Re: gEDA-user: Magnetic bike operation

[Dave McGuire <mcguire@xxxxxxxxxxxxx>]

  Of course it'd work.  It doesn't matter where the magnetism comes  
from. ;)

          -Dave

On Mar 29, 2010, at 12:35 PM, David C. Kerber wrote:
> I would think that would work.  IIRC from my college days, higher  
> conductivity in the disk gives you stronger braking, so copper  
> would be ideal, but most people's budgets call for either aluminum  
> or steel.  Of course steel could handle higher temperatures, so you  
> wouldn't need as much cooling...
>
> D
>
>
> > -----Original Message-----
> > From: geda-user-bounces@xxxxxxxxxxxxxx
> > [mailto:geda-user-bounces@xxxxxxxxxxxxxx] On Behalf Of Rob Butts
> > Sent: Monday, March 29, 2010 12:23 PM
> > To: gEDA user mailing list
> > Subject: Re: gEDA-user: Magnetic bike operation
> >
> > So I'd lke to make this programable; therefore, in lieu of a
> > permanent magnet and bringing it closer to the disk to
> > increase the resistance I could use an electromagnet and
> > increase the magnetic field?
> >
> > On Mon, Mar 29, 2010 at 11:39 AM, David C. Kerber <
> > dkerber@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > > Just attach a disk of some conductive material to the axle of the
> > > thing you want to brake, and mount a strong permanent
> > magnet so that
> > > it's near but not touching the flat surface of the disk.  I think a
> > > C-shaped magnet with the opening just big enough to clear the disk
> > > would work even better, but it's not required.  I believe
> > my trainer
> > > uses two magnets, one on each side of the disk, facing each
> > other.  If
> > > you're putting any significant continuous load on it, you will need
> > > some cooling; my trainer's load box get pretty warm after I've been
> > > using it for 20 minutes or so, and it has fan blades to
> > drive air flow through it whenever it's turning.
> > > > -----Original Message-----
> > > > From: geda-user-bounces@xxxxxxxxxxxxxx
> > > > [mailto:geda-user-bounces@xxxxxxxxxxxxxx] On Behalf Of Rob Butts
> > > > Sent: Monday, March 29, 2010 11:15 AM
> > > > To: gEDA user mailing list
> > > > Subject: Re: gEDA-user: Magnetic bike operation
> > > >
> > > > 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.  Then wikipedia talks about using
> > electromagnets and
> > > > varying the breaking force by varying the magnetic field.
> > > >
> > > > On Sun, Mar 28, 2010 at 8:03 PM, David C. Kerber <
> > > > dkerber@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > > >
> > > > > My bicycle trainer uses an eddy current brake; there
> > are no wires
> > > > > anywhere in the load; just a ventilated disk and a magnet
> > > > that I can
> > > > > move closer or further away from the disk by turning an
> > > > adjustment dial.
> > > > > D
> > > > >
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: geda-user-bounces@xxxxxxxxxxxxxx
> > > > > > [mailto:geda-user-bounces@xxxxxxxxxxxxxx] On Behalf
> > Of Rob Butts
> > > > > > Sent: Saturday, March 27, 2010 4:29 PM
> > > > > > To: gEDA user mailing list
> > > > > > Subject: gEDA-user: Magnetic bike operation
> > > > > >
> > > > > > I'm having a debate with an ee friend about how the magnetic
> > > > > > resistance works on an excersice bike.
> > > > > >
> > > > > > It occurred to me this would be the best place to solve it.
> > > > > >
> > > > > > Does anyone know if it is simply an electro-magnet close
> > > > to a metal
> > > > > > wheel where the stronger the magnetic field the stronger the
> > > > > > resistance?  Or is it alternating magnets in a flywheel type
> > > > > > configuration with a toriodal coil surrounding the
> > flywheel and
> > > > > > a variable resistance in the coil circuit resists the
> > > > induced current
> > > > > > providing the resistance to user who would be spinning
> > > > the flywheel?
> > > > > > (Sorry if I didn't describe that well).
> > > > > >
> > > > > > Or is it something completely different?
> > > > > >
> > > > > > Thanks
> > > > >
> > > > >
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> > >
> > >
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>
>
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--
Dave McGuire
Port Charlotte, FL



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