Re: [TCML] Sphere Topload Coil

["Peter Terren" <pterren@xxxxxxxxxxxx>]

A big sphere is a poor termination for a TC.  I never use it. The simple 
reason is that the high breakout voltage mean that sparks will come from the 
sharpest curvature ie at the junction of the coil and sphere or from the 
coil itself down to the primary.
You will not see a sphere performing with sparks 2 or more times the length 
of the secondary because of this UNLESS it has a breakout point but then you 
are defeating the purpose of a sphere.
If you want to have the lowest chance or primary strikes then a large toroid 
on a smaller one is the most practical and allowed me to get 3 times 
secondary length with a SGTC.

Peter
www.tesladownunder.com

----- Original Message ----- 
From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>


> Hi Everyone,
>
> Sometime back (quite a while I guess), I remember photo's of a pretty good 
> sized coil with a large sphere top terminal (I'm thinking about 20" 
> diameter). For some reason, Gary Lau comes to mind but I'm not sure. I'm 
> curious of big sphere's and the system that drove them. I'm looking at 
> breakout voltage as based on surface field strength and it would be nice 
> to know a little something on the basic specs of those coils.
>
> So if anyone meeting those specs isn't too busy with life, please post 
> some specs. I don't need the whole gap scene or anything of that nature. 
> Just the basic secondary, top load, cap, and power supply data. Also, was 
> a breakout point required or not would be nice to know.
>
> Reason: I'm advising someone regarding a rather large coil with a very 
> large sphere. From my calculations, the sphere I think is too big for 
> breakout on it's own. Calc's are one thing and those of you well 
> experienced with sphere's may help fill the gap of uncertainty.
>
> Thanks,
> Bart
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