automotive alternators, three phase, RSG

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

It occurs to me that an interesting experiment (I'm a great one for ideas
for experiments, but I rarely actually get a change to try them) would be
to rig up a big motor (gas, electric, hamster wheel, it matters not)
driving a 3 phase alternator (as from a car, with the diodes removed) and a
rotary spark gap on the same shaft.  By definition, the phasing of the
spark gap will be locked to the electrical phase.  You can change the break
rate by changing the speed of the prime mover (crack the whip on the
squirrels) and you can change the output power by changing the field
current on the alternator.

You could probably drive 3 NSTs with the alternator (or maybe GMHEI Coils),
then feed each one through a set of gaps, all feeding a common primary
capacitor/inductor, at high break rates.  Maybe even 3 static gaps might
work, if properly set. Or, for a real weird setup, how about 3 primaries on
the same secondary?

The NST won't put out much current (the frequency will be higher than 60 Hz
from the car alternator so the leakage inductance impedance will be higher
in proportion... I think they run several hundred Hz.. Anybody know how
many poles the typical alternator has?

This has the nifty advantage of having no electrical connection to the
power lines, so back conducted EMI isn't an issue (for that matter, you
could run an insulating shaft through the wall of a faraday cage and have
your three phase TC totally isolated).

Before you all leap on me, I know that Tesla built systems just like this,
and they were also used in commercial radio in the days of spark.  

The interesting thing here is that it uses cheap parts: Alternators cost $5
at the "pick your part" junk yard, and dead alternators are even cheaper. A
dead alternator is usually dead because one of the diodes (or the internal
regulator) has failed, and you would remove those anyway.