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>


Malcolm -

Sorry - the two R's are shown in the following equations:

   Q = Xl/Rq  Rq = Xl/Q

   F = .159 sqrt(1/LC - (Rf/2L)^2)

   Rf = 2L sqrt(1/LC - (6.283F)^2)

The Rq in the Q factor equation is the one to which you are referring. The
other Rf is the one in the Resonant Frequency equation and is a different
resistance. This resistance affects the resonant frequency of the RLC
circuit.

The meager TC operating test data (scope/antenna probe) I have been able to
collect from coilers indicates this Rf may be involved in reducing the
resonant frequency compared to the low voltage, low current
Wheeler/Medhurst/Freq meter test.

This resonant frequency reduction has resulted in coilers and TC programers
having to make an adjustment in the calculation of the resonant frequency
compared to the operating test. Apparently you haven't noticed this
reduction.

John Couture

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


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, April 01, 2001 11:30 PM
To: tesla-at-pupman-dot-com
Subject: RE: Tesla Coil Blunders


Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<m.j.watts-at-massey.ac.nz>

Hi John,

On 1 Apr 01, at 21:33, Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
>
> Malcolm -
>
> Good questions. What are these two mysterious R's of the Tesla coil
> secondary circuit? What are their relationship to one another? The
> resonant R appears to be about 10 times greater than the Q factor R.
> The interesting part is that we have the equations to calculate these
> R's and the simple schematic circuits  but sofar coilers have done
> little with them. These R's mean losses and reducing them would
> increase TC performance.

Perhaps it would be a good idea if you defined exactly the various
R's of which you speak.
     For my part, it is simple: ESR is the equivalent series
resistance of the circuit (unloaded). This will have one of two
values depending on whether you model the coil as lumped or
distributed (with correct parameter distributions of course).
Rshunt is simply ESR*(1+Q^2)  (simple series -> parallel transform).

> You have made a large number of tests in the past with TC secondary
> coils with and without toploads  and as I recall the resonant
> frequencies at low voltage, low current agreed closely with the
> Wheeler/Medhurst/Freq equations. I believe these were made with
> generator/scope/freq meter connected to the base of the secondary
> coil. Did you find a difference in resonant frequency when you tested
> these coils at high voltage, high current operation using a scope and
> antenna probe?

No major difference.

Regards,
malcolm

> John Couture
>
> -----------------------
>
>
> Original poster: "Malcolm Watts by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>
>
> Hi John,
>
> On 29 Mar 01, at 16:54, Tesla list wrote:
>
> > Original poster: "John H. Couture by way of Terry Fritz
> > <twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
>
> --------------------  snip
>
>
> Wow! 35k Ohms. Is that effective series resistance or equivalent
> shunt resistance? That can't be an unloaded measurement can it?
> Does that figure include spark loading? I guess it must.
>
> Regards,
> malcolm
>
>
>
>
>
>
>