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Last light >:-| (fwd)
---------- Forwarded message ----------
Date: Sun, 17 May 1998 22:29:22 -0600 (MDT)
From: Chip Atkinson <chip-at-pupman-dot-com>
To: tesla-at-pupman-dot-com
Subject: Last light >:-|
Greetings all,
I finally got the right conditions of readiness, wind and light to fire up
my 9" coil outside. Mike Hollingsworth and I fired up this coil in the
garage a few weeks ago and it seemed to work well. This time when I fired
it up outside, it self destructed in a matter of seconds. In fact, I
don't recall even seeing any break out at all before seeing gobs of sparks
up and down the secondary, as well as sparks from the top turn (?) to the
main body. These sparks were not "attached" to the coil form, but sort of
arched out. Since there was a very thin coating on the windings, the arcs
quickly burned a hole in the insulation and fused a turn. It's amazing
how fast a shorted turn on the secondary will heat up. I noticed a little
smoke escaping and quickly shut it down. Inspection in the light showed
that there were two burned areas that had bare copper. Bummer.
One thing perhaps someone may have some comments on is the way I did the
toroid this run. When Mike was over, I had the coil set up with a
conductive tube on top of the coilform bulkhead. This 10" section of Al
tape coated PVC pipe then lead directly to the toroid. This time, I put a
10x3" toroid on top of the coilform and then the 10" riser followed by the
toroid. I suspect that this small toroid, rather than providing extra
corona shielding allowed spark breakout at the top of the turns and
the subsequent arcing from the top to the middle of the coil.
Ok, so what did I learn? I think I'm going to skip the smaller toroid
"corona shield". I don't want to destructively test this though, so I'm
going to just shy away from the new configuration and go with the tried
and true.
The other thing is that I now feel that a good coating on the secondary is
important. I believe that this extra insulation may have allowed the coil
to last long enough to fuss with it and fix it up before it totally fried.
Well, back to the winder. BTW, what gauges are people using for 9-10"
coils? I used 22ga.
Chip
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Chip Atkinson
http://www.pupman-dot-com
--- If I can't fix it, I can fix it so it can't be fixed --
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