Harold Stephen Black

Infobox Scientist
name = Harold Stephen Black


birth_date = birth date|1898|4|14
birth_place = Leominster, Massachusetts
death_date =death date and age|1983|12|11|1898|4|14
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nationality = United States
ethnicity =
field = Electrical engineer
work_institutions =
alma_mater = Worcester Polytechnic Institute
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doctoral_students =
known_for = negative feedback
author_abbrev_bot =
author_abbrev_zoo =
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Harold Stephen Black (1898-1983) was an American 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 or smaller intermodulation). 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. Once the stability problem is solved, the negative feedback amplifier is extremely useful in the field of electronics. Black published a famous paper "Stabilized feedback amplifiers" in 1934.

Biography

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.

According to Brittain, 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.

Work

Fifty years after his 1927 invention, he published an article in IEEE Spectrum regarding the historical background of his invention. Harold S. Black, "Inventing the negative feedback amplifier", IEEE Spectrum, vol. 14, pp. 54-60, Dec. 1977.] He published a classical paper on negative feedback amplifier in 1934 [H.S. Black, "Stabilized feed-back amplifiers", Electrical Engineering, vol. 53, pp. 114-120, Jan. 1934.] , which have been re-printed in the Proceedings of IEEE two times in 1984 and 1999 [H.S. Black, [http://ieeexplore.ieee.org/search/wrapper.jsp?arnumber=1457189 Stabilized feed-back amplifiers] , Proc. IEEE, vol. 72, no. 6, pp. 716-722, June 1984.] [H.S. Black, doi-inline|10.1109/JPROC.1999.740032 |Stabilized feed-back amplifiers, Proc. IEEE, vol. 87, no. 2, pp. 379-385, Feb. 1999.] 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. [B. Friedland, doi-inline|10.1109/JPROC.1999.740031|Introduction to "Stabilized feed-back amplifiers", Proc. IEEE, vol. 87, no. 2, pp. 376-378, Feb. 1999.] James E. Brittain wrote about him in 1997. 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.] An obituary regarding Harold Black was published by IEEE Transactions on Automatic Control in 1984. [* C.A. Desoer, [http://ieeexplore.ieee.org/search/wrapper.jsp?arnumber=1103645 In memoriam: Harold Stephen Black] , IEEE Trans. Automatic Control, vol. AC-29, no. 8, pp. 673-674, Aug. 1984.]

According to Black 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 wrote a book on "Modulation Theory". He held many patents the most famous of which was US Patent 2,102,671 "Wave Translation System", which was issued to Bell Laboratories in 1937, covering the negative feedback amplifier.

Publications

He has written a book and several articles:
* 1953, "Modulation Theory", Van Nostrand .

Articles, a selection:
* 1934, "Stabilized feed-back amplifiers", in: "Electrical Engineering", vol. 53, pp. 114-120, Jan. 1934.
* 1997, "Inventing the negative feedback amplifier", in: "IEEE Spectrum", vol. 14, pp. 54-60, Dec. 1977. (50th anniversary of Black's invention of negative feedback amplifier)
* 1984, " [http://ieeexplore.ieee.org/search/wrapper.jsp?arnumber=1457189 Stabilized feed-back amplifiers] ", in: "Proc. IEEE", vol. 72, no. 6, pp. 716-722, June 1984. (Re-print of Black's 1934 paper.)
* 1999, "doi-inline|10.1109/JPROC.1999.740032 |Stabilized feed-back amplifiers", in: "Proc. IEEE", vol. 87, no. 2, pp. 379-385, Feb. 1999. (Re-print of Black's 1934 paper.)

References

External links

* [http://www.invent.org/hall_of_fame/16.html HS Black] in the Hall of fame.