In this way, gaps of the order of micrometres are achievable.Ī record head, on the other hand, has a gap typically six times larger than that of the replay head, this gives a larger flux to magnetise the tape. 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. 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 (which equals to more output with high frequency signals in the case with playback heads). Having separate heads for recording and playback has other advantages, such as off-tape monitoring during recording, etc. In the very best tape recorders, separate heads are used to avoid compromising these desirable characteristics. One of these is the impedance of the coil - playback preferring a high impedance, and recording a low one. While a head is reversible in principle, and very often in practice, there are desirable characteristics that differ between the playback and recording phases. 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. A coil of wire wrapped around the core opposite the gap interfaces to the electrical side of the apparatus. The flux thus magnetises the tape or induces current in the coil at that point. ![]() 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. This gap is filled with a diamagnetic material, such as gold. 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. 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. That voltage can then be amplified and connected to speakers in the case of audio, or measured and sorted into ones and zeroes in the case of digital data. Since the moving tape is carrying a changing magnetic field with it, it induces a varying voltage across the head. It then moves at a constant speed over an electromagnet. Cassettes, reel-to-reel tapes, 8-tracks, VHS tapes, and even floppy disks and early hard drive disks all use the same principle of physics to store and read back information. 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. ( June 2017) ( Learn how and when to remove this template message)Ī tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. Please help to ensure that disputed statements are reliably sourced. Relevant discussion may be found on the talk page. This article's factual accuracy is disputed.
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