Re: Sphere top load

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

Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>

Ed,
   it has been a hypothesis of mine that if the windings go all the way up
to the shere you might not get sparks comming out of the top windings, but
I've not checked it out yet.

My 3.5"x12" coil gives out neat looking sparks with a 4" sphere (very
different from a toroid), but a 6" sphere causes all the problems you observe,
and I've wanted to try again without the vertical separation between the top
of the coil and the sphere but have not had time to wind a special coil for
this.

My favorite combination is to put a 2" ball about 4" above my 2"x8" toroid,
this causes sphere-type sparks which look better (imho) than just the toroid.
I've put a 4" ball up there, and a 6" ball, but that doesn't improve anything.
I'ld pick a ball whose diameter matches the minor diameter of the toroid, and
position it about so its top is at the toroid's major radius up from the 
center.

works for me, YMMV,
Peter Lawrence.


>
>Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
<Esondrmn-at-aol-dot-com>
>
>I finally got my 3" coil set up last night with the new 12" diameter stainless
>steel sphere that I picked up last week, scratched, for $15.  I normally run
>this coil with a 1.75" x 10" toroid on top of the coil, with a 5" high
aluminum
>cylinder on top of that and a 4" x 13.5" toroid on top of that.  It works
well,
>with most of the sparks coming off the upper toroid and away from the
primary. 
>This is necessary since the winding length is only 13" and the coil produces
>sparks in the 24" to 26" range. 
>
>My first setup was to remove the 13.5" toroid on top and replace it with the
>12" ball.  This and every other combination I tried forced all the discharges
>to leave from the lower toroid and go down to the primary & strike rail.  I
>could not even run it at full power.  I could get break out on the sphere with
>a small nail taped on top, but it did not help much.  I also tried it with
just
>the sphere, no toroid, and the results were worse.  All the sparks now wanted
>to leave from the top windings of the coil and some from the taped on nail. 
>
>What are other coilers experience using a sphere for a top load?  Is this ball
>just too large for this small coil?  It probably is not large enough for my
>bigger coil.  This is a 6" coil running at about 7 kva with two toroids, 33"
>and 40".  Terry, have you tried your very large 20" ball on any of your
coils? 
>
>Ed Sonderman
>
>