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Re: Spark Gap Design Alternatives (fwd)
---------- Forwarded message ----------
Date: Sun, 23 Feb 1997 05:20:28 -0500 (EST)
From: TimRaney-at-aol-dot-com
To: tesla-at-poodle.pupman-dot-com
Subject: Re: Spark Gap Design Alternatives (fwd)
Folks:
I've built series spark gaps with the entire assembly being held together by
compression. It consisted of two phenolic blocks approx. 2" square and 3/8"
to 1/2" thick as end pieces, brass disc electrodes and mica washers as
spacers. An outline of construction details follow. This series gap has 7
gaps and is used on a relatively small Tesla coil (3" X 20" secondary with a
60mA, 15KV neon sign transformer).
Electrodes were 7/8" O.D. brass discs, 3/16" thick with a central hole (made
them from a brass plate using a 1" hole cutter saw. I then mounted the brass
discs on mandrel (1/4-20" threaded rod) and turned them down to a uniform
diameter and smooth finish. I did this on a lathe, but you can use a drill
chuck on a motor and turn the discs down with a file. However, it's the disc
face that's important and should be smooth without any deep scratches or
burrs. Spacers were 1" O.D. mica washers (alot of them). I believe these
are used to insulate the stud on high current diodes.
The series spark was held together by compression; the phenolic end pieces
were drilled in each corner (11/64" through hole for 8-32 threaded rod) and
the brass discs and the requisite number of mica washers were stacked on one
end piece. Two brass strips with binding posts were added to the two end
disc electodes for connections. The assembly was then held together with
four 8-32 "tie rods" and clamped together. It's mounted to the Tesla coil
with angle brackets on top of standoff insulators.
This particular design has a high quench rate and when used in the Tesla coil
I briefly described. The discharge is radiated and will brightly light a
fluorescent light held 2-3 feet away. I good "lamplighter coil" for
discharge tubes, etc. However, you can obviously design your Tesla coil for
sparks, I wanted to use it for discharge tubes.
TIM RANEY,TCBOR