A bit off topic...but can one build a perpetual motor if we replace the electromagnet with permanent magnet? I know many here seem to have some electrical engineering background...so I am asking. I looked at the bottle dynamo..and basically it seems it's run to 2 magnets (the rorating shaft is permanent magnet and stator is electromagnet)...and there are no commutator to reverse the current...so I am a bit baffled how it works.

http://en.wikipedia.org/wiki/Commutator_%28electric%29

http://www.youtube.com/watch?v=F6ppevDxpw8