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Re: (ET) Any takers? Sounds like a scam but who knows?



At 02:02 PM 2/3/05 -0500, David Roden (Akron OH USA) wrote:
Wild guess: he's built a mechanical PWM device, using a modified commutator from a starter motor, driven by another motor. Envision a commutator where the segments are cut into triangles, so at one end of the com the segments are close together, and at the other they're far apart. With something like this, the commutator is just a big switch. You spin it and vary the duty cycle by moving the brushes fore and aft.

The idea is an old one; I believe it was tried on a few EVs early in the 20th century. It was also advocated for hobbyist EVs about 30 years ago in a couple of magazine articles. So (if I'm right) it's no wonder he can't patent it. Note that I'm just guessing
at this; it could be anything.

Rather clever, I suspect you would still need a flyback diode and brush wear might be an issue.

Reminds me a bit (in a round-about way) of a control mechanism apparently used in some French material handling vehicles. They would run a tap off of each cell and switch in a varying number of cells depending on throttle position. There was a mechanical mechanism to cycle which cells were tapped on each acceleration so that the battery would discharge evenly.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,
be they legal, genetic, or physical.  If you don't believe me, try to
chew a radio signal. "

                        Kelvin Throop, III