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First firing of 4" coil! Suggestion for improvement?




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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.

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.

TOROID
1.75 X 12" foam covered with aluminum tape about 2" above top winding.

TRANSFORMER
9KV 30mA Franceformer 

SPARK GAP 
Two 1" ball bearings spaced approx 3/16" or less apart (varied during 
testing).

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.

PROTECTION
Safety gap on each side of the transformer spaced about 3/16 of an inch. 
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!

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