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Re: Recycled: Measuring Coupling Coefficients
From: bmack[SMTP:bmack-at-frontiernet-dot-net]
Sent: Sunday, December 07, 1997 1:47 PM
To: Tesla List
Subject: Re: Recycled: Measuring Coupling Coefficients
John,
The equation you cited as an "exception" : k=1/sqrt(QpQs), is for
CRITICAL COUPLING k. It's intended use is to optimize the coupling
to avoid overcoupling the system which produces two "humps" on
one above and below resonance. This is a different issue than calculating
the actual value, irregardless of it's effect on the system.
Hope this clears it up.
Jim McVey
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
> Subject: Re: Recycled: Measuring Coupling Coefficients
> Date: Sunday, December 07, 1997 10:27 AM
>
>
> From: John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
> Sent: Sunday, December 07, 1997 1:22 AM
> To: Tesla List
> Subject: Re: Recycled: Measuring Coupling Coefficients
>
> At 05:41 AM 12/6/97 +0000, you wrote:
> >
> >From: Mark S. Rzeszotarski, Ph.D.[SMTP:msr7-at-po.cwru.edu]
> >Sent: Friday, December 05, 1997 6:57 AM
> >To: Tesla List
> >Subject: Re: Recycled: Measuring Coupling Coefficients
> >
> >Hello All,
> >
> -------------------------------- snip
> > K depends only on geometry. M, Lp and Ls depend only on
geometry.
> >The equation above considering the two Q factors is the value of K one
> >should strive for for maximum energy transfer between the primary and
> >secondary. Of course, you also want that to be equal to one of those
nice K
> >values where all of the energy happens to be transferred to the
secondary
> >when the gap turns off (1st, 2nd or 3rd notch, generally). In addition,
you
> >may want to match Qp to Qs under full firing conditions. To do this you
> >must measure the load Q of both circuits during spark production.
> > You can precalculate M and K quite easily using Neumann's
formula.
> >It is a slow numerical integration, but yields accurate results. The
power
> >series approximation described in Grover's Inductance text is inaccurate
for
> >typical tesla coil geometries. I have written the numerical integration
> >code, and it is fairly straightforward. It has worked well for me for
> >solenoidal and flat spiral primaries, and gives an approximate solution
for
> >inverted cones. (M is accurate, but Lp is approximated.) I plan to
post
> >the program to the net after some more fine tuning. It is in beta
testing now.
> >Regards,
> >Mark S. Rzeszotarski, Ph.D.
>
> -------------------------------------------------------------
>
> Mark -
>
> As I mentioned in an earlier post the K factor appears to be related
only
> to the physical characteristics and geometry of the coil. However, this
> appears to be contrary to K = 1/sqrt(QpQs) and Q = 6.283 F L
> where the K factor is related to the frequencies, unlike the other K
> equations where the frequencies cancel out. Do you have a an explanation
for
> this apparent contradiction ?
>
> The transfer of energy between the two coils is always 100% and purely
> inductive. The K factor only affects the time for the total transfer.
There
> are, of course, losses due to currents in the windings. These losses do
not
> affect the transfer which is inductive and reactive with no losses.
>
> The JHCTES TC computer program determines the mutual inductance from
the
> physical characteristics and geometry of the coils. It also calculates
the
> Lp and Ls using the Wheeler equation so the K factor can be found. This
> method has been found to closely agree with K factor tests when properly
> performed. The program also calculates and coordinates 46 of the major
Tesla
> coils parameters while keeping the complete system in tune.
>
> The Tesla List will be looking forward to your Neumann numerical
> integration computer program.
>
> John Couture
>
>
>