2. MAGNETIC TAPE RECORDER
• To record data in such a way that they can be reproduced in
electrical form, magnetic tape recording is used.
• It can be used at higher frequencies in instrumentation system.
• BASIC COMPONENTS OF A TAPE RECORDER:
It consists of following basic components:
1. Recording head
This device responds to an electrical signal in such a way that a
magnetic pattern is created in magnetisable medium. The
construction of magnetic head is as shown below.
3. • A fine air gap of length 5 to 15 um is shunted by passing magnetic tape. A current in the coil
causes a flux of same shape to bridge the air gap and hence to pass through the magnetic tape
thereby, magnetizing the ion oxide particles as they pass the gap.
• The state of magnetization of oxide as it leaves the gap is retained. Thus, actual recording
takes place at the trailing edge of the gap.
4. 2. Magnetic tape:
It consists of a coating of fine magnetic iron oxide particles(Fe2O3) on a plastic ribbon.
A typical tape is 12.7 mm wide and 25.4 um thick.
3. Reproducing head:
It detects the magnetic pattern stored in them and converts it back to original electrical
signal. It is similar in appearance to that of recording head.
4. Tape transport mechanism:
It moves the tape along the recording or reproducing head at constant speed. It must be
capable of handling the tape during various modes of operation without staining, distorting or
wearing the tape. A simple arrangement is as shown below:
5. • As shown above, the capston and pinch roller are used to drive the tape.
5. Conditioning devices:
It consists of amplifier and filter required for modifying the signal to a format that
can be properly recorded on a tape.
BLOCK DIAGRAM OF MAGNETIC TAPE RECORDER:
The block diagram of magnetic tape recorder is as shown:
6. • As shown above, microphone receives the sound signal and converts it into
electrical signal.
• This signal is amplified by preamplifier and to increase the power level, it is fed to
power amplifier.
• This amplified electrical signal is then fed to the recording head.
• The recording head responds to an electrical signal and creates a magnetic pattern
on a magnetizable medium i.e. tape.
• This magnetic pattern on the tape is converted into an electrical signal by
reproducing head.
• This electrical signal then again amplified by preamplifier and power amplifier
which is fed to the loudspeaker to convert it into sound signal.
• ADVANTAGES:
1. Wide frequency range from DC to several MHz.
2. Wide dynamic range exceeds 50 dB.
3. Low distortion.
4. No time lost in processing.
5. Permits multichannel recording.
