Re: Flat Spiral Tesla Coils
Sent: Tuesday, July 01, 1997 10:07 AM
To: Tesla List
Subject: Re: Flat Spiral Tesla Coils
To: Richard Wall
I believe Tesla was running his flat spiral with a tap on it. In this
manner it served in an autotransformer mode as both a primary (innermost
turn to (example) 5 turns out) and also a secondary inductor. This allowed
the complete resonance transformer to lie in one flat plane. Low
distributed capacitance is achieved due to the spacing from turn to turn as
the spiral progresses outward.
David Sloan also experimented with this concept and developed one million
volts across a water cooled tapped pri-sec system consisting of 18 turns of
1 inch dia. copper pipe. Output power level was in excess of 100
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
> Subject: Flat Spiral Tesla Coils
> Date: Monday,June 30,1997 10:45 PM
> 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
> 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.