retroelectro
January 1928 Bell Labs begins developing a new transcontinental cable- carrier system using Black’s feedback amplifiers to carry nine voice channels over a single wire pair spaced 25 miles apart.
January 1875 Elisha Gray holds public demonstrations of his liquid- transmitter telephone, broadcasting tunes like ‘Yankee Doodle’ over a one-mile line, generating nationwide excitement. 1879 Western Union sues Bell Telephone in the Gray–Bell dispute but ultimately loses, formally beginning the Bell Telephone Monopoly.
March 1876 Alexander Graham Bell and Thomas Watson file a complete patent application for Bell’s telephone; Bell’s patent is granted within weeks. Elisha Gray sells his interests in Western Electric Manufacturing Company to Western Union.
August 8, 1928
U.S. patent application filed for Black’s negative-feedback amplifier.
1930 Morristown field trial simulates a 7,650-mile-long connection link, delivering excellent voice quality.
Western Union sells Western Electric to Bell Telephone.
January 1915 First transcontinental telephone call.
December 21, 1937
U.S. Patent No. 2,102,671 for the negative-feedback amplifier is finally issued after a nine-year examination.
July 5, 1921 Harold Black joins Western Electric’s West Street Labs, earning $32 per week.
Bell Labs sues Zenith Radio Corp. for infringing Black’s feedback amplifier patent. 1948–1953
March 16–17, 1923 Inspired by Charles Steinmetz’s lecture, Black sketches and tests feed-forward amplifier prototypes.
1953
Western Electric and the West Street Labs are rebranded as Bell Laboratories. 1925
Black publishes Modulation Theory, a definitive textbook on communications and modulation techniques.
Aboard the Lackawanna Ferry, Black conceives the negative- feedback amplifier—scribbling inverted-feedback loop diagrams on a New York Times newspaper. August 2, 1927
December 11, 1983 Harold S. Black passes away in Summit, New Jersey, at age 85— leaving a legacy of 62 U.S. patents and 271 international patents across 32 countries.
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