Valdemar Poulsen
Encyclopedia
Valdemar Poulsen was a Danish
engineer
who developed a magnetic wire recorder
in 1899.
The magnetic recording was demonstrated in principle as early as 1898 by Valdemar Poulsen in his telegraphone. Magnetic wire recording, and its successor, magnetic tape recording, involve the use of a magnetizable medium which moves past a recording head. An electrical signal, which is analogous to the sound
that is to be recorded, is fed to the recording head
, inducing a pattern of magnetization similar to the signal. A playback head (which may be the same as the recording head) can then pick up the changes in the magnetic field from the tape and convert them into an electrical signal.
Poulsen obtained a Telegraphone Patent in 1898, and with his assistant, Peder O. Pedersen
, later developed other magnetic recorders that recorded on steel wire, tape, or disks. None of these devices had electronic amplification, but the recorded signal was easily strong enough to be heard through a headset or even transmitted on telephone wires. At the 1900 World's Fair in Paris
, Poulsen had the chance to record the voice of Emperor Franz Josef of Austria which happens to be the oldest surviving magnetic audio recording today.
Poulsen developed an arc converter
in 1908, referred to as the "Poulsen Arc Transmitter", which was widely used in radio before the advent of vacuum tube
technology.
He died on 23 July 1942.
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
who developed a magnetic wire recorder
Wire recording
Wire recording is a type of analog audio storage in which a magnetic recording is made on thin steel or stainless steel wire.The wire is pulled rapidly across a recording head which magnetizes each point along the wire in accordance with the intensity and polarity of the electrical audio signal...
in 1899.
Biography
He was born on 23 November 1869 in CopenhagenCopenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
The magnetic recording was demonstrated in principle as early as 1898 by Valdemar Poulsen in his telegraphone. Magnetic wire recording, and its successor, magnetic tape recording, involve the use of a magnetizable medium which moves past a recording head. An electrical signal, which is analogous to the sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
that is to be recorded, is fed to the recording head
Recording head
A recording head is the physical interface between a recording apparatus and a moving recording medium. Recording heads are generally classified according to the physical principle that allows them to impress their data upon their medium...
, inducing a pattern of magnetization similar to the signal. A playback head (which may be the same as the recording head) can then pick up the changes in the magnetic field from the tape and convert them into an electrical signal.
Peder Oluf Pedersen
Peder Oluf Pedersen was a Danish engineer and physicist. He is notable for his work on electrotechnology and his cooperation with Valdemar Poulsen on the developmental work on the telegraphone and the Poulsen Arc Transmitter....
, later developed other magnetic recorders that recorded on steel wire, tape, or disks. None of these devices had electronic amplification, but the recorded signal was easily strong enough to be heard through a headset or even transmitted on telephone wires. At the 1900 World's Fair in Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
, Poulsen had the chance to record the voice of Emperor Franz Josef of Austria which happens to be the oldest surviving magnetic audio recording today.
Poulsen developed an arc converter
Arc converter
The arc converter, sometimes called the arc transmitter or Poulsen arc after its inventor Danish engineer Valdemar Poulsen, is a device that used an electric arc to convert direct current electricity into radio frequency alternating current...
in 1908, referred to as the "Poulsen Arc Transmitter", which was widely used in radio before the advent of vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
technology.
He died on 23 July 1942.
See also
- Timeline of historic inventions
- Sound recording
- List of people on stamps of Denmark
External links
- "1898 – 1998 Poulsen's patent". 100 years of magnetic recording.
- Katz, Eugenii, "Valdemar Poulsen". Biosensors & Bioelectronics.
- Poulsen, Valdemar, " Method of Recordings and Reproducing Sounds or Signals". Magnetic Tape Recorder.
- 1900 World Exposition recording of Emperor Franz Joseph of Austria by means of Poulsen's telegraphone.