Re: 60 vs. 30 ma - charging
From: Bert Pool[SMTP:bertpool-at-flash-dot-net]
Sent: Monday, June 30, 1997 1:55 PM
To: Tesla List
Subject: Re: 60 vs. 30 ma - charging
> From: Pete Demoreuille[SMTP:pbd-at-cybernex-dot-net]
> Sent: Thursday, June 26, 1997 9:36 PM
> To: Tesla List
> Subject: Re: 60 vs. 30 ma - charging
> On another note:
> I have almost finished my first coil:
> powered by a 15kV neon -at- 30mA
> Caps: two crates of 14 snapple bottles each, each crate rated at 11uF,
> which are connected in series to give around 5.5uF of capacitance
Those must be the giant 100 gallon Snapple bottles! Perhaps you
meant 5 and 11 nanofarads?
> One single spark gap made with 2 carriage bolts, housed in a box with an
> exhaust fan at one end.
You really need to make an RQ gap, or at the very least, make a
simple gap out of a dozen or so copper cylinders mounted
side-by-side. A single gap make from carriage bolts will quench very
> Primary is 12 turns of 1/4 inch copper refrigerator tubing, at a 30
> angle to make it ~4in high and 11in radius.
11 inch radius or 11 inch diameter? A primary for a coil this size
which is 22 inches in diameter seems a bit large.
> Secondary is ~450 turns of plastic insulated wire, (couldn't find any
> i am working on it) for a total wrapping length of 21.5in
> separation between primary and secondary is 2in
You're going to be mighty low in inductance with plastic covered wire
unless you use a large diameter secondary.
Since you did not say how large your secondary is in diameter, I
cannot calculate the inductance or resonant frequency. Are you
planning on placing a toroid on top, and if so, how large? I'd
guess that a 12 inch diameter toroid with a 3 or 4 inch cross section
would work well with a coil in this power range.
> Any suggestions, comments, improvements (I am sure there are many, I am
> working on getting some mica for making some real good plate caps, and
> making a better, closer secondary, and getting a new transformer)
Pete, mica has a poor dissapation factor for Tesla coil use.
Polyethylene makes a far superior cap, and will cost you a
tiny, tiny fraction of what mica will cost. It is =very= difficult
to find capacitor grade mica anymore, and it is outrageous in price
when you can find it.
> Any clue how much separation the spark gap should have, and where i
> should tap the primary??? Please HELP! I have not a clue.
If you'll provide =complete= and accurate dimensions and values on
all your coils, caps, etc., and toroid size, I or one of the other
coilers on this list can give you a good ball park estimate for a
starting tap on the primary.
BTW, a cylinderical gap allows you to simply clamp onto different
cylinders to change the gap. Typical spacing between gaps is very
small - I normally space them about the thickness of a business card.
> If you could give a suggestion, that would be greatly appreciated,
> but if you could explain how you got the suggestion, that would make
> you a god.
> Happy Coiling!
> Pete Demoreuille
Good luck, Pete.