Tape head

A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. They can also be used to read credit/debit/gift cards because the strip of magnetic tape on the back of a credit card stores data the same way that other magnetic tapes do. Cassettes, reel-to-reel tapes, 8-tracks, VHS tapes, and even floppy disks and modern hard drive disks all use the same principle of physics to store and read back information. The medium is magnetized in a pattern. It then moves at a constant speed over an electromagnet. Since the moving tape is carrying a changing magnetic field with it, it induces a varying voltage across the head. That voltage can then be amplified and connected to speakers in the case of audio, or measured and sorted into '1's and zeroes in the case of digital data. D6 HDTV VTR Scanner and video head, removedInside a D6 HDTV VTR Tape Deck, VTR Scanner and video head in place.Type B videotape video Scanner HeadType B VTR, BCN 20 Tape Desk and video ScannerQuadruplex videotape Ampex AVR-2 Video HeadSony U-Matic Video headAmpex audio recorderVHS headsNagra audio heads: erase, record and play A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. They can also be used to read credit/debit/gift cards because the strip of magnetic tape on the back of a credit card stores data the same way that other magnetic tapes do. Cassettes, reel-to-reel tapes, 8-tracks, VHS tapes, and even floppy disks and modern hard drive disks all use the same principle of physics to store and read back information. The medium is magnetized in a pattern. It then moves at a constant speed over an electromagnet. Since the moving tape is carrying a changing magnetic field with it, it induces a varying voltage across the head. That voltage can then be amplified and connected to speakers in the case of audio, or measured and sorted into '1's and zeroes in the case of digital data. 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, and also forces the magnetic flux out of the magnetic tape medium into the gap more than air would. The flux thus magnetises the tape or electrifies the coil at that point. A coil of wire wrapped around the core opposite the gap interfaces to the electrical side of the apparatus. 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 at the gap. While a head is reversible in principle, and very often in practice, there are desirable characteristics that differ between the playback and recording phases. One of these is the impedance of the coil - playback preferring a high impedance, and recording a low one. In the very best tape recorders, separate heads are used to avoid compromising these desirable characteristics. Having separate heads for recording and playback has other advantages, such as off-tape monitoring during recording, etc.