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RE: Conical primary formula questions.



Original poster: "Pete Komen by way of Terry Fritz <twftesla-at-uswest-dot-net>" <pkomen-at-zianet-dot-com>

John,

It seems to me that we should strive to make sure that the information that
we (Tesla coilers) put out should be accurate.  If the conical coil formula
is wrong, it could contribute to someone's failure to build a good working
coil on the first try.  If the flat spiral formula is good enough for use up
to 30 degrees, then that should be published as the "good enough" formula.
It may be nit picking, but I thought it was worth posing the question.

Regards,

Pete Komen

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, January 10, 2001 5:36 PM
To: tesla-at-pupman-dot-com
Subject: RE: Conical primary formula questions.

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


Bart, All -

In my tests for the JHCTES computer program I found that between 0 and 30
degrees the primary inductance varied less than 1%. I decided it was not
worth changing the calcs for primaries from 0 to 30 degrees. There are much
more important problems to consider in a Tesla coil program.

 The calcs for 90 degree coils are different because there are big
differences in the primary inductance.

John Couture

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


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, January 10, 2001 7:01 AM
To: tesla-at-pupman-dot-com
Subject: Re: Conical primary formula questions.


Original poster: "Barton B. Anderson by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Pete,

Good post! I too (many times) have found the conical equations odd in the
respect of increasing L as it varies up then down depending on degree input,
but I never asked the question or studied the problem. I use the conical
equations in my personal and JavaTC programs due the ability to enter angles
including 0 for flat and 90 for helical (and everything in between).
However,
you are correct that there is error with the conical equation.

I just ran a check. My primary input was as follows.
12 turn, 0.375 wire dia., 0.158 spacing, 16.75 ID.

At 0 degree, I calc 118.13uH. As an angle is entered, L increases to a max
at
27 degrees at 123.94uH. It then begins to decrease down to 61.43uH at 90
deg.
It actually matches the 0 degree angle when 42.88 degrees is used.

I then used Acmi to check. I used the highest inductance of 27 degrees
calc'd
at 123.94uH with the conical equation. Acmi result was 116.7uH which is far
more reasonable than the conical equation. So, Acmi agrees with you, and
although I haven't been able to verify conical inductances yet with Acmi, I
have a good feeling that the current filiment solving method Paul has put
together is fairly accurate.

It should be noted that using an angle of 0 for the flat primary results in
a
pretty accurate inductance with the conical equation.

I'm not sure how to fix this. You presented a method but I haven't checked
that
yet. I will soon. If it fairs well, I'll replace the equations in my
personal
and JavaTC programs.

Thanks again for posting this.

Bart

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