all the time with commercial machines by
    overlapping the coils. If one side of a coil is over a N pole, the other
    side doesn't have to be over the adjacent S pole. It can be over a S pole a
    couple of magnets away. If you try my idea about arranging the magnets so
    poles oppose, then the coil can be wound sized so when one side is at the
    'gap' between two magnets, the other side can be at the 'gap' between two
    other magnets, some distance away. Then arrange all the coils so the left
    side of each one tucks under the right side of its neighbor.

    You can also 'flatten' the coils, spreading the conductors wider around the
    circumference a bit. Don't spread them out so far that different turns in
    the same side of a coil span more than about 3/4 the distance between N and
    S pole pairs though. This spreading allows you to keep the 'thickness' of
    the coils down so more copper is closer to the magnets and there will be
    less gaps where there is no copper conductor.

    If you ever do want to go three phase, you are going to need at least 3
    coils for each magnetic pole, so finding ways to overlap / spread the coils
    could be worth the effort.

    Three phase will give you smoother output with less 'cogging' when you load
    the unit. Or is this the reason you have so many more coils than poles, to
    reduce the 'cogging' effect even though it sacrifices voltage generated??

  9. FrankG

    FrankG Guest


    Thanks for taking the time to provide such a thoughtful post...

    I have had others offer similar thoughts, though I don't think anybody had
    suggested alternating "Opposing" poles.

    The next posting (later in January 06) will document a few variation on the
    magnet placement and the results with the same coils as a reference point.

    So far I have retrieved 48 Single pole or half magnets from the pile of HD
    magnets and arranged them in a ring of 16 poles alternating N - S - N - S
    .... The reuslts were consistently a lower output voltage for 1 layer, 2
    layers and finally 3 layers .

    With 3 magnets stacked over each other over 16 poles it equates to the same
    quantity of magnetic material as 24 poles in 2 layers. The difference being
    the spacing of approx 2/3rds of a pole gap between magnets.

    My rational for using "Factory" shaped single pole magnets was that I had a
    nagging suspicion that the act of breaking the dual pole magnets would
    weaken then as a result of the mechanical force and that there would be a
    measure of inconsistency in how accurately they parted along the division of
    N & S.

    Over the next span of time I have available, I will try your suggestion and
    document accordingly, as well I feel that I can invest a bit more time with
    just a pair of dual-faced magnets and the "Black-Sand" to more clearly
    visualize the flux properties and how they are modified by adjacent magnets.

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