Re: HV wiring
On 03/02/99 17:12:41 you wrote:
>Original Poster: Bob Misiura <misiura-at-nccoast-dot-net>
>What may be an elegant solution is something I saw in a publication (but
>haven't tried). Someone has built a top terminal using a plywood
>support to hold what looked like 1/2" copper tubing rolled into a
>generally spherical shape for the top terminal as well as the final
>turns of the coil. The sphere over shadowed the top turns by about one
>diameter of the coil. The tubing seemed to be spaced at roughly two
I place a rather small toroid about 2"-3" larger in diameter than the
secondary coil form about 1"-2" above the last wire turn. The big toroid
is placed several inches above the small one. Results are excellent ---
no upper coil or small toroid break out. My favorite one is a 9" metal
plate with a 3/4" metal pipe welded around the circumfrence. I came out
of an old x-ray machine where it was used for corona suppression.
The idea is shaping of the electrostatic field at the upper end of the coil.
To avoid a huge increase in terminal capacitance design and use as small
of a toroid as it takes to do the job. A little trial and error helps here.
Annealed soft copper tubing filled with sand and gently bent around a
form is an easy way to go. Or, of course, any small commercial plastic or
styrafoam toroid covered with Al foil is a less permanent, but effective