Re: need suggestions for general sizing in a multi coil setup

["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 Jim,

Haven't run a coil this size but I do have opinions (as always). Because
the size of the
secondary is "small" in comparison to typical toroid minor diameters used,
"I" think a toroid
with a relatively large minor diameter can be used because the proximity
capacitance effect will
be less. Because of this, I think your free to go with a 3:1 or 4:1 aspect
ratio (major
diameters).

As I've mentioned on the list, I personally like to keep the minor diameter
about the same as
the secondary diameter. Assuming this, somewhere between 6" x 18" and 6" x
24" toroid sizes.
You'll get more topC from the 6" x 24" and there will be less proximity
effects between toroid
and secondary. If you go with a larger minor diameter (say 9"), I'd keep
the toroid about even
with the top winding to help shield the upper winding from premature breakout.

I like your choice of a 5:1 h/d on the secondary. I'm winding a smaller
size of 8 x 40 myself as
compared to my 12.75" coil. I'd recommend 22awg or even a little smaller to
put a high
inductance on the secondary.

I'm not sure on the power to apply. Assuming a little over a thousand turns
on the secondary
with 22awg (and 6 x 24 toroid), you'll be around 140kHz loaded (about a 12
turn primary with a
20nF cap). Your coil sounds similar to Ed Sondermans'. I know he put 8kva
to it and produced
104" sparks. This was a dual-stack toroid separated by a good distance with
a sheet metal
cylinder between the two. The minor diameters were about 5 or 6 inches.

Take care,
Bart Anderson

Tesla list wrote:

> Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
>
> I'm looking for general opinions (no lack of those on this list) on
> appropriate toroid/top load  sizes for a secondary 6" in diameter and about
> 30" long.
>
> Also, max power and breakrates that folks have run on a coil this size.