1. TESLA COILS ARE JUST AIR-CORE TRANSFORMERS? Not exactly.No, Tesla Coils are very different from turns-ratio conventional transformers such as air-core induction coils.
First of all, Tesla's later work wasn't based on the transformer.
Instead, his device was a single coil connected to an AC dynamo; a
with electrical energy being injected into one end and high voltage
appearing at the other.
No primary coil. A very strange invention! Its closest relative is one
that's common in ham and cb radio: the base-driven
quarter-wave groundplane antenna. Today Tesla's one-coil
device has come to be known as the "Magnifier" as opposed to a
"transformer." Tesla drove such coils directly through their ground
connection. Or, sometimes he adjusted the amount of coupling by adding a
conventional transformer between the dynamo and the main coil, but this
wasn't essential. And finally: it's perfectly possible to build a Tesla
coil with capacitive coupling: with a single coil, AC-driven metal
plate placed near its base, and no primary coil.
As for older transformer-type Tesla coils such as "theatrical"
...conventional transformers achieve voltage step-up based on
turns-ratio of their primary and secondary coils. But with Tesla coils
the turns-ratio is nearly irrelevant. Instead, the step-up effect is
caused by the phenomenon known as "resonant rise." In Resonant Rise, the
central role is played by the bell-like ringing or "Q-factor" of the
resonant coils. The longer a coil can ring, the greater the energy it can
accumulate, and the higher the voltage it can produce. In this sort of
losely-coupled, tuned-primary tuned-secondary RF coil, Z and Q are the
main characteristics, not turns-ratio.
Also see: What is a Tesla Coil, REALLY?
2. THE "SKIN EFFECT" PROTECTS US FROM TESLA COIL ZAPS? Wrong.WRONG!
Wrong wrong wrong. This misconception is actually hazardous. It's also
very widespread and appears in numerous books. The true situation has
serious safety implications. If you misunderstand these issues, you
could injure yourself and others.
The skin-effect mostly applies to extremely conductive materials:
to wires and metal objects. Not to salt water, not to hamburger.
bodies aren't metal.
At the usual operating frequencies of Tesla
the "skin depth" of electric currents in metals is a fraction of a
millimeter. But for human flesh, skin depth is around 50cm, HALF A METER.
If you're zapped by a big TC, the path of current isn't on the surface.
It's internal. You could accidentally cook your bone marrow. Don't
forget that two common devices rely on this effect for their operation:
2GHz microwave ovens cooking the inside of meat, and in sports medicine,
27MHz diathermy muscle-warming devices used for deep tissue
heating. These devices employ frequencies a hundred times higher than
Tesla Coils, yet the "skin effect" isn't preventing the currents which
produce the deep heating.
Why then no shocks? If TCs can't electrocute you, well, why not? It's
simply because human nerves don't respond to AC
frequencies higher than about 5KHz. Tesla Coils can drive fairly high
currents through our flesh, but they're operating at far higher than 5KHz.
More like 100 to 1000KHZ, so we can't feel the electric shock; only the
heating effects of the currents.
So, whenever you allow the arcs of a large TC to strike a metal wrench
held in your hand, the current dives deep into your muscles. If your
joints seem a bit painful afterwards, that's because you were being
slightly cooked internally.
(human tissue resistivity in ohm-cm is 50-200)
3. EDISON TOOK TESLA'S IDEAS WITHOUT PAYING, SO TESLA QUIT THE COMPANY?Nope. In hindsight, basic physics shows that Edison's "long legged Mary-Anne" design was misguided. It might even be called an embarrassingly stupid design. While working for Edison, Tesla spent a year designing vast improvements using short-path cylindrical stators and very compact iron cores. This was all wasted; they fell on deaf ears probably because these weren't small incremental advancement, but instead were revolutionary. They showed clearly that Edison's belief in excessively long iron cores was wrong. (Imagine if someone recommended discarding Edison's wax-cylinder phonograph and instead using flat disks? Would Edison welcome such changes, or despise them? Similar situation!) If Edison had adopted Tesla's redesign, the Edison Corp might own those products, but they'd clearly be Tesla dynamos and Tesla motors, not Thomas Edison inventions.
Tesla quit because of this issue, but Edison apparently didn't use any
of Tesla's compact
core designs. They later ended up as a main feature of the Westinghouse
product line. Edison only adopted them many years later. The "Long
legged" electric motors and generators faded
away, and Tesla's short-core cylindrical motor designs (even for DC
motors!) soon took over the world.
Oddly enough, Edison's industrial DC dynamos in his European branch
were being redesigned by J. Hopkinson, based on basic physics knowledge.
They eventually pushed out the Long Legged format in Edison corp.
(Speculation: Hopkinson succeeded within the Edison Co., where Tesla
failed, because the distant Edison branch in Europe wasn't aware that the
efficient short-path designs were probably a personal affront to Edison
himself, while the improved efficiency of this design were of course
obvious to their European customers.)
By the way, and this is a painful reflection, it was Schmidt and I who developed this type of frame and this general arrangement which is universally adopted now ...I remember years ago, some of my friends, Messrs. Crocker and Wheeler, started with those long magnets and I told them, "The sooner you throw these away and adopt (my) construction, the better it will be for you." They have got it now; it is all right. - N. Tesla, 1916Edison fan
4. TESLA WAS SCREWED OVER BY FINANCIERS AND DIED PENNILESS? NOPE.
Don't forget that Tesla lived his life in a suite of rooms in downtown
NYC. That's the situation of a penniless failure? Not quite! Sure, his
inventions should have made him fantastically wealthy. They didn't, but
that wasn't only the fault of financiers. Besides, "not a billionaire" is
very different than being "penniless." Don't forget that Tesla worked as
a consulting engineer for years following the failure of Wardenclyffe
(remember his bladeless turbine project?) He lost Wardenclyffe because he
gambled on putting his own income into equipment and experiments, then
he ignored bills for hotel rent, and then his landlord took over the
Wardenclyffe property to cover those bills. Apparently Tesla held back no
retirement savings, and put every cent into self-funding his personal lab.
That wasn't the fault of "financiers." After the 1929 financial crash,
Tesla perhaps would have died penniless, except the Tesla Foundation and
Yugoslav government paid him a monthly pension of $7,200 (that's in 1940s
dollars, around $100,000/yr today.) Even so, Tesla still put every cent
into research, failed to pay his rent, and during his last years was still
two years behind on the bills!
Tesla's financial problems had many causes. For example, he
absolutely refused to charge for (or even patent) any of his medical
inventions, nor would he pursue the many idea-thieves who were reaping
rewards for those inventions. His medical devices made millions for the
companies who produced them without attribution to Tesla. Also, Tesla did
court investors, but he then spent all his own hundreds of thousands in
personally paying for research equipment and entire labs. When
Westinghouse was pushed to the wall by stockholders, Tesla threw away
millions (possibly billions in today's money) by tearing up his
dollars-per-watt contract. In the end this didn't even help
Westinghouse, since the
stockholders took the company away from him anyway. Another: while
building Wardenclyffe and dealing with JP Morgan, Tesla's remaining
fortune was nearly wiped out in a stock crash. And finally, his major
wealthy supporters died: Westinghouse after being forced out of his
company; JJ Astor went down with the Titanic.
Perhaps part of the "penniless" myth comes from Tesla's odd health
beliefs and dietary experiments. At the end of his life he practiced
extreme vegetarianism, and people of the time might conclude that he was
too poor to afford normal food. Rumor has it that he reduced this even
further, and lived entirely off milk.
5. WORLDWIDE WIRELESS POWER CAN'T WORK, INVERSE SQUARE, AND LOSSES ARE TOO GREAT?Wrong, but this old chestnut was used against Tesla right from the start. In the 1950s, this particular bit of ridicule became irrelevant, when W. O. Schumann discovered the low-frequency ionospheric waveguide effect and Earth-resonance. The central idea here is that, if losses really did dominate; if EM pulses cannot circle the Earth multiple times, then the Earth-resonance spectrum peaks cannot exist.
For Schumann Resonance to occur, the waves cannot radiate out into
space, instead they must travel repeatedly around the entire Earth over
and over before dying away. Going further ...the older measurements of
Earth's VLF Q-factor gave a value ~10, meaning that EM waves will circle
the Earth ten times before reducing to about half. Newer Q-factor
measurements give values one or two orders of magnitude higher, so EM
pulses will pass around the Earth hundreds of times before fading. Yet the
same pre-1950 wrong argument about "excessive losses" is still being used
against Tesla today. There are quite good arguments against Tesla's
scheme, but this particular debunking ...was itself debunked decades ago.
Does the P=1/r^2 inverse square law forbid worldwide wireless? Nope, and
it's for the same reason that food in a microwave doesn't need to be
near the magnetron port. The microwave oven is a driven resonant cavity,
and so is the Earth. Both employ standing waves, and both exhibit
patterns of intense
e-fields far from the actual transmitting antenna. There are nodes
and antinodes, and yes, a receiver will work poorly if placed right at a
Think about it this way: if your power receiver is placed out in the
Indian Ocean exactly
180deg away from the transmitter in the USA, wouldn't you expect to find
a HUGE signal out there? Don't all the waves focus themselves at
the opposite point in
the atmosphere? Yes, because the system is using a driven standing wave,
not a conventional radio system. (And if you traveled away from that
distant maximum-spot, the power would decrease *NOT* as inverse square,
but as cosine,
falling to near zero at the 1/4 wavelength 1st node location, and then
rising again to the peak in the next ring-shaped antinode.)
6. TESLA WAS CRAZYThe public regarded Tesla as crazy for speculating that intelligent life existed on other worlds ...that he'd received numeric code signals coming from outer space ...and that the signals appeared only during hours when the planet Mars had peeked above the horizon. ALIENS!
The scientific community regarded Tesla as crazy for claiming that
radio waves could bend over Earth's horizon, that the waves could travel
repeatedly around the entire Earth, and that a radio broadcasting station
could send signals to receivers located anywhere on the planet. All of
these ideas were direct violations of known physics at the time (this was
before the Heaviside Layer, even before Marconi.) Their disdainful
disbelief in worldwide radio apparently prevented any investigation of
Tesla's discoveries, and Earth Resonance was only rediscovered decades
later after the parties in the controversy were dead.
Tesla was obviously crazy for building that giant tower at Wardenclyffe.
Hold on a sec. That giant construction was for worldwide broadcasting
using a megawatt transmitter. What did BBC world service use? And Voice
of America? And the USSR competitors? GIANT RADIO TOWERS AND MEGAWATT
TRANSMITTERS. So perhaps Tesla only seems crazy because investors pulled
out, and Long Island never became a transmitter complex for the first
major worldwide radio service? Or was he only crazy because his giant
radio tower was wood rather than metal, was also much shorter than many
others built later, and his version had a metal sphere on top? Marconi's
antennas blew down repeatedly in storms. Wardenclyffe tower, when
dynamited, remained complete as it lay on its side. (PS, Tesla's letters
reveal that the Wardenclyffe tower was supposed to be three to six times
taller than it was, but Tesla couldn't afford the newly-quoted
7. THERE'S A GLOBAL CONSPIRACY TO SUPPRESS TESLA!No, because suppression doesn't require any conspiracy. Tesla can be suppressed just fine by widespread disbelief and universal dismissive disdainful attitudes. All those people who deride Tesla's work, and who also make it their business to attack his supporters with sneering contempt ...they didn't attend any secret meetings. No conspiracy. It's the same with bigots and bullies everywhere: their motivations are individual and personal, and bullies don't have to be Hired-By-The-Oil-Companies before embarking on a poison-pen campaign against their weak defenseless victims. Think a second: when racial or religious minorities complain about widespread ongoing suppression, they never magically turn into "conspiracy theorists." Women aren't kept down in job advancement and salary because of secret conspiracies of sexist employers.
So why is it that when Tesla-supporters complain about the rotten
treatment dished out
by the history experts and contemporary scientists, why all the
accusations of "Conspiracy Theory?" Isn't this a logic fallacy, "straw
Heh, perhaps those who complain loudest about Tesla
supporters being conspiracy-theorists ...are actually GOVERNMENT AGENTS
who were planted to DISCREDIT the community of Tesla
fans by equating "Conspiracy Theorists" with our legitimate
complaints of suppression. It's all a BIG CONSPIRACY to make it look like
a conspiracy when actually it ISN'T a conspiracy!!!! (Well, that's my
all-caps exclamation-points THEORY at least.) :)
8. A MAGNIFYING TRANSMITTER IS A 3-COIL DEVICE?
No, since we actually don't know what Tesla's Magnifying Transmitter
The modern "Tesla coiler" community has declared that a any
base-driven 3-coil device is a "Tesla Magnifier," yet Tesla himself had
been using such
setups at least since 1892, so to him they were not a new breakthrough
deserving a new name. What was being magnified in the new "Magnifier"
device? Not voltage, since all his coils did that. Perhaps peak power
was "magnified" during pulse-mode operation? Or perhaps the term
was simply part of Tesla's marketing hype for the Wardenclyffe project: an
improved coil with heavy conductors, extensive grounding system, and a
terminal covered with small adjustable hemispheres.
Or there's this pure speculation: apparently the Wardenclyffe tower contained racks for supporting some large glass devices: powerful sources to pre-ionize a discharge path above the main terminal. A Tesla Coil transmitter with a glass globe on top is fundamentally different from his other inventions. Perhaps "Magnifier" refers to a special Tesla coil including a gigantic plasma-contactor: a device for generating an invisible plasma-antenna much taller than the physical tower's height.
I saw that I would be able to transmit power provided I could construct a certain apparatus -- and I have, as I will show you later. I have constructed and patented a form of apparatus which, with a moderate elevation of a few hundred feet, can break the air stratum down. You will then see something like an aurora borealis across the sky, and the energy will go to the distant place. ...I came to the conviction that it would be ultimately possible, without any elevated antenna --- with very small elevation --- to break down the upper stratum of the air and transmit the current by conduction. -N. Tesla 1916
9. THE US GOVT BLEW UP WARDENCLYFFE TOWER TO PREVENT WW-1 GERMAN SPIES FROM CONTACTING U-BOATS? NOPE.No, actually it was destroyed by its new owners after Tesla went bankrupt. Tesla hadn't been paying rent on his downtown NYC apartment suite, so his landlord (the Waldorf Hotel) took over the mortgage on his land at Wardenclyffe. They wanted to sell it to developers, but the giant "crazy tower" had greatly lowered the value on the property. They had it dynamited. Later Hugo Gernsback in his magazine "The Electrical Experimenter" published several fearmongering articles about foreign "spies" erecting hidden secret radio antennas to communicate with German submarines off the coast. His magazine claimed that the US Government destroyed Tesla's tower because people were convinced it was being used by german spies. But actually the situation was much like the recent one at Wardenclyffe today: Afga, the owners of the Wardenclyffe land, still wanted to demolish Tesla's brick lab building in order to make the land more attractive to real estate developers.
10. TESLA DESIGNED THE NIAGARA FALLS GENERATORS?No, George Forbes designed the inside-out "umbrella design" dynamos with no sliprings, with static center coils and rotating outer field coils. But this basic design was already in use elsewhere. Tesla did patent the AC power grid. Perhaps the confusion arises because the actual generators did feature a bronze nameplate with Tesla's name and patent numbers.
11. DON'T TRUST TESLA BECAUSE HE ALWAYS EXAGGERATES?No, and that's circular reasoning. Here's the circle: first, Tesla describes what his latest invention can do, should it ever be funded and built. Skeptics, without evidence, accuse him of exaggerating. His invention is never built, so nobody knows whether Tesla was right. Now repeat! After many years Tesla has described many inventions which were not funded and never tested. His enemies accuse him of being an untrustworthy habitual exaggerator, but this is based on their own string of assertions that Tesla's inventions wouldn't have worked, had they actually been tested. In other words, they claim that Tesla is an exaggerator, based on the fact that they've repeatedly accused him of exaggeration. They act as if his devices were all tested and shown to fail. But for all we know, if investors actually let Tesla build his creations, all would have worked exactly as he described. Or not! Nobody can claim that Tesla was OR WAS NOT trying to fool people with intentionally overblown claims *unless* we first fund his projects and watch them succeed/fail.
(Note that even Wardenclyffe never "failed" in this respect,
instead Tesla ran out of money before the device was up and running.)
Science involves "Let the
experiment be made," not "bold untested ideas are as crazy as they seem;
A less irresponsible method of examining untested devices and determining
Tesla's trustworthyness would be to examine his track record. In the past
did he make any apparently crazy claims which actually proved to be crazy?
In the mid-1800s everyone knew that brushless motors were impossible, and
in addition, DC is the obvious choice for power systems (otherwise the
great Edison wouldn't have chosen it!) Tesla's crazy AC motor ideas
couldn't attract a single investor in Europe. Finally after his move to
the USA, Westinghouse takes him seriously, and all of Tesla's "impossible"
claims are completely vindicated. Tesla was right all along. Any
physicists calling the induction
motor a "perpetual motion machine" were shown to be fools. The entire
expert community was wrong, while one lone voice was right.
claims to send signals around the curve of the Earth and that the Earth
has a fundamental resonance and overtones. He claims that a megawatt
transmitter could be built to send broadcasts to the entire world. This is
impossible: goes directly against 1890s physics. Tesla keeps his radio
experiments secret. Marconi does not, and performs the impossible by
inexplicably broadcasting around the curve of the Earth.
(Later, ionospheric reflection and Heaviside's layer is discovered.)
Then, oddly, the scientific community never bothers to look for Earth
resonance. It was real, of course. Today it's named for its
"discoverer," W.O. Schumann. Tesla's "physics-violating" crazy idea is (silently)
vindicated. Tesla invents other ridiculous things: vehicles with
transparent bubble cockpits, particle beam weapons, secure encoded
communications, cruise missiles, VTOL aircraft. All are obviously
ridiculous and were bad-mouthed in public. None attract any investors,
yet each is vindicated decades later.
TESLA LIT UP 200 BULBS, 26 MILES FROM HIS TRANSMITTER!
This claim was in the O'Neill biography of Tesla. No other evidence.
But wait a minute. Was Tesla bragging about sending kilowatts of wireless
power over that distance? Or might he have been bragging about managing
to transmit actual genuine signals over that distance? In 1899 neither
one had been done, so it could have been the second one.
That 26 miles ...was it roughly the distance from his lab to Pike's Peak?
If so, here's a bunch of pure speculation below.
Why would *you* decide to set up a huge bank of bulbs ~30 miles away,
for radio experiments? (Not Tesla. You.) It's obvious: it's for
instantly testing distant receiver equipment. Yes, I could pay a
telegraph company to string 40KM of wires and poles out to a distant
receiver shack. Or I could have my assistants riding horseback, back and
forth daily, delivering timed lab-notebook entries of the receiver
readings. Or they could be signalling me at the main lab with large
sun-mirrors. Or ...or ...I could set up a huge cluster of BATTERY
OPERATED light bulbs, then view them through a telescope. High watts,
large battery bank needed, to be seen 30mi away in daylight.
Rats, that doesn't work! The problem is that anything more distant
than ~15KM is hidden by the curve of the Earth. I'd need a tower a
quarter-mile tall, with bulbs on top. Unless! Ho ho ho, unless I find a
laboratory location with a nearby mountain, and I place my receiver-shack
at a few hundred feet elevation, up in the foothills with dirt roads.
Yessss, a distant lab way out in the boonies, with no industrial spies
watching my every move, even no educated eyewitnesses. I'd pulse my
transmitter, and watch the distant bank of bulbs through my binocs, and
instantly I know the power level needed to trigger the receiver. Sweep my
beam across the receiver, plot its sectional profile!
Mister Cisco! Pack all the trunks, we're taking the next train to
Hmm, oddly enough, three years before his 1899 lab, Tesla apparently
was in Colorado Springs, even climbed up Pikes Peak
and performed resonance experiments with portable radio equipment. Wow.
13. TESLA DISCOVERED X-RAYS!yes and no.
glass plate x-ray of a human foot inside a shoe, sent to Roentgen
massive burns to chest of Tesla worker
"sensitive brush tube" of 1892 a prodigious source of x-rays, same problem with most carbon-button lamps.
14. TESLA COULDN'T HAVE DISCOVERED X-RAYS: VACUUM PUMPS WEREN'T GOOD ENOUGHWrong. In his 1892 UK lecture to the Royal Society Tesla describes cathode-ray glass fluorescence and the (accidental, unrecognized) process of ion-pumping to pressures below glow-discharge threshold. His "sensitive brush" tube as well as some of his carbon-button lamps should have been prodigious sources of soft x-rays. Like Roentgen, Tesla could easily have unexpectedly encountered fluorescing screens and fogged film plates. Apparently his NYC lab was full of large film plates stacked on edge along the walls, since he was experimenting with photographers with artificial lighting. But all this could have started some time before 1892, years before Roentgen.
15. THE SECRET OF TESLA'S DEATH-RAY IS LOSTBrought from behind the Iron Curtain in 1984.
A huge VandeGraaff DC generator with a fluid pump replacing the physical belt, powering a weapon based on a sort of water-jet cutter using electrically-accelerated micro-droplets of tungsten or mercury.
16. TESLA'S "STATIC ELIMINATOR" IS A PAIR OF ADJUSTABLE PANCAKE COILSNo, instead it was a pair of adjustable, disk-shaped wooden enclosures, each of which contains several coils and capacitors.
By the term "static eliminator," Tesla was describing an invention
somewhat akin to Edwin Armstrong's FM radio scheme: a system which was
immune to thunderstorm static, such static being AM-only. In other words,
FM radio is a "static eliminator" invention.
We have little direct evidence of how Tesla's version worked, but it
was probably a variation on spread-spectrum "frequency hopping." Most
probably it was a spinoff from his "Method of Individuation," of secure
and non-interceptable comms employing the concept of the "Wave Complex."
Wave Complex was a signal employing a beat-wave or "line-splitting"
frequency effect produced by an excited multi-resonator device. In modern
terms this was FHSS, a Spread-Spectrum comm system based upon near-random
Frequency-hopping. But Tesla's frequency-hopping was analog, not digital;
and his random hopping effect was produced naturally via several
interacting tuned circuits. Visualize a radio receiiver with several
tuning knobs for a channel, rather than just one knob, and where
thunderstorms cannot duplicate the odd multi-peak spectrum to which only
the special receivers will respond. "Static free" reception like FM! But
based on spread-spectrum technique.
"Static Eliminator" was a cleaned-up prototype; a demonstration model to show off Tesla's unjammable radio modulation principle which he named "Method of Individuation".
It is what I call a 'static preventer.' A great trouble, when I came to Colorado, was that I could not 'operate' at all. You know that the static interference is today the great bane of the wireless transmission. The reason for that is defective construction of the plants, but with this invention I am enabled to even make these defective plants operate satisfactorily.
17. THE TESLA-PROMOTERS ARE LYING. EVERYONE IS FAMILIAR WITH TESLA'S ACCOMPLISHMENTS!
18. TESLA IS SERBIAN! TESLA IS CROATIAN!
19. TESLA CAUSED THE TUNGUSKA BLASTThe idea that Tesla blew up the Tunguska forest seems to have been started by a 'psychic channeler' in the 1980s. It happened when he was asked (during a trance state) about the cause of the explosion. He said it was an experiment gone wrong, then in later questions revealed that it was Tesla's experiment. But besides psychic channelers, there are even more problems with this explanation...
1. A 10 megaton blast, or about 40 billion megajoules, would require broadcasting radio energy at a level of 10 megawatts for 130 years (that is, if the process was 100% efficient, longer if not.) In other words, the power-grid connected to Wardenclyffe can't produce megaton-scale explosions.
So, Tesla could not have caused the blast unless...
So "Tunguska blasts" may possibly be man-made. Still there's #2, and
it would require an antenna very much larger than Wardenclyffe tower to be
able to transmit anything more than a tiny-wattage signal at VLF
20. TESLA COILS ARE AMAZING LIGHTNING MACHINESActually, if they're making lightning, they're being misused according to Tesla. Tesla coils are radio devices better known as "Spark Transmitters." (...theatrical coils used for decades in Vaudeville and Side Shows)
21. TESLA COILS ARE ALWAYS HORIZONTAL AND UNGROUNDED. ANY VERTICAL COIL IS AN OUDIN COIL.
Back before WWII, this strange notion was heavily propagated by hobbyist
radio magazines. Vertical coils are always called "Oudin Coils?" But
used both configurations. (coughWardenclyffe&Colorado) Perhaps the idea
was motivated by confusion over Marconi's stolen "Spark Transmitter"
system ...which of course was a Tesla Coil.
The "Tesla coil" was actually invented by three separate people: Thompson,
Oudin, and Tesla. Their discoveries were independent. Thompson and Tesla
both investigated capacitor-discharge, and found that the damped ringing
impulses could be stepped up to high voltage. But when Thompson and Tesla
faced off in the press, Thompson politely backed down and gave the credit
to Tesla. At about the same time Oudin in France was doing the same
thing. Oudin's was a single coil with a clamp-on tap (although a similar
setup appears in Tesla's 1892 presentation to the Royal Society.)
More important, Oudin's was
exclusively a medical invention for "electrical therapy," while Tesla's
was intended to be a radio transmitter. So, an Oudin coil *IS* a Tesla
coil, which *IS* a Thompson coil.
22. EDISON BURNED DOWN TESLA'S LAB IN COLORADONo, don't be misled by stuff you see on TV. "The Prestige" got it wrong, and Tesla's CS lab was never burned down at all. Tesla went back to NYC, and had much of the lab sold off as scrap.
23. OK, THEN EDISON BURNED DOWN TESLA'S LAB IN NYCUmm...