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Generating electricity through magnetic repullsion - theory/experiment help

  1. Jun 30, 2011 #1
    Hello world. Recently, I've started diving into the world of magnets.

    Here is a rough drawing of my experiment (not homework/coursework, simply doing it for personal interest) (I have found the items on ebay and what not, just creating the ideas before purchasing the magnets and other items):

    [PLAIN]http://img857.imageshack.us/img857/8793/1309381768093.jpg [Broken]

    I'm using the neodymium magnets to repel each other, and the extremely low friction (between board & smooth-surfaced-magnet), to spin the board.

    In the image (rough drawing):

    * 1st image: Side view, board (has a few neodymium magnets on the edge which I forgot to draw), it sits on 2 neodymium magnets repelling each other for "levitation", it is placed in a dome.

    * 2nd image, top view/angled: The dome also has neodymium magnets placed all along the walls, perfectly aligned with the neodymium magnets on the board, however all magnets are set at an angle & opposites (so they repel each other to give the board with also angled magnets the repelling push), with angled magnets my theory is it gives it more of a repulsing factor when the board-magnet leaves the dome-magnet's half )

    * 3rd image: the angled magnets of board/dome wall would be repelling each other creating the spinning movement of the board. Everytime a board-magnet passes a dome magnet it would generate a push, and multiple magnets on the dome/board would be generating multiple pushes many times a second (however force would eventually drop due to, angled magnets give a strong push however they also have a strong repulsion when the board-magnets are coming into the dome-magnets (thus [equal] velocity required for the board-magnet to pass the initial half of the "repulsing" magnetic field until the dome-magnets center, however when board-magnet passes the dome-magnet center, the dome-magnets strong repulsing magnetic field will be positively generating a strong pushing velocity on the board-magnet)).

    To start the experiment, you would need to give the board an initial a spin to generate some momentum (here in lies the problem, and manual pushes would be needed to continually generate force since input > output).

    Now what I need help with was, can I generate/capture if possible electricity from the moving board (without interfering with the movement) or something, and then redirect it to e.g. a motor on the top of the board, which would then give it another push (instead of me manually pushing it), that would be more efficient than simply letting it spin then stop (due to the force decreasing, and the "bad" repulsion (by "bad" repulsion I mean, the part where the velocity needed to enter the magnets magnetic field is high) ), so a new manual "motor" push is given every so often, to make the slowing down force, go slower.
    The motor is simply for giving it a push, instead of me manually pushing it. I would be using some sort of output to generate more input.

    My question is, would this theory work in general, is the motor a good idea (or do you have something more useful to convert output into input), how long would the spinning last, what is the maximum RPM you think it could achieve?
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Jun 30, 2011 #2

    sophiecentaur

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    Your system is basically producing a set of periodic pulses of force as the poles pass each other. Because the relative positions of the magnets is constantly changing this is producing a varying magnetic flux which could be used to induce a voltage in a coil placed appropriately. One possibility would be to wind a coil in the space between two of the magnets in one of the rings (axis of coil in the same axis as the magnets. An oscilloscope should show you something from that but I don't think it is an optimal design for an actual generator.
     
  4. Jun 30, 2011 #3
    Hi thanks for the explanation.

    However I'm not understanding where you think the coils should be placed.
    Is this what you mean?
    [PLAIN]http://img577.imageshack.us/img577/5047/magnetictheoryimage2v1.jpg [Broken]
    * Top image: coils placed in between each magnet on board
    * Next image: All coils, end bit of wire from all coils combine together in middle and all coils wire twist into 1, which attached to the motor (in this case I drew a propeller), but in real life I would use a motor.

    If this is correct, how much energy will be produced (as hopefully it's producing a viable amount of electricity to simply run the motor). So I will be using that electricity to power the motor (which would be attached to the centre of the board) which will add more velocity to the spinning board (removing the need of my manual pushes later on), thus repeating this cycle over & over.

    Also should I then attach coils to all the spaces in between the magnets on the dome, and also connect all the coils to the big central twisted coils, which attach to motor. (However if this is more work than results are produced, I can leave it).



    I know it's not probably the optimal design, I'm just testing around too see the results.
     
    Last edited by a moderator: May 5, 2017
  5. Jun 30, 2011 #4

    sophiecentaur

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    Not sure from your diagram what you mean but imaging winding a coil round one of the magnets and then slipping it off the end without changing its orientation. Its axis will be in line with the axis of the rods.
    i.e.
    N-S -one end of coil - other end of coil - N - S
    Does this make sense?

    To get as much as you can out of the system you would need to have coils in each gap and the coils would all be connected in series, with attention to the sense of the connection of each coil to make sure the volts add and to avoid volts cancelling out.
     
  6. Jun 30, 2011 #5
    [PLAIN]http://img717.imageshack.us/img717/6631/magnetictheoryimage3v1.jpg [Broken]
    Do you mean like any of these?

    - Top image: Coils curled, and simply touch 1 side of the magnet, and the end of coiled wire touches other magnet.
    - Bottom image: Coil curled and wrapped around all magnets, looping around?

    Also my magnets won't be N-S sideways. It will be NORTH, on the front face; SOUTH on the back. (Is this what you mean, e.g. my Top image I drew, but start of coil touches front of magnet "N", and other end of coil touches back of magnet "S", but won't this weaken the force which is repelling the dome-magnet)

    if you look at my image, the 3rd magnet on the top image explains in. The front face is NORTH pole, to repulse the NORTH poled facing dome-magnet.
    - Here's a simple ascii art version, from a top view (looking down):

    (Board magnet)
    S
    +-----+
    +-----+
    +-----+
    N

    ~~~~ Magnetic repulsion

    N
    +-----+
    +-----+
    +-----+
    S
    (Dome magnet)
     
    Last edited by a moderator: May 5, 2017
  7. Jun 30, 2011 #6

    sophiecentaur

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    Ascii diagram seems most understandable. I was confused by the pencil diagram.
    My original statement that the axis of the coil axis should be parallel with the NS axis of the magnets still holds. The induced voltage is proportional to the rate of change of Magnetic Flux so, by alternating the poles on one of the magnet (i.e. NS SN NS SN) wheels you would find a greater force needed to move from one stable position to the next. This implies more variation in magnetic flux as the wheel is rotated so more output from your coil(s)
     
  8. Jun 30, 2011 #7
    So your saying the coils should be placed in the middle between in the air-gap between the dome/board like this, and would have loads of coils? So it will end up looking like a giant circle of individual coils i:

    (Board magnets [these would be constantly moving around & around])

    +--S--+ +--S--+ +--S--+ +--S--+ +--S--+ +--S--+
    +------+ +-----+ +------+ +------+ +-----+ +------+
    +--N--+ +--N--+ +--N--+ +--N--+ +--N--+ +--N--+

    (-------) (-------) (--------) (-------) (--------) (-------) coils

    +--N--+ +--N--+ +--N--+ +--N--+ +--N--+ +--N--+
    +------+ +-----+ +------+ +------+ +-----+ +------+
    +--S--+ +--S--+ +--S--+ +--S--+ +--S--+ +--S--+

    (Dome magnets)

    Full image:
    [PLAIN]http://img194.imageshack.us/img194/134/magnetictheoryimage4coi.jpg [Broken]
    So this method, would it decrease the repelling factor of the magnets, or not?. Since remember, the goal of this was to generate spin for as long as possible (and this extra part was to (if viable) grab output and covert it to input, hopefully not affecting the output of the magnetic repelling too much)
     
    Last edited by a moderator: May 5, 2017
  9. Jul 1, 2011 #8
    Wait a minute, shouldn't it be attracting instead of repelling for inducing a voltage with in the to work?

    Since if you think about it:

    +--S--+
    +------+
    +--N--+

    (-------) coils

    +--N--+
    +------+
    +--S--+
    Both magnets are repeling, thus the magnetic field will always be pushing electrons from the coil into the center, instead of flowing in a 1-way direction.

    Thus if my thinking is correct should it be like this:
    (board)
    +--N--+ +--N--+ +--N-+ +--N--+
    +------+ +-----+ +-----+ +-----+
    +--S--+ +--S--+ +--S-+ +--S--+

    (-------) (-------) (-------) (-------) coils .. ^ upwards is the direction of the flow

    +--N--+ +--N--+ +--N--+ +-N--+
    +------+ +-----+ +-----+ +-----+
    +--S--+ +--S--+ +--S--+ +--S--+
    (dome)
    Since this will allow the electron to flow through the coil in 1 direction, and also have the pushing-factor that the previous repelling factor had. Instead of gaining velocity when both magnets repel each other, this method will gain velocity when magnets attract, however lose velocity when they pass the center of each other.

    However can anyone confirm that this is the correct method of me placing the coils in this position for the optimal position.

    (I've bought all the items from eBay needed, so now a few days of waiting will be required, and I can test this). However the motor hasn't been purchased yet, I'm going to first see the amount of voltage produced from all these coils too see if it's worth powering the simple motor.
     
  10. Jul 1, 2011 #9

    sophiecentaur

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    The way to make this thing turn for as long as possible would be to take out the magnets completely! They can only constitute a loss mechanism - except that they could act like a bearing, I suppose and reduce mechanical friction.

    Have you taken my point that you need to be changing the magnetic flux cyclically if you want to 'generate' a voltage. Unless you alternate the polarities in some way how can you achieve this?

    But, apart from having a play with some magnets, I cant imagine that you could be seriously using an arrangement like this for generating significant power. Good generator design would involve iron cores for the coils and a way of maximising the flux change with position.

    I think you should read about alternators work, basically, if you want to make any real progress. There are a few basics you need to know.
     
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