Tape recorder

Tape recorder, instrument for sound recording on magnetic tape and subsequent playback. A microphone changes sound to an electric current, which is in turn changed in the recording head into magnetic flux variations. The tape, consisting of small particles of iron oxides on a thin plastic film base, is wound from the supply reel to the takeup reel by a rotating capstan that controls the speed. The tape passes in turn: the erase head, which by applying an alternating field reduces the overall magnetization to zero; the recording head, which magnetizes the particles; and the playback head. Most recorders use two, four, or even more tracks side by side on the tape. The most common form of audio tape recorder is the cassette recorder, in which the cassette (a small plastic case) is simply snapped into a recorder and is ready to be played.