awesome ballast?

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

Original poster: "Oxandale, Terry by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Toxandale-at-SPP-dot-org>

Just wanted to share something with you guys that I saw at the local
welding equipment salvage yard. It was a toroid inductor. Physically,
the iron core was about 6" in diameter and about 4" tall. The windings
are what was really special though. Looking at the top of the core at
the 12:00 position was the starting point for the windings which were
very thin and flat .030" X 1/2" (narrow edge facing the core) copper
conductor. Going clockwise aroung the core, the coil conductor got
progressively thicker and thicker until at the 10:00 position (last turn
of the windings) the conductor was about .250" thick and about 3/4" wide
(again, the narrow end of the conductor facing the core). Then, much to
my surprise, the inside of these windings had a set of brushes that spun
around inside the toroid I.D.(like a variac only on the inside of the
toroid). If it wasn't for the fact that 3 of the turns were broken out,
I would have loved to experiment with this as a variable ballast. 
I then saw a lot of "normal" looking cores that had one side of the
windings bare of any insulation, but had a set of bushes that slid up
and down on a threaded shaft, giving a variable current to this device
too. I can see the wheels spinning now!

(un)Terry