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Re: Capacitor "tap" in Primary?



Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

Antonio,
The capacitively-coupled tesla coil you mentioned is an interesting idea, I
have thought about that one myself -I don't know if it has ever been used to
generate high voltages but I have visited a German website
http://www.hcrs.at//KAPTRAFO.HTM which gives details of just such a
capacitive transformer which does much the same thing except in reverse.
Perhaps it is time to "let the experiment be done".
Jolyon.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, June 29, 2002 4:29 AM
Subject: Re: Capacitor "tap" in Primary?


> 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>
> >
> > Is it possible to get an autotransformer-like step up on a primary of a
> > spark-gap TC using a capacitor tap -in a manner  similar to that
exhabited
> > by the tuned circuit of  a Colpitts oscillator (but without the
amplifier
> > and feedback)?
>
> A capacitor in parallel with the gap would be immediately discharged
> when
> the gap fires, and have little effect while the gap is conducting.
>
> It seems possible, however, to feed a "capacitive transformer" (a
> grounded
> coil in parallel with two capacitors in series) through the tap between
> the capacitors with a signal at the resonance frequency of the system
> and
> get high voltage at the top of the coil. It would be curious to see if
> this
> works with the upper capacitor being a distributed capacitor between the
> coil and a terminal above it and a plate below (as a ground plane)
> connected to the lower, grounded, capacitor.
>
> > By the way, how does the "Poulsen Principle" work
> > only it seems strange that adding a capacitor directly across a spark
gap
> > would would do anything to make it run cooler. Are there any good
references
> > to the technique and does anyone know how it works?  Could it be that
the 2
> > nF cap act to remove HF transients that would otherwise heat the gap -a
bit
> > like a snubber across a TRIAC or a Zobel network across a loudspeaker,
by
> > any chance?
>
> I have never heard about this, but a capacitor across the gap may serve
> to quickly heat up the air in the gap, reducing losses during the
> oscillations that follow, may reduce spurious RF being irradiated, and
> may cause the gap to quench more easily when the energy in the primary
> tank drops. This last function may be really useful.
>
> Antonio Carlos M. de Queiroz
>
>
>
>