Re: gEDA-user: Magnetic bike operation

["David C. Kerber" <dkerber@xxxxxxxxxxxxxxxxxxxxxxxxxx>]

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
> > > > >
> > > >
> > > >
> > > >  _______________________________________________
> > > > geda-user mailing list
> > > > geda-user@xxxxxxxxxxxxxx
> > > > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
> > > >
> > >
> >
> >
> > _______________________________________________
> > geda-user mailing list
> > geda-user@xxxxxxxxxxxxxx
> > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
> >
> 


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user