Tesla coil

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A Tesla coil is a series of electrical resonance transformers designed by inventor Nikola Tesla in 1891. It is used to produce high voltage, low current, high-frequency electric alternating current. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electrical circuits.

Tesla uses this circuit to conduct innovative experiments in electric lighting, phosphorescent, X-ray generation, high-frequency alternating current phenomena, electrotherapy, and the transmission of cordless electrical energy. The Tesla Coil series was used commercially in sparkgap radio transmitters for wireless telegraphy until the 1920s, and in medical devices such as electrotherapy and purple devices. Currently, their primary use is to show entertainment and education, although small rolls are still used as leak detectors for high vacuum systems.

Video Tesla coil

Operasi

Tesla coil is a radio frequency oscillator that drives an air-core resonant transformer to produce high voltage at low currents. The original series of Tesla as well as the most modern coils use a simple spark gap to generate oscillations in the tuned transformer. More sophisticated designs use transistors or thyristor switches or electronic oscillators of vacuum tubes to drive the resonance transformer.

Tesla coils can produce an output voltage of 50 kilovolts up to several million volts for large coils. The alternating current output is within the low radio frequency range, usually between 50 kHz and 1 MHz. Although some oscillator-driven coils produce continuous alternating current, most of Tesla's coils have pulsed output; The high voltage consists of a fast row of radio frequencies alternating current.

Tesla spark-spirited coil circuits are common, shown below, consisting of components:

• High voltage supply transformer (T) , to drive AC mains voltage to high enough voltage to jump over the splash gap. The typical voltage is between 5 and 30 kilovolts (kV).
• The capacitor (C1) that forms the circuit set with the primary winding L1 of the Tesla transformer
• A slit (SG) that acts as a switch on the main circuit
• The Tesla coil (L1, L2) , an air-core core-resonant transformer, which produces a high output voltage.
• Optionally, the capacitive electrode (top load) (E) in the form of a fine metal sphere or torus attached to the secondary terminal of the coil. Large surface area suppresses premature air damage and arc discharge, increasing Q factor and output voltage.

Resonant transformer

The special transformer used in the Tesla coil circuit, called a resonant transformer, an oscillating transformer or a radio frequency transformer (RF), functions differently than the ordinary transformer used in the AC power circuit. While an ordinary transformer is designed to efficiently transfer energy efficiently from primary to secondary winding, the resonant transformer is also designed to temporarily store electrical energy. Each winding has its transverse capacitance and functions as an LC circuit (resonant circuit, tuned circuit), storing electrical energy oscillating, analogously to the tuning fork. The main roll (L1) which consists of relatively few turns of heavy copper wire or tubing, is connected to the capacitor (C1) through the splitting gap (SG) . The secondary coil (L2) consists of many rounds (hundreds to thousands) of fine wire on a hollow cylindrical shape inside the primer. The secondary is not connected to the actual capacitor but also functions as the LC circuit, the inductance (L2) resonates with the stray capacitance (C2) , the number of parasitic capacitances lost between coil windings, and capacitance of toroidal metal electrodes attached to high voltage terminals. The primary and secondary circuits are tuned so that they resonate at the same frequency, they have the same resonant frequency. This allows them to exchange energy, so the oscillating currents alternate back and forth between the primary and secondary windings.

The strange design of the coil is dictated by the need to achieve low resistive energy loss (high Q factor) at high frequency, which produces the largest secondary stresses:

• A typical power transformer has an iron core to increase the magnetic coupling between the coils. However at high frequency iron core causes energy loss due to eddy current and hysteresis, so it is not used in Tesla coils.
• The usual transformer is designed to be "tightly paired". Because of iron core and rolling distance, they have high mutual inductance (M) , coefficient coupling is close to unity 0.95 - 1.0, which means almost all main magnetic field winding through secondary. The reverse Tesla transformer is "loosely coupled", the primary winding is larger and separated from the secondary, resulting in a lower reciprocal inductance and the coupling coefficient of only 0.05 to 0.2. This means that only 5% to 20% of the magnetic field from the primary coil passes through the secondary when the circuit is open. Loose couplings slow down the energy exchange between the primary and secondary coils, allowing the oscillating energy to remain on the secondary circuit longer before returning to the primer and beginning to dissipate in the spark.
• Every winding is also limited to one layer of wire, which reduces the loss of proximity effects. The main one carries a very high current. Since high-frequency currents are mostly flowing on the surface of the conductor due to skin effect, they are often made of copper tubes or strips with large surface area to reduce resistance, and their turns are spaced apart, reducing the loss and the close curvature of the turns.

The output circuit can have two forms:

• Unipolar - One end of the secondary winding is connected to a single high-voltage terminal, the other end is grounded. This type is used in a modern coil designed for entertainment. The main winding is located near the bottom, low end secondary potential, to minimize the arc between the reels. Since ground (Earth) functions as a return path for high voltage, the streamer arcs from the terminal tend to jump to nearby grounded objects.
• Bipolar - There is no secondary earthed coil end, and both are brought to the high-voltage terminals. The primary winding is located at the center of the secondary coil, spaced equally between two high-potential terminals, to prevent arcing.

Operation cycle

The circuit operates in a fast and repetitive cycle where the supply transformer (T) fills the primary capacitor (C1) , which then releases it through the splash through the splash. , creating a short pulse oscillating current in the main circuit that excites a high oscillating voltage in the secondary:

1. The current from the supply transformer (T) loads the capacitor (C1) to high voltage.
2. When the voltage across the capacitor reaches the breakdown voltage of the spark gap (SG) the spark begins, reducing the splash resistance to a very low value. This completes the main circuit and current from the flow of the capacitor through the primary coil (L1) . The current flows rapidly back and forth between the capacitor plates through the coil, producing a radio frequency oscillating current in the main circuit at the resonant frequency of the circuit.
3. The oscillating magnetic field of the primary winding induces the oscillating current on the secondary winding (L2) , by Faraday's induction law. Over several cycles, the energy in the primary circuit is transferred to the secondary. The total energy in the tuned circuit is limited to the energy originally stored in the capacitor C1 , so that when the voltage oscillates in the secondary increase in amplitude ("rings") the oscillation in the primary decrease to zero ("rings"). Although the ends of the secondary coil are open, it also acts as a circuit tuned because of the capacitance (C2) , the number of parasitic capacitances between the coil windings plus the electoid toroid capacitance E . The current flows rapidly back and forth through the secondary coil between the ends. Because of the small capacitance, the oscillating voltage in the secondary coil that appears at the output terminal is much larger than the primary voltage.
4. The secondary current creates a magnetic field that induces a return voltage in the primary coil, and more than a few additional cycles of energy are transferred back to the primer. This process is repeated, the energy shifts back and forth between the primary and secondary tuning circuits. The oscillating current in primary and secondary gradually dies ("ring down") because energy is dissipated as heat in the spark gap and resistance of the coil.
5. When the current through the spark gap is no longer sufficient to keep the air in the ionized gap, the spark stops (quenches), terminating the current in the primary circuit. The oscillating current in the secondary can continue for some time.
6. The current from the supply transformer begins to charge the capacitor C1 again and the cycle repeats.

The whole cycle is very fast, dying oscillations within a millisecond. Each spark in the spark gap produces a damped sinusoidal high-voltage pulse at the output terminal of the coil. Each pulse dies before the next spark occurs, so the coil produces a series of damped waves instead of continuous sinusoidal stresses. The high voltage of the supply transformer that fills the capacitor is a 50 or 60 Hz sine wave. Depending on how the spark gap is set, usually one or two sparks occur at the top of every half of the electric current, so there are more than a hundred sparks per second. Thus the spark in the spark gap appears continuously, as does the high-voltage tape from the top of the coil.

The supply transformer (T) the secondary winding is connected throughout the primary tuning circuit. It may seem that the transformer will be the leak path for the RF current, the damping of the oscillations. But its large inductance gives it a very high impedance at the resonance frequency, thus functioning as an open circuit for oscillating currents. If the supply transformer has inadequate leakage inductance, radio frequency choking is placed in its secondary lead to block RF current.

Oscillation frequency

To produce the largest output voltage, the primary and secondary tuning circuits are adjusted for resonance with each other. Since secondary circuits are usually not adjustable, this is usually done with taps that can be set on ${\ displaystyle L1 \,}$ , the main coil.

Jika kedua koil itu terpisah, frekuensi resonan dari sirkuit primer dan sekunder, ${\ displaystyle f_ {1}}  ÂÂ$ dan ${\ displaystyle f_ {2}}  ÂÂ$ , akan ditentukan oleh induktansi dan kapasitansi di setiap rangkaian

${\ displaystyle f_ {1} = {1 \ over 2 \ pi} {\ sqrt {1 \ over L_ {1} C_ {1}}} \ qquad \ qquad f_ {2} = {1 \ over 2 \ pi} {\ sqrt {1 \ over L_ {2} C_ {2}}} \,}  ÂÂ$

However, since they are combined together, the frequency at which the secondary resonance is affected by the primary circuit and the coupling coefficient ${\ displaystyle k}$ , and occurs at its antillesonan frequency while the original resonance frequency acts as an antireson frequency. The frequency at which the coil should be driven is the serial resonance frequency.

${\ displaystyle f_ {2} '= {1 \ over 2 \ pi} {\ sqrt {1 \ over (1-k ^ {2}) L_ {2} C_ {2}}} \,}$

Jadi resonansi, dan tegangan tertinggi terjadi saat

${\ displaystyle {1 \ over 2 \ pi} {\ sqrt {1 \ over L_ {1} C_ {1}}} = {1 \ over 2 \ pi} { \ sqrt {1 \ over (1-k ^ {2}) L_ {2} C_ {2}}} \,}  ÂÂ$

Dengan demikian kondisi resonansi antara primer dan sekunder adalah

${\ displaystyle L_ {1} C_ {1} = (1-k ^ {2}) L_ {2} C_ {2} \,}  ÂÂ$

Namun transformator Tesla sangat longgar digabungkan, dan koefisien kopling ${\ displaystyle k \,}  ÂÂ$ kecil, dalam rentang 0,05 hingga 0,2. Jadi faktor ${\ displaystyle {\ sqrt {1-k ^ {2}}} \,}  ÂÂ$ mendekati satu kesatuan, 0,98 hingga 0,999, sehingga dua frekuensi resonan berbeda paling banyak 2%. Oleh karena itu, sebagian besar sumber menyatakan trafo resonan ketika frekuensi resonansi primer dan sekunder sama.

The resonant frequency of the Tesla coil is within the low radio frequency range (RF), usually between 50 kHz and 1 MHz. However, due to the impulsive nature of their sparks generating broadband radio noise, and without shielding can be a significant source of RFI, disrupting nearby radio and television reception.

Output voltage

In a resonant transformer, high voltage is generated by resonance; the output voltage is not equal to the ratio of the rotation, as in the normal transformer. This can be calculated roughly from energy conservation. At the beginning of the cycle, when the spark begins, all the energy in the main circuit ${\ displaystyle W_ {1}}$ is stored in the main capacitor ${\ displaystyle C_ {1}}$ . If ${\ displaystyle V_ {1}}$ is the voltage in which the sput gap is broken, which is usually close to the peak output voltage of the supply transformer T , this energy

$Â\; ÂÂ\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â{\displaystyle Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂW_{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â1Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â=Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\frac{1}{2}Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â\; Â\; Â\; ÂC_{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â1Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂV_{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â1Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}^{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â2Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\{Annotation\; encoding\; =\; "application/x-tex">\; \{\backslash \; displaystyle\; W\_\; \{1\}\; =\; \{1\; \backslash \; over\; 2\}\; C\_\; \{1\}\; V\_\; \{1\}\; ^\; \{2\}\; \backslash ,\}\; Â\; Â$

During this "ring" the energy is transferred to the secondary circuit. Although some are lost as heat in the sparks and other resistance, in modern coils, more than 85% of the energy ends in the secondary. At the top ( ${\ displaystyle V_ {2}}$ ) from the secondary waveform sinusoidal voltage, all the energy in the secondary ${\ displaystyle W_ {2}}$ is stored in capacitance ${\ displaystyle C_ {2}}$ between the ends of the secondary coil

$Â\; ÂÂ\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â{\displaystyle Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂW_{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â2Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â=Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\frac{1}{2}Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â\; Â\; Â\; ÂC_{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â2Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂV_{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â2Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}^{Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â2Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\; Â\; Â\; Â\; ÂÂ\; Â\; Â\; Â\; Â\; Â}Â\; Â\; Â\; Â\{\backslash \; Displaystyle\; W\_\; \{2\}\; =\; \{1\; \backslash \; over\; 2\}\; C\_\; \{2\}\; V\_\; \{2\}\; ^\; \{2\}\; \backslash ,\}$

Dengan asumsi tidak ada kerugian energi, ${\ displaystyle W_ {2} \; = \; W_ {1}}  ÂÂ$ . Substitusikan ke dalam persamaan ini dan menyederhanakan, tegangan sekunder puncak

Rumus kedua di atas berasal dari yang pertama menggunakan kondisi resonansi ${\ displaystyle L_ {1} C_ {1} \; = \; L_ {2} C_ {2}}  ÂÂ$ . Karena kapasitansi koil sekunder sangat kecil dibandingkan dengan kapasitor primer, tegangan primer ditingkatkan hingga nilai tinggi.

The above peak voltage is achieved only in rolls where air discharges do not occur; in rolls that produce sparks, such as the entertainment coil, the peak voltage at the terminal is limited to the voltage at which air is damaged and becomes conductive. When the output voltage increases during each voltage pulse, it reaches the point where the air next to the ionized high voltage terminal and coronas, the brush exhaust and the streamer arc, exit the terminal. This occurs when the electric field strength exceeds the dielectric strength of the air, about 30 kV per centimeter. Since the electric field is the largest at the point and the sharp side, the air discharge starts at these points at the high-voltage terminals. Voltage at high voltage terminals can not rise above the voltage of air damage, because the additional electrical charge pumped to the terminal from the secondary winding only passes into the air. Tesla coil output voltage is limited to about a few million volts by air damage, but higher voltages can be achieved by rolls submerged in oil insulation pressurized tanks.

Top load or "toroid" electrodes

Most of the Tesla coil designs have spherical or fine toroidal metal electrodes at high voltage terminals. The electrode serves as a single plate of a capacitor, with the Earth as another plate, forming a circuit that is tuned with secondary windings. Although the "toroid" increases the secondary capacitance, which tends to reduce the peak voltage, the main effect is that the large diameter curved surface reduces the gradient potential of the high-voltage terminals, raising the threshold of the tension where the air emits like corona and brush impurities occur. Suppressing premature air damage and energy loss allows the voltage to build higher values ​​at the top of the waveform, creating longer and more spectacular bands.

If the top electrode is large enough and smooth enough, the electric field on its surface may never be high enough even at the peak voltage to cause air damage, and air discharges will not occur. Some entertainment rolls have a sharp "spark point" that is projected from the torus to begin the release.

Maps Tesla coil

Type

The term "Tesla coil" is applied to a series of high voltage transformer voltages.

The Tesla circuit can also be classified by how many windings (inductors) it contains:

• Double coil or a double resonance circuit - Almost all Tesla coils are present using two coil spool transformers, consisting of a primary coil in which the current pulse is applied, and high-voltage secondary windings, invented by Tesla in 1891. The term "Tesla coil" usually refers to this circuit.
• Three coils , triple-resonance , or magnifying glass circuit - This is a circuit with three coils, based on the Tesla transmitter circuit which began experimenting with a time before 1898 and installed in the Colorado Springs laboratory 1899-1900, and patented in 1902. They consisted of two core transformers-a pull-air coil similar to a Tesla transformer, with the secondary connected to the three coils not magnetically coupled to the other, the so-called "extra" or "resonator" coils, which are series-fed and resonate with their own capacitance. The presence of three energy storage tank circuits gives this circuit a more complicated resonance behavior. This is the subject of research, but has been used in some practical applications.

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History

Electrical oscillations and even air-resonance transformer circuits have been explored and developed before Tesla, including Joseph Henry in the Leyden jar (1850), and resonance transformers developed by Henry Rowland (1889) and Elihu Thomson (1890). Tesla patented his Tesla winding circuit on April 25, 1891. and first demonstrated it on May 20, 1891 in his lecture " Experiments with Very High Frequency Alternate Flows and Their Applications to Artificial Lighting Method " before the American Institute of Electrical Engineers at Columbia College, New York. Although Tesla patented many similar circuits during this period, this is the first to contain all the elements of the Tesla coil: the main transformer of high voltage, capacitor, spark gap, and the air core "transformer oscillation".

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The modern Tesla trial

Modern high-voltage fans typically build Tesla coils that are similar to some of Tesla's "coil" core designs. This usually consists of a main tank circuit, a series of LC (inductance-capacitance) circuits consisting of high voltage capacitors, splashes and primary coils, and secondary LC circuits, series-resonance circuit consisting of secondary coil plus terminal capacitance or "top load". In a more advanced Tesla design (magnifying glass), a third coil is added. The secondary LC circuit consists of a secondary coil of tightly coupled air-transformer that moves the lower portion of a separate third-coil helical resonator. The modern 2-coil system uses a single secondary coil. The secondary top is then connected to the topload terminal, which forms one 'plate' of a capacitor, the other 'plate' into earth (or "ground"). The primary LC circuit is tuned so that it resonates at the same frequency as the secondary LC circuit. The primary and secondary windings are magnetically coupled, creating a transformer with dual-tuned air resonance. The previously oil-insulated Tesla coil requires a large, long insulator at its high-voltage terminals to prevent air discharges. Later, Tesla rolled their electric fields to a greater distance to prevent high electrical pressure in the first place, allowing the operation in the free air. Most modern Tesla coils also use a toroid-shaped output terminal. These are often made of spun metal or flexible aluminum ducting. The toroidal shape helps to control the high electric field near the top of the secondary by directing the sparks out and away from the primary and secondary windings.

The more complex version of the Tesla coil, called the "magnifying glass" by Tesla, uses a closer air-core resonant "rider" transformer (or "main oscillator") and a smaller long-distance output coil (called "extra coil "or simply a resonator) that has a large number of rounds on a relatively small coil shape. The underside of the driver's secondary winding is connected to ground. The opposite end connects to the underside of the extra coil through an isolated conductor which is sometimes called a transmission line. Since the transmission line operates at a relatively high RF voltage, it is usually made of a 1 "diameter metal pipe to reduce corona losses Because the third coil is located some distance away from the driver, it is not magnetically coupled with it.RM energy is not directly coupled from the driver output to the below the third coil, causing it to "ring" to a very high voltage.The combination of the two-coil driver and the third coil resonator adds another degree of freedom to the system, making the tuning much more complex than the 2-coil system.The temporary response to multi-resonance networks ( where Tesla's tool is a subset) has recently been completed.Now it is known that various useful "mode" tunings are available, and in most modes of operation, the extra coils will ring at different frequencies from the parent oscillator.

Primary redirect

Modern transistors or Tesla vacuum tube coils do not use the main spark gap. In contrast, the transistor (s) or vacuum tube (s) provide the switching function or amplify required to generate RF power for the primary circuit. Solid-state Tesla coils use the lowest primary operating voltage, usually between 155 and 800 volts, and drive the primary winding using a single, half bridge or full bridge of bipolar transistors, MOSFETs or IGBTs to switch the mainstream. The vacuum tube rolls typically operate with plate voltages between 1500 and 6000 volts, while most split slit coils operate with a primary voltage of 6,000 to 25,000 volts. The main winding of the traditional transistor Tesla coil only rotates at the bottom of the secondary coil. This configuration describes a secondary operation as a pumped resonator. The primary 'induces' the alternating voltage to the lower part of the secondary, providing a regular 'boost' (similar to giving precise time pushing into the playground swing). Additional energy is transferred from primer to secondary inductance and over-load capacitance during each "push", and a secondary output voltage build (called 'ring-up'). An electronic feedback circuits are typically used to synchronize the main oscillator adaptively with secondary growing resonance, and this is the only consideration of setting beyond a reasonable initial choice of the upper load.

In the Tesla dual-status resonance coil (DRSSTC), electronic switching of the solid-state Tesla coil is combined with the resonant primer circuit of the Tesla spil-gap coil. The primary resonant circuit is formed by connecting the capacitor in series with the coil's main coil, so the combination forms a series circuit with a resonance frequency near the secondary circuit. Because of the additional resonant circuit, one manual and one adaptive tuning adjustment are required. Also, interrupters are typically used to reduce the duty cycle of the switching bridge, to improve peak power capability; Similarly, IGBT is more popular in this application than bipolar or MOSFET transistors, due to its superior handling power characteristics. The current limiting circuit is usually used to limit the maximum primary tank current (which must be enabled by IGBT) to a safe level. DRSSTC performance is comparable to Tesla coils with medium power, and the efficiency (as measured by spark length versus input power) can be significantly greater than that of Tesla spark-gap that operates on the same input power.

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The practical aspects of design

High voltage production

A large Tesla coil with a more modern design often operates at very high peak power levels, up to many megawatts (millions of watts). It is therefore carefully adjusted and operated, not only for efficiency and economy, but also for safety. If, due to improper tuning, the maximum voltage point occurs below the terminals, along the secondary coil, the release (spark) may break and damage or destroy the coil wire, support, or nearby objects.

Tesla experimented with this, and many others, circuit configuration (see right). The main coil of Tesla coil, spark gap and capacitor tank are connected in series. In each circuit, the AC supply transformer fills the tank capacitor until the voltage is sufficient to break the split gap. The gap suddenly fires, allowing a charged tank capacitor to be discharged into the primary winding. As soon as the fire breaks, the electrical behavior of the two circuits is identical. Experiments have shown that no sequence offers real performance advantages over others.

However, in a typical circuit, the short-circuit action spark gap prevents high-frequency oscillation from 'backing up' into the supply transformer. In alternate circuits, high-frequency oscillations of high amplitudes that appear throughout the capacitor are also applied to the supply transformer windings. This can induce corona discharges between weakened bends and eventually destroy the isolation of the transformer. The experienced Tesla builder builder almost exclusively uses the top circuit, often adding it with a low pass filter (resistor and capacitor (RC) network) between the supply transformer and the spark gap to help protect the supply transformer. This is especially important when using transformers with volatile high-voltage coils, such as neon sign transformers (NSTs). Regardless of the configuration used, the HV transformer must be of a kind that limits itself to secondary currents by means of inductance of internal leakage. A normal high voltage transformer (low leakage) should use an external barrier (sometimes called a ballast) to limit the current. NST is designed to have a high leakage inductance to limit their short circuit current to a safe level.

Tuning

The primary resonant frequency of the primary coil is set for the secondary, using low power oscillations, then increasing power (and retuning if necessary) until the system operates properly at maximum power. While tuning, a small projection (called "breakout bump") is often added to the upper terminal to stimulate corona and spark discharges (sometimes called streamers) into the surrounding air. Tuning can then be adjusted so as to achieve the longest band at a given power level, corresponding to the frequency match between the primary and secondary coils. Capacitive "loading" by the tape tends to decrease the resonant frequency of the Tesla coils operating under full force. Toroidal toploads are often preferred over other shapes, such as balls. A toroid with a main diameter that is much larger than the secondary diameter gives an increase in the formation of an electric field at the upper load. This provides better protection against secondary winding (from breaking destructive streamers) than in similar diameter balls. And, a toroid allows enough independent control of the topload capacitance versus the spark breakout voltage. Toroid capacitors are largely a function of the main diameter, while the spark breakout voltage is primarily a function of its minor diameter. A grid dip oscillator (GDO) is sometimes used to help facilitate initial tuning and assistance in design. The secondary resonance frequency can be difficult to determine except by using GDO or other experimental methods, while the closer primary physical properties represent the first approximation of the RF tank design. In this secondary scheme built somewhat arbitrarily in mimic other successful designs, or wholly so with inventory at hand, the measured resonance frequencies and the main designed corresponding.

Water discharge

When generating exhaust, electrical energy from secondary and toroid is transferred into the surrounding air as electrical charge, heat, light, and sound. The process is similar to charging or discharging the capacitor, except that the Tesla coil uses AC instead of DC. The current emerging from the charge shift in a capacitor is called the displacement current. The Tesla winding loop is formed as a result of the displacement current as the electrical charge pulse is quickly transferred between the high voltage toroid and the nearest area in the air (called the space charge region). Although the charge space of the area around the toroid is not visible, they play a very big role in the appearance and disposal location of Tesla.

When the spark gap is on, the charged capacitor will flow into the primary winding, causing the primary circuit to oscillate. The oscillating primary currents create an oscillating magnetic field paired with a secondary winding, transferring energy to the secondary side of the transformer and causing it to oscillate with the toroidal capacitance to the ground. The transfer of energy occurs for several cycles, until most of the original energy on the primary side is transferred to the secondary side. The larger the magnetic coupling between the windings, the shorter the time it takes to complete the energy transfer. When energy is formed within an oscillating secondary circuit, the amplitude of the toroid RF voltage increases rapidly, and the air surrounding the toroid begins to suffer a dielectric breakdown, forming a corona release.

Because the energy of the secondary coil (and the output voltage) keeps increasing, the larger pulses of the displacement current will ionize further and heat the air at the point of initial damage. It forms a very electric electrical "roots" of the hotter plasma, called a leader, which projects out of the toroid. Plasma in the leader is much hotter than corona discharge, and is much more conductive. In fact, its nature is similar to the electric arc. The leader shrinks and branches out into thousands of thinner, colder liquids, like hair (called ribbons). The tapes looked like a bluish haze at the edge of lighter leaders. The streamer transfers the charge between the leader and the toroid to the nearest space charge area. The displacement currents of the countless streams all feed into the leader, helping to keep the heat and conductive of electricity.

The main dropout rate of the Tesla coil triggers slowly compared to the resonant frequency of the topload-resonator assembly. When the switch closes, energy is transferred from the primary LC circuit to the resonator where the voltage rings up over a short period of time until it reaches its peak at the discharge of electricity. In the Tesla coil splash, the primary-to-secondary energy transfer process occurs repeatedly at a typical pulsing rate 50-500 times per second, depending on the frequency of the input line voltage. At this stage, the pre-formed channel of the channel has no chance of cooling completely between pulses. Thus, on consecutive pulses, new discharges can build up the hot lines left by their predecessors. This causes incremental growth of the leader from one pulse to the next, extending the entire discharge at each consecutive pulse. Repeated pulsing causes the release of the load up to the average energy available from the Tesla coil as each pulse balances the average energy lost in the waste (mostly as heat). At this point, the dynamic balance is reached, and the discharge has reached its maximum length for the Tesla coil output power level. The unique combination of increased high-frequency radio frequency envelopes and recurrent pulsing seems ideal for creating long-lasting branching distances that would be expected only by consideration of output voltage alone. Low-voltage and low-energy loading produces a purplish-blue filamentous multibrane disposal. High voltage, high energy energy produces a thicker release with fewer branches, pale and luminous, almost white, and longer than low energy release, due to increased ionization. Strong ozone and nitrogen oxide odor will occur in the area. Important factors for maximum discharge length seem to be low voltage, energy, and air to moderate humidity. There are several scientific studies on the initiation and growth of pulsed low frequency RF pulsation, so some aspects of Tesla coil air waste are not well understood when compared to DC, AC power frequency, HV impulses, and lightning discharge.

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Apps

Today, although small Tesla coils are used as leak detectors in high scientific vacuum systems and igniter in arc welders, their primary use is entertainment and educational displays.

Source of the article : Wikipedia