# Coil Length

• To: Tesla-at-grendel.objinc-dot-com
• Subject: Coil Length
• From: Alan.Jones-at-kaboodle.is-dot-net
• Date: Sun, 3 Sep 1995 12:08:22 -0400
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```PID: ProBoard 2.02 g4Sr
I have read in several places that a coil should be wound with between
800-1000 turns. And I have read about diameter-to-height ratios. And then I
see a picture of a coil 2 ft. across and looks like slightly over 3 ft.
tall. And they say it puts out 10 ft. discharges with 750 close turns of 22
gauge wire. I am completely confused now. If this coil is 2 ft. diameter,
then shouldn't it be 6 ft. tall using the 3:1 ratio for any size over 8
inches diameter. And using 22 gauge wire means 2664 turns. I am definitely
missing something here since 750 turns would only be 20 inches high.

I was thinking about winding one on a 6 inch pvc form with 24 gauge wire. I
wanted to use the 24 gauge simply because I already have it, along with a
section of 6 inch pvc. But to wind on the 6 inch pvc (which is 6.625 inches
o.d.) I would need to wind 26.5 inches if I follow the diameter-to-height
standard of 4:1 and that would be 1227 turns. What if I did wind one like
this? Would it work right or should it just be wound up to 1000 turns,
about 21.5 inches, and then stopped?

Richard, I am beginning to think you are correct when you say that coiling
is an art and not science. I realize that there is a big difference between
a 6.625 inch o.d. form and a 2 ft. o.d. form, and that the same rules might
not apply in this case, but this example seems to be stretching it pretty
thin. Maybe I need to just wind a few and see, and forget about the math.
That would suit me just fine, anyway, since I'm not that fond of math to
begin with.

If any of my math is wrong, well blame it on my calculator and not me :-)
But I think every figure I have given is correct.

Later,
Alan

* KWQ/2 1.2i * If it isn't broken, I can fix it.

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