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Ernst Alexanderson 1878 - 1975
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Ernst Alexanderson
Ernst F. W. Alexanderson
Ernst Alexanderson invented the high-frequency alternator, used in radio broadcasts - National Inventors Hall of Fame.
Ernst Alexanderson
Ernst Alexanderson was one of America's great inventors, with important patents in radio, television, power transmission, and computers.
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By Mary Bellis

Dr. Ernst Alexanderson was the General Electric engineer who built a high-frequency alternator (a device that converts direct current into alternating current) that greatly improved radio communication. Prior to Alexanderson' alternator, radio was broadcast by what was called spark machines that used dots and dashes of signals or morse code. Ernst Alexanderson's alternator allowed radio to be broadcast in a continuous wave. In 1901, Swedish-born Ernst Alexanderson emigrated to the United States and began working for the General Electric Company in Schenectady, N.Y., under Charles P. Steinmetz.

Alexanderson designed his alternator to complement the work of radio pioneer Reginald A. Fessenden as part of a high-frequency generator. That led to Fessenden's 1906 Christmas Eve broadcast of the world's first radio program with voice and a violin solo using Ernst Alexanderson's high-frequency alternator for undamped oscillations.

Ernst Alexanderson was issued U.S patent #1,008,577 on February 22, 1916 for a selective tuning device for radios that became an integral part of modern radio systems and led to his being honored in the Inventors Hall of Fame. He was also General Electric's most prolific inventor, receiving a total of 322 patents. 

Among Ernst Alexanderson's achievements:

  • He continued to improve the alternator and in addition made important improvements in radio antennas, electric railroads, ship propulsion, and electric motors.
  • On June 5, 1924, he transmitted the first facsimile (fax) message across the Atlantic. 
  • In 1927, he staged the first home reception of television at his own home in Schenectady, New York, using high-frequency neon lamps and a perforated scanning disc. 
  • He gave the first public demonstration of television on January 13, 1928. 
  • From 1952 onwards, he worked for the Radio Corporation of America (RCA) as a consultant. His 321st patent granted in 1955 was for a color television receiver that he developed for RCA.
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