Historical Notes

Nikola Tesla
Robert J. Van de Graaff
Leyden

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Michael Faraday
Ampere
Geissier
Marx
Henry

Nikola Tesla and Tesla's High Voltage Resonance (Tesla Coils) Transformers Development

Dr. Nikola Tesla, a Serbian immigrant, studied electrical engineering in 1875 at the Austrian Polytechnic School, in Graz, and in 1882, Tesla worked on high voltage equipment for Thomas Edison in Europe.

Tesla emigrated to American in 1884 and worked for Thomas Edison a brief period of time and then Tesla began pursuing his own ideas of high frequency alternating electrical currents. Edison's direct current could not be efficiently transferred over long distances while Tesla's high voltage alternating current could be efficiently modified with high voltage transformers and sent over long distances to deliver high voltage high energy electric power to distant factories and cities.

In 1887 the Tesla Electric Company opened at 33-35 South Fifth Street, New York City. Nikola Tesla quickly developed the alternating current motor and then developed a special high voltage power distribution system. Tesla also developed special high frequency high voltage alternating current air core transformers that are named in his honor: Tesla coils or Tesla resonance transformers.

Resonance (Tesla coils) Transformers use a primary oscillating circuit consisting of a high voltage capacitor and a high voltage inductor. As the high voltage high frequency currents oscillate in the primary inductor of the Tesla coils they produce a power high energy electromagnetic field which surrounds the secondary high voltage coil. This powerful high energy high voltage electric field sets up extremely high voltage high frequency currents in the secondary high voltage coil. These high voltage currents break out into the air and actually break down the air molecules creating a giant high voltage lightning like spark.

Resonance (Tesla coils) Transformers use convential iron core high voltage transformers to charge up high voltage energy discharge capacitors.

The high voltage high energy capacitors store the charge until the voltage is high enough to break down the air in a high voltage spark gap. As the spark gap breaks down it conducts the high voltage charge directly in the high voltage inductor coil which forms the primary circuit of the high voltage Tesla coils. The high voltage charges rush back and forth between the high voltage capacitor and the high voltage inductor coil. The speed of this oscillation depends on the physical geometry of the high voltage capacitor and high voltage inductor coil. Typical high frequency operating values for a high voltage Tesla coil resonance transformer are in the range of 20 KHZ through 1 MHZ. Most medium size demonstration Tesla coil resonance transformers operate in the 100 KHZ through 500 KHZ range.

Nikola Tesla, using his newly developed high voltage Tesla coil resonance transformers, delivered an astounding lecture before the American Institute of Electrical Engineers on May 16, 1988. Tesla, using his special high frequency high voltage Tesla coil resonance transformers impressed both the electrical engineers in attendance and also many Wall street investors who now wanted to invest in Tesla's high voltage power distribution systems.

It is not clear exactly when the Tesla coil resonance transformer was actually developed by Nikola Tesla because he did not publish on a regular basis, but it is though the Tesla coil resonance transformers were developed around 1880. Tesla patented the idea of high voltage high frequency tuned electrical circuits a few years later. Tesla's friend, George Westinghouse, purchased many of Tesla's patent rights and began manufacturing these high voltage polyphase electrical power distribution systems.

Tesla noted his large Tesla coil resonance transformers were producing high voltage high energy electrical charge in excess of 4,000,000 Volts, These huge lightning like sparks were rapidly becoming a fire hazard and Tesla decided to move his large Tesla coil resonance transformers to Colorado Springs, Colorado, where he would have more room for his high voltage high frequency experiments.

Nikola Tesla arrived at Colorado Springs, Colorado, on May 18, 1899, and immediately began building a massive high voltage laboratory with an extremely large Tesla coil resonance transformer measuring over 52 feet in diameter. A large fence surrounded the Tesla coil with the sign, "Keep Out - Great Danger.

Tesla constructed many Tesla coil resonance transformers in his lab and discovered the concept of tuned electrical circuits. A separate and smaller Tesla coil resonance transformer that is tuned to the same high frequency as the large high voltage Tesla coil resonance transformer will actually "receive" electrical energy from the massive Tesla coil which acts as a "transmitter" of wireless electrical energy. Tesla was later nominated for but declined the Nobel Prize in Physics for his experiments with tuned circuits using his large high voltage high frequency Tesla coil resonance transformers. Nikola Tesla first logged these observations into his diary on July 3, 1899. This information was later used to confirm his patent for radio which he received posthumously in 1946, 3 years after his death.

Tesla coils / resonance transformers linger on today as the high voltage transformers found in most computer CRT's. Tesla coils are used by dental surgeons to painlessly cut gum tissue in their treatment of gum disease. Hospital surgeons use modified high frequency Tesla coil generators to cauterize blood vessels during surgery thus preventing excessive bleeding. Every large television set has a Tesla coil resonance transformer called a flyback transformer which provides the high voltage necessary to operate the picture tube.

Robert J. Van de Graaff and Van de Graaff High Voltage Electrostatics Generators Development

Robert Van de Graaff, the inventor of the high voltage electrostatics Van de Graaff generators, was an American mechanical engineer who later switched to high energy physics and developed the modern machine named in his honor: The Van de Graaff high voltage electrostatics generator.

Robert J. Van de Graaff was born in Tuscaloosa, Alabama, in 1901. Van de Graaff attended the Tuscaloosa public school system and received his B.S. degree in mechanical engineering from the University of Alabama in 1922. Van de Graaff also received his M.S. degree in mechanical engineering one year later from Univ. Alabama.

Van de Graaff attended lectures by Madam Curie at the Sorbornne, Paris, France in 1925. Van de Graaff also went to Oxford as a Rhodes Scholar in late 1925 receiving his B.S. degree in physics in 1926 and later a PhD in physics in 1928.

Ernest Rutherford introduced to Van de Graaff the urgent need to develop a better method of accelerating atomic particles to very high speeds. In the early days high voltage accelerators known as 'Cockroft-Walton high voltage multipliers' provided the high voltages necessary to accelerate particles, but these crude transformer-rectifier systems broke down often due to the poor high voltage insulating materials of this period. Van de Graaff now understood the requirements of nuclear experimenters for the development of a high voltage particle accelerator.

After joining the high voltage physics laboratory at Princeton, in 1929, he constructed his first working model of an electrostatic high voltage generator which he dubbed the Van de Graaff high voltage electrostatics accelerator. The first working Van de Graaff generator produced 80 kV DC. A dual positive-negative Van de Graaff generator developing over 1 MEV was presented to the 1931 meeting of the American Physical Society.

Van de Graaff high voltage electrostatics generators were very simple using only 1 moving belt and 2 pulleys to produce high voltage direct current. High voltage Van de Graaff generators were quickly developed to accelerate charged particles including, in November, 1933, a Van de Graaff generator large enough to produce over 7 MEV. This large Van de Graaff high voltage electrostatics generator was operated in South Dartmouth, Massachusetts, and eventually transferred to M.I.T.. At M.I.T. the Van de Graaff high voltage generator was enclosed in a pressurized tank filled with a blend of insulating gases which enabled the Van de Graaff generator to achieve even higher accelerating potentials. At present this Van de Graaff high voltage generator resides in the Boston Museum of Science. The two high voltage Van de Graaff generator terminals, measuring over 15 feet in diameter, were grafted together to form a singular huge terminal.

Van de Graaff high voltage electrostatics generators were later used for medical research at Harvard in 1937 and the Van de Graaff produced particle beams used for cancer treatment. The radiation from a large pressurized tank horizontal Van de Graaff high voltage generator had enough high energy to kill cancerous tumors.

Van de Graaff high voltage generators also have many industrial applications including polymerization of plastic materials and food irradiation.

Van de Graaff high voltage electrostatic generators are used in public schools and universities for teaching basic principles of high voltage electrostatisc charge and the laws of electrostatics. Table top Van de Graaff generators develop over 400,000 Volts and floor models offer up to 1,000,000 Volts of high voltage lightning electrical discharges. In school demonstrations Van de Graaff generators operate high voltage electrostatic motors and light up gaseous spectrum discharge tubes. Each high voltage charge, when transferred to a high voltage spectrum discharge tube, produces a pure spectral color which depends on the type of gas enclosed in the sealed tube.

Small table top Van de Graaff generators are fun, safe, and very interesting to children. They enjoy working with Van de Graaff high voltage electrostatics generators and use these machines for school science projects. Many top award winning science projects contain a Van de Graaff generator as a central part of the science experiment. Science museum exhibits also employ them to educate visitors on the basic laws of electrostatics.

Leyden Jar Condenser (high voltage capacitor)

English experimenter Stephen Gray, in 1936, discovered the concept of electrical conductors and electrical insulators. Gray was the first to electrify a human being in 1936 by suspending a boy in the air with insulating silk strings, and then charging him up with static electricity. Grays experiments in static electricity ushered in a long period of electrostatic experiments with many different methods used to produce the static electricity.

In 1745 electrostatic experiments became so popular that public “physics lectures” were conducted extensively in Germany and Holland. In 1745 Edwald von Kleist produced an electric charge in a bottle of water. Von Kleist held in his hand a small water-filled vial with a nail inserted thru a cork stopper. He charged up the vial with a static machine and when he touched the nail with his other hand received a powerful electric shock that stunned his arm and shoulder.

In 1746, at the University of Leyden, in Holland, Pieter Van Mussenchenbroek independently repeated this experiment and also received a very powerful electric shock. Mussenchenbroek used a much larger bottle in his experiment and was immediately thrown to the floor by the high power of the electric shock he received. Mussenchenbroek reportedly stated that “he would not take another such shock for all the kingdom of France”. Thus was born the “Leyden jar” condenser (capacitor).

Other experimenters, including Abbe Nollet, of France, arranged a demonstration in which he discharged a Leyden jar capacitor thru 180 of the King’s guards who all jumped in the air when the spark discharge occurred. Later, in Paris, Nollet discharged a Leyden jar capacitor thru a 900 foot long line of Cathusian monks. 700 monks simultaneously jumping into the air was a very humorous sight indeed.

He killed small animals and birds with the discharge of a large Leyden jar, and passed the Leyden jar discharge great distances across rivers and lakes. He also magnetized small needles and melted thin wire with the high current discharge from a Leyden jar capacitor. The discovery of the Leyden jar was hailed as a great advance in science.

In America, Benjamin Franklin also experimented with Leyden jars and noticed that they could also be charged by nearby lightning strikes.