Originally Posted by
Tourist in MSN
I do not think there are any brushes in a bottle dynamo. Just spins a permanent magnet inside of a non-rotating armature with the windings. Can't get any simpler than that. I have never disassembled one, so maybe I have that backwards and the windings spin in perminent magnets? But that would be the hard way to build one.
The bottle dynamos I had (Union brand from Germany) had no holes to shoot in any tuner cleaner, they were supposed to be sealed against the weather.
I have never heard of any capacitors or diodes in them.
Now that I think about it, you are probably right.
I had forgot that "bottle dynamo" is a misnomer. "Magneto" is actually the correct term for what is used on bicycles.
I was thinking it may have had a commutator &/or may have had a rectifier for some reason. DC generators & dynamos have brushes & contacts to be cleaned & serviced. Whereas magnetos don't.
As to being sealed up tight: On bicycles they probably never saw enough age or use to justify maintenance access. And in, magneto there just isn't anything to "go bad." So there's no reason to consider maintenance at all.
On a resistive bulb electricity "type" would hardly have mattered, anyway...OP: Flip the AC meter to DC & see what it reads. That'd tell us what kind of device you have.