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FW: A Puzzle


From: 	gweaver[SMTP:gweaver-at-earthlink-dot-net]
Sent: 	Saturday, September 06, 1997 9:46 AM
To: 	Tesla List
Subject: 	Re: A Puzzle

I am not sure I can add much to what has already been said.  I have noticed
something similar with 2 coils that I have.

Both my coils are wound on white pvc pipe.  Both have 998 turns of #24 wire.
The small coil measures 4.5" diameter and the larger coil measures 6.5"
diameter.

I built a TC designed for the small 4.5" coil.  When I replace the 4.5" coil
with the 6.5" coil and keep everything else the same the output sparks are
about 2" longer.  The thing that is most noticable is the larger coil
produces much thicker and hotter spark.

Small coil inductance is 21459 uh and the larger coil is 43124 uh and
increase of 200.9%

Wire length increased by 523" and increased the resistance from 27.1 to 39.2
ohms.

Ratio of the small coil is 4.8 and the ratio of the larger coil is 3.3.

Q has increased by 15 unloaded.

Small coil resonance frequency is 386.1 KHz compaired to 239.0 KHz for the
larger coil.

I can clearly see a difference between the output of the 2 coils but I can
not tell you exactly what caused the difference.

Gary Weaver



>Greetings All,
>               This is a genuine enquiry (no, I don't know all the 
>answers regrettably). Last night, I replaced the large resonator in
>my work system with a much smaller one with the same sphere on top.
>I am using the same primary but k would be somewhat different.
>
>      The large resonator is a 10" x 44" space wound job (Ctot about 
>26pF). The small resonator is 4" x 17" and with the same topload 
>resonates at exactly the same frequency as the large one. This coil 
>has around 1800 turns of wire one it and consequently its inductance 
>is much higher (which it would have to be to resonate at 146kHz as 
>its Ctot is much less than the larger coil). OK, I know the wire 
>losses are a lot higher in the small one so on to the next bit of 
>information.
>
>     Under single shot conditions, the spark length is pretty much 
>the same as the large resonator so that implies that output voltage 
>is pretty much the same. Now that is reasonable because of higher 
>losses and possibly reduced k probably compensated for by reduced 
>total capacitance.
>
>    The cruncher: The large resonator has created those rare long 
>sparks measured well over 4 feet p-p. The little one is struggling to 
>get to two feet p-p. This is with exactly the same primary coil and 
>cap, energy and gap setting. This situation echoes someone recently 
>switching from a 3" (?) coil to a 6" one. The air discharges from the 
>terminal are a bit shorter with the small one suggesting the reduced 
>capacitance might be a factor. I have not as yet taken any real 
>measurements but will sometime today.
>
>    The question: why?  Any input sought, Ideas welcome from all. 
>I'd like to hear from anyone, no matter how trivial you think your 
>contribution might be.
>
>Regards All,
>Malcolm
>
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