# RE: Optimum toroid size

```Hi Ted:

It's always good to get more data-points on such a poorly understood
problem, so your input is worth a good deal more than \$0.02.

I would guess your topload is pretty nearly optimum-sized.  I'd bet if you
go to a 4" diameter toroid, you'll get many, smaller, simultaneous streamers
instead.  Something just slightly smaller than what you have may be right.

I've been thinking about the numerous responses on this topic and the
significance of using breakout points or bumps.  It's been suggested that
the use of a bump may result in a lesser-than-optimum breakout voltage.  I'm
thinking of when my tuning wasn't quite right and without a breakout point,
it would almost breakout by itself.  By "almost", I mean it would breakout
for a short while, then not, then breakout again.  It was as if the presence
of a streamer was the same as having a bump; it just needed an occasional
extra-powerful bang-nudge to get it to start to break out, after which the
streamer would act as the bump, until the streamer decides to go away.  So
it would appear that the effect of a bump is nearly duplicated by a streamer
- you just have to get it started.

FWIW, I use a 15/60 NST, with a 4.5"x15.5" and a 6"x23" toroid, and get
multiple streamers whether or not using a breakout point.  See
http://people.ne.mediaone-dot-net/lau/tesla/super_banjo.jpg

Regards, Gary Lau
Waltham, MA USA

Original poster: "Ted Rosenberg" <Ted.Rosenberg-at-radioshack-dot-com>

Gary and friends:
I hate to add my 2 cents to this mix but I think the toroid on my coil is
too large because:
1. without breakout points I get virtually zero breakout. One or two measley
streamers.
2. with breakout points, it is incredible---2-3 footers with a 15/60 NST.

When the Halloween gig is over, I will experiment with a smaller toroid. Now
I use a 6" duct and 22" diameter. Thinking of seeing what happens using 4"
diameter.

I get a feeling that toroid efficiency is to a degree hit and miss. I
originally went by Wintesla but I'm having second thoughts.

```