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Re: doubled up toroids
Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Kevin,
Tesla list wrote:
Original poster: "MakingLightning" <MakingLightning@xxxxxxxxxxx>
I see a lot of people using a toroid on top of a toroid to help prevent
spark jumps to the secondary.
I have 2 questions about this.
1). Does this really work?
Yes! Typically, we shield the top few turns with a toroidal shape to
prevent premature breakout (out of the top of the coil windings). It
doesn't take a large toroid to do this and smaller toroidal shapes
are fine to shield and act as a corona ring. But, they can be
increased in size providing a bit more capacitance on the topload.
2). If let's say you have calculated out that you need a 8x24 toroid, what
size toroid would you use if you were to use the 2 torrid setup and how
would you determine or calculate that?
Use a program. Javatc can handle up to 10 toroids (I limited the
inputs to 10 for each topload object - the more toploads, the longer
it takes to run the program).
http://www.classictesla.com/java/javatc.html
Javatc will accurately solve the topload capacitance as well as the
system capacitance. Two toroids will never double the capacitance
coupled to the secondary system and as Dr. R mentioned, maybe 1.5
times, but even that changes with toroid sizes and proximity to
one-another. If you want to "predict" Fres, a program is very helpful
these days. It wasn't that long ago that the best we could do were to
use fudge factors applied to free-space capacitance numbers for each
toroid and of course we would base our fudge factors on our own
experience or that of more experienced coilers. Nowadays, we can
actually simply enter our dimensions and out pops the data, which is
the whole idea.
All programs accuracy is greatly dependent on input data accuracy.
Also, with more inputs we gain accuracy (more effects accounted for).
But, with that, also comes more complexity not only in the equations,
but also in the users dimensional or electrical measurements
required. It really helps to be as accurate as possible with your
dimensional measurements. If you ballpark your inputs, you will get
ballpark outputs. If you ever have questions about Javatc, just email me.
Take care,
Bart