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RE:Spheres vs Toroids (was - Source for Aluminum Spheres (up to 12" threaded)



Original poster: "John H. Couture" <couturejh-at-mgte-dot-com> 


It is generally accepted that a toroid is better than a sphere for a TC
topload. But how do you determine the optimum toroid size because for a
certain size sphere diameter there are many different sizes of toroids that
have the same capacitance?

For example if yon need a topload of 60 pf a sphere of about 43 inches
diameter will do the job. The possible toroids with the same 60 pf
capacitance are as follows.

    3" x 70" toroid
    4" x 66"    "
    6" x 62"    "
    8" x 60"    "
    12" x 56"   "
    15" x 55"   "
    20" x 52"   "

There are many other possibilities. The minor diameter will give a certain
breakout voltage and the major diameter will determine the  amount of
protection for the secondary coil. But how would you go about selecting the
minor and major diameters?

I show a graph in the Tesla Coil Notebook with curves for spheres and
toroids. The graph makes it easy to find the toroids that have the same
capacity of a certain size sphere. However, I have never seen any
information or graphs that show recommended spheres or toroids for use with
a certain size TC to obtain the maximum spark length and also give the
proper protection for the secondary coil. It is obvious that if the topload
is too large the available TC power will not be capable of charging it
properly.

John Couture

-----------------------------


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, October 25, 2003 3:01 PM
To: tesla-at-pupman-dot-com
Subject: Re: Source for Aluminum Spheres (up to 12" threaded)


Original poster: Ed Phillips <evp-at-pacbell-dot-net>

Tesla list wrote:
   >
   > Original poster: "Mccauley, Daniel H" <daniel.h.mccauley-at-lmco-dot-com>
   >
   >  >      Has anyone here ever compared large spheres with toroids for top
   >  > loading of high-power TC's?
   >  >
   >  > Ed
   >
   > Toroids do much better than spheres.  I believe the first person to
   > start using toroids was back in the 1970's from
   > what i've read from Richard Hull's historical notes.
   >
   > Dan

	In what way better?  Clearly they work just fine but wonder what their
edge is over a sphere with the same breakdown voltage.

Ed