Magnetic Tape Recorder 303624

Gunjan K.Vyas M.Sc(ECI) Sem 7

Introduction  A recorder is measuring instrument that display a time

varying signal in a form easy to examine, even after the original signal has ceased to exist .

Types of Recorders  Galvanometer recorder  Potentiometric recorder

 Magnetic recorder

Magnetic Recorder  A major advantage of using a magnetic tape recorder is

that once the data is recorded, it can be replayed an almost indefinite number of times.  The recording period may vary from a few minutes to several days.  Speed translation of the captured can be provided, i.e. Fast data can be slowed down and slow data speeded up by using different record and reproduce speed.

Basic components of tape recorder  Recording head  Magnetic head  Reproducing head

 Tape transport mechanism  Conditioning devices

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 es over the gap.  As the magnetic field varies in strength so does the magnetism stored on the tape.  During playback the tape es 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 www.hobbyprojects.com

A Course in Electrical and Electronic Measurements

and Instrumentation –A.K.Sawhney.  Dhanpat Rai &Co

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