-=> Mike Ross said to Wayne Chirnside
 -=> about "VEHICLE LED'S" on 09-02-03  21:36.....

 MR> How was the power taken out, insulated slip ring? I'm guessing it

Rotating magnets and stationary windings, same as the friction
driven one. The windings were directly connected to terminals on
the side of the case.

 MR> Consider that 1mph is about 1.5ft/sec and a wheel periphery measures
 MR> about 7 ft, then 1 revolution/sec = 4.75mph, so 20mph is only about
 MR> 4.2 rps or 252 rpm. A 60 hz generator needs turn at 3600rpm! Luckily

What has 60Hz got to do with it? The bulbs aren't that sensitive
to frequency. They will work from DC up to megaHertz.

 MR> with the rim generator, the gear ratio is about 35:1 so in priciple at
 MR> 20mph it is generating at about 150Hz.

The friction driven one usually has only a single pair of poles
on the rotor and stator. The hub dynamo can be made with 50 poles
on the rotor and stator without a lot more cost or complexity.

And it can be built to a larger size, which should mean that it
can be made much more efficient.

From Greg Mayman, in beautiful Adelaide, South Australia
   "Queen City of The South"    34:55 S  138:36 E

... All things being equal, the fatter you are the more soap you use
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