Generators #5: The Permanent Magnet RotorPosted: 2005-April-24
I glued a couple magnets onto a wooden dowel with a screw through it to make a permanent magnet rotor. The magnets aren't particularly strong, and my first attempt had the poles opposite one another: that is, the north on one magnet mated with the south on the other, so the field was even weaker. (This all fit into the field coil from the Dirt Devil motor.) At 3,100 rpm, I could output 53 Hz AC at 2.7 volts open, 2.1 volts into 51 ohms (0.086 watts) and 0.7 volts into 3 ohms (0.16 watts).
While this isn't particularly promising, I purchased a pack of 50 0.25" diameter neodymium rare-earth magnets from K&J Magnetics. They're supposedly rated at N45 which I guess is almost as strong as you can get.
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