Re: Hi Power Discharge "Disruptive"

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

On 8 Nov 2004, at 8:08, Tesla list wrote:

 > Original poster: "chris rutherford" <chris1-at-hackinghardware-dot-com>
 >
 > Hi Guys,
 >
 > I've been interested in 'Tesla' coils for about  7 years now since I
 > first picked up a book called "The fantastic inventions of Nikola
 > Tesla".  I have a degree in Electronic + Electrical Engineering so I
 > have some idea of how to build a coil.
 >
 > I am a little concerned about the standard Tesla coil that everyone is
 > building as it does not appear to follow the models in the original
 > patents.  i.e. people still seem to like the idea of  using  an  LC
 > circuit for energizing the primary, where the capacitor is after the
 > spark gap and in parallel with the coil primary, thus producing a tank
 > circuit.  Tesla never only ever did this when working with AC and it
 > had nothing to do with 'Disruptive Discharge' which I believe is the
 > main principle of the Tesla Coil.  What should happen is a fully
 > charged capacitor should discharge all of its energy in to the coil in
 > one burst via a spark gap.  Once discharged the spark gap should close
 > stopping any LC oscillations.  The process would then be repeated with
 > the capacitor fully charged again.  Is this what you guys do?

Yes. The gap you were looking at may have been the safety gap giving
the transformer some protection.

 > Also everyone seems to be using rectangular shaped coils, where as
 > Tesla used cone shaped coils as shown in the patient below:-
 >
 > http://www.pbs-dot-org/tesla/res/593138.html

Shouldn't that be "cylindrical"?

 > Has anyone done experiments with a cone shaped coil and a pure
 > disruptive discharge with no LC oscillations?  I think one of Teslas
 > objectives was to completely eliminate all possible LC and focus
 > purely on disruptive discharge.

Given the degree of coupling, the coil could not work without being
resonant. I proved this to my own satisfaction while struggling to
get my first ever coil working many moons ago. I see no advantage
whatsoever for conical coils. The turns at the apex are so small that
they contribute no worthwhile inductance. The basic operating
principle of a disruptive coil is to deliver a shot of energy from a
large capacitance to a small one thereby elevating the voltage.

      Tesla recognized that the generated potentials were being
slugged by energy storage in parasitic capacitances in the resonators
and did his best to eliminate the self-capacitance of the structures
he built. Unfortunately nature was against him (where there is a
current there is inductance; where there is a potential difference
there is capacitance).

   Also Tesla gave up on using  motor
 > driven rotary spark gap devices as they were too slow, instead he used
 > a strong magnetic field and air blasts to 'quench' the spark as soon
 > as the current discharged from the capacitor started to drop.  I can't
 > find a link right now, but he insulated an electromagnet from the
 > spark gap using mica.  i.e. the spark discharged through a hign
 > magnetic field, greatly reducing its puls duration.

 > Has anyone tried these designs out yet as his articles say the
 > resultive 'spark' effects on the primary are more like 'fire' and
 > exhibit different colors and shapes to standard HV air breakdown
 > sparks.  i.e. He said they were smooth and flowing and more gentle.

He was right. They also waste more energy.

 > I would very much appreciate it if anyone could let me know if they
 > have seen anything other than standard 'lightning' sparks.
 >
 > Hope to hear from someone soon and I am delighted that this forum
 > exists as I believe Tesla was a genius and none of us mere mortals
 > have the slightest idea of what he was thinking when submitting these
 > designs.

I think a hundred years of subsequent physics actually does give us a
pretty good idea of how these things work. I think you'll find that
the list members are not in the bottom quarter of the class.

Malcolm

 > Thanks
 >
 > Chris Rutherford
 >
 >
 >