Re: Flat Spiral Tesla Coils (low temp)
Sent: Wednesday, July 02, 1997 2:14 PM
To: Tesla List
Subject: Re: Flat Spiral Tesla Coils
Use caution -- at these temps most "normal" insulations will become so
brittle that they will crack and fall off your wire -- we learned this the
hard way. Special insulations must be used and they are quite expensive.
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
> Subject: Re: Flat Spiral Tesla Coils
> Date: Tuesday,July 01,1997 11:16 PM
> From: Bert Pool[SMTP:bertpool-at-flash-dot-net]
> Sent: Tuesday, July 01, 1997 6:06 PM
> To: Tesla List
> Subject: Re: Flat Spiral Tesla Coils
> > From: Richard Wayne Wall[SMTP:rwall-at-ix-dot-netcom-dot-com]
> > Sent: Monday, June 30, 1997 5:46 PM
> > To: Tesla List
> > Subject: Flat Spiral Tesla Coils
> > 6/30/97
> > Nikola Tesla in the June issue of the 1919 Electrical Experimenter
> > wrote the fifth article in a series called "My Inventions". In this
> > article he states that his laboratory was destroyed by fire in 1995.
> > NT wrote, " . . . . This calamity set me back in many ways and
> > most of that year had to be devoted to planning and reconstruction.
> > However, as soon as circumstances permitted, I returned to the task.
> > Although I knew that higher electro-motive forces were attainable with
> > apparatus of larger dimensions, I had an instinctive perception that
> > the object could be accomplished by the proper design of a
> > comparatively small and compact transformer. In carrying on the tests
> > with a secondary in the form of a flat spiral, as illustrated in my
> > patents, the absence of streamers surprised me and it was not long
> > before I discovered that this was due to the position of the turns and
> > their mutual action. Profiting from this observation I resorted to the
> > use of a high tension conductor with turns of considerable diameter
> > sufficiently separate to keep down the distributed capacity, while at
> > the same time preventing undue accumulation of the charge at any point
> > The application of this principle enabled me to produce pressures of
> > 4,000,000 volts which was about the limit obtainable in my new lab
> > oratory at Houston Street as the discharges extended through a distance
> > of 16 feet. A photograph of this transmitter was published in the
> > Electrical Review of November, 1998. . . . "
> > Tesla goes on to say that he had to go out in the open and this
> > ultimately was why he went to Colorado Spring in 1999 where he remained
> > for more than one year.
> > Recently, others on this list have had NT's same experience of very
> > unimpressive flat spiral discharges. Tesla nailed the problem of high
> > interturn distributed capacitance and seems to have corrected it with
> > spaced windings and high tension conductors. I'm not sure he could
> > accurately measure a 4,000,000 volt discharge, but he could probably
> > quite accurately measure a 16 foot discharge. To wit, our TC
> > measurement technologies have not changed that much in a century.
> > None the less, Tesla was quite successful in design and function of his
> > flat spiral geometries which were far more compact than his helical
> > coils. To that end, perhaps we should investigate the various
> > parameters of flat spiral secondaries such as distributed capacities
> > and inductances as we do in the helical varieties. After
> > "conventional" flat spiral secondaries are re-researched, a logical
> > extension would advance to "magnifier" spiral secondaries. And,
> > ultimately flat spirals in liquid N2.
> And it is for similar future experiments that I have
> acquired a 40 liter dewar flask for storing a large quantity of
> liquid N2! My first low temperature tests will be with a
> conventional "extra" coil, but I too am fascinated with the
> possibilities of large flat spiral secondaries. It will be far
> easier to insulate and immerse a small extra coil like Richard Hull's
> "E" coil (approx. 4 inch by 12 inch) than a flat spiral.
> Bert Pool