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RE: Sphere/Toroid Comparison Chart

Original poster: "John H. Couture by way of Terry Fritz <twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>

Terry -

I entered your coil's data into the JHCTES Ver 3.2 program to see what it
comes up with for a toroid. To get the 87.66 Khz the program came up with 29
pf for the capacitance. This is about 12% less than the graph shows (space
33 pf) for an 8 x 30 toroid. On my web site I mention that the graph
capacitance would be reduced about 20% when placed on the TC secondary. It
appears this may be too high a percentage. We will have to wait until more
data is obtained.

Did your coil test about 87 Khz when it was operating? Did you test the
secondary with toroid by connecting a funtion generator to the bottom of the
secondary? I don't remember seeing this information on your web sites.

I was able to run the E-Tesla5 version OK but I get a "bad command" message
when I try the Ver 6. Have other coilers had this trouble? I agree that your
E-Tesla5 is an excellent program and is a great supplementary program for
programs like the JHCTES for finding the actual secondary terminal

The secondary terminal capacitance is an input for the JHCTES program but
only a graph with a rough capacitance approximation is given. A much better
capacitance approximation is now available when coilers use the E-Tesla

John Couture


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, May 07, 2001 9:56 PM
To: tesla-at-pupman-dot-com
Subject: RE: Sphere/Toroid Comparison Chart

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi John,

"E-Tesla6" a program I wrote that was vastly improved by others, can find
the resonant frequency of a one or two torroid (or sphere) Tesla coil
secondary system within a percent or two.  It does all the nasty
electrostatic field calculations and even has elements of Paul's TSSP
project added.  It is freely available at:


A web page with info is at:


It is very useful for determining the resonant frequency of a secondary
coil and top terminal before they are built.  Everyone seems to like it a
lot and it seems to work very well.  I ton of effort went into the darn
thing ;-))



At 09:48 PM 5/7/2001 -0700, you wrote:
>Bart -
>My graph was strictly a one toroid only graph. Note that all these space
>capacitances are reduced when the toroid is placed on the secondary coil.
>Just how much reduction can only be found by actual tests while the TC is
>operating. Or you can use the JHCTES Ver 3.1/3.2 programs to find the
>capacitance if you know the operating frequency.
>John Couture
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Monday, May 07, 2001 7:10 PM
>To: tesla-at-pupman-dot-com
>Subject: Re: Sphere/Toroid Comparison Chart
>Original poster: "Barton B. Anderson by way of Terry Fritz
><twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>
>Yes John, but does you graph indicate the same compacitance as was posted
>for overlapped toroids? I'm guessing
>it doesn't because Bert Pool's equation calc'd exactly as was posted on
>these toroids.
>Tesla list wrote:
>> Original poster: "John H. Couture by way of Terry Fritz
><twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>> The overlap is not a problem with the Toroid Capacitance Graph I show in
>> Tesla Coil Notebook because I did not use Bert Pool's equation. The
>> equations I used are shown on my web site. Look for  Secondary Terminal
>> http://home.att-dot-net/~couturejh/
>> John Couture