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Re: First Coil Works --Tuning Help

Hi Adam,

	The system sounds way out of tune!  For that much input power, a well
tuned coil can push four or five foot streamers.  However, for a first
light sounds like all is going well.
	On big caution!  Be SURE to use safety gaps across the transformer
outputs.  Without knowing what the primary cap value is, you could easily
hit resonance between the transformers and the primary cap which could send
the voltage so high it could blow both transformers.  In you case that
would occur at 20nF.  This is the first mistake many people make and that's
why they always need new transformers.  However, sounds like your cap is
far too small.  Also be sure the main spark gap is across the transformer's
outputs.  This will short their outputs during the firing cycle instead of
presenting the full high power AC burst signal to the neons.  I hope you
have a variac to control the neons.  this makes things MUCH easier.

	I would have to know more to tell you where everything needs to be set but
your primary and secondary circuits are not tuned to the same frequency (if
they were, your coil would be blowing the paint of the ceiling :-)).  The
other things you would need to know to tune the sytem by calculation
(rather than trial and error) are as follows:

Primary capacitor value - You will need some kind of meter to determine
this.  Perhaps someone can guess at the values for a gallon jug?

Primary inner diameter - the diameter of the inside turn of the primary
pancake.

Maximum turns possible on the primary - hopefully you have enough.

Primary Pitch - The distance between the centers of the turns on the primary.

Secondary diameter - 6 inches you said.

Winding length on secondary.

Turns of wire on the secondary.

With this information a number of computer programs can determine pretty
closely were your coil's tunning is at now and were you need to go.  Feel
free to send me this information and I can run it.

	Off hand, I bet your primary cap is way to small.  For a 120mA input
current you should run about 35nF of primary capacitance for maxiumum
output.  You may have to upgrade you primary cap system substantially.  The
spark gap needs work to but worry about the capacitor right now.

Good luck your off to a great start!

	Terry



At 07:57 AM 11/12/98 -0600, you wrote:
>Last night I finally got some output from my coil...  A 1/2 inch spark --to
>a grounded target. Definately NOT the best performence for a six-inch
>coil running on 1.5kVA! I figure I really need some tweaking help.
>
>This is my current setup:
>
>Two 15kV, 60mA Neons in parallel
>A lossy salt water cap (made from a gallon glass jug, I have 4 smaller
>ones)
>A single, static gap. about 1/2 to 3/4 inch space --the spark was sorta
>erratic and bluish...
>An 8 turn primary coil --my coilform can handle up to 14 turns
>Finally, I use a toroid about 14" in diameter. 4" sewer pipe. I have a
>larger one as well.
>
>I'm willing to do pretty much anything to the setup to get good results, I
>know this isn't a good way of running now --more primary turns?
>Anyway, I'll appreciate ANY help.
>
>Adam
>KF4ZVW
>
>