How were tape recorders invented?
Magnetic recording dates to 1898, when Danish engineer Valdemar Poulsen developed a method for recording sound on a steel wire. He stretched this wire across his laboratory and put the recording apparatus on a trolley that traveled along that wire. He would run along with the moving trolley, talking into its microphone to record sound on the wire. To play back this sound, he would roll a second trolley containing the playback equipment along the wire and it would reproduce the sound. Having proven the principle of magnetic recording, Poulsen and others began to develop wire recorders. In these devices, a wire rolling from one drum to another was used to record and play back sound. In 1927, American inventor J. A. O’Neill replaced the wire with a magnetically coated ribbon and since then magnetic tape recorders have dominated the recording industry.