Re: Restoration of an old electrostatic machine / Piffard Hyperstatic Tesla Coil

Jeff Behary wrote:

> What an incredible machine!  Those are the nicest static electric machine
> pictures I have seen in a long time, and the only "real photograph" pictures
> of a multi-plate machine that I have seen.
> A real work of art!

Thank you. It was a lot of work to restore it, and there is some work to
do yet (adjustments, motor, control panel). It is the only old Bonetti 
machine that I have seen. I will take better photographs (true ones. My
digital camera is horrible as a camera) when the restoration is complete
> As for running a Tesla Coil from a Static Machine, there was a small gadget
> from the turn of the century called a "Piffard Hyperstatic Transformer",
> that was merely 2 leyden jars with a spark gap across the top posts, and a
> small bi-polar Tesla Coil connected to the outer terminals.  (basic
> old-style 2-series condenser arrangement for TC: like spark gap across
> induction coil with 2 condensers in series with TC)

Can you mention references about from where come this name? This
connection is seen frequently in old literature, usually associated with
induction coils. It certainly works too with a static machine. The 
connection is particularly convenient, because there is no need of high
insulation in the connections of the outer plates of the Leyden jar
capacitors. I will see if I can get capacitors that tune correctly
with the coil. Along with that machine come two sets of large Leyden
jars, with one jar broken.
> I have made one of these in the past, and it was powerful enough to light up
> one of the geissler type vacuum electrodes, and the frequency was extremely
> high from the Tesla Coil -- sparks were very soft, low current, very high
> frequency.  I was using a Wimshurst machine that was adjusted to make 2-3"
> sparks to power it.

With Leyden jar capacitors, the frequency must be rather high, because
difficult to make capacitances of more than a few 100 pF in this way.
Some pictures that I have seen show really huge jars, as in this 
Oudin coil:
The connection works very well for powering gas tubes of several kinds.
I have used it to power neon tubes and Crookes tubes with success.

> So far as sparks go, the results weren't terribly impressive, but show how
> to get Tesla type currents from static type currents. (well, "sort of" in my
> opinion)
> 16 - 20" induction coils were used to power Oudin Resonators, as were to a
> smaller extent large multi-plate static electric machines.  You might not
> get the longest sparks from a static-electric driven Tesla Coil, but perhaps
> a very interesting display of "effluve treatments" from a Tesla Coil and a
> pointed set of metal electrodes for the top terminal directed towards the
> patients--er, spectators!

The question is power. Even a large static machine as the R&M doesn't 
produce more that a few 100 W of power...
> Gee, some people find the neatest toys...


Antonio Carlos M. de Queiroz