William Du Bois Duddell (1 July 1872, in Kensington, London – 4 November 1917, in

Wandsworth Wandsworth Town () is a district of south London, within the London Borough of Wandsworth southwest of Charing Cross. The area is identified in the London Plan as one of 35 major centres in Greater London. Toponymy Wandsworth takes its nam ...

, London) was an English physicist and electrical engineer. His inventions include the moving coil

oscillograph An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...

, as well as the thermo-ammeter and thermo-galvanometer.

Life and career

Duddell was born William Du Bois to Frances Kate Du Bois, who married George Duddell in 1881. At the age of four he constructed an automaton by combining a toy mouse with clockwork. His younger sister Gladys Duddell was a tennis player. Duddell was privately educated in England and France and rose quickly through the prestigious City & Guilds Schools via scholarships. He died at the age of 45.

Duddell's "singing arc"

Prior to the invention of the

incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxid ...

, arc lamps were used to light the streets. They created light using an electrical arc between two carbon electrodes. These lamps often produced audible humming, hissing, or even howling sounds. In 1899 Duddell, a student of William Ayrton at London Central Technical College, was asked by Ayrton to look into this problem. The sounds were created by instabilities in the current caused by the arc's

negative resistance In electronics, negative resistance (NR) is a property of some electrical circuits and devices in which an increase in voltage across the device's terminals results in a decrease in electric current through it. This is in contrast to an ordina ...

. Duddell connected a

tuned circuit An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can a ...

consisting of an

inductor An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a c ...

and

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

across an arc. The

of the arc excited audio frequency

oscillation Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

s in the tuned circuit at its resonant frequency, which could be heard as a musical tone coming from the arc. Duddell used his oscillograph to determine the precise conditions required to produce oscillations. To demonstrate his invention before the London Institution of Electrical Engineers, he wired a keyboard to produce different tones from the arc, and used it to play a tune, ''

God Save the Queen "God Save the King" is the national and/or royal anthem of the United Kingdom, most of the Commonwealth realms, their territories, and the British Crown Dependencies. The author of the tune is unknown and it may originate in plainchant, bu ...

'' making it one of the first examples of electronic music. This device, which became known as the "singing arc", was one of the first electronic oscillators and

Plasma speaker Plasma speakers or ionophones are a form of loudspeaker which varies air pressure via an electrical plasma instead of a solid diaphragm. The plasma arc heats the surrounding air causing it to expand. Varying the electrical signal that drives t ...

s. Duddell's circuit was limited to audio frequencies. However, Danish physicists

Valdemar Poulsen Valdemar Poulsen (23 November 1869 – 23 July 1942) was a Danish engineer who made significant contributions to early radio technology. He developed a magnetic wire recorder called the telegraphone in 1898 and the first continuous wave rad ...

and P. O. Pederson were able to increase the frequency of Duddell's oscillator to the radio range, and in 1902 patented the Poulsen arc radio

transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...

, the first transmitter which could generate continuous waves. Poulsen arc wireless transmitters were used worldwide until the 1920s.

Honours

Duddell was made a Fellow of the

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

in 1907. The British

Institute of Physics The Institute of Physics (IOP) is a UK-based learned society and professional body that works to advance physics education, research and application. It was founded in 1874 and has a worldwide membership of over 20,000. The IOP is the Physic ...

named its

Duddell Medal and Prize The Dennis Gabor Medal and Prize (previously the Duddell Medal and Prize until 2008) is a prize awarded biannually by the Institute of Physics for distinguished contributions to the application of physics in an industrial, commercial or busines ...

in his honour. In 1907–08 he served as president of the

British Institute of Radiology The British Institute of Radiology (BIR) is a radiology society and charity based in London, United Kingdom. It is the oldest institute of its kind in the world, forming on 2 April 1897. History The society can be traced back to two separate i ...

. In 1912 he became the youngest

president President most commonly refers to: *President (corporate title) * President (education), a leader of a college or university * President (government title) President may also refer to: Automobiles * Nissan President, a 1966–2010 Japanese ...

of the

Institution of Electrical Engineers The Institution of Electrical Engineers (IEE) was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. It began in 1871 as the Society of T ...

and served two terms.http://todayinsci.com/D/Duddell_William/DuddellWilliamBio.htm William Duddell biography. Retrieved 13 August 2014 In 1906 and 1911 he was invited to deliver the Royal Institution Christmas Lecture on ''Signalling to a Distance'' and ''Modern Electricity'' respectively.

References

External links

Duddell's Singing Arc on '120 Years of Electronic Music'

Obituary
Proceedings of the Institution of Electrical Engineers, 1918, Volume 56, pp 538–540 {{DEFAULTSORT:Duddell, William 1872 births 1917 deaths Fellows of the Royal Society English electrical engineers English physicists English inventors