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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
>
> -----------------------
>
>
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Monday, June 04, 2001 7:43 PM
> To: tesla-at-pupman-dot-com
> Subject: 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 all,
>
> Over the past few months I have built a medium sized Tesla coil
> based mainly on  John Freau's efficiency theories.
> http://hometown.aol-dot-com/futuret/page3.html
>  (Very good info John)!
>
> I feel this coil is a  good performer and I wanted to share
it's
> specs with everyone. (Shameless coil gloat)!
>
> Secondary:
> Material= Home Depot HDPE drain pipe. (White on the outside,
> black on the inside).
> Diameter=4.2"
> Form length=26"
> Winding length=24.5"
> Total # turns=1830, (approx).
> Wire size=28
> Inductance=56mH, (measured).
> Fres, (bare)=219.3kHz, (calculated, my Navy surplus audio
signal
> generator only goes to 200kHz)!
> Fres, (loaded)=104.4kHz, (measured).
> Toroid minor dia=5"
> Toroid major dia=27", (tube center to tube center)
> Toroid capacitance=32.24pF
> I also use a 1 7/8" x 6" control toroid that just fits over the
> secondary.  The lower surface of the control toroid is even
with
> the top turn of the secondary.
>
> Primary:
> 21 turns of 3/16" copper tubing spaced 1/4". Tap point is 19.25
> turns, (measured 145.9uH).
> Measured Fres at this tap position is 94.7kHz, about 10kHz
lower
> than the secondary Fres. (Coil tuned for maximum spark length)
> Tank cap=0.0187uF MMC, (Terry's Panasonic caps, 15 caps in each
> string, 5 parallel strings).
> Coupling, (K)=0.106
>
> Gap:
> 120bps SRSG.
>
> Power transformer:
> Unmodified 12kV 60mA Magnetek/Jefferson NST, (max input
140Vac).
> VA input=3220, 23A at 140Vac. (No PFC caps).
> Actual power input=1080Watts (Measured with Wattmeter)
> Maximum spark=61"
>
>
> Any comments or questions welcomed.
>
> Jon
>
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