Principles of Operation
The electromagnetic arrangement of a tape head is generally similar for all types, though the physical design varies considerably depending on the application - for example videocassette recorders (VCR) use rotating heads which implement a helical scan, whereas most audio recorders have fixed heads. A head consists of a core of magnetic material arranged into a doughnut shape or toroid, into which a very narrow gap has been let. This gap is filled with a diamagnetic material, such as gold. This forces the magnetic flux out of the gap into the magnetic tape medium more than air would (it also prevents the gap filling with rubbed off material from the tape which would have the reverse effect). The flux thus magnetises the tape at that point. A coil of wire wrapped around the core opposite the gap interfaces to the electrical side of the apparatus; thus either supplying a signal in the case of recording, or being fed to an amplifier in the case of playback. The basic head design is fully reversible - a variable magnetic field at the gap will induce an electric current in the coil, and an electric current in the coil will induce a magnetic field in the core and hence in the tape drawn across the gap.
Read more about this topic: Tape Head
Famous quotes containing the words principles of, principles and/or operation:
“Though the ancients were ignorant of the principles of Christianity there were in them the germs of its spirit.”
—Herman Melville (1819–1891)
“A bureaucracy is sure to think that its duty is to augment official power, official business, or official members, rather than to leave free the energies of mankind; it overdoes the quantity of government, as well as impairs its quality. The truth is, that a skilled bureaucracy ... is, though it boasts of an appearance of science, quite inconsistent with the true principles of the art of business.”
—Walter Bagehot (1826–1877)
“Waiting for the race to become official, he began to feel as if he had as much effect on the final outcome of the operation as a single piece of a jumbo jigsaw puzzle has to its predetermined final design. Only the addition of the missing fragments of the puzzle would reveal if the picture was as he guessed it would be.”
—Stanley Kubrick (b. 1928)