In this note, we are going to know about the Magnetic Recording on Tape and Its Block Diagram. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.
Author Name: Arun Paul.
What is Magnetic Tape Recording?
Magnetic tape recording is a method of storing audio, video, or data that involves magnetizing a thin plastic strip covered with a ferromagnetic substance, such as iron oxide. It was commonly used for analog audio recording, video recording, and early digital data storage.
Magnetic Tape Recorder Block Diagram
Here is the magnetic tape recorder diagram of production and reproduction –
Magnetic Tape Recording – Production
Sound pressure variations are converted into electrical variations (audio signals) by a microphone. The audio output of the microphone is amplified and fed to the coil of an electromagnet. The electromagnet (called ‘Head’) has a minute gap through which magnetic lines of force cannot pass easily due to the high reluctance of air. When a tape with a coating of a magnetic material ( like iron oxide) is made to pass across the gap, the lines of force get an easy path through the iron oxide which is formed into elementary magnets.
The magnetic strength of electromagnet, and hence, through the gap covered by the iron oxide of the tape, depends on the audio current. Thus, the coating of iron oxide on the tape is magnetized in the accordance with the audio current and hence, by the sound pressure variations. The magnetism in the iron oxide can remain retained for a long time. This means that sound had been recorded in the form of varying magnetic fields.
Magnetic Tape Recording – Reproduction
In reproducing the recorded sound, the tape is again made to pass through a similar gap (or even the same gap), and it causes change in lines of force through the coil. This induces e.m.f. ( audio signal) in the coil, which is by the rate of change of magnetic flux in the tape. The induced e.m.f. is amplified and is fed to a loudspeaker which converts the audio signal into sound.
The figure shows a magnetized tape for 3 cycles of audio signal. The figure shows that as wavelength decreases, the length of bar magnets formed on the tape decreases. Each cycle gives rise to two bar magnets.
Magnetic Tape Recorder Working Principle
Magnetic tape recording is based on electromagnetic induction. The process begins when a magnetic tape passes by a recording head, which serves as an electromagnet. The recording head receives an electrical signal, which can be audio, video, or data. This electrical signal produces a magnetic field, causing the small magnetic particles on the tape to align in a pattern that corresponds to the input signal. Once magnetized, the tape maintains the recorded data, allowing it to be saved for later playback or processing.
During playback, the recorded tape passes through a playback head, which detects the stored magnetic patterns. These magnetic changes generate an electrical signal in the playback head, which is amplified and transformed back into sound, video, or data. This allows for the recovery and reproduction of the original recorded information.
Advantages of Magnetic Tape Recorder
Here we have listed some advantages of magnetic tape recording –
- Magnetic Tape can store large amount of data.
- The cost per unit storage is less as compare to other recording systems.
- These tapes has long lifespan compare to others.
- Magnetic tapes, unlike hard drives, do not contain moving parts, which reduces the danger of mechanical failure.
- Magnetic tapes are simple to transport and store, because they do not require constant power.