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Construction Articles in Magazines
- Aug 1997 ELECTRONICS NOW (magazine), Build the Poor Man's Plasma
Globe, by R. Iannini and Marc Spiwak. Use a decorative spherical light
bulb and a 12v power supply based on FETs and a flyback xformer.
- 1990 RADIO
ELECTRONICS ELECTRONIC EXPERIMENTERS HANDBOOK (magazine), ELECTRONIC
TORNADO, by Robert Iannini. Schematic and construction instructions for a
variable power supply for a plasma sphere, with audio input, variable
pulse and intensity (note: plasma spheres don't really need a vacuum pump,
use a jar full of pure helium or pure argon at 1-ATM)
- 1990 RADIO ELECTRONICS ELECTRONIC EXPERIMENTERS HANDBOOK (magazine),
(magazine), BUILD THE LIGHTNING BULB, By Vinny Vollono. Plans for a simple
plasma sphere based on an automotive ignition coil, a triac, and a 6"
light bulb
Back issues of RADIO ELECTRONICS magazine, HANDS-ON ELECTRONICS magazine,
and EXPERIMENTER'S HANDBOOK magazine are available from your local
public library via the Interlibrary Loan service. Contact the reference
desk.
Bill B's short Plasma Sphere instructions for experienced
electronics hobbyists:
First built a tiny tesla coil based on a flyback-trans former. Flyback
units can be had from old TV sets or dead computer monitors. Use
one of the following schematics and build a tesla coil:
Your coil needs to be able to generate a spark of about 1.5cm
length. Next, obtain a "decorator" 40 watt 4-inch clear spherical light
bulb. Large hardward stores like Ernst or Fred Meyer carry these.
Connect the high voltage lead from your mini tesla coil to the base of the
light bulb. (It doesn't matter which light bulb contact you use.) Turn off
the lights and turn on your coil, and you'll see purple "plasma fingers"
spewing out of the filament supports in the light bulb.
If you want to get ambitious you can build your own glass globe. Use a
glass jar, or better yet a boiling flask from a mailorder chemistry
supplier or a lab glass outfit. Stopper with a 3-hole
stopper. Provide two hoses, one to
inject gas, the other as an outlet. Push the inlet hose deep into the
flask so the injected gas can push the air ahead of it. Tape a layer of
paper towel around the exit to act as a diffuser, to prevent turbulent
mixing. Insert a wire
into one hole as the H.V. terminal, with the tip of the wire centered in
the flask. Turn on the tesla coil, turn out the lights, then slowly flush
the nitrogen out of the glass globe with argon (welding argon is pure
enough. Note that argon is slightly heavier than air.) The small corona
discharge on the wire in the globe will grow larger and larger as the
nitrogen gets replaced with argon. When the discharge is large and white,
turn off the argon and clamp the hoses. Seal with epoxy if desired (don't
use silicone caulk, the acetic acid fumes destroy the plasma effect.)
A note about x-rays. Some small bulbs fail to produce purple
streamers of plasma. Instead the space inside the bulb remains dark.
But the glass flickers blue, or white, or sometimes green. This shows
that the bulb contains a fairly hard vacuum. And at high voltage (above
10KV,) such a bulb will produce soft x-rays as electrons slam into the
glass and make it fluoresce. USUALLY the x-ray intensity is
insignificant. It's way too little to light up a fluorescent screen. (No
viewing your own bones! Too bad.) It might pass through aluminum and
cardboard, but it won't pass through steel. But it will make a geiger
counter click, but only if the probe has a thin window (for alpha
particles.). The alpha-window geiger counter response is about the same
as that for
a hunk of uranium mineral. Most types of small appliance bulbs, aquarium
lights, exit sign lamps, etc., will produce weak low-energy x-rays when
used as a "plasma globe." The x-ray output is a bit higher if the filament
is lit, and much higher if a piece of grounded metal foil is glued to the
end of the bulb. So, to avoid even the slightest x-ray hazard, use only
the large 4-inch spherical bulbs for your "plasma globe." Stay away from
those small green-fluorescing aquarium bulbs! Here's some radiation info, compare
canoe trips and peanut butter to x-ray risk
Also see Plasma Sphere
without vacuum pump for more info.
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