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Re: Top Toroid
Re:
"With a conventional
xformer the charging current at the .707 point would only be limited by
the impedance/resistance of the xformer winding. Therefore it appears to
me that trying to run neons with more than one cap discharge per half
cycle is self defeating because we cannot recharge the cap fast enough
to make any difference."
Not so. Because the net reactance of the charging circuit is
the sum of the transformer leakage reactance (positive) and the
capacitor leakage reactance (negative) you can have a great deal of
charging current available, and easily get several discharges per
half cycle. In fact, when the reactances are "matched" the charging
current is limited only by the resistance of the secondary plus the
reflected resistance of the primary. As a consequence, the secondary
voltage without load can try to go to several times the rated voltage,
with resultant destruction of the transformer. When you connect a
capacitive load on the transformer the open-circuit voltage will be
greater than the no-load voltage, at least for capacitances whose
reactance is less than the somewhat higher than the "matched" value.
I have run a bunch of simulations of this which seem to
agree with experimental observations quite well. One thing which
shows up with rather large capacitors is that it may take several
half (or even full) cycles for the voltage to build up to the point
where it will fire the simulated gap.
If I get time and ambition I'll post some of these results,
but have neither at the moment.
Sorry for the incomplete discussion,
Ed