Re: Newbie with a few questions...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Mike,

At 11:32 PM 4/8/2001 +0000, you wrote:
>
>Hi there, first of all, thank you all for all the information on this
>list. I've been checking out the archives for a little while now and
>thanks to you guys I've been able to build my first coil. :)
>
>Last night I finally tested it and was only getting about 1" sparks, with
>or without various toploads. :(  My problem is I'm in a second story
>apartment and can't ground the darn thing anywhere. Don't want to use
>the line ground, and don't want to use a cold water pipe, ( and I believe
>it goes to plastic downstairs anyway ) so all I was using for a "pseudo"
>ground was about 80' of 10 gauge wire strewn out about the floor in my
>place.

You should try aluminum foil and making a ground plane under the coil.
Sort of like the one under the secondary system being tested here:

http://hot-streamer-dot-com/temp/2001-01/P1210001.jpg

Most of the RF currents will be limited to the immediate area and such a
simple ground plane will provide the RF ground well.  I would also ground
this to the electrical ground for safety.

>The coil is very low power (1) 10kV 23ma OBIT, would it be safe
>to try to ground the secondary to the ground in my wall?  Or does anyone
>else have any ideas on how I could ground this sucker? (short of dropping
>wire down outside my window to a ground rod in the flower garden where
>my manager sees and comes knocking on me door)

A coil with that input power may put out 25 inch arcs if everything were
just right.  I wonder if the primary to secondary tuning is off a bit...

>
>Next question, I want to remake my primary. It's 8 turns of 1/4 copper
>refridgerator tubing, and a pretty good spiral but I want a better one.
>What I plan to do is slide the copper into this 1/4 inside diameter
>clear PVC tubing I have, then start it around a round form, and wind it
>as a flat pancake with no spacing. (don't worry, I'm gonna tap it
>internally with a copper slug that just fits, connected and being pushed/
>pulled by a length of stiff 10 gauge, thought of it this morning and
>tried it and it actually worked pretty well, I can even mark 'sweet
>spots' on the insulation) Anyway, the tubing is only about 1/16" thick,
>:
>my question is, is 1/8" too small a spacing between primary turns???
>:
>In case you were wondering why I wanted to slide it into a clear tubing,
>I want to shine the copper up, and keep it away from the air so it'll
>keep shiny and not tarnish in like 12 hours. :P  And of course also it'll
>help reduce arcing between topload/secondary and the primary. But not
>like I have to worry about that with my 1" arcs. ;)

My big coil has 1/8 inch spacing.  It is more a matter if you can get it
built to that tight spacing rather than electrical concerns.  In primary
voltage divides among the spaces so it is typically not a concern.  Maybe
think about coating the primary with spray polyurethane.  Sliding tubing
over a long length of copper is very difficult.

Cheers,

	Terry

>
>Thanks for you time,
>_Mike
>
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