Re: Sizing the toroid to the coil, was Effects of the size oftoroids

• To: tesla-at-pupman-dot-com
• Subject: Re: Sizing the toroid to the coil, was Effects of the size oftoroids
• From: FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Sat, 04 Mar 2000 11:59:24 -0700
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

In a message dated 00-03-04 08:18:21 EST, you write:

<< Some
> people actually use the secondary as a "size" guide for the toroid. I
> personally use a factor of 2.8 x Cself to find a toroid capacitance. I then
> try to find that capacitance based on 2.5 x the o.d. of the secondary. This
> get's me into the ball park, but may not be perfect for everyone's coil.
 
> Bart >>

Bart,

I size the toroid based mostly on the TC "bang size" (joules of energy 
per gap firing).  I may then modify this to make the proportions more 
reasonable if needed.  The toroid can also sized to the spark length;

    Spark length = 10X  to  12X  toroid minor diameter (thickness)

For instance if the spark will be 40" to 50" long, then the toroid should
be 4" thick.  However higher breakrates can tolerate a smaller toroid, 
because the sparks coalesce easier at higher break-rates.  Also, most
folks use a smaller bang size at higher break-rates, so a smaller toroid
is required unless they use a breakout point.

Of couse in general, a smaller toroid will tend to give more individual
streamers for a given coil.

I don't think the toroid size should relate to Cself, but rather more to
the power input or to the bang size especially.  This way coils that
are abnormally small or large for their power inputs will still work well.

In many cases you can get away with using a Cself relationship
however.

Cheers,
John Freau

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