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Tips on capacitor and toroid design
The aluminum air duct tubing will work as a toroid, however, the surface is
still irregular enough to interfere with the electric field as compared
with a more expensive, smooth toroid. If you are using air duct tubing or
dryer hose, you might consider making a final overall wrap with aluminized
mylar tape. This will present a very smooth electrical surface, however,
due to the thin size of the alum. tape, you must use a discharge rod to
vent the discharge off your toroid. A direct discharge from the smooth,
thin, tape surface will damage it.
Capacitor builders should consider Kapton over polyethylene or polystyrene.
Kapton has a dielectric constant of 4.2 - 4.2 which allows very small unit
construction. Another great feature of Kapton is it's operating
temperature max is nearly equal to Teflon --- over 500 degrees F. for
Kapton. A typical design with Kapton dielectric will produce a 1,000 pF HV
capacitor element with an element size of only 2 x 2 x 1 inch. Elements
are series-parallel connected to obtain proper value. Kapton is
distributed by DuPont Co. -- consult your local library Thomas Register for
a rep in your area.
Another interesting application for Kapton sheets is to find a nice medium
size surplus air variable capacitor. Now, attach Kapton sheets to the
metal blades with the Kapton sheets extending approximately 3 inches beyond
each blade. Immerse in xmfr oil and your have a wide range variable
capacitor that can be connecting in parallel with your normal Tesla coil
capacitor for tuning while the system is running. Just use a very long
nylon shaft extention on the capacitor shaft and adjust while coil is
running for dynamic tuning. A lot easier than trying to construct a
variable inductor.
DR.RESONANCE-at-next-wave-dot-net