Re: Freau's efficiency theory=Success!

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

Original poster: "R.E.Burnett by way of Terry Fritz <twftesla-at-qwest-dot-net>" <R.E.Burnett-at-newcastle.ac.uk>


Hi Jon, all,

Excellent stuff.  That is a great spark length for one NST. Thanks for
making all of the measurements too. I see that you use a large number of
primary,  and secondary turns.  This also seems to help efficiency along
with the sync rotary.

Other than 61" sparks from 1080 watts !!!,  the only thing that stands out
from your spec is the measured VA.  3220 VA sounds very high,  implying
that the power factor is quite poor.

When I tried 100BPS sync here in the UK,  I got poor spark growth for
some reason, but the power factor was very good.  I wonder if there is
another phase setting of the rotary that would give the same real power,
(and spark performance,) with a current draw below 23 Amps ???  John Freau
might be able to comment further here ???

There is nothing really wrong with this setup,  but the NST windings are
seeing more than FOUR times their intended current !   If you added PFC
capacitors you could drop the line current by about 75%,  but it would do
nothing to stop the NST from sweating :-(

Congratulations on your spark length,  and thanks again for posting all 
the details.  John's paper is like the standard reference for efficiency
now.
							Cheers,

							-Richie,
On Mon, 4 Jun 2001, Tesla list wrote:

> 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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