Valdemar Poulsen was a Danish engineer who developed a magnetic wire recorder called the telegraphone in 1898. He also made significant contributions to early radio technology, including the first continuous wave radio transmitter, the Poulsen arc, which was used for a majority of the earliest audio radio transmissions, before being supplanted by the development of vacuum-tube transmitters.
Valdemar Poulsen (c. 1898)
Poulsen's magnetic wire recorder
Poulsen's 1900 US patent for a magnetic wire recorder
"Telephonograph after Poulsen, for permanently fixing and conveniently repeating a telephonic conversation." From a 1911 catalog of physical apparatuses.
Wire recording, also known as magnetic wire recording, was the first magnetic recording technology, an analog type of audio storage. It recorded sound signals on a thin steel wire using varying levels of magnetization. The first crude magnetic recorder was invented in 1898 by Valdemar Poulsen. The first magnetic recorder to be made commercially available anywhere was the Telegraphone, manufactured by the American Telegraphone Company, Springfield, Massachusetts in 1903.
A Webster-Chicago Model 7 wire recorder from 1948
Poulsen Telegraphone recorder from 1922.
First US patent issued 1900 for a magnetic wire recorder by inventor Valdemar Poulsen
German Reichhalter Reporter W102 wire recorder (c. 1950)