Re: Parametric pumping for tesla coils?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

On 16 May 2003, at 8:16, Tesla list wrote:

 > Original poster: "Jolyon Vater Cox by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
 >
 > Malcolm,
 > I understand your point energy needed to change the capacitance must be
 > equal the energy loss to sustain continuous oscillation, but does
 > capacitance actually have to go to zero to replenish energy lost in the
 > circuit resistances -after all, parametric amplifiers used in radio
 > applications work perfectly well -they use varactor diodes to effect the
 > change in capacitance needed to maintain continuous  oscillation- and I
 > doubt very much if these diodes are capable of reducing their capacitance
 > values to zero either!

To address your first point: the implication is that the capacitance
has to go to zero. Sustaining oscillations by reducing it means
either reducing it to zero to maintain the oscillations, or reducing
to some particular value whereupon the oscillations do what?

Amplifiers with varactor diodes have a continuous DC power feed to
overcome the losses.

Malcolm