Harold Stephen Black
From Wikipedia, the free encyclopedia
Harold Stephen Black (1898-1983) was an electrical engineer who revolutionized the field of applied electronics by inventing the negative feedback amplifier in 1927. To some, his invention is considered the most important breakthrough of the twentieth century in the field of electronics, since it has a wide area of application. This is because all electronic devices (vacuum tubes, bipolar transistors and MOS transistors) invented by mankind are basically nonlinear devices. It is the invention of negative feedback which makes highly linear amplifiers possible. Negative feedback basically works by sacrificing gain for higher linearity (or in other words, smaller distortion). By sacrificing gain, it also has an additional effect of increasing the bandwidth of the amplifier. However, a negative feedback amplifier can be unstable such that it may oscillate.
He was born in Leominster, Massachusetts in 1898. He went to Worcester Polytechnic Institute (WPI) for his first degree. (Note: Leominster is part of the Worcester County, Massachusetts, USA.) Subsequently, he received the B.S.E.E. degree from WPI in 1921 and then joined Western Electric, which has been the manufacturing arm of AT&T. Bell Telephone Laboratories was established 1925 by Walter Gifford (then president of AT&T) as a separate entity which would take over the work being conducted by Western Electric's engineering department's research division. Ownership of Bell Labs was evenly split between AT&T and Western Electric. From 1925 to his retirement in 1963, he was a member of technical staff of Bell Telephone Laboratories (research arm of AT&T). WPI conferred him the D. Eng. degree (honorary) in 1955.
50 years after his 1927 invention, he published an article in IEEE Spectrum regarding the historical background of his invention [1]. He published a classical paper on negative feedback amplifier in 1934 [2], which have been re-printed in the Proceedings of IEEE two times in 1984 and 1999 [3]-[4]. Inside his 1934 classical paper "Stabilized feed-back amplifiers", he mentioned Harry Nyquist's work on stability criterion because a negative feedback amplifier can be unstable and oscillate. Thus, with the help of Nyquist's theory, he managed to demonstrate a stable negative feedback amplifier which can be used in reality. Bernard Friedland wrote an introduction for the 1999 re-print in Proc. IEEE [5]. James E. Brittain wrote about him in 1997 [6]. An obituary regarding Harold Black was published by IEEE Transactions on Automatic Control in 1984 [7].
According to Black [1], he got his inspiration to invent the negative feedback amplifier when he was travelling from New Jersey to New York City by taking a ferry to cross the Hudson River in August 1927. At that time, Bell Laboratories headquarters were located in 463 West Street, Manhattan, New York City instead of New Jersey and he lived in New Jersey such that he took the ferry every morning to go to work.
He has also worked on pulse code modulation. He has written a book "Modulation Theory", which was published by Van Nostrand in 1953. He got a lot of patents but the most famous one was US Patent 2,102,671 "Wave Translation System", which was issued to Bell Laboratories in 1937, covering the negative feedback amplifier. According to Brittain [6], Black tried to write an autobiography with the tentative title "Before the ferry docked". However, he died in December 1983 at age 85 before he could finish it. He was inducted into the National Inventors Hall of Fame in 1981.
[edit] References
[1] Harold S. Black, "Inventing the negative feedback amplifier", IEEE Spectrum, vol. 14, pp. 54-60, Dec. 1977.
[2] H.S. Black, "Stabilized feed-back amplifiers", Electrical Engineering, vol. 53, pp. 114-120, Jan. 1934.
[3] H.S. Black, "Stabilized feed-back amplifiers", Proc. IEEE, vol. 72, no. 6, pp. 716-722, June 1984.
[4] H.S. Black, "Stabilized feed-back amplifiers", Proc. IEEE, vol. 87, no. 2, pp. 379-385, Feb. 1999.
[5] B. Friedland, "Introduction to "Stabilized feed-back amplifiers"", Proc. IEEE, vol. 87, no. 2, pp. 376-378, Feb. 1999.
[6] J.E. Brittain., "Scanning the past: Harold S. Black and the negative feedback amplifier", Proc. IEEE, vol. 85, no. 8, pp. 1335-1336, Aug. 1997.
[7] C.A. Desoer, "In memoriam: Harold Stephen Black", IEEE Trans. Automatic Control, vol. AC-29, no. 8, pp. 673-674, Aug. 1984.
[edit] External link
This article about an engineer, inventor or industrial designer is a stub. You can help Wikipedia by expanding it.
