Re: gEDA-user: Magnetic bike operation

[Larry Doolittle <ldoolitt@xxxxxxxxxxxxxxx>]

Rob -

On Mon, Mar 29, 2010 at 11:14:51AM -0400, Rob Butts wrote:
>    I've read about the eddy current breaks but it's still not clear to me
>    how to construct one.  The wikipedia talks about a rotor connected to a
>    spinnning coil.  I would think the rotor would spin inside a coil.

Any time you have a conductor (aluminum is a good choice)
moving in a magnetic field (a permanent magnet is fine) it
will have a repulsive force (not always easy to detect)
and a drag (actually decreases at high speeds, as the repulsive
forces kick in).

It's easy to try out yourself with a spinning aluminum disk
and a strong permanent magnet.  This is also how an old-fashioned
mechanical speedometer works.

   - Larry


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