Re: split toroid

From: 	Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Sent: 	Wednesday, June 25, 1997 12:52 AM
To: 	Tesla List
Subject: 	Re: split toroid

Tesla List wrote:
> From:   Dan Kline[SMTP:ntesla-at-vishnu.csd.sc.edu]
> Sent:   Thursday, June 19, 1997 9:14 PM
> To:     tesla-at-pupman-dot-com
> Subject:        split toroid
> Hi all,
> I have a toroid question:
> I'm making a toroid out of two toroid-halves, sorta, like if one was to cut
> a bagel in half, and I'm putting those two halves together to make a toroid.
> The question is, should I join the two halves around the outside
> perimieter, or should I leave the outside perimeter separated?
> If capacitance is a function of surface area, then not joining the outside
> perimeter would increase the capacitance, wouldn't it?
> In other words, I'd have a toroid with a split all the way around the
> outside edge, with an inside surface and an outside surface, rather than a
> joined perimeter, with only an outside surface.
> I hope that's not too unclear...
> Dan


It's not quite that simple. The effective capacitance is actually a
function of the "outer" surface and it's distance to everything around
it that's not tied to the same electrical potential. Splitting the
toroid into two halves, but connecting them together is sort of like
adding two half-toroid's worth of capacitance together to arrive at a
full-toroid's worth. The inner surfaces really don't contribute much
additional capacitance unless you were to seperate them by a
considerable distance. 

BTW, since the top of the secondary is electrically connected to the
toroid, some of the toroid's effective capacitance is correspondingly
reduced (or "shaded") from the value it would have if it were isolated

Hope this helps...

-- Bert H --