Secondary coil arcing to itself
From: Kevin Christiansen[SMTP:kevin+-at-cs.cmu.edu]
Sent: Thursday, June 26, 1997 7:25 PM
Subject: Secondary coil arcing to itself
I just put togeather a small Tesla Coil that is exibiting
a behavior that I have never seen before: the secondary
coil arcs to itself at various points along its length.
Basically, an arc will break out somewhere along the length
of the secondary, streak up (or down) the secondary for 2 to
4 inches, and then re-enter the secondary. While these little
arcs playing all over the surface of the secondary are certainly
neat-looking, I am sure that they are murduring the insulation on
the wire and are robbing me of power. (Note that these are NOT
torroid-secondary, primary-secondary, etc. arcs - these arcs just
streak from here to there along the surface of the secondary.)
Any suggestions on how to stop them?
(I have a can of that 2 part Devcon Flexane Urethane rubber
stuff, which claims a dielectric strength of 350 volts/mil.
Should I glop a thick layer of that over the top of the
Here are the specs on the coil, for those that are interested:
7.5 A variac
15 Kv 30 mA neon
misc RF protect chokes, protect gaps, etc.
.005 uF, 60 Kv energy storage cap by High Voltage Components, inc.
12.75 turns of .08" house wiring: 5" tall and 10.5" diameter
Wound on a plastic bucket
.25" static gap, in 10 to 40 equally sized "mini-gaps".
Tungsten carbide electrodes
#24 magnet wire: 17.75" tall and 4" diameter, close-wound
Wound on a PVC pipe that was sanded, heated, and painted
with several layers of oil-based polyurethane varnish.
Coil was varnished after winding as well.
Torroid is 3" Al dryer duct, 12.5" wide
About 30' of Belden 8213 heavy 0.5" coax, using both the shield
and the center conductor, clamped to the plumbing system of my
appartment in 2 different places.
Currently, I am getting 14" arcs from a small wire taped to the side
of the torroid, to ground. How long of arcs should I be able to
get out of a 15 Kv 30 mA neon?
Thanks for any suggestions/comments that you can give me!
Kevin D Christiansen
Human Computer Interaction Institute - Carnegie Mellon University
"The universe is composed of space, galaxies, and intergalactic
dust. Galaxies themselves are composed of space, stars, and
interstellar dust. From the omnipresence of dust, we conclude
that nature abhors a vacuum and won't pick up a broom, either."