G S T Poonam MSc -I

Introduction Magnetic recording is a backbone technology of the electronic age. It is a fundamental way for permanently storing information. A tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape machine is an audio storage device that records and plays back sound using magnetic tape, either wound on a reel or in a cassette, for storage. It records a fluctuating signal by moving the tape across a tape head that polarizes the magnetic domains in the tape in proportion to the audio signal

Block Diagrams of Tape Recorder

Working The tape head consists of a ring of soft magnetic material, called the core, with a small gap in it. A coil is wound around the core. The tape travels over the gap in the core. During recording, an audio signal causes current to flow through the coil producing a magnetic field in the gap, as shown by the blue lines of force in the diagram. As the audio signal varies in amplitude and frequency so does the magnetic field. The tape consists of a plastic film coated with a material that is magnetized by the field as it passes over the gap. As the magnetic field varies in strength so does the magnetism stored on the tape. During playback the tape passes over the same head. (it is called the record/playback head). This time the magnetism stored on the tape induces a voltage in the head coil. This voltage is amplified and used to drive a loudspeaker.

Advantages  It has wide frequency ranges from DC to several MHz.  They have a low distortion.  The magnitude of the electrical input signal is stored in magnetic memory.  The recorded signal is immediately available with no time lost.  When the information has been processed, the tape can be erased and reused to record a new set of data.  It permits multi-channel recording.

Applications Instrumentation Systems Recording Audio Recording Video Computers Electrocardiograph Flight Test Data Recording and Processing Systems

References:  Internet  Google.com   A Course in Electrical and Electronic Measurements and Instrumentation –A.K.Sawhney.  Dhanpat Rai &Co