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Re: Malcolm Watts' comments on my t.c. comments
Kennan C Herrick wrote:
> As to capacitance, perhaps t.c.-ers ought to
> contrive to wind their coils with as high a distributed capacitance as
> possible, the better to soak up energy before the big event.
Actually, the opposite of this. The energy trapped in the
"self-capacitance" is not immediately available to supply sparks,
and most of it is not available at all, insulated from the terminal
by the inductance of the coil.
Efficient designs shall concentrate the maximum possible fraction
of the secondary capacitance in the terminal capacitance.
Some related considerations involving magnifiers:
Assuming the same primary capacitance and the same terminal,
it is possible to reduce the energy trapped in the output coil
by using a "magnifier" structure, where, with proper design, only
the energy trapped in the self-capacitance of the third coil is
not available.
The problem is that for this, the self-capacitance of the third
coil would have to be significantly smaller than the self-capacitance
of a coil used as secondary in a conventional coil. If these coils
are made with the minimum length that can support the output
voltage and the same diameter, they would have identical
self-capacitances, and a small gain would be obtained only
because the third coil can be mounted in a support high above
ground and far from other parts, as the primary coil.
The magnifier can also be designed for faster energy transfer,
allowing the use of more lossy thinner third coils, what also
reduces the self capacitance.
Antonio Carlos M. de Queiroz