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Re: Calculating Sec. Voltage
At 07:25 AM 2/7/97 +0000, you wrote:
>Subscriber: lod-at-pacbell-dot-net Fri Feb 7 00:13:09 1997
>Date: Wed, 05 Feb 1997 15:18:40 -0800
>From: lod-at-pacbell-dot-net
>To: tesla-at-pupman-dot-com
>Subject: Re: Calculating Sec. Voltage
>
>Rodney Graham Davies wrote:
>
>> big snip ---------------------------------------------
>>
>
>Calculating the secondary voltage of a Tesla coil is a speculative venture
as I mention in one of my books. Greg Leyh and Richard Hull apparently agree
to this according to their postings. So why bother wasting time on this
parameter?
Several years ago when I was developing the JHCTES computer program I asked
the same question. Should this parameter be in a Tesla coil program? My
answer was no because it appeared to have no use for other parts of the
program. However, after reconsidering the matter I realized that if the
secondary voltage is divided by the number of turns on the coil I would know
the voltage stress on the coil wiring insulation. This information would be
very useful in determining the thickness of the insulation required for the
secondary wire.
Many secondary coils have been ruined because of inadequate insulation on
the wiring. Also, if this thickness is not enough the RF losses will be too
great to get the maximum output from the T.C. It became obvious that if the
secondary voltage could only be approximately determined it would be a very
important parameter to calculate. It would be preferable to err on the high
side because this would result in a coil that would be better protected and
would provide more output because of reduced RF losses.
So finding a method that would give an approximate secondary voltage became
a worthy effort. To start I did what every engineer has to do in confronting
this type of problem and that is to use the method of empirical design. This
is design based on both theory and experience. In this case the theory
involved over two dozen standard theoretical electronic equations. The
experience that I used came from data I had accumulated from coils built and
tested by myself and many other coilers.
The trick was to convert all of this data into a form that a computer could
use. This normally is done by mathematical regression methods and this is
what I used. After much research and work was done I ended up with what gave
me a secondary voltage based on other parameters of the T.C. system. This
voltage was then used to give an insulation thickness that was equivalent to
what coilers had been using on successful coils. An approximate secondary
voltage was useful after all.
Connecting anything to the secondary terminal to determine the secondary
voltage will load the circuit and lower the voltage by an unknown amount so
this method can not be used. An indirect test method can be used as I show
in one of my books, however, with the JHCTES program this is not necessary.
With the rough approximation of the secondary voltage the secondary wire
thickness can be obtained so the T.C. will work at its maximum efficiency.
The secondary voltage is only one of the 46 parameters that the JHCTES
program uses. This program has been used to design many sucessful coils so
why not use it and save yourself the labor of doing all those pesky
calculations? This program is for classical coils only. At this time there
are no comparable programs for magnifiers, tube coils, etc. Designing and
building these coils have to be done by the old trial and error methods.
This is one reason why experienced coilers like Richard Hull and a few other
dedicated coilers are valuable to the advancement of Tesla coil
understanding. Using their test information, someone someday will develop
computer programs for these more complex coils.
One of the problems regarding the JHCTES computer program is that there is
not enough enough documentation to cover all of the many details of Tesla
coil design. My books cover many of the parameter details but there always
are more. The above is only for one parameter ! I have 45 more parameters to
go ! Thank you Chip.
Questions etc. are welcomed.
John C.
>