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FLAT PLATE CAPACITORS
MC> Richard,
MC> I have been thinking about making a whole lot of roll
MC> capacitors (miniature versions of the ones you make), put
MC> them upright in a big square tupperware container and then
MC> wire them in series-parallel to get the required voltage and
MC> capacitance. mconway-at-deepthnk.kiwi.gen.nz
Yes, you can do this. However the one problem I have had with
large groups of rolled plastic capacitors is the corresponding
drop in tank circuit Q that comes from the capacitor self
inductance and the excessive number of sharp angle tank circuit
connections (include all "off axis" capacitor bussing).
If you are going to the trouble of building a cap from scratch,
and you cannot get the 60 mil poly for the rolled design (and I
know you have looked) then build a vertical plate, flat stacked
capacitor as we have been discussing. The rolled capacitor is
popular here in the "states" simply because the materials are
easily and inexpensively obtained, and the capacitor construction
goes fast. The performace with 1 - 4 rolled capacitors in the
circuit is not bad, but adding additional rolled caps into the
circuit drops the circuit Q to a point where I can see it on the
O'scope and in the coil performance.
Your idea will work, but I know for a fact that you are looking
for exceptional performance and efficiency (and I can't blame
you). You would be better off experimenting with the flat plate
type of capacitor. If you decide to bump up to larger coils,
higher powers, and bigger sparks, the flat plate capacitors you
build now will also serve best in the future.
I begin to realize now, what with the difference in materials
standards in New Zealand, how much trouble you have gone through.
I wish you the best of luck!
Richard Quick
... If all else fails... Throw another megavolt across it!
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