Re: Freau's efficiency theory=Success!

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Jon,

Tesla list wrote:

> 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.

My calculations suggest the generator is off by about 4 to 6 hz (low). No
big deal.

> 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.

Very good! I've done this myself several times. It is reliable and
repeatable. My experience here
is to use a current limiting device which remains stable over the period of
measurement. I've used
high watt resistors (I have in my possession a 10 ohm, 3500W resistor -
kind of BIG) and several
other devices. The limiter which remains stable is a hair dryer. Yep, odd
but true. The hair dryer
reaches a temperature stability due to the current though the heater coils
and the air flow over
the heater coils. Similar to why sparkgap behavier is "stabilized" with the
right amount of air
flow in a static gap. Although accuracy should increase with greater
current flow, a hair dryer can
typically provide about 10A and does pretty well.

> Jon

Hope your flight isn't work related. I use to travel 60% of the time and I
know the pains of travel
for a job and trying to keep up with the Tesla List. I'm glad to say that's
a past life.

Take care,
Bart Anderson

>
> > 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
> >