Re: Topload and Arcing

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Danny, John,

Nope, JavaTC won't calc stacked toroids. However, you could easily
double-up on the
capacitance and use the toroid reduction input, placing it to 50%. The only
program
I trust is E-Tesla6 for stacked toriods. It's been mentioned here and there
on the
list that top C in a stacked toroid would be about 50%. A few months back I
made
measurements with stacked toroids (not identical toroids which I thought would
throw a wrench into the gears), but it didn't. I measured 50% in a stacked
configuration and various spacings (directly stacked all the way up to 16 or so
inches between the two, and E-Tesla6 confirmed my measurements everytime).
Now if I
would have raised both toroids up from the secondary, I would expect that
value to
change, but I didn't think of that at the time.

Take care,
Bart

Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<FutureT-at-aol-dot-com>
>
> In a message dated 8/13/01 10:35:38 PM Eastern Daylight Time,
> tesla-at-pupman-dot-com writes:
>
> > I've seen on the web have two toroids,
> >  and I recall reading somewhere on the list that this configuration can
> >  prevent (or alleviate) arcing to the primary. Is this correct? If so, how
> >  does this work? Is this primarily why the stacked toroids are used?
> >  Finally, how do I calculate the total capacitance of the stacked toroids?
> >  Do I treat them as two separate toroids, calculating their free-space
> >  capacitance (from the equation) and summing them as two parallel
> capacitors?
> >
> >  Thanks,
> >  Danny
>
> Danny,
>
> If you coil is 30" tall, and the sparks are 40" long, they won't
> have much of a tendency to arc down and strike the primary,
> no matter what toroid you use.  The double toroid idea is
> needed when the secondary is rather short.  For example on
> my TT-42 TC, the secondary is only 19" long, and the sparks
> are 42" long.  Without the small toroid under the main toroid,
> (which raises the main toroid), the arcs do hit the primary at
> times.  The small toroid raises the main toroid a little, so
> the arcs don't hit the primary.  I could have simply made
> the secondary 2" taller, and the sparks would not strike the
> primary.  Since your planned secondary is much taller than
> 19", you shouldn't have any problem.  If only a small toroid
> is added such as I did, it hardly changes the toroid capacitance
> much.  But larger toroids will have more effect.  The capacitance
> will not double with 2 identical stacked toroids, but will be maybe
> 50% larger than 1 toroid.  I think Bart or someone on the list
> has some formulas or programs that will calc this.  Maybe
> Bart's JavaTC program does that calc.  Stacked toroids can
> be used for two purposes; to raise the main toroid, or to
> increase the total toroid capacitance.
>
>   My TT-42 coil can be seen at:
>     http://hometown.aol-dot-com/futuret/page3.html
>
> John Freau