Article:Tesla DC Thermoelectric Coils

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High Frequency Patents of Nikola Tesla

by Tim Harwood M.A.

The "Tesla Coil" was continually developed by Nikola Tesla in the 1890s. By the end of this period, it evolved into pulsed DC thermoelectric back emf voltage gain apparatus, with highly specific harmonic frequency tuning. Tesla's patents prove this. OS:Tesla transformer


Tesla's high frequency research

Nikola Tesla in the 1890s pioneered electromagnetic high frequency research. The most accurate record of Tesla’s researches in this period, is contained within his patents. When examining these documents, once should appreciate they were often the result of weeks, months, or in some cases even years of argument with the patent office, and are in consequence deliberate and considered pieces of writing.

To those who are unfamiliar with the life and work of Nikola Tesla, it is probably fair to state he is best remembered as the father of modern electricity, as the pioneer of AC electrical distribution. In this phase of his research he conducted initial tests in the low hundreds of Hertz, and his later high frequency researches with which this article is concerned, were a natural extension of this work.

The first specifically high frequency filing is There was an error working with the wiki: Code[2]. A document Tesla himself frequently cross referenced. In it, Tesla states with pride two distinct novelties, firstly the speed of switching obtained, secondly the novel method by which the make and break is made. Tesla had developed a capacitor charge circuit, whereby the voltage in the capacitor accumulated until it was sufficient to break down a dielectric air gap.

The principals cannot really be better illustrated than by reference to the Figure 1, an adapted illustration taken directly from the original patent itself. I have added an arrowed circuit path, to clarify how the breakdown of the air gap dielectric D, temporarily alters the circuit current path, and routes the accumulated charge through the load(s) G.

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Based upon a similar set of principals was There was an error working with the wiki: Code[3], illustrated directly from the patent in Figure 2. The same novel method of make and break is employed, yet with a step up transformer on the output coils, used to provide high voltage power to florescent lights, or as was also commonly illustrated in later patents, vacuum tubes. In this second patent we clearly see for the very first time all the fundamentals of the ‘Tesla coil.’ This device is a resonant air core transformer, still in use today in the television, radio, automobile, and other industries, to step up a relatively low input voltage, to relatively high output.

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The effect Tesla had discovered with this apparatus, was that at around 20 kHz and 20,000v, such a current applied to a bulb, would cause it to light up not in the ordinary fashion Edison pioneered, but rather as a plasma bulb. Today we call such devices florescent lights, and this is the origin of this technology. As was customary, Tesla was ahead of his time, and it is only comparatively recently this technology has found popularity. While the word ‘Tesla coil’ does not directly feature in the patents, the few turn primary and many turn secondary is unmistakable. If there is a central theme to Tesla’s high frequency researches in the 1890s, it is most certainly his beloved Tesla coil, and this is where it first appears, powering florescent lights. In Figure 3 on the left we see the type of equipment Tesla used in his lab to make his transformers. On the right a blow up illustration from Tesla’s 1896 ozone production There was an error working with the wiki: Code[4].

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These first two patents are especially important, because they help explain where modern ideas of what constitutes a Tesla coil came from. The universally accepted notions of what constitutes a Tesla coil, are derivative from the these two patents, as popularised in part by Lord Kelvin, who visited Tesla’s labs. AC input, capacitor charge, air gap commutation, combined with the classic high voltage air core step up transformer output.

However, a careful reading of the later high frequency patents Tesla filed, reveals the Tesla coil concept in fact underwent substantial development work in the 1890s, and the apparatus Tesla was producing in 1897, was markedly different from the apparatus he was producing in 1892. The later apparatus was in fact DC based over-unity coil pulse apparatus. This was a natural evolution, since the requirements to optimise the back emf discharge effect, are more or less identical to the apparatus and methodology pioneered in the original Tesla coil apparatus.

Basic Tesla Coil theory

A Tesla coil is an air-cored resonant transformer. It has similarities with a standard transformer, but the mode of operation is distinct. A standard transformer uses a tight coupling between its primary and secondary windings, and the voltage transformation is due to the turns ratio alone. For example, if there are 5 turns on the primary, and 50 on the secondary, the output voltage is 10 times more than the input, and the current correspondingly less.

In contrast, a Tesla Coil uses a relatively loose coupling between primary and secondary, and the majority of the voltage gain is due to resonance between the two coil systems. A normal iron core transformer works better at lower frequencies, whereas the Tesla coil is air-cored to operate efficiently typically at much higher frequencies and voltages.

In the original 1892 configuration, the spark gap is initially a non open circuit. Current from a high voltage supply, flows through a ballast inductor and charges the primary tank capacitor to a high voltage. Eventually the capacitor voltage becomes sufficient to break down the dielectric effect of the air gap, and a conductive path is formed allowing current to flow.

The tank capacitor is now connected across the primary winding through the newly conductive spark gap. This forms a parallel resonant circuit, and the capacitor discharges its energy into the primary winding in the form of a damped high frequency oscillation. The natural resonant frequency of this circuit is determined by the values of the primary capacitor and primary winding, and is usually in the low hundreds of kilohertz.

During the damped primary oscillation, energy passes back and forth between the primary capacitor and the primary inductor. Energy is stored alternately as voltage across the capacitor, or current through the inductor. Some of the energy from the capacitor is inevitably lost in the spark gap as light and heat, causing the primary oscillation to decay relatively quickly with time.

The physical closeness of the primary and secondary windings, gives rise to a magnetic coupling effect. The high amplitude oscillating current flowing in the primary, causes a similar current to be induced in the secondary coil. The self capacitance of the secondary winding, and the capacitance formed between the toroid and ground, result in another parallel resonant circuit being made with the secondary inductance, the resonant frequency of which, is determined by the values of the secondary inductance and its stray capacitances. The resonant frequency of the primary circuit is selected so as to be the same as the resonant frequency of the secondary circuit, so that the secondary is excited by the oscillating magnetic field of the primary.

In this fashion, energy is gradually transferred from the primary resonant circuit, to the secondary resonant circuit. Over time, the amplitude of the primary oscillation falls, and that of the secondary rises. When the secondary voltage is sufficiently large, the toroid is unable to prevent breakout, and sparks are formed at the top of the coil, as the surrounding air breaks down.

Eventually all of the energy has been transferred to the secondary system, and none is left in the primary circuit. In theory the spark gap would cease to conduct this point, but this does not always happen in practice, resulting in energy conducting back from the secondary to the primary circuit.

Tesla continued to strive to find improvements to this classic apparatus, for example in There was an error working with the wiki: Code[5], where Tesla used rotating oil as a medium around the point of making and break. This reduced the tendency of the current to linger in the gap between the circuit make and break point when discontinued, improving performance. But for reasons of practically, it is not surprising modern day researchers have been reluctant to implement this innovation.

Back-emf as output

But the most important innovation in Tesla’s high frequency art, occurs in There was an error working with the wiki: Code[6], whereby the current supply was passed through coils wound on a laminated iron core, with a specific pulse frequency, such that each pulse caught a remnant of the previous pulse field in the core. Or to quote Tesla’s wording, such that the core was repeatedly subject to a "partial demagnetisation".

Tesla gave few clues as to this deceptively important change in device operation, perhaps wishing to keep his secrets hidden for commercial interests, terming the enhanced output simply "discharge current". Allow me to quote from the patent, with modern terminology in brackets to clarify Tesla's meaning, "current of high electromotive force (voltage) which is induced at each break of the main circuit (back emf) furnishes the proper current for charging the condenser (capacitor)."

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Figure 4 Patent Illustration Key:

A – DC current supply

B – Laminated iron cores pulsed such as to catch the remnant of the field established in them by the previous pulse

D – Insulated teeth to break the circuit

E – Conducting teeth to make the circuit

H – High voltage capacitor

K – Tesla coil primary

L – Tesla coil secondary

Because of the apparent elusiveness of this patent, the weight of proof that this is in fact Tesla’s original back emf capacitor charge patent, comes not so much from the document itself, although it is highly suggestive, but rather from the repeated references made to this document in later filings, in which Tesla clearly marks it out as possessing characteristics distinct from his previous high frequency art.

So while previous apparatus may have manifested the point of switch closure effect in some manner, especially when operated at higher voltages, this patent appears to be the first distinct art, that we can say with reasonable confidence, was specifically optimised for the effect in question. It is the specific timing of the input pulse, creating a constantly collapsing magnetic field in the core, that is responsible for turning ordinary back-emf, into Tesla's somewhat different coupled field vector, discharge current. Tesla's physics, has been too subtle for casual researchers to grasp.

Harmonic frequency output tuning

The next high frequency patent is There was an error working with the wiki: Code[7], and in this one it is demonstrated Tesla subsequently discovered air cores are better suited to manifesting the effect than iron cores. The aether becomes the core, but due to its very fine properties, higher frequencies must be used, as the remnant magnetism of the previous pulse decays must faster than in an iron based core. Specifically, we are given important advice on optimisation procedures, not stated in any other patents, either preceding or following.

It is a well known fact that every circuit provided its ohmic resistance does not exceed certain definite limits, has a period of vibration of its own analogous to the period of vibration of a weighted spring. In order to alternately charge a given circuit of this character by periodic impulses impressed upon it and to discharge it most effectively, the frequency of the impressed impulses should bear a definite relation to the frequency of the vibrations possessed by the circuit itself. Moreover, for like reasons the period of vibration of the discharge-circuit should bear a similar relation to the impressed impulses or the charging-circuit. When the conditions are such that the general law of harmonic vibrations is followed, the circuits are said to be in resonance or in electromagnetic synchronism, and this condition I have found in my system to be highly advantageous. Hence in practice I adjust the electrical constants of the circuits so that in normal operation this condition of resonance is approximately obtained. To accomplish this, the number of impulses of current directed into the charging-circuit per unit of time is made equal to the period of the charging of the charging circuit itself, or generally, to a harmonic thereof, and the same relations are maintained between the charging and discharge circuit. Any departure from this condition will result in a decreased output, and this fact I take advantage of in regulating such output by varying the frequencies of the impulses or vibrations in several circuits. Inasmuch as the period of any given circuit depends upon the relations of its resistance, self induction, and capacity, a variation of any one or more of these may result in a variation in its period.

What Tesla is saying is that for optimal results, the frequency with which pulses are delivered into the input circuit and main coil, should be correlated with the time taken for each pulse to travel the length of the coil (period of the coil). However, in determining the period of the circuit, such factors as the volume of the capacitor and resistance of the coil must also be taken into consideration.

As regards the output circuit, the resistance of a motor may depend upon how heavily it is loaded, or the resistance of a battery may vary depending upon the charge level. Hence, to maintain optimal pulse values, fully dynamic adjustment of the pulse frequency may be required, with the discharge frequency of the main capacitor a dynamically derived function of the main coil input frequency.

Since this level of semi-intelligent functionality is difficult to implement except via modern micro controllers and software routines, it is perhaps another reason why Tesla never managed to develop this technology to commercial benefit. It also helps to explain why this effect has been so difficult to research historically, and why exotic performance gains have so often vanished under real world load scenarios, to the bafflement and embarrassment of inventors the world over.

As regards so called ‘harmonic’ relationships, a subject that has historically caused a great level of confusion in discussions of claimed exotic physics, Tesla is referring to numbers with a high number of common factors, such as 24, 48, 72, 96, 144, 192, 240, 288. The fact that a harmonic value may often substitute for an absolute value in these devices, simplifies construction and optimisation, if not always boosting absolute performance.

As can be seen, taken together, this innocuously simple paragraph illustrates the remarkable depth of understanding Tesla had gained over the somewhat obscure physics involved in manifesting the effect, despite the relatively primitive equipment with which he had to work. But what is even more remarkable, is that this clearly documented aspect of Tesla’s researches, could have been so utterly lost to history for so long. One is reminded of the wisdom that the best way to hide something important is to place it in plain sight.

Output variations

In July 1896, Tesla filed two patents in only 3 days that were later to become There was an error working with the wiki: Code[8] and There was an error working with the wiki: Code[9]. There is little to be said about them. In the former, Tesla noted "When the potential of the source periodically rises and falls, whether with reversal or not is immaterial." In other words, AC systems can be satisfactorily employed, but require more elaborate circuitry. This is one of the greatest misconceptions about Tesla coils, in later experiments Tesla in fact dropped the AC line input and adopted DC, because it was simpler to work with. In the second patent Tesla re-introduced an air gap to the proposed device, recalling Tesla's first two patents in 1891, but the inefficiency this created, clearly led the air gap system to be dropped once again.

One of the more elaborate patents Tesla filed in this series is There was an error working with the wiki: Code[10] illustrated in Figure 5. Note, this time the non conducting blocks are three times longer than the conductive areas, therefore the two input circuits are each pulsed with a 25 % duty. Additionally, the brushes are phased so that on states (discharges) never overlap. The output circuit has a toggled 50% output duty, double the duration of the input pulse.

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The backwards current surge after switch open, as always, is tapped by a high voltage capacitor, and then fed into a Tesla coil, and routed to the standard florescent lights or vacuum tubes. Specifically, the circuit appears to have been optimised for continuous high voltage output, rather than absolute efficiency, and this continual flow of high voltage has been claimed to give the device almost life like properties when tested.

The final patent in the development sequence There was an error working with the wiki: Code[11] was filed a month later, and offers a refinement in capacitor layout, which are charged in parallel and discharged in series. The physical apparatus associated with this device, is illustrated in Figure 6. The box at the bottom contains the capacitors, the center contains a small electric motor to drive the make / break contacts, the pulse coils are located on either side, and on top is the output transformer. Again, so as to remove all reasonable doubt about my analysis of these patents, I will quote directly from the patent itself, "Around the break or point of interruption I have arranged a condenser (capacitor), into which the circuit discharges when interrupted (back-emf)."

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Make / break controllers

With his customary thoroughness, having investigated the nature of the coils he was pulsing, Tesla spent several more months designing custom switches for his apparatus, specifically designed to open and close as fast as possible. This was typical of Tesla, as many times he had to redesign the low quality off the shelf parts available to him, as they did not perform to a standard he found satisfactory. Had he possessed greater practical business sense, he could have made significant profits for himself, by taking some of his improved lab equipment back to the manufacturers, and consulting on how to improve production techniques.

Tesla records in his switching patents the importance of the fastest possible switch rise / fall time, with the emphasis on the former, combined with low junction resistance, in order that switching losses could be minimized. Somewhat ironically, with these parameters in mind, the mechanical switches Tesla used, were in many respects better suited to over-unity experimentation, than many modern day semiconductor switches.

This fact has created numerous problems for contemporary researchers, making it ironically harder to do over-unity research in 2001 in some respects, than in 1897. This is perhaps the main reason why Tesla’s high voltage physics has been lost to mankind for so long. Quite simply the effect is too obscure with semiconductor parts, for anyone to reasonably stumble upon it in modern times, and regard it as anything other than a nuisance or curiosity.

Interesting commentary on the difficulties of making and breaking switches is provided in 611,719, where Tesla talks about a variety of measures he had developed to improve the efficiency of his sparking air gap commutation systems. Specifically, he noted vacuums manifested a faster closure and break, but were to be discarded for reasons of practicality. The medium within which the closure was to take place should have high insulating properties, so that the size of the air gap could be minimized. It should also be chemically inert, to protect against deterioration of the electrodes, as well as being pressurised and circulated with velocity by fan action, to lower the make / break period, especially the later. And finally, several small air gaps were found to manifest superior results to one large air gap.

Of the switching patents, I find There was an error working with the wiki: Code[12] illustrated in Figure 7 one of the most fascinating, simply because of the lengths to which it is reveals Tesla would go in his pursuit of the physics. In seeking the ultimate circuit make / break controller, one has to feel that only Tesla would go so far as to fill a drum with liquids, provide methods for rapidly rotating said apparatus, and use a mercury layer as a contact point for a spinning vane as the circuit make / break switch. At speed Tesla states the surface of the liquid becomes almost as if a solid, and a spring loaded mechanism is provided to keep the vane gently pushed down on the liquid surface, compensating for any wear and tear through use. The apparatus is as beautiful and elegant, is it is wholly impracticable. The patent also provides additional confirmation as to the extent to which Tesla had fully mastered this area of physics from a theoretical as well as practical point of view, proving he fully understood the discharge current effect rapidly decayed from the instant of switch closure, "makes and breaks, and more especially the former, should be positive and abrupt."

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Further patents provide a fascinating commentary on the problems of making and breaking circuits, and give valuable insights into the painstaking work Tesla put into optimising his technologies, attempting to work around the deficiencies of the equipment that was available to him in the period. In particular 609,245 highlights another of the problems involved in commercialising this effect:

"The loss of energy occasioned by the causes mentioned may be very considerable and is generally such as to greatly restrict the use of the circuit controller and render impossible a practical and economical conversion of considerable amounts of energy by its means, particularly in cases in which a high frequency of the makes and breaks is required."


Tesla did indeed develop a negative energy transformer in the 1890s, and in fact patented the basic methodology. But the quality of switches made available to him, and the absence of modern software control methodologies to tune the frequencies in real time to loading scenarios, made the devices largely commercially impracticable during the original 1890s research period in question. Tesla's gift to mankind, is that the beautiful pure physics he understood perfectly, but was not able to manifest commercially, was left carefully encoded in his patents for future generations, where the information was outside the hands of those who would suppress such devices.

High frequency patents

There was an error working with the wiki: Code[13] Method Of And Apparatus For Electrical Conversion And Distribution

There was an error working with the wiki: Code[14] System Of Electric Lighting

There was an error working with the wiki: Code[15] Apparatus For Producing Electric Currents Of High Frequency And Potential

There was an error working with the wiki: Code[16] Method Of Regulating Apparatus For Producing Electric Currents Of High Frequency

There was an error working with the wiki: Code[17] Method Of And Apparatus For Producing Currents Of High Frequency

There was an error working with the wiki: Code[18] Apparatus For Producing Electrical Currents Of High Frequency

There was an error working with the wiki: Code[19] Apparatus For Producing Electric Currents Of High Frequency

There was an error working with the wiki: Code[20] Apparatus For Producing Currents Of High Frequency

There was an error working with the wiki: Code[21] Electrical Circuit Controller

There was an error working with the wiki: Code[22] Electric Circuit Controller

There was an error working with the wiki: Code[23] Electric Circuit Controller

There was an error working with the wiki: Code[24] Electric Circuit Controller

There was an error working with the wiki: Code[25] Electric Circuit Controller

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Factional distillation of current

The manifestation of discharge current / coupled current is the first stage of the process, accumulated in a capacitor, in advanced configurations, Tesla then performed factional distillation of this coupled form of current. This is not in Tesla's patents, so is not part of the main article, but appears from other sources of information, i.e. Gerry Vassilatos Secrets of Cold War Technology: Project HAARP and Beyond, to have been the development path Tesla took, and is in all probability, the much rumoured free energy secret said to have been held by Tesla. I have created OS:Tesla transformer for OS collaboration, to try and validate the methods by which I believe Tesla distilled discharge current.


A person who is demoralized is unable to assess true information. The facts tell nothing to him. Even if I shower him with information, with authentic proof, with documents, with pictures -Yuri Alexandrovich Bezmenov. KGB cold war defector.

If I have seen further than others, it was because their mind control techniques failed on a trained historian. Tim Harwood 2013

See also

PowerPedia:Nikola Tesla

Directory:Nikola Tesla


Directory:Best Exotic Clean Energy Technologies

News:Best Exotic Free Energy Technologies

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Directory:Galactic Sea of Energy

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Directory:Atmospheric Electrostatic Energy

Directory:Dark Energy

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Directory:Electric Universe


Directory:Fractal Antennas as an Energy Source


Directory:Electromagnetic (overunity)

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Directory:Motor-Generator Self-Looped with Usable Energy Left Over

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Directory:Linear Magnet Accelerators

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Directory:Quantum Particles

PowerPedia:Tunnel Magneoresistance -- the TMR Effect

Directory:Solid State

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Directory:Toroidal Power

Directory:Marko Rodin Coil / Torus / Motor

Directory:Power from Ambient Electromagnetic Radiation

Directory:Gravity Motors


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