Valdemar Poulsen (1869 - 1942) was a Danish engineer. In 1899, he developed a magnetic tape recorder.

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 with a constant speed 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 can then pick up the changes in magnetic field from the tape and convert it into an electrical signal.

Poulsen obtained a Telegraphone Patent in 1898. Poulsen developed an Arc Converter in 1908, referred to as the "Poulsen Arc Transmitter". A stamp was issued in honor of Poulsen in 1969.

See also

• Timeline of invention
• 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, "US661619 Method of Recordings and Reproducing Sounds or Signals". Magnetic Tape Recorder.