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Re: Pseudo Toroid Design
From: Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent: Monday, November 10, 1997 3:46 PM
To: Tesla List
Cc: ccurran-at-execpc-dot-com].pupman-dot-com
Subject: Re: Pseudo Toroid Design
> From: Chuck Curran[SMTP:ccurran-at-execpc-dot-com]
> Sent: Sunday, November 09, 1997 8:34 PM
> To: Tesla List
> Subject: Re: Pseudo Toroid Design
>
> >
> >From: Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
> >Sent: Sunday, November 09, 1997 2:16 PM
> >To: Tesla List
> >Subject: Pseudo Toroid Design
> >
> >
>
> Hello Fr. Tom
>
> I found your comments to be most helpful. The first item that helped a lot
> was the point relative to the center section of the toroid. I had become
> fairly sure, remembering past points made over the last couple of years that
> the center didn't appreciably impact the toroid's effectiveness. I am never
> willing to go charging off without, ah, double checking however!
Please note that my comment about the inside not being important was meant
to convey the fact that the inside contributes nothing to the e-field
shaping, and I doubt that it contributes much to the capacitance either.
Bert Poole rightly pointed out that the toroid DOES need to be shorted
internally, and the usual inner disk performs this function better than the
spoke method I outlined, since a flat plate connects at many many points,
whereas a spoke is limited to the number of spokes.
> Your description of a toroid design was very interesting. I do have one
> question about the 2 inch diameter thin walled aluminum pipe. I had been
> using as large a radius as possible on my bigger coil to prevent early
> breakout. Specifically I presently have a 56" diameter toroid with a 10 1/2
> inch diameter "Donut" as the outside ring. I chose that diameter to keep
> the spark in until the toroid was holding as big a charge as possible. How
> would the 10 foot diameter sheet metal ring capped top and bottom by the 2
> inch pipe rings do on breakout?? Have you made one of these already?
My choice of 2" diameter in the example was not well chosen. It would most
likely be way too small a radius of curvature (especially for the size topload
I was describing). You have to keep the radius of curvature large enough
so that premature breakout does not occur. When breakout DOES occur it will
be along the ring, as the pipe has the smallest radius of curvature.
I have made units as described, but with dryer ducting instead of metal pipes.
I used six inch dryer duct for the top and bottom rings and 24" wide
aluminum flashing rolled into a 5 foot diameter circle. I used thin wood
strips internally to give structural stability, building up six triangular
sections that gave me the strength I needed with as little weight as
possible. This topload gave me hotter arcs than just the two sections
of dryer duct sitting on top of one another. The aluminum sheet adds to
the capacitance without adding too much to the cost. Please note that the
breakout voltage is a function of the dryer duct size.
> I was going to draw up a print to show a toroid that you might see clearer
> if I describe it like one of those cookie tins we all seem to see around
> Christmas. It would be thick like the cookie tin across the entire
> diameter. I was going to draw a flat disk with the edges radiused up at a
> 6" radius covering 90 degrees. One of these could be place on top of the
> other and then TIG welded together.
Or, you could connect the top and bottom using a rolled sheet of
aluminum such that the ends formed "caps". Again, that gets you increased
surface area at rock-bottom prices... And you can vary the width of the
sheet aluminum to increase or decrease capacitance as needed. Your
limiting factor for breakout is the 6" radius of curvature.
> A central supporting tube would have to
> be installed internally in the exact center for proper support if a light
> gauge aluminum sheet were used, like 16 or 18 gauge. This shape would
> eliminate the double curve required on a standard shape toroid and reduce
> fabrication costs---Design for Manufacturability and save the wallet!
Back up the aluminum with thin supporting shapes cut from something like
fiberboard. The TOP section could have a piece of plywood glued inside
that would actually take all the support force. Thus the outer metal
sheeting would be sort of draped over the inner skeleton. People would
only see the outside, of course.
> Since
> my current toroid is 56 inches in diameter, I would hope for something in
> this range. If they would tell me they could do it with a 5 1/2 inch radius
> for less money instead of 6", I'd be very pleased, since the exact dimension
> is not critical to me, as long as it was a constant around the entire spun
> half.
> Your idea would really be a lot less expensive, I am very curious about the
> 2" edge radius and how it would compare to the standard toroids most of us
> have been creating. Thanks for your feedback on my post.
>
> Chuck Curran
>
Fr. Tom McGahee