Toroidal inductors

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

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

Vivek posted a link to AlphaCore, and browsing around in there, I found a
fascinating table of inductors wound with flat conductors laminated to
polypropylene...

http://www.alphacore-dot-com/inductor.htm

Interesting stuff... inductances from 0.05 to 8.5 mH, prices from $12 to
$100 (assuming you stick with copper and don't go for the silver wound ones!)

Given the construction.. I'll bet these things would have a pretty good
voltage rating.. very symmetrical construction, vacuum encapsulated in
plastic, etc. The dielectric is 0.0015 inch polypropylene (between windings).

What about using these as the secondary of a TC?   You could either use
them as lumped L's (stringing together a bunch in series to get the voltage
rating and L you need), or stack them, for increased coupling.  There is a
hole in the middle, judging from the picture, so you could conceivably hook
a magnetic core through one or more to drive the bottom of your stack..
Tightly coupling the bottom to drive the LC, but lots of lumped LC outside,
stretched out to reduce racing sparks...

The overall diameter ranges from about 1.5 to 5 inches...

Figuring about an inch for the center hole, on the big ones, this implies
about 2 inches for the separation between input and output lead.. good for
150-200 kV if immersed in oil.  

The conductors are 16,14, or 12 AWG... No power ratings are given, but, you
could figure out how much power you're going to dissipate using the DC
resistance (anywhere from 0.01 to 1.1 ohms, it looks like).  Interestingly,
silver costs a bunch more, and actually has higher resistance than the
12AWG copper... for not much difference in physical size... Must be so that
you can claim you have "silver tape wound inductors" in your hi priced
loudspeaker crossover....