Topic summary
Tape recorders
Extracted from the Wikipedia article Tape recorder.
Early steel tape recorders
In 1924 a German engineer, Kurt Stille, developed the Poulsen wire recorder as a dictating machine. The following year a fellow German, Louis Blattner, working in Britain, licensed Stille's device and started work on a machine which would instead record on a magnetic steel tape, which he called the Blattnerphone. The tape was 6 mm wide and 0.08 mm thick, traveling at 5 feet per second; the recording time was 20 minutes.