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Character
All,
"Character" Interesting title, huh? Some of you may think of this as
regarding personal traits. Many think that I am quite a character,
already! Others, that I have no character at all. I am speaking here of
the TESLA COIL'S character. I believe the character of any tesla coil is
defined solely by its "switch" or non-linear device from which
oscillation is derived.
Even the most novice among us can see that a vast gulf is affixed between
the character of a tube coil, a solid state coil, and the spark excited
coil. The more experienced of us could be blind folded and tell which of
the three were running from the sound alone at a fixed power level.
TOOBZ anyone?
The tube coil is the most mellow and non-descript of them all with its
lapping tongue of RF flame. To many, it is about as inspiring as a BIC
lighter. Those in the know, however, recognize it as the system of
choice for up-close and personal demos. It is a real star for lamp
lighting, coronal motors, and RF effects. It is quiet, clean, and
moderately efficient. One can get a nasty RF burn very easily with these
baby's. A burn that will take a long time to heal. Watt for watt, the
tube coil is a very classey system. However, its spark length
performance is abysmal and tune on this system is easily "pulled off
channel" with the slightest interference from nearby objects.
See you down at the "junction"
The solid state system was never anything more than a flea powered mouse,
iconified by the modified "flyback" and a pair of 2N3055's in a free
running, non-resonant system that would put you on your butt if you
contacted its output. Also, the sparks were underwhelming, to say the
very least, with a 1" spark being "king coil".
Thanks to Duane Bylund in the early 1990s the solid state system has
matured to its next logical stage. Many on this list serve, among them
,Alan Sharpe, have been furthering the Bylund tradition by dinkin' around
with current technology solid state switches. This crowd has brought a
further refinment to the solid state Tesla coil which places it firmly in
the big leagues of coiling and leaves dad's old flyback system of the
50's and 60's in the spare parts bin. (where it should have been all
along.)
Oddly, the solid state system is a close analog of the old tube system in
operational character and appearance. It generally produces longer
sparks than the tube coil (being a magnifier). It still is no match for
a similarly powered spark system, however. The evolution continues,
however. These systems are, again, relatively quiet, though not as much
so as their tube counterparts. They are extremely efficient, something a
spark system will never be. They are also very easy to blow up, at the
current level of refinement.
The modern solid state system differs in the main by its form usually
taking a magnifier like mantle. This was Bylund's crucial gift to this
class of system. He made a true magnifier and not an old fashion Tesla
coil. At the time of his article, a lot of folks railed against his coil
in the "letters to the editor" section in subsequent issues of the
magazine saying that Bylund's coil was not a true Tesla coil at all!
They were wrong, of course. (I didn't recognize a coiler's name in the
bunch of complainers) Bylunds coil was Tesla's darling coil and final
great Tesla coil system, but wearing solid state clothing. Its biggest
shortfall is that like the tube coil, it produces a lot of wasted RF
energy for spark enthusiasts. Thus, it does make a nice demo coil and
tube coil alternative for plasma experiments.
These systems are still evolving and lack the proper switch to allow them
to compete with the plus-ultra spark systems. Good, high power, high
voltage, high current, solid state switches are quite expensive. No
really high voltage, above 4000v, single junction solution exists,
currently.
The devine, devilish, spark!
The spark gap system is unique. They are incredibly noisey, wasteful of
energy and power, volumetrically inefficient, and produce little RF
radiation. It makes up for these short comings by being the best spark
producer yet produced by the hand of man. The spark system stands
instantly ready to be scaled to almost infinite energy levels!
Instead of the quite flutter of the tube and solid state systems we
have a crashing racket with long ribbons of fire leaping out into the
space around the system. This is a function of only one item.....
THE SPARK GAP!!!! This sloppy, ragged, half-baked afterthought of a
switch has so many bad characteristics that they are too numerous to list
or make a detailed accounting of. But...IT WORKS WITH A VENGENCE!
I have seen three types of common air gapped systems which give totally
different signatures. One of these can mime and rival the efficiency of
a tube or solid state coil!
1. The common rotary or series air gapped system at higher powers
(1KW-50KW).
These are the crashers and boomers, the frenetic freddy's. The sparks
are super long and hoppin' all over the' joint! Whether a two coil
system or a magnifier, they are real performers on spark output and waste
little of their already squandered energy on the RF radiation end. What
little energy does make it to the top terminal is all spark! With a
suitable toroid, their performance is mind boggling! Note* neither the
tube coil or the sold state coil take to top hattin' very well.
2. The Synchronous rotary system.
These systems have been around for years, but Bill Wysock seems to have
pushed them onto the promenent end of the coiling spectrum. A
Synchronous system never crashes or booms. It has what appears to be a
continous, somewhat controlled, long delicate ribbon of spark attached to
its terminal which ultimately grows and breaks and is followed by another
"creeper". The spark length of these systems are similar to #1 type, but
of a seemingly more genteel nature. Once seen, the snychronous system
can be immediately identified in seconds from the character of its
output.
Modified, mouse powered, spark systems. (choke 'em off and load 'em down)
3. At low powers, under 100 watts, one can use about 13-25 series,
static gaps and achieve good spark (similar to a tube coil) which is both
quiet and RF laden, provided a grossly over sized terminal toroid is
used. these systems can light lamps with the best of 'em. The system is
so quiet that you might accidently forget it is even on and touch a
dangerous point!! The system should have a frequency of operation above
500KHZ LOADED! I have achieved 5 inch arcs off of a 6" tall 2" diameter
coil with a 12"X3" toroid. with 17 VOLT AMPERE input energy, using a 4KV
neon and a .005 cap with 15 gaps. The input voltage to the neon is about
40VAC -at- .4-.5amp.
The Future
What lay ahead? What new forms of switches will be developed? Will we
ever have a long spark from an electronic super switch? The one thing
that is certain, the charcter of the system will be determined solely by
whatever makes it "tick" or oscillate!
Richard Hull, TCBOR