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First firing of 4" coil! Suggestion for improvement?


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From:  Zuma [SMTP:mwise-at-ns.sosis-dot-com]
Sent:  Monday, February 23, 1998 8:28 PM
To:  Tesla List
Subject:  Re: First firing of 4" coil! Suggestion for improvement?

Tesla List wrote:
> 
> ----------
> From:  Christopher Stone [SMTP:Chris.Stone-at-etak-dot-com]
> Sent:  Monday, February 23, 1998 3:41 AM
> To:  tesla-at-pupman-dot-com
> Subject:  First firing of 4" coil! Suggestion for improvement?
> 
> I, along with some of my friends did our trial runs with my 4" coil
> and I have some questions about whether our results are average.
> 
> Here are the specs:
> 
> PRIMARY
> 15 turns of 1/4" copper refr. tubing 30 degree inverse conical approx.
> 21" outer diameter 6.5" inside.  Tapped on turn 14 and 15 for best
> results.
Sounds good to me.
> 
> SECONDARY
> 4.2 X 21.5" Secondary wound on PVC/ polyethelyne drain pipe (white
> outside, black inside) with approx 995 turns of 24 gauge enameled wire.
Curious? Is this pipe conductive on the inside or outside?
> 
> TOROID
> 1.75 X 12" foam covered with aluminum tape about 2" above top winding.
Instead of 1.75" step it up a few more inches and try varying the height
from the top winding.
> 
> TRANSFORMER
> 9KV 30mA Franceformer
Great. Altough it would improve output if you stepped up to a 15kv or a
9kv-at-60ma
> 
> SPARK GAP
> Two 1" ball bearings spaced approx 3/16" or less apart (varied during
> testing).
Go with the series cylindrical gap.
> 
> CAPACITORS
> Salt water bottle caps, started with a value of .005 and found that
> removing two bottles with a total value of .004 gave the best output.
Step the value up to .0088uf and consider less lossy capacitors.
> 
> PROTECTION
> Safety gap on each side of the transformer spaced about 3/16 of an inch.
Sounds good.
> Two small toroids with about 18 turns of enameled wire, I know these are
> probably too small, but better than nothing.
> 
> GROUND
> We grounded the secondary to the kitchen faucet which read 0 ohms to some
> ground rods we had also put in next to the house which were not touching
> any pipes!  It has been raining for many days and the ground was soaked.
> We used a 10' 00 gauge welding cable to connect to the faucet!
In a coil of this size grounding usually doesn't affect output a whole
lot, but just to eliminate the possibility find a good ground that is
not tied into you house wiring.
> 
> PERFORMANCE
> Maximum sparks so far are in the range of 5-6" to a grounded wire. We
> were able to make 2' fl. tubes light about 5' away.  I was expecting to get
> a slightly longer sparks, is this normal?  What changes should I work
> on to improve the coil? I am already planning to make a copper pipe/ fan
> quenched multiple spark gap to improve performance.  Is the limitation
> with my current set up with my transformer after that?  Can I widen up
> the spark gap farther?  With the max results the safety gaps were firing
> almost constantly depending on load (grounded wire, tube, etc.)
> 
> Thanks to all for helping me get this far,
> 
> Chris
I would not risk widing the gaps to much because it back lashes your
tranny. I did not get tremendous results from my 4" coil but I did get
19" out of it using a 15kv-at-30ma neon until my neon fried(did not use
safety gaps).

CJ