On Tue, 14 Oct 2003 11:35:32 +0100, Lawrence
With a magnetising rig, which you can make yourself. DAGS on dynamo
rebuilding - the stationary engine crowd do this regularly. Or ask
again in uk.rec.engines.stationary
Basic technique is to place the magnet in a coil, then to charge up a
capacitor bank and discharge it through the coil.
Problems are that the coil may need to be a funny shape, especially
for alternator / magneto work. Also coils need a lot of turns to
generate a large field from a small current. But more turns means more
inductance, which reduces the current you can force through them in a
pulse. So there's some juggling to be done for optimum size of coil,
capacitors and voltage.
Alternatively, ignore the old magnet (maybe saw it up for pole pieces)
and slip some powerful new rare earth magnets into the middle of it.
Modern ceramic magnets are so powerful that you can replace a big old
magnet with something tiny these days.
Die Gotterspammerung - Junkmail of the Gods