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Showing papers on "Electromagnetic coil published in 1968"


Journal ArticleDOI
TL;DR: In this paper, the axially symmetric eddy-current problems are solved in two configurations of wide applicability. But the solutions are in the form of integrals of first-order Bessel functions giving the vector potential, from which other electromagnetic quantities of interest can be obtained.
Abstract: Solutions have been obtained for axially symmetric eddy‐current problems in two configurations of wide applicability. In both cases, the eddy currents are assumed to be produced by a circular coil of rectangular cross section, driven by a constant amplitude alternating current. One solution is for a coil above a semi‐infinite conducting slab with a plane surface, covered with a uniform layer of another conductor. This solution includes the special cases of a coil above a single infinite plane conductor or above a sheet of finite thickness, as well as the case of one metal clad on another. The other solution is for a coil surrounding an infinitely long circular conducting rod with a uniformly thick coating of another conductor. This includes the special cases of a coil around a conducting tube or rod, as well as one metal clad on a rod of another metal. The solutions are in the form of integrals of first‐order Bessel functions giving the vector potential, from which the other electromagnetic quantities of interest can be obtained. The coil impedance has been calculated for the case of a coil above a two‐conductor plane. The agreement between the calculated and experimental values is excellent.

1,027 citations


Patent
24 Oct 1968
TL;DR: In this paper, a thin film inductor for use with miniaturized integrated circuits is fabricated by forming a first level of parallel metal strips on a substrate and then forming an insulating layer over the strips.
Abstract: Thin film inductors for use with miniaturized integrated circuits are fabricated by forming a first level of parallel metal strips on a substrate and then forming an insulating layer over the strips. A bar of magnetic material is disposed along the center portions of the metal strips and a layer of insulation is deposited over the bar of magnetic material. A second level of parallel metal strips is then formed over the layer of insulation and is connected between opposed ends of adjacent ones of metal strips at the first level to form a continuous flattened coil around the bar of magnetic material. In other embodiments of the invention, the bar of magnetic material may be omitted, or may be disposed outside the continuous flattened coil formed by the metal strips.

124 citations


Journal ArticleDOI
TL;DR: In this article, power supplies used in field-cycling nuclear resonance experiments are described, which are used to switch an air coil from high field to low field as rapidly as possible, then back to high field after a short time.
Abstract: Power supplies used in field‐cycling nuclear resonance experiments are described. These are used to switch an air coil from high field to low field as rapidly as possible, then back to high field after a short time. This sequence must be repeated every few seconds or minutes. An example of a simple regulator is described, and methods of output switching with relays are discussed. A circuit is described which delivers up to 10 kG (15 A) in a 2.6 cm i.d. superconducting coil with a switching speed of 5×105 G/sec and an accuracy probably as great as 1 G. Speed is achieved by automatic connection, during up or down switching, of energy storage capacitors across the magnet, operating at much higher voltage than the steady‐state voltage level across the magnet and pass transistors.

103 citations


Journal ArticleDOI
TL;DR: In this article, an explosive-driven magnetic field compression device can be used as a source of a large pulse of electrical energy, and the authors describe a number of such systems, showing how their measured output currents compare with theoretical calculations.
Abstract: An explosive‐driven magnetic‐field compression device can be used as a source of a large pulse of electrical energy. We describe a number of such systems, showing how their measured output currents compare with theoretical calculations. Both large‐inductance coil geometries and low‐inductance coaxial geometries are discussed. Energy losses due to resistive heating, wall compression, electrical breakdown, and gas compression are considered. A numerical calculation procedure for coaxial generators is also described. We have built and tested coaxial generators whose measured output current can be accounted for by calculations of resistive heating and wall compression. Coil geometry generators are measured to be less efficient than calculated. Our results also show that further investigations of electrical breakdown and gas compression effects are needed.

92 citations


Journal ArticleDOI
01 Oct 1968
TL;DR: In this article, the possibilities of using magnetic, instead of electric, equivalent circuits for eddy-current devices, which have recently been pointed out by Laithwaite, are explored further.
Abstract: The possibilities of using magnetic, instead of electric, equivalent circuits for eddy-current devices, which have recently been pointed out by Laithwaite, are here explored further. Couplings between distributed flux paths and windings can be expressed in terms of a generalised linkage parameter N, which is associated with flux linkage in electric circuits, and with an analogous current linkage in the magnetic equivalent. The magnetic-circuit treatment extends to rotating, as well as to static, devices, and leads to a view of induction machines as nonpassive magnetic elements. The relationships between the energy flow through the terminals, the mechanical forces and the magnetic terminal parameters are examined, and an alternative equivalent circuit, in which the analogue of current is not the flux but its rate of change, is shown to be in many respects a more useful one. The force equations are applicable, in particular, to devices in which induced currents are important.

81 citations


Patent
27 Dec 1968
TL;DR: In this paper, a sub-surface missile is equipped with three mutually orthogonal coils in its body and a fourth suitably fixed in an articulatable steering member, which is guided along any desired underground trajectory defined with reference to a coordinate system including the plane of a dipole-quadrupole antenna system.
Abstract: A subterranean missile is equipped with three mutually orthogonal coils in its body and a fourth suitably fixed in an articulatable steering member. The missile is guided along any desired underground trajectory defined with reference to a coordinate system including the plane of a dipole-quadrupole antenna system laid on the ground above. Voltages induced in the noncenterline body coils are used in a closed feedback loop to maintain the resultant magnetic field circularly polarized at the mole location. Heading errors are then revealed as a voltage phasor on the centerline coil. Rotation of the steering member sufficiently to bring the voltage induced in its coil into phase with the centerline coil voltage also aligns the steering member such that its articulation will reduce the heading error to zero. Any new trajectory may be defined as a suitable new voltage added to the centerline coil voltage.

74 citations



Patent
Marcel J. E. Golay1
18 Oct 1968
TL;DR: In this article, an improved field homogenizing coil arrangement of a type having a generally tubular coil form extending about a test sample in an NMR apparatus is described, which includes a plurality of separate coils which are orthogonally related and which are formed of conductive segments positioned on opposite surfaces of the coil form and are conductively coupled through the form.
Abstract: An improved field homogenizing coil arrangement of a type having a generally tubular coil form extending about a test sample in an NMR apparatus is described. The coil arrangement includes a plurality of separate coils which are orthogonally related and which are formed of conductive segments positioned on opposite surfaces of the coil form and are conductively coupled through the form. The coils include arcuate-shaped segments positioned on one surface of the form and aligned normally with respect to a main polarizing field component, and rectilinear shaped segments positioned on an opposite surface of the form and extending in a direction substantially parallel to the main polarizing field component. The conductive segments are fabricated on the form by printed circuit techniques and the form is adapted to be rolled into a scroll-shaped configuration. With this arrangement, a relatively large number of field corrective coils are positioned on the form while overlapping rectilinear segments cancel undesired fields established by current return paths.

46 citations


Patent
21 Mar 1968
TL;DR: In this article, a color television display device provided with two systems of deflection coils formed with symmetrical coil halves and with a correction circuit for correcting the deflection errors caused by the anisotropic astigmatism of the systems of coils.
Abstract: A color television display device provided with two systems of deflection coils formed with symmetrical coil halves and with a correction circuit for correcting the deflection errors caused by the anisotropic astigmatism of the systems of coils. The coil halves of at least one system of deflection coils are provided with at least one tapping which form part of the correction circuit in which in parallel with the number of turns located between one tapping and one end and a different tapping of a coil half a line and field frequency controlled current source or impedance and an impedance only controlled at the line frequency, respectively, are connected.

32 citations


Patent
Joe T Pierce1
30 Sep 1968
TL;DR: In this paper, a method for fabricating an array of read-write heads for a magnetic storage means, such as a disk or drum, is disclosed, and the two assemblies are then bonded to opposite sides of the coil assembly so that the magnetic loops mate through holes in the substrate to form the complete gapped magnetic loops.
Abstract: A method for fabricating an array of read-write heads for a magnetic storage means, such as a disk or drum, is disclosed. Each head is comprised of a flux-carrying means, such as a gapped magnetic loop inductively coupled to a flux-producing means, such as a pair of coils. The coils, together with a portion of the associated addressing circuitry, are formed on a high resistivity substrate. The halves of the magnetic loops that lie on opposite sides of the coil assembly are fabricated in the relative position on two separate assemblies. The two assemblies are then bonded to opposite sides of the coil assembly so that the halves of the magnetic loops mate through holes in the substrate to form the complete gapped magnetic loops. The excess material of the assemblies is then cut away as required to leave magnetically isolated magnetic loops and the associated coils embedded within a solid body. The sensing gaps of the magnetic loops are formed by vacuum depositing a thin layer of nonmagnetic material on a face of one ferrite part, disposing a second ferrite part against the thin nonmagnetic layer and bonding the two ferrite parts together, taking a section of two ferrite parts normal to the nonmagnetic layer, and bridging the nonmagnetic layer with a third ferrite part to complete the magnetic loop. The loop assemblies may be formed by cutting grooves in the faces of ferrite blocks to form a number of ferrite mesas corresponding to the number of read-write heads. The grooves are then filled with a nonmagnetic material to magnetically isolate the ferrite mesas. The loop assemblies are then bonded to opposite sides of the coil assembly before being separated from the ferrite block. Alternatively, the ferrite assembly may be formed by laminating a layer of ferrite material, or two layers of ferrite material separated by a thin layer of nonmagnetic material for forming a sensing gap, between two layers of nonmagnetic material, slicing the layers in a plane normal to the layers to produce a number of slices each having a strip of ferrite disposed between strips of nonmagnetic material, then laminating these slices such that each strip of ferrite is isolated by nonmagnetic material. This laminated structure is again sliced normal to the last laminating joints to produce slices having individually isolated ferrite islands extending normal to the slice. Each ferrite island is then incorporated into a magnetic loop.

32 citations


Patent
David F Brower1
15 Oct 1968
TL;DR: An electromagnetic forming apparatus utilizes a forming coil having separable die portions for receiving a workpiece which is configured in such a manner that it could not otherwise be worked by a high intensity magnetic field as discussed by the authors.
Abstract: An electromagnetic forming apparatus utilizes a forming coil having separable die portions for receiving a workpiece which is configured in such a manner that it could not otherwise be worked by a high intensity magnetic field. An improved design of the forming coil increases its operating life.

Journal ArticleDOI
TL;DR: In this paper, a systematic analysis of the conditions in which the measurements of resistivities of metallic samples by the eddy current decay method give meaningful and accurate results is presented, and most of the important conclusions are displayed in graphical form to assist workers in the field.
Abstract: A systematic analysis is presented of the conditions in which the measurements of resistivities of metallic samples by the eddy current decay method give meaningful and accurate results. Coil sample geometry and material parameters are examined by means of equivalent circuits, and ways of extracting the desired information from the signal are discussed. We report selected measurements on critical parameters. A carefully designed and tested apparatus for the accurate determination of resistivity at room and helium temperatures with an operational logarithmic amplifier has been constructed. Most of the important conclusions of this study are displayed in graphical form to assist workers in the field.

Patent
15 Nov 1968
TL;DR: In this paper, a high-impact tool is discussed as part of a RAM component of an ELECTRO-MECHANICAL GUN, as shown in FIG. 1, which combines a RAPIDly CHANGING ELECTRIC Current Passing THROUGH its coil into a MECHANical FORCE ACTING BETWEEN a CONDUCTOR PLATE on the RAM and the coil to push the RAM AND its forming surface against a workpiece to form it.
Abstract: A HIGH-IMPACT TOOL IS DISCLOSED AS PART OF A RAM COMPONENT OF AN ELECTRO-MECHANICAL GUN, AS SHOWN IN FIG. 1, WHICH CONVERTS A RAPIDLY CHANGING ELECTRIC CURRENT PASSING THROUGH ITS COIL INTO A MECHANICAL FORCE ACTING BETWEEN A CONDUCTOR PLATE ON THE RAM AND THE COIL TO PROPEL THE RAM AND ITS FORMING SURFACE AGAINST A WORKPIECE TO FORM IT. A PAIR OF PORTABLE ELECTRO-MECHANICAL RIVERTING FUNS, AS SHOWN IN FIGS. 3-7, IS DESCRIBED ALONG WITH AN ELECTRICAL SYSTEM, SHOWN IN FIG. 8, WHICH INTERLOCKS THEIR OPERATION TO INSURE A SIMULTANEOUS RAM IMPACT ON EACH END OF THE RIVET. THE POWER SUPPLY, FOR OPERATOR SAFETY, IS ISOLATED FROM GROUND AS IT DISCHARGES THROUGH THE COILS. A SYSTEM, SHOWN IN FIGS. 5-7, FOR PROPER GUN ALIGNMENT IS DISCLOSED WHEREIN INCREASED BACK-PRESSURE OF FLUID OR GAS OUTLETS, BLOCKED BY PROPER GUN POSITIONING AGAINST THE WORKPIECE, OPERATES CONTROL SWITCHES PERMITTING FIRING OF THE GUNS.

Patent
20 Aug 1968
TL;DR: In this paper, the authors describe a direct current (DC) motor with a rotor formed of a material having high magnetic permeability and having a plurality of salient poles, which is rotatably mounted adjacent to the field winding so that magnetic flux induced in the poles interacts with the current passing through the armature windings.
Abstract: This disclosure describes a direct current (DC) motor structure having stationary (immovable) field and armature windings A rotor formed of a material having high magnetic permeability and having a plurality of salient poles is rotatably mounted adjacent to the field winding so that the field winding electromagnetically induces magnetic flux in the poles The armature windings are also mounted adjacent to the rotor In operation, the magnetic flux induced in the poles interacts with the current passing through the armature windings The current flow in the armature windings is controlled by a solid-state commutator in a manner normally associated with brushless DC motors By controlling the magnitude of the current supplied to the field windings, the speed of the motor is controlled In addition, the windings can be connected in a series, shunt or compound configuration as desired

Patent
02 Jan 1968
TL;DR: In this article, the authors describe an improved super-constrained magnetnet or coil in which the supercondent is wound and positioned by GENERALLY LOINGITUDINALLY EXTENDING SPACERS HAVING SLOTS for the TURNS and RIBS BETWEEN the SLOTS, the SPACers also SEPARATING LAYERS of the WINDING and PERMITTING a CRYOGENIC MEDIUM to COME in Intimate CONTACT with the tURNS.
Abstract: AN IMPROVED SUPERCONDUCTING MAGNET OR COIL IN WHICH THE SUPERCONDUCTOR IS WOUND AND POSITIONED BY GENERALLY LOINGITUDINALLY EXTENDING SPACERS HAVING SLOTS FOR THE TURNS AND RIBS BETWEEN THE SLOTS, THE SPACERS ALSO SEPARATING LAYERS OF THE WINDING AND PERMITTING A CRYOGENIC MEDIUM TO COME IN INTIMATE CONTACT WITH THE TURNS. THE SPACERS HAVE AN INSULATING OR SEMICONDUCTING SURFACE AND MAY BE OF A NORMAL METAL OR AN ORGANIC INSULATING MATERIAL. THE COIL MAY VARY IN SPACING OF TURNS ENDWISE AND MAY VARY IN DIAMETER FROM END TO END.

Patent
26 Dec 1968
TL;DR: In this paper, a compass system utilizing a flux valve responsive to the earth's magnetic field is described, in which the Earth's field vector sensed by pick-up windings is resolved into component values that are converted to proportional DC currents from an infinite impedance current source that is independent of the load of the pick up windings.
Abstract: A compass system utilizing a flux valve responsive to the earth's magnetic field in which the earth's field vector sensed by pick-up windings is resolved into component values that are converted to proportional DC currents from an infinite impedance current source that is independent of the load of the pick-up windings, these currents being fed back into the flux valve in a direction to cancel the earth's field vector whereby to drive the flux valve output towards null.

Patent
11 Sep 1968
TL;DR: In this article, the authors present a method for determining the position of a formation bedding plane in the formation field by deploying one or more ELECTROMAGNETIC FIELDS.
Abstract: IN ACCORDANCE WITH ILLUSTRATIVE EMBODIMENTS OF THE PRESENT INVENTION, METHODS AND APPARATUS FOR DETERMINING THE POSITIONING OF FORMATION BEDDING PLANES BY ROTATING ONE OR MORE ELECTROMAGNETIC FIELDS THROUGH FORMATIONS SURROUNDING A BOREHOLE ARE ILLUSTRATED. IN ONE EMBODUMENT, A SOLENOID-TYPE COIL IS ENERGIZED WITH CURRENT AND ROTATED AT A SUBSTANTIALLY CONSTANT VELOCITY ABOUT AN ADJUSTABLE AXIS. AN AMPLITUDE MODULATED SIGNAL WILL THEN BE PRODUCED IN THE COIL IF THERE IS A CONDUCTIVITY CONTRAST OR GRADIENT IN THE FORMATION PLANE WHICH DEFINES THE SWEEP OF THE ELECTROMAGNETIC FIELD. THIS AMPLITIDE MODULATED SIGNAL IS THEN DEMODULATED AND THE RESULTING MODULATION SIGNAL IS SYNCHRONOUSLY DETECTED BY THE SIGNAL WHICH CAUSES THE COIL ROTATION. THIS PRODUCES PHASE COMPONENTS WHICH ARE USED FOR BRINGING THE AXIS OF ROTATION OF THE COIL INTO A SUBSTANTIALLY PERPENDICULAR DIRECTION TO THE LOW GRADIENT FORMATION PLANE AND INDICATING THE POSITIONING OF THIS PLANE. IN ANOTHER EMBODIMENT, TWO ELECTROMAGNETIC FIELDS ARE ROTATED AROUND A BOREHOLE AT SPACED APART DEPTH LEVELS BY SEQUENTIALLY COUPLING A PLURALITY OF CIRCUMFERENTIALLY SPACED COIL PAIRS TO THE ADJOINING FORMATIONS. THE SIGNALS FROM EACH COIL OF THE COIL PAIRS ARE COMBINED IN SELECTED RELATIONSHIPS TO PRODUCE A COMPOSITE SIGNAL FOR EACH COIL PAIR. THESE COMPOSITE SIGNALS ARE THAN USED TO ADJUST THE RELATIONSHIP WITH WHICH THE INDIVIDUAL COIL SIGNALS ARE COMBINED UNTIL EACH COMPOSITE SIGNAL HAS SUBSTANTIALLY THE SAME AMPLITUDE THUS INDICATING THE POSITIONING OF THE LOW CONDUCTIVITY GRADIENT FORMATION PHASE.

Patent
26 Jul 1968
TL;DR: In this article, an ultrasonic wave is excited in the surface of the object by direct electromagnetic excitation in the presence of a DC magnetic field having a major component perpendicular to the electric vector of the electromagnetic field at the surface.
Abstract: An ultrasonic wave is excited in the surface of the object by direct electromagnetic excitation in the presence of a DC magnetic field having a major component perpendicular to the electric vector of the electromagnetic field at the surface A coil energized with RF may be employed The ultrasonic waves propagate generally perpendicularly to the surface A similar coil and DC magnetic field detect the ultrasonic wave arriving at the object surface after passing through the object, and produce an RF signal varying with flaws or other inhomogeneities in the object Pulsed RF is advantageously employed, and in such case a single coil may be used for both generating the ultrasonic waves and responding to reflections thereof from flaws in the object


Journal ArticleDOI
01 Sep 1968
TL;DR: In this article, the magnetic flux is made to thread a relatively long air path, compensation for the higher reluctance otherwise introduced can be sought by making the area of the flux path large.
Abstract: Every electrical machine consists of electric and magnetic circuits interlinked. Good machines have circuits of low resistance and reluctance, the latter generally achieved by the use of a steel structure. If magnetic flux is made to thread a relatively long air path, compensation for the higher reluctance otherwise introduced can be sought by making the area of the flux path large. The paper shows how useful shapes of machine can be developed in which a large part or all of the magnetic circuit consists of air. Machines included are open-bar transformers, single-sided linear induction motors, and homopolar d.c. machines with superconducting field windings. Vertical forces in open-sided linear motors are calculated. The paper concludes with a brief discussion of the possibilities of electromagnetic current collection for traction systems employing a moving transformer

Patent
Fontaine C Armistead1
30 Apr 1968
TL;DR: In this article, a method and arrangement for BOREHOLE-DIRECTIONAL LOGGING is presented, in which the first and second co-lamps are used to determine the location of the Borehole.
Abstract: A METHOD AND APPARATUS FOR BOREHOLE DIRECTIONAL LOGGING. THE APPARATUS INCLUDES A FIRST COIL ADAPTED FOR ROTATION ABOUT AN AXIS ALIGNED WITH THE LONGITUDINAL AXIS OF THE BOREHOLE AND A GIMBAL MOUNTED MAGNETIC FIELD PRODUCING COIL FOR GENERATING A FIRST MAGNETIC FIELD OF PREDETERMINED DIRECTION WITH RESPECT TO THE VERTICAL IN THE SPACE OCCUPIED BY THE FIRST COIL WHEREBY AN ALTERNATING SIGNAL IS INDUCED THEREIN REPRESENTATIVE OF THE INCLINATION ANGLE OF THE BOREHOLE. A SECOND COIL IS PROVIDED FOR ROTATION AT THE SAME RATE AS THE FIRST COIL WHILE BEING SUBJECTED TO A SECOND MAGNETIC FIELD HAVING AT LEAST A COMPONENT OF KNOWN AZIUM DIRECTION, THEREBY GENERATING AN ALTERNATING SIGNAL IN THE SECOND COIL, THE PHASE ANGLE OF WHICH, WITH RESPECT TO THE FIRST COIL SIGNAL IS RESPECTIVE OF THE AZIUM ANGLE OF THE BOREHOLE. COMPUTING APPARATUS IS SHOWN FOR DETERMINING THE LOCATION OF A SELECTED SEGMENT OF THE BOREHOLE AT ANY DEPTH INCLUDING MATHEMATICAL AND TRIGONOMETRIC FUNCTION OPERATORS FOR GENERATING SIGNALS REPRESENTATIVE OF THE INCREMENTAL CHANGES OF THE BOREHOLE POSITION AND OF THE CORRESPONDING INCREMENTAL LENGTH SEGMENTS ALONG THE BOREHOLE. ALSO INCLUDED ARE COMPUTING ELEMENTS FOR SUMMING THE LATTER SIGNALS THEREBY OBTAINING THE LOCATION OF THE BOREHOLE AT ANY DEPTH. THE METHOD INCLUDES GENERATING FIRST AND SECOND SIGNALS RESPECTIVE OF THE BOREHOLE INCLINATION AND AZIMUTH, RESPECTIVELY, AND IN RESPONSE THERETO GENERATING SIGNALS OF THE INCREMENTAL CHANGES IN THE LOCATION OF SUCCESSIVE SEGMENTS OF THE BOREHOLE CORRELATED WITH A SIGNAL REPRESENTATIVE OF THE LENGTH OF SAID SEGMENTS, AND GENERATING SIGNALS REPRESENTATIVE OF THE BOREHOLE LOCATION ALONG ITS LENGTH BY SUMMING THE LATTER SIGNALS.

Patent
18 Dec 1968
TL;DR: In this article, a coil end and lead connection is embedded in an insulating body which is molded directly around the connection, with the leads extending through the coil channel. And the body is wedged between adjacent coils.
Abstract: A coil end and lead connection is embedded in an insulating body which is molded directly around the connection. The insulating body is wedged between adjacent coils with the leads extending through the coil channel.


Patent
03 Jun 1968
TL;DR: An ignition coil of low internal impedance and high energy storage and transfer characteristics and having an electrostatic shield between the coil primary and the coil secondary surrounding the primary and additional capacity resonating the secondary to a high frequency providing improved operating efficiency and prolonged spark duration of a spark plug load connected thereto as mentioned in this paper.
Abstract: An ignition coil of low internal impedance and high energy storage and transfer characteristics and having an electrostatic shield between the coil primary and the coil secondary surrounding the primary and additional capacity resonating the secondary to a high frequency providing improved operating efficiency and prolonged spark duration of a spark plug load connected thereto

Patent
07 Nov 1968
TL;DR: In this paper, the authors describe a vehicle propelled by a linear electric induction motor with an armature comprising windings and magnetic circuit closure members on the vehicle, which is supplied to the vehicle from the travelling field produced by the induction coils 14 and 16.
Abstract: 1,194,438. Vehicles propelled by linear electric motors; air cushion vehicles. MERLIN GERIN. 11 Nov., 1968 [17 Nov., 1967], No. 53265/68. Headings B7K and B7L. [Also in Divisions H1 and H2] Auxiliary electrical power for heating, lighting, or producing air cushions for lifting and guiding, of a vehicle 18, Fig. 1 (or 28, Fig. 2), propelled along a rail 10 (or 24) by a linear electric induction motor which comprises induction coils 14 and 16 (or 26) in the rail and an armature comprising windings (not shown) and magnetic circuit closure members 20 and 20 1 (or 30) on the vehicle, is supplied to the vehicle from the travelling field produced by the induction coils 14 and 16 (or 26), by providing at least one pick-up coil 22 (or 32) on the armature members 20 and 20 1 (or 30) so that a varying electromotive force is induced in the coil 22 (or 32) which is dependent for its magnitude on the degree of asynchronism between the travelling wave and vehicle; rectifiers and storage batteries are provided to compensate for these variations in the auxiliary power supply.

Patent
15 Feb 1968
TL;DR: In this article, a power radiating head with a variable condenser 27 is adjusted manually, but by an electric motor 73 controlled by the feed-back from an inductance 71 in the head 10 through a servo-loop 70.
Abstract: 1,201,586. Electrotherapeutic apparatus. DY NAPOWER SYSTEMS CORP OF CALIFORNIA. 22 Jan., 1969 [15 Feb., 1968], No. 3560/69. Heading A5R. Electrotherapeutic apparatus includes a power radiating head 10 having means for the transmission of high frequency radiation including coupled primary and secondary coils, 12 and 13, and a capacitor 14 connected to the secondary coil to form a tank circuit tuned to a predetermined high frequency, input means 18 to supply pulses of said frequency, a network 25 and transmission line coupled between the input means 18 and primary coil 12, the network having a variable impedance element and means including a servo loop apparently responsive to patient induced detuning of the circuit to vary the impedance of the element. The apparatus is generally similar to that described in Specification 1,150,524, except that the variable condenser 27 is not adjusted manually, but by an electric motor 73 controlled by the feed-back from an inductance 71 in the head 10 through a servo-loop 70. The loop 70 comprises a pair of band-pass filters 76, 77 feeding a differential amplifier of which the output is fed to the motor 73. The filters are each tuned to a band one on either side of the predetermined frequency of the main circuit so that de-tuning caused by the presence of the patient is picked up by the inductance 71 and the motor 73 is energised to adjust the condenser 27 in such a direction as to restore the system to its original tuning.

Patent
08 Jan 1968
TL;DR: In this paper, an electrical measuring and telemetry apparatus for monitoring physical conditions of objects is presented, in which the condition of the object such as temperature, stress, strain or pressure is measured by an electrical transducer to vary the signal output from a transmitter which receives the generated power and transmits electrical signals in response to the condition being measured.
Abstract: An electrical measuring and telemetry apparatus for monitoring physical conditions of objects. A magnetic power generator having parts movable in response to the motion of an object to generate electrical power and in which the condition of the object such as temperature, stress, strain or pressure is measured by an electrical transducer to vary the signal output from a transmitter which receives the generated power and transmits electrical signals in response to the condition being measured. A temperature measuring apparatus having a power source, an electrical transmitter having a tank circuit for transmitting electrical signals whose frequency is controlled by the tank circuit, and a temperature sensitive capacitor positioned adjacent the object and electrically connected in the tank circuit thereby varying the transmitted signals in proportion to the temperature of the object. A power generator having a coil and magnet movable relative to each other to generate electrical power in response to the motion of the object. A power generator having first and second members one of which is fixed and the second of which moves relative to the fixed member, the first member being a circular toothed disc and the second member including two soft iron pieces having a pickup coil wound thereon and a permanent magnet positioned between the soft iron pieces whereby a voltage is generated in the coil when the coil moves relative to the toothed disc. A magnetic power generator for providing a power source in response to rotating, oscillating, or reciprocating movement of an object.

Patent
18 Apr 1968
TL;DR: De Valrroger and Layet as mentioned in this paper presented a reciprocating electromagnetic diaphragm pump with a permanent magnet armature coupled to the diaphrasm and actuated in at least one direction by triggering a transistor to pulse an operating coil.
Abstract: 1,220,857. Reciprocating pumps. P.A.M. DE VALROGER AND M. LAYET. April 18, 1968 [April 21, 1967], No.18439/68. Heading F1A. [Also in Division H2] In a reciprocating electromagnetic diaphragm pump the diaphragm is connected to a rod on which is slidable a permanent magnet armature resiliently coupled to the diaphragm and actuated in at least one direction by triggering a transistor to pulse an operating coil. Fig.1 shows one embodiment in which the armature comprises a permanent magnet 21 clamped between cup-shaped, soft-iron polepieces 22, 23 and slidable on the roof 26 between springs 27, 30, the latter abutting against a sleeve 31 fixed to the rod. The operating coil B m is located between the pole-pieces together with a pick-up coil B c in which the transistor switching current is induced. As shown in Fig. 5, the coil B m is connected in series with the collector and emitter of the transistor TR across the supply, the pick-up coil B c being connected between the positive supply terminal and the transistor base. A decoupling capacitor C 1 and resistor R ensure automatic starting of the pump since the initial charging current of the capacitor through the resistor when the pump is switched on biases the transistor base just sufficiently to allow current to flow through coil B M .To prevent reaction coupling between the coils B c , B m , they may be placed in separate magnetic fields, Fig. 2 (not shown). In this construction the armature has two permanent magnets clamped together by three cupshaped pole-pieces which provide two air gaps for the coils. Fig.6 shows a double-diaphragm pump in which a permanent magnet armature 43. . .45 is caused to oscillate between springs by coils B M , Fig.7, arranged around the armature, a pick-up coil B c being arranged between two of the main coils. To avoid the necessity for a bulky pick-up coil when a high power transistor is used, a second transistor may be used to amplify the switching current. Such an arrangement may be used with the double diaphragm pump of Fig. 8 which has two operating coils B M1 , B M2 acting on a stack of four annular permanent magnets A 1 . . .A 4 forming part of an armature similar to that shown in Fig.6. The pick-up coil B c is mounted between the coils B M1 , B M2 . When the pump is switched on a resistor braces the reload transistor sufficiently to cause a weak current to flow through the first transistor and coils B M1 , B M2 . This produces a slight upward movement of the armature which induces a voltage in coil B c and consequently increases the flow of current through the operating coils. Spring 71 ultimately stops the armature and the return stroke induces a reverse voltage in coil B c which blocks the transistors until the armature is reversed again by spring 72. To increase the power of the pump a push-pull switching arrangement supplying propulsive pulses to the armature in each direction may be used.

Patent
11 Jul 1968
TL;DR: In this paper, a solenoid construction where a pull coil is only adapted to move a plunger means from its deenergized position to a position intermediate its de-energised position and its fully actuated position when the pull coil means is energized was presented.
Abstract: A solenoid construction wherein a pull coil means is only adapted to move a plunger means from its deenergized position to a position intermediate its deenergized position and its fully actuated position when the pull coil means is energized whereby the plunger means when disposed in its intermediate position is adapted to be influenced by a hold coil means so that when the hold coil means is also energized the same will move the plunger means from its intermediate position to its fully actuated position and hold the plunger in its fully actuated position regardless of whether or not the pull coil means remains energized.

Journal ArticleDOI
C. J. Brown1, J. T. Ma1
TL;DR: In this article, the time-optimal control problem for a moving-coil linear actuator has been worked out by means of functional analysis and a related graphical procedure requiring only data from an impulse response.
Abstract: The time-optimal control problem for a moving-coil linear actuator has been worked out by means of functional analysis and a related graphical procedure requiring only data from an impulse response. On the basis of experience with a test model, there is good correlation between the theoretical and the experimental methods. While the latter is accurate over only very short distances, the usefulness of the technique can be extended as needed by operating the system in piecewise linear fashion. The nonlinearity of the coil inductance can be handled under computer control by including in the program the inductances for successive segments of travel.