Re: gEDA-user: Electromagnetic bike

[Dave McGuire <mcguire@xxxxxxxxxxxxx>]

On 9/8/11 11:26 PM, Rob Butts wrote:
>     So if I have an electromagnetic and I hold it next to the spinning
>     metal disc as I increase the intensity of the magnetic field the metal
>     disc should be harder to spin?

  Exactly, yes.  (please forgive me for jumping in)

>     Define conductive? The eddy current breaks says non-ferromagnetic which
>     means to me not having any magnetic properties like aluminum.

  The resistance unit on an exercise bike that I recently disassembled 
used a pot-metal flywheel with a "tire" of copper around it.  This tire 
was perhaps 1/8" thick.  The adjustable brake consists of a rigid, 
arc-shaped metal strip, anchored with a hinge at one and, and movable by 
a spring-loaded lead screw at the other end.  This was placed close to 
the flywheel, and turning the leadscrew moves it closer to or farther 
away from it.  The metal arc had a handful of large permanent magnets, 
arranged in series, glued to it.

  The tire became quite warm when in use.

             -Dave

--
Dave McGuire
Port Charlotte, FL


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