RE: Effective Resistance

["John H. Couture" <couturejh-at-worldnet.att-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Boris -

I know that most coilers are interested in only long sparks but a few
coilers are also interested in what makes those sparks do their thing and
how can they be made to do better.  For several years I have been working on
developing a TC computer program that can help in understanding the
classical TC. I am still working on it. Many coilers have their own programs
that they have made. However, to my knowledge none of these programs are
comprehensive enough to include all of the major TC parameters and
coordinate them into one interactive program. I am referring to empirical
type programs which model Tesla coils by using both theory and empirical
data.

To keep this short I will refer to only one of these parameters and that is
the secondary terminal voltage (Vs). There are several ways to estimate this
parameter but they all require knowing the overall efficiency which is an
unknown. However, there is one method that does not require efficiency and
that is the equation
     Vs = Vp * Q
where Vs is the secondary voltage, Vp is the peak primary voltage, and Q is
the operating Q factor. The operating Q factor is only one of several TC Q
factors. The Q factor is found by the equation
      Q = Xl/Reff
where Xl = 6.283 * Fres * L   and Reff is the effective resistance. But
first of all the Reff must be cleary defined. For example is Reff the ESR
that coilers talk about? The ESR is referred to as an impedance but the Reff
can not be an impedance. The Reff is a loss type ohms. An impedance is the
sq rt of the squares of the active and reactive ohms. Note that there are
three types of ohms in the electrical world, active, reactive, and
impedance.

As you can see there is much more to the design and engineering of the Tesla
coil once you get beyond the spark stage.

John Couture

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

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, August 24, 2000 10:34 AM
To: tesla-at-pupman-dot-com
Subject: RE: Effective Resistance


Original poster: "boris petkovic" <petkovic7-at-yahoo-dot-com>


--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "John H. Couture"
> <couturejh-at-worldnet.att-dot-net>
>
>
> Bart -
>
> What I tried to point out is that ESR has two
> answers, Rac and Reff. In the
> past coilers have used both categories of
> calculations for ESR and always
> end up with different answers and wonder why. Like
> is the Q factor 100 or
> 900? The Rac calculation is standardized but the
> Reff calculation has too
> many unknowns to produce explicit answers at the
> design stage. It is obvious
> that this situation must be taken into consideration
> when developing a TC
> computer program.
>

John,
I wonder why so much  interest of yours relating
secondary spark unloaded Q and radiation resistance(?)
There could be some reasons such as CW operation and
relation Energy radiated/Energy dissipated in a coil
structure or you want to build better radio transmiter
of TC?
Most of us are however interested in disruptive TC
designs ,with big secondary sparks that lower  Qs down
to ~10.In that case ,it is of really small importance
for successful performance whether Q secondary
unloaded  =100 ,200 or 500 (energy delivered to arc 1%
more or less).
I would pay much more attention to the modeling  of  Q
of TC primary.


Regards,
Boris





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