# Re: Toroid Design

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Ed, Richard -

There are some equations that can be used to design the sphere or toroid
on the Tesla coil as follows:

Sphere dia = Ct/1.4   Ct = Sphere capacitance

Ct = Cp x (KVp/KVs)^2

Sphere dia = KVs/35  (70 KV air breakout potential)

Q = KVs/KVp

J = .5 Ct x V^2   J = energy in terminal

Ct = 12.34 x cuberoot(KVp^2 * Cp)  Ballpark figure

From these equations it is obvious that the sphere or toroid size is
dependent on several other Tesla coil parameters.

John couture

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At 09:05 PM 12/22/98 -0700, you wrote:
>Original Poster: Richard Hull <rhull-at-richmond.infi-dot-net>
>
>
>Tesla List wrote:
>
>> snip
>>
>> I am thinking about going to a 8" or maybe 10" x 50" toroid to replace the
>> existing 5" x 40".  I would like comments on this.  I don't want to get
>it so
>> large that I can't break it out.
>>
>> The two existing toroids are made from 5" diameter corrugated black plastic
>> drain pipe bent into a circle around a .25" thick acrylic disk.  It is then
>> covered with clear packaging tape then aluminum foil tape.  Does this same
>> pipe come in larger diameters like 8" or 10"?  I don't think the local
>> building supply places carry anything larger than 5".  I don't want this
>thing
>> to be too heavy.  The coil can't support too much weight.  When I built
>it, I
>> thought a 4" x 14" toroid was large.  Pretty funny now.
>>
>> Ed Sonderman
>
>Ed,
>
>As we actually use coils we live and we learn.  It sounds like you have
>learned.
>Their are no equations for your situation.  I would build the size you note
>above
>and see if it functions.  Actually I like to have a system that breaks out at
>about 75% then I can be assured of full control of spark.  You may already be
>there.
>
>Remember, you ideally would like to have a tad more reserve energy after
>minimum
>break out potential to feed the formed arc.  This often requires a bit more
>sauce
>up to the point of a second simultaneous arc forming.  This is how I have
>done the
>business since 1990.  It is key to achieving maximum spark to a grounded
>target.
>
>Richard Hull, TCBOR
>
>
>

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