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First firing of 4" coil! Suggestion for improvement?
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From: Alfred A. Skrocki [SMTP:alfred.skrocki-at-cybernetworking-dot-com]
Sent: Friday, February 27, 1998 1:04 AM
To: Tesla List
Subject: Re: First firing of 4" coil! Suggestion for improvement?
On Monday, February 23, 1998 3:41 AM Christopher Stone
[SMTP:Chris.Stone-at-etak-dot-com] wrote;
> > 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.
This is typical for this size coil.
> > 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.
THe height/diameter ratio of two coil Tesla coils should be in the range of
3/1 to 4/1, yours is over 5/1 which will introdurce too much resistive
losses ie. lower the Q and the output!
> > TOROID
> > 1.75 X 12" foam covered with aluminum tape about 2" above top winding.
Try 3-4 X 12" so you can have more energy built up befor break out occurs.
> > TRANSFORMER
> > 9KV 30mA Franceformer
OK, but the more power the better the output anything larger up to
15KV at 120 ma. would be a distinct improvement.
> > SPARK GAP
> > Two 1" ball bearings spaced approx 3/16" or less apart (varied during
> > testing).
Poor design, too much losses and poor quenching either go with a Richard
Quick multible cylinderacle gap or at least a multible series gap to
improve quenchinmg.
> > 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.
Ditch the glass it is absorbing too much of your R.F> go with polyethylene
in mineral oil either the stacked plate design (easiest) or the rolled
design.
> > PROTECTION
> > Safety gap on each side of the transformer spaced about 3/16 of an inch.
Good.
> > Two small toroids with about 18 turns of enameled wire, I know these are
> > probably too small, but better than nothing.
I prefer to use like a pound of #28 for an R.F. choke, yours is just about
useless!
> > 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!
On a coil of this size a ground is not neccessary.
> > 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.)
I built a similar sized coil many moons ago and with a 12KV 60 ma
transformer it yielded 2 foot discharges and with a 15KV 120 ma
transformers it yielded close to 3 foot discharges.
Sincerely
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-----o00o-(_)-o00o-----
Alfred A. Skrocki
Alfred.Skrocki.Sr-at-JUNO-dot-com
alfred.skrocki-at-cybernetworking-dot-com
Visit my Do-It-Yourself Aquarium WEB page at;
http://www.geocities-dot-com/CapeCanaveral/6251
.ooo0 0ooo.
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