A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. A transducer is a device that converts one type of energy to another, or responds to a physical parameter. ... In general, a tape recorder, tape deck, cassette deck or tape machine is any device that records a fluctuating signal by moving a strip of magnetic tape across a tape head, which is a strong electromagnet. ... Jump to: navigation, search In physics, magnetism is not one of the phenomena by which materials exert an attractive or repulsive force on other materials. ...

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 video recorders 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 (an air gap or other insulating material). This gap causes the magnetic flux to spill out of the material at that point, which is where the tape is made to run. 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! Quadrupole (four-pole) magnet, focus particle beams in a particle accelerator. ... Jump to: navigation, search Internal Links Related to Video recorder Digital video recorder Video tape recorder Videocassette recorder Video Recordings Act 1984 ... Helical Scan, or striping is a method of recording higher bandwidth signals onto magnetic tape than would otherwise be possible at the same tape speed with fixed heads. ... A toroid is a doughnut-shaped object whose surface is a torus. ... Magnetic flux, is a measure of quantity of magnetism, taking account of the strength and the extent of a magnetic field. ... Jump to: navigation, search An electronic amplifier is a device for increasing the power of a signal. ... The term induction has more than one meaning in the English language. ... Jump to: navigation, search In electricity, current refers to electric current, which is the flow of electrons. ...

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. In electrical engineering, Impedance is a measure of opposition to a sinusoidal electric current. ...

The width of the head gap is also critical - the narrower the gap, the better the head will be - a narrow gap gives much better transcription in the magnetic domain (the magnetic flux density is higher, and hence will give stronger recording for a given signal, or greater signal pickup for a given tape). A narrow gap also permits higher frequency signals to be recorded for a given tape speed. The desirability for a narrow gap means that most practical heads are made by forming a narrow V-shaped groove in the back face of the core, and grinding away the front face until the V-groove is just breached. In this way, gaps of the order of micrometres are achievable.

The physical design of a head depends on whether it is fixed or rotating. In either case, the face of the head where the gap is must be made hard wearing and highly smooth to avoid excessive tape or head wear. It can also be seen that due to the construction method of the head gap, tape wear will tend to widen the gap, reducing the head's performance over time. The vertical alignment of the heads (the azimuth) must also match between recording and playback for good fidelity, and the gap should be as close to exactly vertical as possible for highest frequency response. Most tape transport mechanisms will allow fine mechanical adjustment of the azimuth of the heads. Sometimes this can be achieved by automatic circuitry - the actual mechanical azimuth adjustment being carried out by taking advantage of the piezo effect of certain types of crystal material. Azimuth is the horizontal component of a direction (compass direction), measured around the horizon toward the East, i. ... Frequency response is the measure of any systems response to frequency, but is usually used in connection with electronic amplifiers and similar systems, particularly in relation to audio signals. ... Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ...

Rotating heads as used in video recorders, digital audio tape and other applications are used to achieve a high relative head/tape speed while maintaining a low overall tape transport speed. The wear characteristics of such heads are even more critical, and highly polished heads and tapes are required. The electrical signals of rotating heads are coupled either inductively or capacitively - there is no direct connection to the head coils. Jump to: navigation, search This article needs to be cleaned up to conform to a higher standard of quality. ... Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ...

Erase heads have a similar design to the signal heads, but are generally far less critical in design. In very cheap audio cassette players (particularly very early designs), a permanent magnet has occasionally been used as an erase head, which simply wipes the tape as it is drawn across the head. The disadvantage of this approach is that the head must be held away from the tape when it is not required, and the tape ends up with a lot of random noise on it. Most recorders use a high frequency alternating current signal to erase a tape - this can be switched on only when required so the head can remain in contact with the tape at all times, making it mechanically simpler, and the way the tape is erased leads to much lower noise. The erase signal can be conveniently derived from the same oscillator used to generate the bias signal. A standard audio cassette Cassette may refer to: A small cartridge of some form. ... Magnetic lines of force of a bar magnet shown by iron filings on paper A magnet is an object that has a magnetic field. ... Jump to: navigation, search NOiSE is a one volume manga created by Tsutomu Nihei as a prequel to his much-acclaimed ten-volume work, Blame! It offers some rather sketchy information concerning the Megastructures origins and initial size, as well as the beginnings of silicon life ... Jump to: navigation, search city lights viewed in a motion blurred exposure. ... Oscillation is the periodic variation, typically in time, of some measure as seen, for example, in a swinging pendulum. ... It has been suggested that this article or section be merged with bias (disambiguation). ...