RE: Freau's efficiency theory=Success!

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

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


Jon -

There is an easier and slightly more accurate method of making this test
shown in my Tesla Coil Design Manual. This method uses only a single value
current and the readout of millivolts is the mutual inductance in
microhenries (no calcs necessary). A lamp is shown for ballast and the non
linearity is not a factor because only one value of current is used (2.65
amps).

The equation I show below is even more accurate because the K factor is
found directly and the inaccuracies of the coil inductances are eliminated.

John Couture

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


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, June 05, 2001 10:56 PM
To: tesla-at-pupman-dot-com
Subject: Re: Freau's efficiency theory=Success!


Original poster: "Jon Rosenstiel by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jonr-at-pacbell-dot-net>

Hi John,

I tried your method but for some unknown reason had trouble. (The
coupling values didn't progress in a orderly fashion as I raised
the secondary, the numbers were all over the place). The problem
may have been my signal generator, it's a surplus Navy audio
generator and doesn't have  real smooth control of the frequency.

The method I did use was to apply about 10A of 60Hz  current
through the primary and measure the voltage across the secondary.
Terry Fritz described this method in a post  "Best Method to Find
Coupling Coefficient"
dated Thu, 27 Nov 1997.   For me this method is very repeatable
and I feel quite comfortable with the results.

There is another method that I've used that jives pretty closely
with the above method that consists of  measuring the primary
inductance with the secondary shorten and then open, but I'll be
darned if I can find it now. (It's getting late and I have a
early flight)! Anyway, I just checked my coil and the primary
inductance with the secondary open is 146.2uH and with the
secondary shorted it is 144.8uH. You'll have to do the
calculation.

Jon




> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
>
> Jon -
>
> I ran your TC numbers with the JHCTES programs and your numbers
and the
> programs were in close agreement except for the coupling. You
show a K =
> .106 and the program shows a k = .17 coupling.
>
> In one of my books I show how the coupling can be easily tested
using the
> standard equation
>
>       K = sqrt(1-(Fo/Fs)^2)
>
>       Fo = Frequency with secondary open
>       Fs = Frequency with secondary shorted
>
> I would be interested in what you find if you make this test.
>
> The JHCTES also shows an overall efficiency of 40%.
>
>      Eff = output/input = 432/1080/12 = 85 watts per foot
>
> The old standard is 500 watts per foot so your coil is doing
much better.
> The 500 watts actually doesn't make much sense because it is
obvious that
> modern coils can do much better.
>
> John Couture
>
> -----------------------
>
>