# [TCML] Considering a new coil build...

Weinhold Shannon L Shannon.L.Weinhold at doc.state.or.us
Thu Mar 26 16:19:45 MST 2009

```Well...I don't know what capacitance you need, but a 15" sphere is quite
different from a toroid electrostaticly speaking.
My calculator tells me that a 15" sphere has a capacitance of 21.167 pf
and a minimum breakout voltage of 1,143,000 volts.
A 15" toroid is 16.575 pf and the breakout is 330,000 volts, a fairly
significant difference.
Looking back I see that you already have the two big toroids on hand.
They are about 26.52 pf each, 528 kv breakout, so I guess the 15"
spheres are out unless you did something like you mentioned. Although
you could use the 15" sphere covered with about 30 half hemispheres of
the 6" size bowls surrounding it to emulate the multi-element topload
that Tesla described in his magnifier patent.
"...to so construct the elevated conductor, that its outer surface, on
which the electrical charge chiefly accumulates, has itself a large
radius of curvature, or is composed of separate elements which,
irrespective of their own radius of curvature, are arranged in close
proximity to each other and so, that the outside ideal surface
enveloping them is of a large radius."
I love quoting Tesla. What an eloquent writer.
Anyway, that would give you the equivalent of a 27" sphere, with a
capacitance of 38 pf and a breakout voltage of 2,057,000 volts, which
would be a little  less capacitance then the 40" X 12" toroid (44.485 pf
/ 834kv) that David recommended,  but would have significantly higher
breakout voltage.

Regarding the ringed top loads, it seems to me that the ring toroid or
sphere would be fairly simple to build with larger diameter copper
tubing.
You could draw out (on wood, metal, or whatever) the size discs that you
need for the cord diameter of your toroid, and then map out circles just
slightly larger than the copper pipe diameter around those discs that
would serve as um...countersinks,(for lack of a better word coming to
mind at the moment) so you could slightly inset the rings into the cord
formers, holding them in place . Drill the inset holes, cut out the
disc, repeat 6 to 8 times or so, wrap them with aluminum or copper tape
if nonconductive, cut your inner copper pipe to size, weld it into one
piece,  and affix it (with fast dry epoxy?) to the inside of the toroid
former discs spaced equidistant from one another, then wrap the copper
pipe around the largest diameter and mark the exact place to cut for a
perfect fit. Cut it, wrap the outer ring around that largest diameter,
affix it to the inner diameter ring, temporarily, using wire or what
have you, to hold it in place and to hold the ends together, then
solder/weld them together. Then move to the next set of opposing rings.
Wouldn't be too bad of a project. I think copper rings would make a
really sharp looking toroid.
You could use the same techniques to build a spherical model.

I notice that Greg Leyh's Electrum coil used a ring type spherical
It can be seen here:
http://www.pupman.com/current/gleyh/gl3/glmap.html
Its topload was big enough to sit in.

All I can say about that coil is "wow, I wish I could see it in person"

Shannon Weinhold

"The problems of today cannot be solved by thinking the way we thought
when we created them."
-Albert Einstein

-----Original Message-----
From: Travis Tabbal [mailto:travis at tabbal.net]
Sent: Thursday, March 26, 2009 9:06 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Considering a new coil build...

On Wed, Mar 25, 2009 at 2:36 PM, Weinhold Shannon L <
Shannon.L.Weinhold at doc.state.or.us> wrote:

Or if you're like me and don't particularly care for toroids anyway, you
> can go to IKEA and pick up 2 of their stainless salad bowls that are
> rimless and have someone weld them together. They form a perfect
> sphere, and they're cheap. They have several different sizes, 8, 11,
> and 15" I think. The thing to watch for here is that they aren't
> always exactly matching in size, so you may have to  try lining up
> several of them and make sure that their outer diameters match. People

> will look at you funny when you do it, but who cares.
>

Nutty idea, how about getting a bunch of 15" spheres made like this then
connecting them into a ring? I don't think a 15" sphere will do as a
topload for this size, but a bunch of them together... maybe? The drain
pipe Dr.
Resonance mentioned sounds interesting as well. I'm going to have to
check out some farm supply places around here.

I also like the stacked ring idea, but I have no idea where to source
the rings. I doubt I can bend up my own.

```