Abstract: A rotary variable differential transformer for measuring angular displacement and method of manufacturing the same are provided herein. The rotary variable differential transformer includes a stator configured to house a primary coil configured to receive an alternating current, a first secondary coil electromagnetically coupled to the primary coil, and a second secondary coil electromagnetically coupled to the primary coil. The rotary variable differential transformer also includes a rotor positioned concentrically within the stator. The rotor is configured to receive a shaft and rotate with the shaft while the stator remains stationary. The primary coil is positioned at a first radial position within the stator spaced between about 90 to 150 degrees from each of the first secondary coil and the second secondary coil.

Abstract: Embodiments of the present invention are directed to a novel inductive rotational position sensor that includes a sensor module having transmitting and receiving coils formed on a printed circuit board with a signal processor located in a center area enclosed by the transmitting and receiving coils. This arrangement permits a more compact sensor module. The entire sensor module can be positioned inside a cavity, which has a diameter generally the same as the diameter of the rotational element whose position is being sensed. The arrangement also permits a coupler to be formed on the end of the target. The sensor is concentric with the transfer case shaft and an annulus bore of a transfer case. The sensor is non-contacting and has no movable parts.

Abstract: A nuclear magnetic resonance (NMR) sensor including a magnet that generates a static magnetic field, a soft magnetic core secured to the magnet, and an antenna extending at least partially about the soft magnetic core and generating a radio frequency (RF) magnetic field. A magnetic permeability of the soft magnetic core in a direction of the static magnetic field is less than the magnetic permeability of the soft magnetic core in a direction of the RF magnetic field.

Abstract: Turbine engine (1), in particular for an aircraft, comprising at least one axial shaft (2) rotatably mounted in a casing (3) of the turbine engine (1), the turbine engine (1) comprising an annular reference part (10) comprising short (11) and long (12) longitudinal reference teeth, first means for detecting the passage of the short (11) and long (12) reference teeth so as to measure the speed of the shaft (2) of the turbine engine (1) about its axis (X), an annular measurement part (20) comprising longitudinal measurement teeth (21); and second means for detecting the passage of the long reference teeth (12) and the measurement teeth (21) so as to measure the torque of the shaft (2, 102) of the turbine engine (1).

Abstract: A contactless inductively coupled power transfer system is provided including multiple pairs of power transmitter and power receiver coils and a power management module for controlling the supply of power to transmitter coils or the power supplied by the power receiver module to loads. The design is particularly suited for use in a wind turbine to supply power to the nacelle. The transmitter coils may be driven in phase at the same frequency or at different frequencies selected to avoid interaction between transmitter coils and the power transmitter module. The transmitter and receiver coils may be arranged in a traditional slip ring type configuration with adjacent coil pairs are physically spaced apart to avoid cross coupling with adjacent transmitter and receiver coil pairs shielded from each other. The power transmitter module may employ Zero Voltage Switching (ZVS).

Abstract: A brushless linear rotary transformer apparatus for determining angular position and velocity of a rotor includes a rotor, a stator, a primary coil winding, pairs of secondary coil windings, bearings, an excitation power supply, and a signal receiving and processing system. The primary coil winding is wrapped around a hollow cylinder body on one end of the stator. One end of the rotor shaft is arranged in the hollow cylinder body. Another ends of the rotor shaft and the stator are connected by a bearing. Pairs of secondary coil windings are embedded in the stator and on the inner side of the stator. An alternating magnetic field is generated by the excitation power supply through the primary coil winding. The amplitudes of the induced electromotive force at the ends of the secondary coil windings are linearly proportional to the angular position of the rotor.

Abstract: An electrical assembly is provided. The electrical assembly includes a ring having at least two annular segments. Each annular segment includes a first portion and a second portion. The second portion tapers from the first portion toward an end of the second portion to define a circumferential cross-sectional area of the ring that is substantially constant along a radius of the electrical assembly. At least one winding is coupled about the ring.

Abstract: Axisymmetric solid of revolution derivable from section at FIG. 5 is generally toroidal with electric current(s) in windings 110, 160 preferably flowing circumferentially along major circle(s) during power coupling device operation. Current(s) in windings 110, 160; current(s) in half-shields 120, 170; and the volume of space swept out by shield airgap(s) 101 emerge from plane of paper perpendicularly at FIG. 5 but as these emerge therefrom they curve to follow toroidal major circle(s). Cores 115, 165 preferably shunt and align magnetic flux such that magnetic field lines escape therefrom primarily only in region(s) of core airgap(s) and such that magnetic flux loops lie in planes of toroidal minor circle(s).

Abstract: An isolation transformer is provided having primary and secondary cores (2, 4) and primary and secondary coils (3, 5) with the primary coil and the secondary coil being disposed with a gap G provided therebetween. Each of the primary coil and the secondary coil is formed of a wire having at least two substantially parallel long sides, and a length of the two long sides in each of the wires is set to be longer than a distance between the two long sides in each of the wires. Each of the wires is wound to have a plurality of turns in a manner such that an outer one of the two long sides of each inner one of the turns is adjacent to an inner one of the two long sides of each respective adjacent outer one of the turns.

Abstract: In an oscillator circuit employing a pattern coil on a printed-wiring circuit board as a resonator circuit, in order to satisfactorily adjust dispersion in oscillation frequencies, an air-core coil wound by 0.5 turn and less than one turn is provided so as to be connected to the pattern coil in parallel and mounted on the printed-wiring circuit board. The oscillation frequency is adjusted by adjusting the angle of the air-core coil relative to the printed-wiring board.

Abstract: A switch lever of an electrical switch can be moved into various switch positions. A ferrite core is disposed at the switch end of the switch lever. A primary coil and a secondary coil are disposed about each switch setting. The primary coil induces a voltage in each secondary coil. The amplitude of the induced voltage is greatest in the secondary coil in the vicinity of which the ferrite core is situated. The actually adopted switch position can be determined from the difference in the voltages.

Abstract: A group of secondary windings are distributively provided on a stator over a predetermined range, and the respective inductance of the secondary windings in the group is set in such a manner to present predetermined inductance distribution. A rotor has an eccentric shape so as to cause variations in magnetic coupling at individual poles of the stator in response to its current rotational position. By combined use of the magnetic coupling variations between primary and secondary windings on the stator and the predetermined inductance distribution of the secondary windings, high-accuracy detection of a rotational position is achieved with a simple structure. A plurality of primary windings may be set so as to present predetermined inductance distribution.

Abstract: A Rotary Variable Differential Transformer, having a short axial length, small diameter, and a wide angle, linear output range, is provided. The Rotary Variable Differential Transformer (RVDT) comprised of a housing, a hollow cylindrical coil form made of non-magnetic, non-conductive material, about which a first and second secondary coils, adjacent to each other, are circumferentially wound. A primary coil is circumferentially wound about a segment of said first secondary coil, and about a segment of said second secondary coil.An elongated ferromagnetic core is disposed within the hollow coil form. The core is an axial section of a ferromagnetic cylinder which serves to couple said primary coil to said secondary coils.The output voltage measured across said secondary coils terminals is indicative of the angular position of said ferromagnetic core relative to the coil form assembly.

Abstract: An electrical fault limiter having first, second, third, and fourth magnetic cores. The first magnetic core opposes the second magnetic core and is adjacent to the third magnetic core. The fourth magnetic core opposes the third magnetic core and is adjacent to the second magnetic core. A rotor is disposed between the first and second magnetic cores, and the third and fourth magnetic cores. The rotor is rotatable about a rotor axis. The first and second magnetic cores are disposed on a first side of the rotor axis and the third and fourth magnetic cores are disposed on a second side of the rotor axis. Each core has a first arm, a second arm and a body to which the first and second arms are connected. Each body has a superconduction bias coil disposed about it. Each arm has a conduction mode coil disposed about it.

Abstract: A variable inductor includes at most one coil of electrically conductive material and at most two distinct, separately formed portions of magnetic core material positioned to conduct magnetic flux resulting from passage of electrical current through the coil. At least one of the portions of magnetic core material is located at least partially within a space surrounded by the coil and is movable with respect to the coil. A control device is attached to the movable portion of magnetic core material in a manner such that the movable portion can be moved in its entirety, by manipulating the control device, to change the configuration of a gap within the space surrounded by the coil and defined in part by the movable portion, to vary thereby the inductance of the coil.

Abstract: An active hand controller system is provided wherein a feedback loop detects the position of a control stick to control a motor driving the control stick to thereby provide certain force feel characteristics to the control stick. The feedback loop includes a detector for detecting force exerted for the control stick to generate a signal indicative of the force or torque being applied to the control stick. In a more specific aspect, the invention includes the use of variable reluctance transformers, preferably in a push/pull configuration to detect the forces being exerted on the control stick.

Abstract: Two members 21,22 are relatively displaceable along a linear or circular path. One member 21 provides a plurality of coil portions along the path. Their individual inductances are dependent on the configuration of the second member 22. For example, the first member 21 may be an annular stator with inward radial projections k,l,m . . . on which the coil portions are wound, alternately in different senses so that the flux path tends to loop in and out. The second member 22 may be an annular rotor, one section 23 being ferromagnetic and the other section 24 being non-ferromagnetic and/or having a conductive screening layer. Alternatively the second member may be mercury 42 half-filling an annular conduit 40 which surrounds a static ferromagnetic core 44 (FIG. 9). A particular characteristic is that for any relative position of 21 and 22, half the coil portions of 21 have a different inductance from the other half.

Abstract: In an angular pulse generator having a movable generator part and a read head, the read head has a primary winding (W1) fed with an alternating voltage of a defined frequency and has a secondary winding (W2) whose induced secondary voltage is modulated by passing teeth and intervening gaps of the generator part. An evaluation unit evaluates the phase difference between the alternating voltage and the secondary voltage and forms a pulse for every passing tooth. A stray flux return line surrounds the primary winding (W1), so that the majority part of the primary flux linked to the primary winding (W1) flows via the stray flux return line for a large gap distance of the generator part.

Abstract: A rotary variable differential transformer produces a substantially linear output over about 180 degrees of rotation of a rotor core. The transformer includes a base housing having a central bore, and a rotor having a shaft whose angular displacement is to be determined and a generally planar, circular rotor core mounted off-center at one end of the shaft and in a plane normal thereto. The rotor core is rotatably disposed within the opening of the base housing. Also included is a primary coil disposed in the opening of the base housing to circumscribe the shaft at a location rearwardly of the rotor core. First and second windings, with cores, are carried by the base housing and positioned about the base housing opening so that the axes of the coils are oriented radially of the opening and generally in a common plane with the rotor core. The first and second windings are connected together in series opposition.

Abstract: A torque detection apparatus for measuring a torque applied between a drive shaft and an output shaft which is applicable to an electric power steering system of a motor vehicle. The torque detection apparatus is provided between the drive and output shafts and comprises first and second rotating bodies which are respectively at one end portions coupled fixedly to the drive and output shafts, the first rotating body being rotatable in accordance with rotation of the drive shaft and the second rotating body being rotatable in accordance with rotation of said output shaft. The first and second rotating bodies are shaped cylindrically and the first rotating body has on its outer circumferential surface magnetic toothed portions and the second rotating body has on its inner circumferential surface magnetic toothed portions.

Abstract: A joystick for generating electric control signals comprises the following components: a housing, an operating rod, a universal joint for the operating rod, sensors and an element acting upon these in a positionally dependent manner. The distance of the element from the sensors can be varied by the operating rod. The sensors are in the form of induction coils through which alternating current circulates. The induction coils, in turn, are each part of an electric oscillatory circuit. It is adequate to provide only two such sensors. The element acting upon the induction coils is an induction body, more particularly, in the form of a spherical part which is rigidly connected to the operating rod. The center of the induction body is spaced from the center of the universal joint. By changing the distance of the induction body from the induction coils, the amplitude, frequency and/or phase of the respective oscillatory circuit can be changed in order to generate the electric control signals.

Abstract: Two-phase voltage signals for use with a resolver-to-digital converter (RDC) are produced as a periodic function of permeance developed across an air gap between a rotor and stator wherein the permeance varies as a periodic sinusoidal function which can be related to the electrical angle of the position of the rotor. The two-phase voltage signals are developed as a function of inductive reactance and follow the form ##EQU1## wherein the phase angle between V.sub.x and V.sub.y is exactly 90.degree. and the term [A+A.sub.n +B+B.sub.n ] is completely free of second harmonics.

Abstract: On a circumferential side surface of a single cylindrical member constituting a main body of a rotor section are disposed, in parallel, a first pattern which repeats change in the circumferential direction with a predetermined pitch and a second pattern which has a change of one cycle with respect to one circumference. A detection head section which is provided in proximity to the rotor section changes its relation of correspondence to the respective patterns in accordance with rotational position of the rotor section and produces output signals corresponding to the relation of correspondence. A relatively rough absolute value of a rotational position within one rotation is established by an output signal produced in response to the second pattern and its accuracy is established with a high resolution by an output signal produced in response to the first pattern.

Abstract: A control device for producing electrical signals which correspond to manual movements of a stick part and which are used for adjustment of a controlled element has a relatively stationary body part with a hand supporting surface and a stick projecting outward from that surface to be embraced by an operator's hand. The stick comprises a laterally swingable outer stick part end-to-end with an inner stick part fixed to the body. A rod-like spring element in a chamber in the stick has an end portion fixed to each stick part to swingably connect the outer stick part of the inner one and bias the outer one to a neutral position. A signal emitting device in the chamber is mounted alongside the spring element and is operatively connected with it.

Abstract: A resolver which in a preferred embodiment utilizes a stator member, preferably made of a single piece of ferrite material, which has active stator sine poles and active stator cosine poles and a rotor member which has passive rotor poles. The active stator poles have excitation voltage inputs supplied thereto and, as the rotor poles rotate relative thereto, the sine and cosine stator poles supply voltage outputs which vary sinusoidally and co-sinusoidally, respectively, as a function of the angular position of the rotor member relative to the stator member. Multiple stator and rotor pole combinations can be used to provide resolver operation at different speeds.

Abstract: A sensor for magnetizable materials is comprised of an inductive component and an evaluating circuit. The inductive component is constructed by thin-film techniques. The core is made of a ferromagnetic amorphous metal. Such a sensor can detect the presence of magnetizable materials with very high position accuracy. The sensor is employed in revolution counters and in angular-displacement transducers.

Abstract: A contactless electric control handle having a field coil for forming an electro-magnetic field, inductive pick-up coils angularly spaced apart around the axis of the field. The rod of the control handle constitutes the core of the field coil. The field coil and the pick-up coils have the shape of annular, concentric conductors, whereas ferrite is applied to the rod in order to employ high frequencies up to 1 MHz.

Abstract: This invention relates to a harmonically graded airgap reluctance-type rotating electric resolver. The magnetic permeance of the airgap is made to vary sinusoidally. Therefore, only the fundamental wave exists, free of higher harmonics. The invention has application in numerous fields, including commutation of brushless motors and to precisely position machinery tools relative to work pieces in numerically controlled machines.

Abstract: This device comprises a first detector having a first rotor and a first stator for detecting an absolute rotational position within one cycle which corresponds to 1/N circumference, said rotor having teeth of N, and a second detector having a second rotor coupled with the first rotor and a second stator for detecting an absolute rotational position within one circumference within one cycle which corresponds to one circumference. The first and second stators are respectively provided with primary coils and secondary coils. The respective primary coils are excited by reference AC signals generated in response to a clock pulse signal from a clock pulse generator. Phase differences between first and second output signals produced from the secondary coils of the respective detectors and the reference AC signals are obtained by counting the clock pulse signal.

Abstract: A rotary variable differential transformer has coil windings at an angle with respect to the longitudinal axis of the transformer and a core rotatable about this axis with end faces cut at projected angles therewith such that a rotation of the core varies the coupling between the primary and secondary windings. Amplitude and phase variations at the secondary windings are measurements of core rotation.

Abstract: A positional transducer includes a nonconductive plate having four ferrite tube inductors mounted at preselected locations in the plate. Two interconnected permanent magnets are mounted on either side of the plate with opposite poles facing the plate for magnetic interaction. Manual movement of the permanent magnets varies the impedance of the inductors to indicate the relative position of the magnets to the inductors.

Abstract: A magnetic recording medium comprises a magnetic alloy layer on a substrate wherein said magnetic alloy layer is made of 70-90 wt. % of Co and 30-10 wt. % of at least one of Si, Sb, Li, V, Ta, Ge and Pt and a magnetization axis of said magnetic alloy is substantially vertical to said layer.

Abstract: A rotary converter machine which includes a stator with three-phase primary, and secondary windings, and a rotor mounted within the stator which includes a damping winding. The primary and secondary stator windings are arranged on a common stator pack and located in continuous stator slots, both windings extending over the whole axial length of the common stator pack. The converter machine provides a direct transfer of the electrical energy by flux linkage between the two windings. The rotor is driven by the rotating magnetic field either asynchronously, if a drum rotor is provided, or synchronously, if a salient-pole rotor is provided.

Abstract: An induction device comprises a winding support with a base having connection points. The upper side of the base carries a centering member having an exterior surface that defines either a cylindrical or conical surface co-axial with the cylindrical central portion of a core. A winding is provided about the central portion of the core. The core has a non-circumferentially or rotationally symmetrical upper flange. A ferromagnetic adjusting core in a form of a cap is arranged over the core that carries the coil, the portion of the cap facing the base having internally a shape a radial dimensions corresponding to the cylindrical or conical surface of the centering member. The cap encloses the centering member with a close fit, so that the adjusting core is rotatable about the axis of the core that carries a winding. The portion of the adjusting core adjacent to the upper flange portion of the core that carries a winding is also non-circumferentially (i.e., rotationally) symmetrical.

Abstract: An angular displacement transducer of the variable reluctance type is disclosed. It utilizes two relatively rotatable rotors with two sets of magnetic circuits and a coil associated with each magnetic circuit. Each set of magnetic circuits has a set of magnetic cores, one-half the cores on one rotor and one-half on the other rotor. A pair of cores in the first set, one on each rotor, coact with each other to provide a first variable reluctance magnetic circuit which is magnetically linked with the first coil and which has a reluctance that varies with relative rotation of the rotors. A pair of cores in the second set, one on each rotor, coact with each other to provide a second variable reluctance magnetic circuit which is magnetically linked with the second coil and which has a reluctance that varies with relative rotation of the rotors.

Abstract: A joystick mechanism generates output signals corresponding to the X and Y components of a manual command. A transducer mounted in a housing includes a ferromagnetic vane member connected to the bottom of a handle extending into the housing. The transducer also includes a stator member having nine legs mounted in a 3 by 3 rectangular array. The primary winding is wound around the central leg. Two pairs of opposed secondary windings are wound around each set of three outside legs, wherein the X-axis is disposed between one pair of secondary windings and the Y-axis is disposed between the other pair of secondary windings. Primary windings may be wound around the central three legs to form a symmetrical cruciform. The handle can be fixed to a deformable top plate or be supported at a rigid top plate by a ball and socket.

Abstract: A rotary differential transformer is provided which has a constant amplitude output the phase angle of which varies with the angular displacement of a rotor. The rotor contains a pair of core segments of magnetic material which serve to couple portions of first and second primary coils to a secondary coil. The primary coils are connected to AC sources 90.degree. out of phase with each other.

Abstract: In combination with a control stick having a grip handle, a control stick force transducer includes a flexure means having a pair of parallel plates, one secured to the grip handle and one secured to the control stick and at least three compliant columns interconnecting said plates and forming at least three parallelograms disposed in vertical planes so that the one plate deflects relative to the other in accordance with rectilinear forces applied thereto but is insensitive to any moments applied thereto through the control handle. The force transducer further includes inductive pick-off means designed to be insensitive to moments applied to the handle about its vertical axis and a suspended mass and lever means pivoted relative to said columns so as to produce equal and opposite forces on the grip handle to compensate for the acceleration forces acting thereon.

Abstract: Contactless, electric control-handle comprising a field coil provided with a core for producing an alternating, electro-magnetic field, pairwise series connected, inductive pick-ups angularly spaced apart and each having a core, and an actuating-rod subjected to a bias stress directed towards a neutral position and connected with a core of the field coil to affect the alternating, electro-magnetic field such that there is a linear relation between the displacement of the actuating rod and the output signal of the inductive pick-ups.

Abstract: A coupling mechanism is disclosed for coaxially connecting a pair of connectable components, such as a pair of transducer assemblies each having a stator. A coupling ring is carried by one stator and engageable with the other for drawing the stators together axially in response to relative rotation of the coupling ring. First friction mechanism between the stators prevent relative rotation between the stators after the stators are aligned angularly to align the electrical zeros thereof. Second friction mechanism of lesser coefficient of friction between the coupling ring and the one stator permit relative rotation therebetween whereby the stators can be finally coupled by further rotation of the coupling member while the first friction means maintains the stators in zero electrical alignment. Subsequently, locking washers are fastened between the coupling ring and stators to permanently lock the stators in relative aligned position.

Abstract: A volume flow sensor of the gear wheel motor type having a pair of circular gear wheels which are mounted in a housing on fixed axles by means of ball bearings and without wall contact so as to rotate freely. At least one non-magnetic inset is positioned within the housing in the region of the teeth of one of the gear wheels. The inset has two poles of a material of good magnetic conductivity passing through it, the ends of the poles nearer to the gear wheel are situated substantially on the same gear wheel diameter and the other ends of the poles are positioned adjacent a field plate differential sensor.

Abstract: A rotary variable differential transformer is provided having a substantially linear output over .+-.35.degree. of rotation of the rotor. Two secondary windings in series opposition extend over adjacent nominal quadrants of the stator. A primary winding extends about substantially half the stator. The rotor includes two diametrically opposed pole pieces each defining arcuate segments. One segment is approximately one half the arcuate length spanned by the secondaries and the other segment one third the arcuate length of the remainder of the stator.

Abstract: A rotary variable differential transformer is provided comprising a pair of RVDT units disposed along a common shaft. A third RVDT is positioned along the shaft between the two units. The third RVDT comprises two pairs of secondary coils each pair being connected in series opposition. One of the coil pairs is connected to the secondary coils of one of the RVDT units and the other pair is connected to the secondary coils of the other RVDT unit. The third RVDT unit does not contain a primary and its secondary coils are excited only by the leakage flux from the other units.

Abstract: A multipolar resolver is so constructed that the need of the conventionally indispensable coil on the resolver rotor is eliminated by providing a center coil on a stator, and 5n or 3n rotor poles and 4n stator poles are provided where n is a positive integer. Sine and consine coils are wound on the stator poles alternately, thus simplifying the construction of the multipolar resolver.

Abstract: Electromagnetic structure is described useful as either a position indicator or a differential transformer. The structure includes a pair of magnetic bodies, one of which is rotatable on its axis with respect to the other. The stationary body has three magnetic flux conductive poles projecting from the same to be in alignment with corresponding lobes circumscribing the rotatable body. Aligned poles and lobes define a portion of a pair of closed-loop magnetic flux paths through the two bodies. The middle one of the lobes extends generally transverse to the rotatable axis of the rotatable body, whereas the two outer lobes are spirally related thereto. Rotation of the rotatable body with respect to the stationary body will vary the transverse area of the magnetic material of each of its lobes facing corresponding poles of the other body and, hence, vary the amount of flux which can travel along the flux paths.

Abstract: A signal transducing means for receiving input signals and delivering output signals comprising a bistable magnetic device which alters its magnetic state when the density of magnetic flux to which it is subject passes through a predetermined value, and detecting means providing an output signal responsive to a change in magnetic state of the bistable device. A conducting means for magnetic flux subjects the bistable magnetic device to conducted magnetic flux and comprises a first portion providing a path of high permeability and a second portion providing a path having a permeance which is alterable in response to input signals for varying the reluctance of the conducting means and the density of magnetic flux to which said bistable device is subject.

Abstract: This disclosure relates to a novel tracer head comprising a stylus, stylus support and housing, and two perpendicular differential transformers. The stylus has a unique configuration enabling more precise memory of its null position when the stylus is not deflected. Further, the stylus has a rotating top pin for contacting the pattern or template that assures a condition assumed in tracer control systems but not achieved under all conditions, i.e., the stylus will deflect away from the template normal to the template edge.

Abstract: An inductive transducer intended, according to the invention, for converting the displacement of mechanical objects into an electric signal, comprising primary and secondary coils with cores, connected to one of mutually moving mechanical objects. The coils are arranged one opposite the other with a gap, wherein a main screen connected to the other moving object and at least one auxiliary screen are located. The auxiliary screen is set movably in a plane parallel to the main screen. The inductive transducer of this invention permits obtaining a functional relationship between the output signal and two or more displacements of mechanical objects, and thereby enables the relationship, including the slope thereof, to be controlled by simple means.

Abstract: Several embodiments of a variable flux transformer are described which are quite simple in design and yet provide a greater range of adjustment of the output emf than prior art arrangements. Each transformer includes a core of a magnetic flux-conductive material having three legs extending from a common cross bar, which legs terminate at free ends which are spaced from one another. A primary electrical coil is interactively associated with one of the legs, and a secondary electrical coil is interactively associated with another leg. The third leg is used to complete a magnetic flux path from the primary coil leg bypassing the secondary coil leg. A magnetic flux control switch which is also of magnetic flux-conductive material is positioned at the free ends of the legs for appropriately bridging the spacings therebetween to complete only those low reluctance flow paths between such legs desired at any given time.

Abstract: A device for controlling an A.C. motor having an electromagnetic field ining coil wound around a conductive element having at least one inwardly directed opening bound by surface areas thereof and having a gap a between the surface areas defined by the formula a .gtoreq. .delta., wherein .delta. is the wave penetrating depth of an instantaneous operating frequency of the induced electromagnetic energy, the coil being wound so as to surround the open space and the element.