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Re: Toroid size on Big Coils

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>

Contact me off-list --- I can't send photos to the list.

Dr. Resonance

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>


Please share Big Bruiser's toroid design with the list of forward me a copy.
I saw it but didn't study it well.

Jim Mora

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Wednesday, February 08, 2006 5:17 PM
To: tesla@xxxxxxxxxx
Subject: Re: Toroid size on Big Coils

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>


If you use a 36 inch dia. toroid on a coil similar to my M-150
design, which has 18 inch dia. sec coil, there will not be any toroid
to coil strikes.

I didn't have in stock a large enough toroid for the M-200 design
that you saw get damaged.  We normally use a 60 inch x 20 inch toroid
size on this coil and during the Cheesehead event we only used a 48 x
12 inch toroid which didn't offer enough electrostatic shielding for
the sec coil.

Good rule of thumb is to use 3-4 x dia. of sec coil for major toroid
dia. and then you will not have any problems.  A 3:1 major to minor
toroid dia. also gives the correct ratio for this toroid design ---
either spun or mesh toroid --- makes no difference to the sparks.

Email off-list and I can share a unique design for a chicken wire
toroid like we had on the Big Bruiser that can be constructed for
under $125 in sizes up to 6 ft. in dia.  Big Bruiser uses a 10 ft dia
x 24 inch cross section for it's toroid.

Dr. Resonance

Subject: Toroid size on Big Coils

>Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>
> From what I see on the profesional coiling sites, in particular KVA
> effects, and Tesla Technology Research, the toroids seem small for
> the size of the larger coils. I know the cost of large spun toroids
> is prohibatively expensive. In the case of the M-13 magnifier, the
> majority of pics, show the discharges comming off the corona ring
> and not the toroid. With this coil, and Electrum, many of the arcs
> seem to be hitting the secondary. At the Cheesehead teslathon this
> past summer, the M-200 of D.C. Cox had several secondary strikes,
> one of which severely damaged the sec. He said 'that's what happens
> with too small of a toroid.  How does one avoid this kind of
> catastrophic damage? I'm planning to make a coil similar to DC's
> M-150. It uses an 18" form, and I have a 36" spun toroid. I don't
> want to destroy my secondary.