Alternator using recycled hard-disk magnets

[joegatt]

Here's an alternator I rigged using recycled hard-disk magnets. 21SWG wire may be a little too thick for magnets of this size. 24SWG wire seems more appropriate.  The coil size limits the proximity of the two rotors and hence also the magnetic field strength.

The voltage pulses have a 2Volt peak and cannot be easily rectified. The output power is presently 0.25 Watts but this can be improved with a sturdier construction allowing the magnets to be nearer to the coils.

To increase the power, one can use bigger magnets. (Or use superconducting wire, yeah!, and bring the magnets closer.)
One can always add more magnets and more coils, but when adding coils in series, the coil impedance also adds up.
So there you have it ... you would need bigger magnets to get more power.  And rare earth magnets don't come cheap.
I wouldn't like to have a wind turbine that spends its working life just trying to pay for itself. But if you can get big matching magnets from scrap ... then go for it!

Regards
Joseph

[joegatt]

Here's a clip showing some more detail of this setup

[joegatt]

And here's a power test using a small incandescent lamp.

[gyulasun]

Hi Joseph,

Nice setup, thanks for showing it. I would like to know if you placed magnets under the coils too (not only above them) ?
I cannot see clearly the bottom part of your setup, this is why I ask. (If you did place magnets under the coils, then do the upper and lower magnets facing each other and the coils are between them?)
Also would like to know the pole arrangements of your magnets, how you placed them.

[joegatt]

Yes, Gyulasun.

Using two acrylic discs, I placed magnets both above and below the coils to try to maximize magnetic field strength. There should be a South pole opposite each North pole and vise-versa to hopefully link the flux into a straight line crossing the coil conductor at right angles.

The hard-disk magnets have two poles on the same face. In theory they can be laid out in a complete circle of alternating north and south poles. However, my decision to recycle also the backing steel plates, (instead of using a complete steel disc,) meant that there would be gaps in this rotor.

Morover, these magnet pairs can be left-handed or right-handed ie. approaching them from a particular angle, you meet the North first with some, and South first with the others. To cater for this, I laid the magnets out in alternating right-handed and left-handed pairs going round the rotor. Then the eight original coils, which were wound together in series, had to be laid out in an alternating clockwise and anticlockwise sequence, so that the voltage pulses would add up.(See diagram attached)

Finally, in order to try and raise the power output a bit more, I winded an extra set of eight coils and installed them in the gaps between the other coils. I connected this set of coils in series with the orignial set. It was a gamble. Only one of these two sets of coils would be truly active at an instant. And now the overall coil impedance will be double. However as the frequency of the pulses was now effectively doubled the power output showed a marked increase.

Regards
Joseph