> I think you will have trouble getting enough power out of a magnet
> and coil.

As this is essentially how all alternators and generators work, it is more
likely that the specific implementation is flawed than the method itself.

> I was curious about this, so I built a test setup. For a
> coil I used the coil that drives a pendulum in quartz clocks. These
> coils are wound from exceptionally thin wire and so have a very high
> number of turns.

What was is the coil resistance?
What is the open circuit voltage?

Volts = 4.44 N f Bmax.
With a bit of deduction you may be able to determine whether Bmax is as high
as you would expect with the given magnet.

B= uH.
Increasing u will help. An air only path gives u = 1.
Airgap and magnetic path will affect the results. Adding a metal "pole
piece" may assist.

The frequency is low (3000 rpm = 50 Hz) so coil inductance may be inadequate
(but ought not be given the coil used).

Resonating the inductor in such cases MAY make a substantial difference.

Stephen Barnes link to
http://hot-streamer.com/hilo90mhz/electronics/prop_clock.htm
gives a very nice solution. Note that the power oscillator drive seems to be
at around 100 kHz which will allow much smaller magnetic components to be
used than at the 50 Hz of the rotating magnet version.



        Russell McMahon

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