Valdemar Poulsen Biography (1869-1942)


Valdemar Poulsen was a Danish engineer who invented the magnetic recorder in1898. His ideas were the basis of magnetic recording and led to crucial developments in communications and computer technology. Born in Copenhagen on November 23, 1869, Poulsen exhibited an early interest in science. He later studied various aspects of science in depth, though he never earned a degree. Around 1890, Poulsen began working in local machine shops, finally joining the Copenhagen Telephone Company as an assistant engineer in its technical sectionin 1893. It was while working there, at the age of 20, that he developed thetelegraphone, a machine that recorded sounds magnetically on a wire.

The concept of recording sounds magnetically had originated with the Britishinventor Oberlin Smith (1840-1926) in 1888, but Poulsen put that concept intopractice ten years later. Smith's ideas had involved using "tapes" of fabriccontaining iron filings, but Poulsen's device used magnetized steel piano wire to record and reproduce sounds. The wire, running between spools, could record continuously for 30 minutes, moving at a speed of 84 inches per second.Poulsen conceived the telegraphone initially as a message-taking machine foruse with telephones; messages could be erased at will. He applied for a patent on the device in 1898.

While a working model created great interest at the Paris Exhibition in 1900,its impact did not reach beyond that initial presentation. Since Poulsen could not find financial backers in Europe, he came to the United States in 1903and obtained benefactors who founded the American Telegraphone Company (in Springfield, Massachusetts) to produce and sell his machine. The telegraphonewas promoted as an office dictation apparatus and an automatic telephone message recorder, but it did not find wide application due to its drawbacks: pooramplification via earphones and unwieldy bulk. Inept company management alsoaffected the product's success. However, Poulsen's system was sound in principle and laid the basis for later inventors (such as Marvin Camras ) to develop commercially successful magnetic recorders.

Poulsen had also described methods to magnetize steel or paper tape coated with magnetic powder. With these methods, the recording medium could be erasedand reused many times without loss of sound quality. Thus Poulsen's helped pave the way for the development of modern recording tape. German engineer Fritz Pfleumer refined Poulsen's ideas and created the first magnetic recording tape in 1928. Initially made of paper and then of plastic, the tape was coatedwith magnetic materials as Poulsen had described. While plastic tape is lighter and more flexible than Poulsen's original wire and allows multiple trackson the same tape, wire is still used for flight recorders on aircraft, wheredurability is the most important consideration. Poulsen later turned his attention to radio communications.

In 1903 he aided the development of radio broadcasting when he invented a device for generating continuous radio waves. He then went on to patent an adaptation of an arc oscillator, or "singing arc," for radio transmitting purposeswhich helped make long-wave radio broadcasting possible by 1920. The U.S. Navy adopted his arc generator as standard equipment in 1912. However, subsequent devices by other inventors in the 1920s would rapidly make Poulsen's arc generator obsolete. Poulsen continued his research into radio communications until his death in Copenhagen in July 1942.

User Contributions:

Comment about this article, ask questions, or add new information about this topic: