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RE: Tesla calculator frustration.

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

Bill -

This could be a good time to point out to the List that the actual
capacitance of the toroid on an operating TC can not be determined at the
design stage. This is because of the many unknown variables involved while
the TC is in operation.

The JHCTES programs assume the secondary terminal (toroid) reduces about 20%
but this is only a guesstimate. The E-Tesla6 program appears to do much
better. However, there have not been enough tests made to check out the
accuracy of this program.

There is only one way to find this secondary terminal capacitance during
operation and that is to determine the resonant frequency while the TC is
operating. This is not an easy test and has been done by only a few coilers.
Unfortunately the coilers who have made these test have not followed thru
completely and published the proper calculations that would confirm the true
secondary terminal capacitance.

Finding the true secondary terminal capacitance is done by taking the actual
test resonant frequency and reverse engineering the calculations to find the
secondary terminal capacitance. This can be easily done with the JHCTES
programs. When all of the correct inputs of the coil are entered into the
program there will be shown an operating frequency that is the assumed
design resonant frequency.

This frequency will probably not be the same as the actual test frequency.
Therefore, the secondary terminal capacitance will have to be adjusted in
the program until the actual test frequency (reverse engineering) appears in
the outputs. This new secondary terminal capactance will then tell the
designer how much the "toroid" capacitance has reduced when placed on the
operating TC.

Several years ago I did this test with a couple of my coils and found the
reduction to be about 20%. However, my test setup was very crude so I have
been waiting for coilers to perform more accurate tests to confirm what I
found. This may now be the time to pin down this elusive parameter mystery.

John Couture


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, May 30, 2001 3:29 PM
To: tesla-at-pupman-dot-com
Subject: Tesla calculator frustration.

Original poster: "Bill Vanyo by way of Terry Fritz <twftesla-at-qwest-dot-net>"

This really should be quite simple, but no...

I just want to calculate where I *should* tap my primary, given the
Cap: 0.06uF
Primary: Inner diameter = 9.75", 1/2" spacing (center to center), 1/4"
Secondary: 1000 turns, 27.625" winding length, 6.625" diameter.
Topload: 8" chord, 23.5" center to center (capacitance = 34.845?)

Previously (with a smaller topload), I managed (or so I thought) to do
the calculation using JHCTES version 3.2, at

but now I can't see how I ever did it.  The weird thing here is that
what I would logically like to specify as input parameters, like primary
interturn spacing, are output parameters.  I have to try to adjust the
input parameters to get output parameters that match my existing

I've also tried E-Tesla 5 and 6 - got significantly different results,
and don't quite see how to calculate my tap point anyway.

Are the specs I've listed sufficient for calculating the tap point?

Another question, about toroid topload shape:  I made mine from 8" dryer
duct and two 16" pizza pans, but the pizza pans are about 4" apart.
Should that be a problem?  Any idea how much that affects the toploads

	Thanks again,
	Bill V.