Hi there, I've put together a very small alternator which I was planning to use as a rear-hub dynamo for a push bike (they don't seem to make rear wheel integrated dynamo hubs anymore and I'd like to be able to turn the bike over and spin the cranks by hand to charge batteries while relaxing in a park or on a camping trip)
Anyway, the unit I built is a 10cm radial alternator, the rotor consists of 24 3 x 3 x 3mm ndfeb magnets and the stator is wound with 3 sets of 6 coils each of 40 turns .0135mm enameled wire, wired in star and recitfied by a small diode array.
However when I hooked it up I was only generating 200mv, less than a tenth of the voltage I need.
I'm wondering whether this is just a case of having very undersized field magnets, too few turns of wire or something else?
I'd thought of rewiring the stator with a single coil (like this
http://www.windstuffnow.com/main/mini-gen.htm) but I'm having trouble figuring out exactly how to?
The other option is rewind the stator with many more turns of wire per coil, I don't really want to spend much more money on this project so more powerful magnets are out.