Re: New Twin Transformerless Tesla Coil

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
 
> Original poster: "Jolyon Vater Cox by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
> 
> Today I modified my capacitive transformer mini-coil to operate in "twin
> transformerless" mode by winding an identical secondary and connecting it
> directly to the influence ring of my first coil.

This setup is quite difficuit to adjust at high-power. Even with an
oscilloscope at low power the tuning is quite problematic. I was
just experimenting with this using some capacitor and inductor decade
boxes.
 
> Performance was pretty rotten at first with only a protruding wire and no
> proper terminal (small purple arcs to grounded object only).A 1 2/8" copper
> disc was then  attached to the top of new secondary which, -judging from
> increase in spark length to grounded object- caused an increase in
voltage, no
> doubt due to better tuning of the new secondary.

Note that for proper balance both resonators must be identical, with
identical top loads, and each must have an influence ring. And more,
the capacitances shall be adjusted so the influence ring captures
half of the capacitance from the resonators to ground.
 
> There is voltage also between the terminals of the two secondaries as
evidenced
> by sparks between a wire attached one of the secondaries to the other.
> and there is definate attraction of corona towards the space between the two
> terminals.
> The sparks appear weak and corona-like however -due to the high-impedance of
> the parallel-network source, perhaps?

The system is probably out of tune. Two identical resonators require
the doubling of the primary capacitance, and the division by 2 of the
primary inductance.
 
> I also feel that the series-resonant input is very current-hungry with two
> resonators since each from the input side is a series-tuned circuit (ie. low
> impedance) and there are two of them  in parallel (lower impedance still!)
> Incidentally, L1 is same inductor (61.08 uH)
> as used for the single capacitive transformer TC.

Note that the two series resonant resonators don't drain their maximum
current immediately, but just aftes some cycles. This is the normal
energy transfer process. Anyway, the currents in L1 and C1 are much 
higher than the currents that go to the high-impedance resonators.

> Am I reaching the limits of what is possible with an rectified
ignition-coil HV
> supply
> powered off a 13.8V 5 Amp power unit?

Not yet, I think.
 
> I intend to build another ring same size as the first at the same height
to go
> around the base of the second secondary and to be connected to it. Could
it be
> that by slowing the voltage rise on the second resonator (by connecting a
ring
> to intentionally increase C3) a better overall performance might result?

I think so. But you must divide by 2 the impedance of the tank L1C1 to 
make it feed both resonators, otherwise the system will be out of tune.

Antonio Carlos M. de Queiroz