..... Click the link for more information. , and transformed into an electric current. The current is fed to a transducer transducer, device that accepts an input of energy in one form and produces an output of energy in some other form, with a known, fixed relationship between the input and output.
..... Click the link for more information. in the recording head of the tape recorder, which converts it into corresponding magnetic flux variations that magnetize the particles on the tape. Tape recorders always require that the recording media and the recording or playback tape heads move with respect to each other. A digital audio tape (DAT) recorder transforms the audio signals into digital pulses, which are then stored on the tape. Digital tape recording devices are also used to store information from a computer. Magnetic tape can also be used to store video information. Videocassette recorders use a rotating-head system to increase tape capacity. The recording heads move in a direction almost perpendicular to the tape movement, resulting in diagonal bands of information across the tape width. For audio tape recording, available formats include the compact cassette, digital audio tape, and digital compact cassette. For amateur videotape recording, VHS, VHS-C, SVHS, 8mm, and Hi8 are available formats. See sound recording sound recording, process of converting the acoustic energy of sound into some form in which it can be permanently stored and reproduced at any time.
..... Click the link for more information. ; television television, transmission and reception of still or moving images by means of electrical signals, especially by means of electromagnetic radiation using the techniques of radio and by fiberoptic and coaxial cables.
..... Click the link for more information. .
tape recorder
Recording system that makes use of electromagnetic phenomena to record and reproduce sound waves. The tape consists of a plastic backing coated with a thin layer of tiny particles of magnetic powder. The recording head of the tape deck consists of a tiny C-shaped magnet with its gap adjacent to the moving tape. The incoming sound wave, having been converted by a microphone into an electrical signal, produces a time-varying magnetic field in the gap of the magnet. As the tape moves past the recording head, the powder is magnetized in such a way that the tape carries a record of the shape of the wave being recorded.
tape recorder
tape recorder [′tāp ri‚kȯrd·ər]
Tape Recorder
a device for the magnetic recording and reproduction of sound.
Depending on their quality and intended use, tape recorders are classified as professional, studio, semiprofessional, or home models. Professional tape recorders are designed for the synchronous recording of sound (with a visual image) on perforated magnetic tape and are used in sound films. Studio recorders for recording on unperforated 6.25-mm magnetic tape are used in radio broadcasting, motion-picture studios, recording studios, television centers, and wherever high-quality sound recording is required. Semiprofessional recorders, most of which require 6.25-mm tape, are used for recording dispatcher communications in transport and for audio-frequency signals in scientific studies. For amateur recording and the playback of commercial tapes, home models are adequate. In addition, there are dictating machines; reporters’ models, light portable machines with independent power supplies; and students’ models, which are designed for parallel dual-track recording and which may be plugged into external monitors in foreign-language labs. Tape decks, as well as combinations of tape recorders and other types of equipment, such as radios and turntables, are available.
A tape recorder consists of a tape drive mechanism to advance the tape; electric signal amplifiers; magnetic heads for recording, playing back, and erasing the recordings; a high-frequency oscillations generator; a recording level indicator; and a power supply. The high-frequency (40-200 kilohertz) current from the generator is fed into the coils of the recording head (for magnetizing the tape) and erasing head. The basic quality of the recorder depends on the degree of magnetization. The optimal strength of the magnetization current is chosen for each type of magnetic tape. To simplify and reduce the cost of tape recorders (particularly, those for consumer use), a universal amplifier head is used (for sequential recording and playback) in conjunction with a universal magnetic head (see Figure 1).
The magnetic tape is usually wound on a spool (in professional recorders) or reel (in semiprofessional and home recorders). In the new cassette recorders the tape (occasionally, the magnetic wire) is contained in a closed cassette that is easily inserted and removed. Cassettes protect the tape from dust and manual contact and simplify the operation of the recorder.
Unlike the monophonic recorders described, which have a single channel for recording and playback, stereophonic recorders have a more complex design: each channel requires separate amplifiers, heads, and speakers. Consumer-model stereophonic recorders have two channels; professional stereophonic recorders may have as many as six.
The basic quality indexes for magnetic recorders with nonperforated tapes are established by GOST (All-Union State Standard).
GOST also specifies tape speeds of 38.1, 19.05, 9.53, and 4.76 cm per sec. Some tape recorders provide for two or three operating speeds, as required. The quality indexes depend on the use for which the recorders are intended, their class, and the operating speed. As a rule, the higher the tape speed, the higher the quality indexes.
REFERENCES
Kurbatov, N. V., and E. B. lanovskii. Spravochnik po magnitofonam, 3rd ed. Moscow, 1970.GOST 12107-66, 12392-66, and 13265-67.
V. G. KOROL’KOV
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