Poulsen's wire-reel telegraphone

Poulsen Telegraphone, for magnetic recording on wire, 1903.

Poulsen Telegraphone, 1903.

The Danish inventor Valdemar Poulsen pioneered magnetic recording in 1898. In this device, which was used as a dictation and answering machine, a long steel wire became magnetised as it passed close to a recording head that carried an audio signal. Although technically successful, Poulsen's system did not come into its own until electronic amplication was developed.

Recording machines based on Poulsen's principle using magnetic wire or plastic tape were introduced by the 1930s.