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Topic: Magnetic core

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	[No title]
		The state of magnetism of a core is explained using the hysteresis loop shown in figure 6-2, The points defined on the loop illustrate the magnetic flux density in gausses (B) as a function of the field (induced by the current) in oersteds (H).
		Actually, this core and all magnetic materials exist in nature in some state of magnetization as a result of the influence of the earth's magnetic field.) The 0 point in figure 6-2 represents a condition of 0 ampere-turns in oersteds (H) and 0 core magnetization in gausses (B).
		The use of windings to magnetize the core and to sense the signal resulting from the application of a read pulse is one method by which data can be readout or written into the internal storage facilities of a computer.
	ed-thelen.org /comp-hist/navy-core-memory-desc.html (3645 words)

	Magnetic core memory (Site not responding. Last check: 2007-10-03)
		This lowered the cost of core to the point where it had become largely universal as main memory by the early-1960s, replacing both the low-cost/low-performance drum memory as well as the high-cost/high-performance systems using vacuum tubes as memory.
		Early core memory systems had cycle times of about 6µs, which had fallen to 1.2µs by the early 1970s, and by the mid-70s it was down to 600ns (0.6µs).
		Another characteristic of core is that the hysteresis loop was temperature sensitive, the proper half select current at one temperature is not the proper half select current at another temperature.
	magnetic-core-memory.iqnaut.net (1799 words)

	Core Memory
		Core memory, or more accurately magnetic core memory is a random access memory (RAM) system that was developed at MIT by Jay Forrester in 1951.
		A core is required for each bit of memory and has three wires passing through it, providing the means to select and detect the contents of each bit.
		Core memory, being a magnetic device, is susceptible to the effects of interference.
	www.psych.usyd.edu.au /pdp-11/core.html (983 words)

	Geodynamo
		The convection in the fluid outer core is thought to be driven by both thermal and compositional buoyancy sources at the inner core boundary that are produced as the Earth slowly cools and iron in the iron-rich fluid alloy solidifies onto the inner core giving off latent heat and the light constituent of the alloy.
		Large zonal flows (eastward near the inner core and westward near the mantle) exist on an imaginary "tangent cylinder" due to the effects of large rotation, small fluid viscosity, and the presence of the solid inner core within spherical shell of the outer fluid core.
		The simulated magnetic field has an intensity and a dipole dominated structure that is very similar to the Earth's (Figure 2) and a westward drift of the non-dipolar structures of the field at the surface that is essentially the same as the 0.2 degrees/year measured on the Earth.
	www.es.ucsc.edu /~glatz/geodynamo.html (1233 words)

	VT100.net: Magnetic Core Memories
		A 20 mil core and a 30 mil core on the wings of a common housefly.
		A complete magnetic core memory consists of a number of ring cores of the type described in the previous section, arranged in horizontal rows and vertical columns.
		In this diagram, cores which are in the 1 condition are shown in fl; cores in the 0 condition in white.
	vt100.net /docs/misc/core (3678 words)

	Core Types
		Magnetically, the binding material acts like an air gap, but this gap is distributed throughout the entire core.
		An insert may be placed in a hollow gapped core to provide a means to adjust the inductance of the core (and its windings).
		The core design is intended for use with windings etched on a printed circuit board, thereby eliminating the winding of a separate coil.
	www.butlerwinding.com /core-types/index.html (3781 words)

	Magnetic core memory - Wikipedia, the free encyclopedia
		Core was in turn replaced by silicon memory chips (RAM) in the 1970s.
		Core relies on the hysteresis of the magnetic material used to make the rings.
		A characteristic of core was that it is current-based, not voltage-based.
	en.wikipedia.org /wiki/Magnetic_core_memory (2086 words)

	Magnetic Core Storage
		MAGNETIC CORE STORAGE.\ Magnetic core storage, although not used as much as it used to be, provides an easy way to show the general concepts of memories, including integrated semiconductor and bubble types of memories.
		These cores are magnetized by sending an electric current through the wires on which the core is strung.
		With core storage, the data is retained even when there is a power failure or breakdown, since data is stored in cores in the form of magnetic charges, not electric current.
	www.tpub.com /incs/3.htm (613 words)

	Magnetic core - Wikipedia, the free encyclopedia
		A magnetic core is the core of an electromagnet or inductor.
		Using this technique, the magnetic core is equivalent to many individual magnetic circuits, each one receiving only a small fraction of the magnetic flux (because their section is a fraction of the whole core section).
		Powdered cores made of carbonyl iron, a highly pure iron, have high stability of parameters across a wide range of temperatures and magnetic flux levels, with excellent Q factors between 50 kHz and 200 MHz.
	en.wikipedia.org /wiki/Magnetic_core (1237 words)

	MEMS Magnetic Devices Research
		Desirable characteristics of magnetic cores for integrated inductors and transformers can be summarized as follows: first, high saturation flux in order to obtain high saturation current; second, high permeability to obtain high inductance; third, high resistivity to reduce eddy current loss at high frequencies.
		In addition, micromachined magnetic devices should be designed to have a completely closed magnetic circuit to minimize leakage flux, since leakage flux does not contribute to the total inductance of the devices and can cause interference with other integrated circuitry on the same substrate.
		Magnetic properties of electroplated cores for such devices may be very different from magnetic properties of the bulk magnetic materials, thus necessitating an in-situ property assessment.
	mems.mirc.gatech.edu /research/magnetic.html (2303 words)

	Magnetic core memory
		The "Donuts" are made of Ferrite, a material that can hold a magnetic field in either of two directions, thus representing "1" or "0".
		This makes them an early version; later core memory, especially in the 60's, had cores that appear as tiny fl dots unless you use a magnifier.
		I already had a couple of Core planes, but they were too dense to see the cores...
	www.nzeldes.com /HOC/CoreMemory.htm (336 words)

	C ORE Magnetic Core
		The core model in PWL mode takes as input a voltage which it treats as a magnetomotive force (mmf) value.
		This value is divided by the total effective length of the core to produce a value for the Magnetic Field Intensity, H. This value of H is then used to find the corresponding Flux Density, B, using the piecewise linear relationship described by you in the H_array / B_array coordinate pairs.
		One final note to be made about the two core model nodes is that certain parameters are available in one mode, but not in the other.
	www.cadmigos.com /manual/refman/rm0093.htm (573 words)

	Earth's spinning core provides magnetic protection and disaster movie material
		The core is made of two sections - a liquid outer core and a solid inner core.
		The earth's magnetic field is generated mainly at the core, as the highly conductive metallic fluid of the outer core rotates with respect to the solid inner core, generating electric currents and an accompanying magnetic field.
		Magnetic particles in the molten lava orient themselves toward the magnetic pole just like a compass, and when the lava solidifies, a record is preserved of the magnetic field existing at that time.
	hvo.wr.usgs.gov /volcanowatch/2003/03_10_09.html (977 words)

	Project History: Magnetic Core Memory (Site not responding. Last check: 2007-10-03)
		Magnetic core memory replaced vacuum tubes and mercury delay lines with a much more compact and reliable technology.
		Semiconductor memories largely replaced magnetic cores in the 1970s, but they remained in use for many years in mission-critical and high-reliability applications.
		This project history will work primarily with the core memory collection in the MIT archives, one of the richest sets of documentation for a particular invention that exists.
	web.mit.edu /6.933/www/core.html (305 words)

	Alpha-Core: Custom Magnetic Winding Cores for Tranformers
		In a toroidal transformer the magnetic flux runs parallel to the grain orientation in all parts of the core, and less wire is needed because the windings are distributed over the entire circumference resulting in a shorter mean turn length.
		Core halves may be shimmed apart to produce defined gaps in chokes and line reactors.
		One reason is that the magnetic flux runs parallel to the grain orientation in all parts of the core and another that less wire is needed because the windings are distributed evenly over the entire core circumference, resulting in a shorter mean turn length,
	www.alphacore.com /cores.htm (498 words)

	Core memory history from the PCmuseum
		In the midst of glistening fine copper wires, the little doughnut could be magnetized one way or the other, thus, signaling an "on" or "off" or 0 or 1 in the binary numbering system needed by computers.
		They would tediously string these rows and rows of core with the needle/wire assembly, then cut the end of the wire close to the appropriate solder land, (leaving a "service loop" for future use), and the coreplane would be completed.
		One defective or broken core (and they are very fragile), would entail removing the wires associated with that core, removing the core, usually a chunk at a time, and inserting a new core in its place.
	www.fortunecity.com /marina/reach/435/coremem.htm (698 words)

	Earth's Core Crystal - Crystalinks
		Deeper yet, at the inner core, the pressure is so great - 3.5 million times surface pressure -- that iron solidifies, even though the temperature is believed to exceed 11,000 degrees Fahrenheit, hotter than the surface of the sun.
		Seeking to explain the unusual behavior of seismic waves generated by earthquakes and the mysteries of the earth's magnetic field, two scientists have found evidence that the answers may lie at the very core of the planet - in a single giant crystal.
		That inner core, which remains a solid despite temperatures believed to exceed 7,000 degrees Fahrenheit, was long thought a featureless ball of matter having little or no effect on the planet.
	www.crystalinks.com /corecrystal.html (2406 words)

	LIS Course Notes - Magnetic Core Memory
		An inelegant program which uses a lot of RAM is occasionally called a 'core hog'.
		Magnetic fields and how to make them", by Andrew Duffy of Boston University.
		Thanks to Keith Thomas for suggesting that the machine for which this particular memory was most likely designed, may have used a 24-bit word length, with 1 parity bit for error detection and correction, hence all the multiples of 25.
	valinor.ca /computing/corememory.html (197 words)

	Core Memory (Site not responding. Last check: 2007-10-03)
		Above: The first magnetic core memory, from the IBM 405 Alphabetical Accounting Machine.
		The one core in the center of the figure is switched, however, by the coincidence of the two currents.
		The IBM 737 Magnetic core storage unit (1954, for the IBM 701)
	www.columbia.edu /acis/history/core.html (317 words)

	magnetic core
		In his thesis, entitled "A Coincident-Current Magnetic Memory Unit" (1950), Papian described magnetic core memories, honeycombs of minute magnetic cores strung on wires, through which storage information was read to electronic circuits in the computer.
		The first bank of core memory was installed in the Whirlwind on August 8, 1953.
		He indicated that there were only a couple of firms that were in the business of suppling OEM core memories and that many many computer companies used these rather than try and make them for themselves.
	ed-thelen.org /comp-hist/vs-magnetic-core.html (487 words)

	Kg Magnetics Inc. - Book 3
		We have increased core data to include the latest magnetic materials, such as Kool Mu, Metglas, and Ferrite materials.
		Manufacturers of magnetic cores use a variety of measurement systems to describe their products, a practice which complicates the task of comparing and selecting cores.
		This innovative, new reference compiles the specifications of over 12,000 cores, all converted to (cgs) units, thereby enabling engineers to quickly compare the components and select the one best suited to their needs.
	www.kgmagnetics.com /book3.htm (230 words)

	Inductor Core Technology Shrinking Power Supplies
		One of the core materials available in the washer shape is distributed air-gapped Molypermalloy powder (MPP) toroids with finished core heights down to 0.7 mm.
		Discrete gapped ferrite cores have a magnetic field that fringes around the two air gaps and can couple into nearby circuit board traces, causing EMI problems.
		The inductor's dc current ensures the core is not saturated, and the switched current, or ΔI, determines core loss.
	powerelectronics.com /mag/power_inductor_core_technology_2 (1294 words)

	Magnetic core - US Patent 5639566 (Site not responding. Last check: 2007-10-03)
		A magnetic core obtained by laminating or winding a magnetic material ribbon and an electrical insulating material wherein the magnetic core has the relationship of 0.5 a≤bmagnetic material ribbon is "a", and the width of the electrical insulating material is "b".
		Yamada Kazuo et al., "Manufacture of Wound Core", Abstract, JP 12 08 822, Aug 22, 1989.
		Ysidro M. Martinez was granted a patent for a "knee implant prosthesis".
	www.patentstorm.us /patents/5639566.html (76 words)

	Ferrite - Applcation notes
		Under "small" bias conditions, increasing the applied magneto motive force E applied to a magnetic core device induces a corresponding increase in magnetic flux F in the core.
		At some value of E the magnetic flux F stops increasing; increasing E beyond this value results in a rapid decrease in the permeability of the part.
		For this condition magnetic theory terms the device's core saturated, as it is unable to support further increases in magnetic flux with increasing magneto motive force input.
	www.topmagnetics.com /ferriteproperties.htm (2515 words)

	A Magnetic Core ROM (Site not responding. Last check: 2007-10-03)
		Each line was hand-threaded through the appropriate cores to produce a '1'; non-threaded cores produced a '0'.
		Just up and to the right we can see the first eight cores, the fuzzy fl things that appear to be wiggling around.
		Two of the four gates in a package were wired as a latch for a single core.
	www.ciphersbyritter.com /MARK8/MAGCORE/MAGCORE.HTM (642 words)

	Kg Magnetics Inc. - Book 2
		Chapter 1 deals with the basics and covers the magnetic field, the simple transformer, the magnetic core, the hysteresis loop (B-H Loop), permeability, the air gap, and the fringing flux.
		Chapter 2 deals with 19 different magnetic materials including iron alloys, ferrites, amorphous and powder cores and their characteristics, such as: the B-H loop, permeability, remanence flux, and core loss.
		It also gives the relationship between core geometry, Kg, and the area product, Ap, for the VA capability of a magnetic core.
	www.kgmagnetics.com /book2.htm (1051 words)

	Magnetic Core Memory
		Organised as 64 rows by 64 columns, this Univac III core memory plane of early 60's vintage has a storage capacity of 4096 bits.
		Conveniently, since I'm only flipping one core, the X and Y select wires are driven in series.
		The prediction was 100ns, but I had no idea if that was OK. According to James R Jones' excellent article [1,2] it "should be about half the core design time for a 1 peak to occur" which turned out to be 400ns, so I was a bit fast.
	www.holmea.demon.co.uk /Core/Flipper.htm (579 words)

	Fil-Tec Magna-Glide Bobbins $28.95 Machine Embroidery Bobbins (Site not responding. Last check: 2007-10-03)
		The Magna_glide magnetic core sideless bobbin contains polyester thread that runs with a consistent sewing tension throughout the entire bobbin allowing you to sew out all the bobbin thread.
		The P-15 Magna-Glide magnetic core embroidery bobbin is wound with the industry standard twisted polyester thread, similar to the Coats V-15 bobbins.
		For the magnetic core bobbins to be most effective, they must be used on machines with metal bobbin cases.
	www.embroiderybobbins.com /s_bmag.html (121 words)

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