An Oudin coil, also called an Oudin oscillator or Oudin resonator, is a resonant transformer circuit that generates very high voltage, high frequency alternating current (AC) electricity at low current levels, used in the obsolete medical field of electrotherapy around the turn of the 20th century.
 It is very similar to a Tesla coil, with the difference being that the Oudin coil was connected as an autotransformer.
 It was invented in 1893 by French physician Paul Marie Oudin as a modification of physician Jacques Arsene d'Arsonval's electrotherapy equipment and used in quack medicine until perhaps 1930.
 The high voltage output terminal of the coil was connected to an insulated handheld electrode which produced luminous brush discharges, which were applied to the patient's body to treat various medical conditions in electrotherapy.
Electrum or Electrum (for Len Lye) (Len Lye being a New Zealand artist), is a 1998 sculpture by Eric Orr and Greg Leyh built around the world's largest Tesla coil.
 The coil operates at power levels up to 130,000 watts, 3 million volts and stands 11.5 meters in height.
 The sculpture is currently installed in a private area at Gibbs Farm in New Zealand, a sculpture park art collection of businessman Alan Gibbs.
 The top, spherical electrode of the sculpture is large enough to hold a human.
 The piece was the subject of a 2000 documentary, "Electrum: Science as Art" and the 2011 documentary "Lightning Dreams", by Alberta Chu.
Paul Marie Oudin (1851–1923) was a French physician and medical researcher.
 He was born, and later died, in Épinal.
 He conducted research in the Victorian era medical field of high frequency electrotherapy, the application of radio frequency electric currents to the body, and collaborated with the founder of the field, pioneering physiologist and biophysicist Dr. Jacques Arsene d'Arsonval.
 In 1893 he modified d'Arsonval's electrotherapy equipment by the addition of a wire coil resonator to produce higher potentials, inventing the Oudin coil.
 This device, very similar to a Tesla coil, could produce very high voltages from several hundred thousand to a million volts.
 In use, the brush discharges from a pointed electrode attached to the high voltage terminal of the coil would be played over various parts of the body to treat a variety of medical conditions.
 The Oudin coil was used in electrotherapy and diathermy through the 1920s.
A violet ray is an antique medical appliance used during the early 20th century in the obsolete medical therapy called electrotherapy.
 Their construction usually feature a combination of a disruptive discharge coil with an interrupter to apply a high voltage, high frequency, and low current to the human body for therapeutic purposes.
 Their basic construction was invented prior to 1900 by Nikola Tesla, who introduced their first prototypes at the World's Columbian Exposition in 1893.
 Most of the antique violet rays in the US were produced before the Depression era and some of the larger US manufacturers of violet rays were Renulife, Fitzgerald and Fisher.
 Companies who manufactured violet ray devices, made many other types of electrical appliances as well, e.g. Star Electric, which also manufactured stock ticker machines.
 Many of the companies who were able to continue manufacturing violet rays after the depression, stopped making them due to World War II when they began manufacturing radio coils or other electrical components for the war instead.
Steve Brudniak (Born April 9, 1961, Topeka, Kansas) is an American artist known for highly crafted and unusual assemblage sculpture.
 His art incorporates, often pioneering, unconventional media and scientific elements such as high voltage electricity, Tesla coil technology, magnetic ferrofluid, gyro mechanics, biological preservations, fiber optics, and lasers.
The singing Tesla coil, sometimes called a zeusaphone, thoramin or musical lightning, is a form of plasma speaker.
 It is a variation of a solid state Tesla coil that has been modified to produce musical tones by modulating its spark output.
 The resulting pitch is a low fidelity square wave like sound reminiscent of an analog synthesizer.
 The high-frequency signal acts in effect as a carrier wave; its frequency is significantly above human-audible sound frequencies, so that digital modulation can reproduce a recognizable pitch.
 The musical tone results directly from the passage of the spark through the air.
 Because solid-state coil drivers are limited to "on-off" modulation, the sound produced consists of square-like waveforms rather than sinusoidal (though simple chords are possible).
23 Envelope was the name given to the graphic design partnership of graphic designer Vaughan Oliver and photographer/filmmaker Nigel Grierson from 1983-1988.
 During this time, they created a distinct visual identity for the British independent music label 4AD through their record sleeve designs for bands such as Cocteau Twins, Dead Can Dance, and This Mortal Coil.
Nikola Tesla ( ; ; 10 July 1856 – 7 January 1943) was a Serbian-American inventor, electrical engineer, mechanical engineer, physicist, and futurist who is best known for his contributions to the design of the modern alternating current (AC) electricity supply system.
Franz von Holzhausen (born May 10, 1968 in Simsbury, Connecticut) is an automobile designer, currently in charge of design at Tesla Inc. after resigning his position at Mazda North American Operations on July 31, 2008.
 He designed the Tesla Model S, an electric premium sedan starting in 2008.
The Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891.
 It is used to produce high-voltage, low-current, high frequency alternating-current electricity.
 Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits.

Question: What was the nationality of the designer of The Tesla coil?
Answer: Serbian-American