Showing papers on "Magnetic core published in 1970"

A molded coil

Abstract: A mold transformer consisting of a blank coil impregnated with an electrical insulating resin composition of epoxy resin or the like, said blank coil having as an insulator a highly impregnable non-woven polyester fabric or non-woven glass fabric interposed between a high-voltage winding and a low-voltage winding, between the high voltage winding and a magnetic core and between the lowvoltage winding and the magnetic core respectively, and a nonwoven polyester fabric between adjacent winding layers of each of the high-voltage and low-voltage windings; and a method of producing said mold transformer.

Magnetic transducer having a composite magnetic core structure

Abstract: A magnetic transducer for read-write applications is disclosed in which the magnetic circuit comprises a stack of laminations of generally ''''C'''' shape having a read-write winding inductively associated therewith. The read-write gap is provided by the opposed ends of the stacked laminations, and the laminations are of two different types; that is, they have different magnetic characteristics and are preferably of different materials. The outer laminations have relatively low initial permeability relative to the remaining laminations so that they are ineffective during the read operation but have sufficiently low coercive force so that they are magnetized during the write operation. The inner laminations of the stack have relatively high initial permeability so that they are magnetized during the read operation. In this way, the effective height of the stack and, accordingly, the width of the read-write gap is narrower during the reading operation than it is during the writing operation, being essentially equal to the total stack for writing and essentially equal to the inner laminations for reading.

Means for measuring magnitude and direction of a direct current or permanent magnet, including clip-on direct current sensing inductor

Abstract: A direct current or magnetic intensity input produces an offset in the average magnetic intensity applied to a sense inductor core of non-linear magnetic material. No electrical connection is required, and the measured current need not be interrupted. The core is coupled to an oscillator constructed so that the duty factor modulation and direct current output are linear functions of the input and restore the average magnetic intensity. Clip-on DC milliameter sense inductors which largely cancel magnetic noise are included with the description of embodiments of this invention. They are sensitive, small in size, inexpensive, and will outperform larger and more costly devices. Power consumption is greatly reduced because fewer components are used more effectively.

Ground fault sensing circuit

Abstract: There is disclosed a ground fault sensing circuit usable with either AC or DC circuits. It includes a closed loop magnetic core having a gap. Two windings are disposed on the core in series, respectively, with the different conductors supplying the load. The windings are arranged in such a manner that, when the currents in the conductors are equal, there is no magnetic flux produced in the core and gap. Positioned in the gap is a solid state magnetic field sensitive element such as a Hall effect device or magnetic transistor. Underground fault conditions, a magnetic field appears across the gap and an output signal is generated by the solid state device. This signal is amplified and trips a circuit breaker in series with the load.

Multi-armature motors

Abstract: A direct current motor having at least two armatures arranged in parallel between parallel magnetic circuits established through the armatures independently exciting the armatures. In one embodiment a pair of iron core coils, positioned on respective opposing sides of a pair of armatures, provides the magnetic circuit. In another embodiment an iron core coil, interposed between two or more parallel armatures, forms the magnetic circuit. This common source of magnetic excitation forms parallel magnetic circuits wherein the motor has a dual operating characteristic in that the speed of one armature varies inversely with the speed of the other armature and vice versa until the higher speed armature reaches its critical rpm permitting the load to be increased without further change in the speed of either armature.

Low frequency magnetic core inductor structure

Abstract: A low frequency magnetic core inductor is provided which exhibits the desirable high quality factor (Q) and low external magnetic field of the prior art toroidal type inductor, but which is constructed to have a bobbin-like configuration for ease of assembly and winding the inductor winding on the core, and for compactness of size and efficient use of available space.

Thin film magnetic transducer head

Abstract: A rectangular thin film transducer head includes a magnetic core composed of overlapping laminations of permalloy film joined together magnetically and electrically, near an air gap, at one end of the rectangle, between the two laminations, which gap couples flux to the magnetic recording medium. Two electrically parallel insulated thin film copper windings starting at the end opposite the gap are deposited about the core joining electrically at the end adjacent to the gap to a conductor coupled to both permalloy laminations which conduct return current through the legs of the core inside of the windings. Alternatively, a single series winding passes around the core and through the gap. The head is manufactured by means of photolithographic, vacuum, and thin film techniques.

Power supply filter for noise suppression

Abstract: The invention provides a power supply filter for noise suppression in which the windings of a plurality of lines for supplying a power supply voltage and current of a predetermined frequency are so wound around same magnetic core that the sum of the magnetic fluxes produced by the windings may become zero, thereby providing an inductance element. This inductance is almost negligible to a power supply frequency component while it is high to a high frequency noise component, so that the power supply frequency component is not attenuated while the high frequency component superposed upon the power supply frequency component is attenuated to a greater extent. A power supply filter for noise suppression which is compact in size and having a large current may be provided.

The calculation of magnetic circuits with permanent magnets by digital computers

Abstract: Numerical methods to calculate two- or three-dimensional static magnetic fields in devices with air, iron, currents, and permanent magnets are described and applied to loudspeaker magnets and dc motors with permanent excitation.

Clamp on current detector

Abstract: A METHOD AND APPARATUS FOR MEASURING DC CURRENT IN A CONDUCTOR BY SURROUNDING THE CONDUCTOR WITH A MAGNETIC CORE HAVING FIRST AND SECOND CORE SECTIONS, THE SECOND CORE SECTION BEING ADAPTED FOR MOVEMENT RELATIVE TO THE FIRST CORE SECTION AND NORMALLY BIASED TO A CERTAIN RELATIVE POSITION SO AS TO PRESENT A CERTAIN RELUCTANCE TO THE MAGNETIC FIELD PRODUCED BY THE CURRENT IN THE CONDUCTOR. THE SECOND CORE SECTION IS MOVED TO A PREDETERMINED COCKED POSITION THEN RAPIDLY RETURNED TO THE CERTAIN POSITION SO AS TO RAPIDLY CHANGE THE MAGNETIC FLUX IN THE MAGNETIC CORE. THE MAGNETIC FLUX CHANGE IS SENSED BY A SENSING COIL AND PRVIDES AN INDICATION OF THE CURRENT MAGNITUDE. A RESETTING COIL IS ALSO PROVIDED FOR RETURNING THE MAGNETIC CORE TO A PREDETERMINED MAGNETIC CONDITION BY GENERATING A PREDETERMINED MAGNETIC FIELD IN THE CORE IN THE SAME DIRECTION AS THE MAGNETIC FIELD GENERATED BY THE CURRENT IN THE CONDUCTOR.

Transformer with bushing compartment

Abstract: Electrical inductive apparatus of the shell-form type, having a tank filled with a liquid dielectric, and a magnetic core winding assembly disposed in the tank and immersed in the liquid dielectric. The magnetic core winding assembly includes a magnetic core, and one or more windings formed of a plurality of axially spaced pancake coils which link the magnetic core and extend outwardly therefrom above and below the magnetic core, towards the cover and bottom portions of the tank, respectively. At least the connection to the high-voltage winding is made by a lead assembly connected to a pancake coil at a point below the magnetic core. The other end of the lead assembly is connected to the encased end of high-voltage bushing assembly which is mounted in a separate bushing compartment attached to a sidewall portion of the tank, through aligned openings in the tank and bushing compartment.

Core constructions for variable inductors and parametric devices

Abstract: Various core constructions are disclosed for use with variable inductors and parametric devices, the cores having supplemental core pieces acting in some cases as magnetic shunts and in other cases as return paths, or both, for the input and/or output portions of a magnetic core such as that disclosed in U.S. Pat. No. 3,403,323.

Magnetic dental appliances and methods for using same

Abstract: Magnetic dental appliances and materials therefor, magnetic denture teeth, magnetic transfer apparatus and method magnetic denture material; and particularly magnetic methods and apparatus for making full dentures and bridges providing an accurate functional balance of occlusion and centric relation for use in the full denture and bridge construction, including the use of magnetic holding means for transferring the upper baseplate and lower bite rim in proper locked relationship to an articulator. Also, a method of retention of the dentures and bridges in place in the mouth during use by magnetic means is provided, including magnetic core artificial teeth, magnetic denture base material, and magnetic alloy inserts for implanting under the soft tissue along and into the alveolar ridge.

Induction linear electric motor

Abstract: An induction linear electric motor comprising a pair of linear stators with their respective windings, movably mounted at the opposite sides of a stationary rotor member. Control of the travelling speed of the linear stators relative to the rotor in the direction of the motion of the traveling magnetic field, produced by the stators and their windings, is effected by displacing the stators and their windings relative to the rotor in a direction perpendicular to the direction of the motion of the magnetic field. When the travelling speed is controlled in the above-described member, with the stators displaced relative to the rotor, a portion of the magnetic flux produced by the stators is taken up by an auxiliary magnetic core of the disclosed; linear electric motor, this auxiliary magnetic core being disposed intermediate of the linear stators.

Magnetic susceptibility tester

Abstract: A testing apparatus for nondestructive testing of the magnetic characteristics of a portion of magnetic thin-film on a magnetic recording disc is disclosed. The recording disc is inserted into a slotted area of the yoke of an electromagnet so that a DC magnetic immersion field is provided parallel to the surface of the disc. This DC field is generated in an increasing magnitude ramp at the same time that a high-frequency stimulus field is generated adjacently parallel to the magnetic thin-film. A sense winding interwoven with the stimulus field coil will pick up signals representative of how well the thin magnetic film couples the stimulus field coil and the sense coil at the various magnitudes of DC field. A plot of the rectified sense signal amplitude against the magnitude of the DC field over a short time period on a readout device indicates the differential magnetic susceptibility of the thin magnetic film by the magnitude of the ordinate of the plotted curve. A balance network is provided to cancel any coupling between the stimulus coil and sensing coil when a negative immersion field is made to saturate the thin film. The magnetic characteristics for assessing merit which may be determined are: the coercive force of the film, and the magnetic susceptibility which is a measure of the relative squareness of the hysteresis loop and therefore a measure of the maximum magnetic switching rate.

Lamp ballast and method of producing same

Abstract: A lamp ballast wherein a magnetic core and coil assembly is encased within a housing and is spaced from the housing with a suitable filler material filling the space between the magnetic core and coil assembly and the housing. The magnetic core and coil assembly is suspended within the housing having an open top, being spaced from the sides and bottom thereof by suspension means. The housing or casing is then partially filled with the suitable filler material in liquid form, to a level wherein at least a portion of the magnetic core and coil assembly is immersed in the filler material. After the filler material has hardened to an extent that it will support the core and coil assembly, portions of the suspension means are removed such that when the housing is completely filled with the filler material the core and coil assembly will be completely surrounded by the filler material and the suspension means will not extend from the core and coil assembly to the casing. Thus, the suspension means does not provide a surface joining the casing and the core and coil assembly along which moisture entering the casing may reach the core and coil assembly.

3-D Magnetic Field Of Coils With An OpenMetallic Core In Boundary-integral Approach

Abstract: Boundary-integral approach to 3-D stationary magnetic fields exited by coils and/or current-carrying rings is presented. Metallic elements placed variously in neighbours of the coils are considered like inner boundaries for outer magnetic field. The boundary-integral model is formulated for indirect boundary quantities: monopole and/or dipole surface densities of the 'magnetic charge'. The author's BIMS package has been performed. Some results of computation of the magnetic field in an open magnetic core put inside or outside of the coils, axially or not, are presented. The original post-processing of the package affords possibilities to accomplish the particular design, rather untypical in engineering practice. This is a matter, among other things, that the coil inductance influenced by both the magnetic flux in the open core and the surface currents on screen plates can be precisely calculated.

A Capacitively Coupled Magnetic Flux Mapper

Abstract: An improved capacitively coupled conducting-paper analog to simulate the two-dimensional magnetic vector potential field of multiple uniformly distributed source regions is discussed A null method is used in obtaining the flux distribution, and a differential probe-amplifier combination is employed in finding flux density infarmation Output of the analog is readily used to calculate reactance, short-circuit forces, and stray-load losses of power transformers

Magnetically coupled core and coil arrangement

Abstract: 1,193,916 Measuring magnetic fields MAGNAVOX CO March 29, 1968, No15113/68 Heading G1N In a magnetic field sensor, a magnetic core 21 is mounted within a non-magnetic casing 10 for free movement relative to a surrounding coil or coils, so that the core 21 may maintain a desired predetermined orientation despite movements of the casing 10 As shown, the core 21 is cemented to a brass ring 22 supported by brass screw threaded rods 23 on a non-magnetic disc 24 which is suspended from the top of the casing through a ball bearing joint (18) A toroidal primary winding 30 and four secondary windings 31 are wound round a plastics former 32 which has holes 36 in its lower annular surface to allow unobstructed movement of the rods 23 Screws 40 permit balance adjustment The core may be arranged to maintain an orientation other than horizontal The core may float on the surface of a liquid contained in the coil form

History effect of ferrite cores as analog storage elements

Abstract: Studies on 2-and 3-mm ferrite cores for use as storage elements in an analog core memory are presented. The information is stored as the flux level of the magnetic core. The partial fluxswitching is performed by voltage pulses with constant amplitude but varying length. Between writing and reading an error appears which is caused by the reversible portion of the flux and whose value depends upon the switched flux level. It is shown that there exists a relation between the magnitude of the error and the characteristic properties of the cores. The measured character of the error depends on how often a particular write-read cycle is repeated before changing the amplitude of the switched flux. A history effect was found to be the reason for this. A special method has been developed to drive the cores in a matrix array [1]. In this mode the history effect did not occur.

Means for controlling the leakage flux in transformers

Abstract: In transformers for high power amounts, for collecting the leakage flux and leading it back to the iron core, plates of laminated magnetic material are arranged close to the ends of the winding coils and at least one end of the plates is in magnetic connection with the core.

Starting controller for electric motor

Abstract: A starting controller is provided for electric motors of the split-phase type. This controller incorporates an electrical switching circuit utilizing a bi-directional, solid-state switching device as the element which effects the switch function. The circuit elements and components are incorporated in a mechanical structure having an electrical current transformer provided with a core that also forms a heat sink for the solidstate switching device. The core thus mechanically supports both the switching device and the transformer windings, performing a heat dissipation function as well as forming a part of the magnetic circuit for the transformer controlling operation of the solid-state switching device. All components including the transformer core, are embedded in a dielectric potting compound within an outer iron core shell forming the remainder of the magnetic circuit for the transformer.

Magnetic core with electrical insulation

Abstract: An electrical insulating material combining resin and a solid particulate filler to obtain thixotropic properties providing more uniform coating coverage in particular at product corner surfaces. In a specific embodiment, the material provides a resilient, matte-finish for non-slip application of coil windings. The electrical insulation material is prepared with a volatile liquid vehicle for spray-on application. In a method for sealing and insulating magnetic cores, the cores are heated above about 225* F. but not above about 425* F. to expand gases within the cores and/or within core encasements and permit gas escape before sealing. Sealing is completed while the magnetic core, and encasement if any, are at an elevated temperature. Curing of the coating is carried out by heating.

Keyboard switch construction

Abstract: The disclosure describes solid-state keyboards employing a saturable magnetic core switch for each key. Each key has a keystem of magnetic material, the keystem having legs extending on opposing sides of the core. Two permanent magnets are attached to the keystem. When a key is not depressed, the magnets are located adjacent opposing sides of the core so that a flux path is formed through the core, the keystem, and the two magnets, to thereby saturate the core. When a key is depressed, the permanent magnets are moved away from the core so that it becomes unsaturated. The core is threaded by one or more wires, at least one of them being excited from an AC drive source. A switch housing of unitary construction is designed to guide the keystem, lock the switch in place in the keyboard, and hold the magnetic core in a position which facilitates threading wires through the cores.

Step motor control circuit

Abstract: A permanent magnet step motor rotor is driven in response to oppositely directed magnetic fluxes coupled by a magnetic core to the rotor. The flux in one direction is derived by selectively feeding D.C. current in one direction through a winding means on the core and a transistor emitter collector path while a switch is open circuited to forward bias the transistor base emitter junction. Flux in the other direction is derived by closing the switch and thereby back biasing the transistor so that D.C. current flows in the winding means in the opposite direction. The rotor is locked in place under steady state conditions with a D.C. current derived from the circuit including the transistor and switch. The steady state current is less than the current required to drive the rotor and is maintained at the lower level by including capacitors in bias circuits for the transistor. To drive the rotor in response to changing magnetic fluxes there may be provided either shading rings, extended, segmented core pole faces, or a rotor having major and minor permanent magnet poles. To provide balanced magnetic flux in opposite magnetic core pole faces coupling flux to the rotor a low resistivity slotted ring is provided.

Multi-channel magnetic head

Abstract: A multi-channel magnetic head composed of a stack of a plurality of elementary head units. Each unit has a substantially D-shaped magnetic core having a magnetic gap. A winding is wound on said core, and a support plate is provided on which said D-shaped core is positioned. The support plate has at least one recess in which said winding is positioned. The support plate is a laminated structure having a magnetic sheet and non-magnetic sheets. The plurality of elementary head units are stacked with the gaps of the elementary head units aligned in a single straight line.