RE: Tesla Coil Blunders

["Tesla list" <tesla-at-pupman-dot-com>]

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


Bart -

It appears that there are two TC secondary circuit resonant frequencies
depending on whether the TC is operating at high voltage and high current or
not. This is important for a TC computer program because the program
calculates the number of turns for the primary coil. With two resonant
frequencies which primary turns should be calculated by the program? Of
course this is not a big deal because the primary usually has plenty of
adjustment, but would be of concern for Tesla coil designs that have fixed
primaries.

John Couture

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

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, March 28, 2001 8:49 PM
To: tesla-at-pupman-dot-com
Subject: Re: Tesla Coil Blunders


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

Hi John C.,

I've tried to calc this in the past, but couldn't get it right. The
effective series resistance was not as easy
as I once thought it was. My personal sonotube coil is off by about a turn
from basic Wheeler/Medhurst calcs. I
find Gary's comment regarding E-Tesla 6 interesting in this investigation.
If E-Tesla 6 can truely identify "on
the mark" the frequency, then the answer is staring us in the face! (should
this be true for all our coils).

Bart A.

Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
> Tesla Coilers may be making the worst of TC blunders when doing
calculations
> for determining the operating resonant frequency of their coils. It is a
> well known fact that the calculated frequencies do not agree with the
actual
> operating test frequencies. Many important design decisions are based on
> this unique frequency so it is important that it be correct. To circumvent
> this problem a fudge factor is used for all TC computer programs but this
is
> only a bandaid for TC design.
>
> The equation that coilers use for finding the TC resonant frequency is
>
>       F = 1/(6.283 x sqrt(LC)
>
> The TC secondary circuit is an RCL circuit but the "R" is omitted by
coilers
> in the above equation which may be the worst of TC blunders. In the Tesla
> Coil Construction Guide page 5-1 the complete resonant frequency equation
is
> shown including the "R" parameter. It is also mentioned that the "R"
reduces
> the resonant frequency and if the "R" is large enough there will be no
> resonant frequency. In other words the "R" could be the reason the
operating
> frequency does not agree with the calculated frequency when the "R" is
> omitted.
>
> To my knowledge no one has ever determined how to find this very important
> "R" for an operating Tesla coil either by calculation or by tests. TC
> programs are hurting because of this lack of information.If anyone has any
> comments I would be interested in them.
>
> John Couture
>
> --------------------------------