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Showing papers on "Inductor published in 1974"


Patent
16 Sep 1974
TL;DR: In this article, a surgically implantable pressure transducer for measuring pressure of fluid or tissue in a body chamber such as brain ventricle of a patient suffering hydrocephalus or a severe head injury is described.
Abstract: A wireless, surgically implantable pressure transducer for measuring pressure of fluid or tissue in a body chamber such as brain ventricle of a patient suffering hydrocephalus or a severe head injury. The transducer includes a coaxial variable capacitor electrically connected across an inductor to form a parallel resonant L-C circuit. Alternatively, a coaxially variable inductor may be connected across a capacitor to form the L-C circuit. A bellows is mechanically connected to the variable component to vary the value of capacitance or inductance and hence the resonant frequency of the L-C circuit in response to pressure changes of the fluid in which the bellows is immersed. The transducer is electromagnetically coupled to an external source of variable-frequency oscillatory energy such as a grid-dip oscillator which enables external detection of the transducer resonant frequency which is in turn indicative of the level of fluid pressure being sensed.

284 citations


Patent
01 Nov 1974
TL;DR: In this paper, a signal generating device and method for producing an RF output signal regulated in power and of decaying amplitude suitable for use in an electrosurgical generator for surgical coagulation purposes is presented.
Abstract: A signal generating device and method for producing an RF output signal regulated in power and of decaying amplitude suitable for use in an electrosurgical generator for surgical coagulation purposes. The device includes a circuit tuned to a predetermined radio frequency suitable to prevent nerve stimulation and the tuned circuit has connected therewith an unregulated power supply with current through the tuned circuit being controlled by means of a solid state switching system. The tuned circuit includes an inductor initially charged to a predetermined energy level. The switching system is automatically controlled so that the switching system is repeatedly urged to the closed position at predetermined time intervals and remains in this position until the current through the tuned circuit reaches a predetermined level at which time the switching system is caused to open and the tuned circuit thereafter rings to produce a regulated output signal of decaying amplitude, this output being taken from the tuned circuit across a transformer and is well suited for surgical coagulation purposes wherein the electrical current passes from an electrode to body tissue in the form of an arc with power dissipation being far greater in the tissue than in the arc for best operation.

93 citations


Patent
Larry Alan Olson1
07 Aug 1974
TL;DR: In this article, a microelectronic LC circuit capable of being tuned to a desired center resonant frequency, comprising a trimmable capacitor, a principal fixed inductor and a printed trimmably inductor having an inductance which is small compared to that of the principal inductor, is presented.
Abstract: A microelectronic LC circuit capable of being tuned to a desired center resonant frequency, comprising a trimmable capacitor, a principal fixed inductor and a printed trimmable inductor having an inductance which is small compared to that of the principal inductor. The printed inductor is one which is capable of having its inductance raised by trimming. In some cases, the fixed inductor can be omitted.

55 citations


Patent
23 Dec 1974
TL;DR: In this article, a static VAR generator circuit has a control system adapted to utilize the values of three phase load currents to generate time delayed firing angles for thyristor controlled inductors which are utilized with parallel capacitors to provide unity power factor and balanced electrical currents to the AC source.
Abstract: A static VAR generator circuit having a control system adapted to utilize the values of three phase load currents to generate time delayed firing angles for thyristor controlled inductors which are utilized with parallel capacitors to provide unity power factor and balanced electrical currents to the AC source. The time delayed firing angles are calculated from integrating furnace load currents over prescribed intervals during real time to thus maintain balanced load current at specified phase angles, usually zero, in the three phase system.

46 citations


Patent
08 May 1974
TL;DR: In this paper, a method and apparatus for use in identification of coins is disclosed in which a coin is passed through the electromagnetic field of an inductor in an oscillator circuit and the changes in both the frequency and amplitude of oscillation of said oscillator circuits are separately detected.
Abstract: A method and apparatus for use in identification of coins is disclosed in which a coin is passed through the electromagnetic field of an inductor in an oscillator circuit and the changes in both the frequency and amplitude of oscillation of said oscillator circuit are separately detected.

33 citations


Patent
10 Jan 1974
TL;DR: In this paper, a single shot type inductor is provided with arrangements for selectively varying the current concentration along portions of the opposed faces of the inductor facing a workpiece there between.
Abstract: A single-shot type inductor is provided with arrangements for selectively varying the current concentration along portions of the opposed faces of the inductor facing a workpiece therebetween. The arrangements provide for a single inductor to be employed to inductively heat workpieces which are of different contour, or to inductively heat different axial lengths of workpieces.

29 citations


Patent
18 Dec 1974
TL;DR: In this paper, the self inductance of the shield substantially equal to the mutual inductance between the shield and the superconducting coil was obtained by inserting a controlled compensating voltage source in series with the shield.
Abstract: An inductor device having a superconducting coil winding capable of maintaining a relatively large current flowing therethrough, and a normal conducting shield winding surrounding the superconducting coil. The superconducting coil and the shield are electrically connected in parallel with the shield functioning to maintain the current and the magnetic field in the superconducting coil substantially constant. The superconducting inductor device can be used to store energy and to return the stored energy to an energy consuming load over a relatively short period without incurring large losses in the superconducting material. This result is obtained by making the self inductance of the shield substantially equal to the mutual inductance between the shield and the superconducting coil, or by inserting a controlled compensating voltage source in series with the shield, so that pulse currents are conducted by the shield. Proper spacing of the shield windings around the superconducting coil will result in substantially no magnetic field present in the coil due to current in the shield.

24 citations


Journal ArticleDOI
01 Apr 1974
TL;DR: In this article, an active RC realization of a lossy floating inductor is presented, which uses two operational amplifiers, each in the unity gain connection, three resistors, and two capacitors.
Abstract: An active RC realization of a lossy floating inductor is presented. The circuit uses two operational amplifiers--each in the unity gain connection--three resistors, and two capacitors, and has low L and Q sensitivities to passive as well as active components.

23 citations


Patent
Erich Zabler1
14 Nov 1974
TL;DR: In this article, a variable inductor with a U-shaped magnetic core with a short-circuiting plate providing a short circuit for both legs of the core movable along the core legs in response to a displacement to be measured is connected in an electronic circuit to generate oscillation of a frequency that is either directly or inversely proportional to the displacement.
Abstract: A variable inductor having a U-shaped magnetic core with a short-circuiting plate providing a short-circuiting ring for both legs of the core movable along the core legs in response to a displacement to be measured is connected in an electronic circuit to generate oscillation of a frequency that is either directly or inversely proportional to the displacement. For the inversely proportional case, the variable inductance component can be combined with an integrator function and connected to an operational amplifier, for generation of the output frequency with a small number of electrical components. Additional circuit means may be used to improve linearity at higher output frequencies, or to provide arbitrary non-linear displacement-frequency characteristics.

22 citations


Patent
05 Aug 1974
TL;DR: In this paper, the authors proposed a method for selectively open circuiting a portion of the cnductor by a laser beam which does not substantially heat the structure, with the heat which is produced being highly localized.
Abstract: A conductor provided on an insulating support has a portion which forms an inductor. Various components are connected to the conductor, as by soldering, to provide an electronic circuit suitable for a particular application. The conductor portion which forms the inductor has parallel branches and the value of the inductance can be changed by selectively open circuiting the branches. This can be accomplished after the components are connected and the complete circuit is tested to determine whether a change in the inductance value is required. The branches can be selectively open circuited by removing a portion of the cnductor by a laser beam which does not substantially heat the structure, with the heat which is produced being highly localized. Accordingly, this does not soften the solder connections of the components and there is no damaging effect on the circuit. The inductor portion as described can be connected in series with a coil, and the total inductance value of the coil and the conductor can be adjusted by cutting sections from the parallel branches to thereby provide the total inductance value required in a particular circuit application.

21 citations


Patent
24 Apr 1974
TL;DR: In this paper, a method and apparatus for calibrating a resonant frequency circuit and in particular an L-C circuit module of a modular filter is disclosed, where the windings of the inductor are located on the core such that a portion of the core remains exposed.
Abstract: Method and apparatus for calibrating a resonant frequency circuit and in particular an L-C circuit module of a modular filter is disclosed. The windings of the inductor are located on the inductor core such that a portion of the core remains exposed. The capacitor and inductor are interconnected and mounted on a base provided with the appropriate input and output terminals. The base is mounted on the test fixture which has the appropriate corresponding terminal receptacles. A test fixture shielding enclosure is placed over the assembly. The test fixture shielding enclosure is identical to that which will be provided in the completed module except that it is provided with an opening aligned with the exposed portion of the inductor core. The circuit is energized, and the resonant frequency of the L-C circuit is monitored. A tool capable of removing a portion of the inductor core material is inserted through the opening in the test fixture shielding enclosure into contact with the exposed portion of the inductor core. The appropriate amount of core material is removed by the tool, thereby altering the resonant frequency to the desired level. In this manner, each of the L-C circuit modules which make up the filter is prealigned under simulated actual operating conditions prior to final assembly, thereby eliminating the necessity of testing and tuning the filter after the modules are assembled.

Patent
02 Jul 1974
TL;DR: In this article, a gap in a magnetic circuit of an iron core inductor is provided, and a plurality of small size permanent magnet pieces are placed in the gap, with the magnetizing directions thereof being provided in side-by-side relation.
Abstract: There is provided a gap in a magnetic circuit of an iron core inductor, and a plurality of small size permanent magnet pieces are placed in the aforesaid gap, with the magnetizing directions thereof being provided in side-by-side relation. If the magnetizing direction of the permanent magnet pieces is opposed to that of a D.C. magnetic field which is produced in a magnetic circuit, yet in case D.C. and A.C. overlapping currents flow through the inductor, then the D.C. magnetic field produced in the magnetic circuit will be off-set thereby, providing a high inductance value, while eddy currents produced within the permanent magnet pieces due to the A.C. magnetic field will be reduced to a considerable amount, because the permanent magnet pieces are small in size, thus minimizing the heat to be produced in the permanent magnet pieces.

Patent
10 Dec 1974
TL;DR: In this article, a magnetoresistive element is disposed in flux coupling proximity to the output inductor of a power supply for providing a control signal corresponding to output current, and the element is mounted in the air gap of the split-loop core of the inductor.
Abstract: A converter power supply is provided with a novel current regulating circuit. A magnetoresistive element is disposed in flux coupling proximity to the output inductor of a power supply for providing a control signal corresponding to the output current thereof. The element is mounted in the air gap of the split-loop core of the inductor.

Journal ArticleDOI
TL;DR: In this paper, a toroidal optimization of the inductor in the LC circuit of a capacitive displacement transducer is described, which has a higher Q than the usual multiturn coil and allows the construction of a rigid LC resonator which does not use any insulators.
Abstract: A single‐turn toroidal optimization of the inductor in the LC circuit of a capacitive displacement transducer is described. It has a higher Q than the usual multiturn coil and allows the construction of a rigid LC resonator which does not use any insulators. When this resonator is used in conjunction with a tunnel diode oscillator, the sensitivity of the capacitor to position changes is conservatively estimated as 7×10−12 cm.

Patent
01 Nov 1974
TL;DR: In this paper, a fault-current limiter is formed as a self-contained unit which can be connected in an existing power transmission system, consisting of a series-connected inductor and capacitor which are resonant with the power line frequency.
Abstract: A fault-current limiter is formed as a self-contained unit which can be connected in an existing power transmission system. The fault-current limiter consists of a series-connected inductor and capacitor which are resonant with the power line frequency, and a normally open switch is in parallel with the capacitor. A sodium fuse connected in series with a calibrating impedance is connected in parallel with the switch and the fuse is operated under predetermined circuit current conditions. The sodium fuse extends an operating plunger upon its operation, and the plunger causes the switch to close, thereby to short-circuit the capacitor and connect the current-limiting impedance of the inductor in the main power circuit.

Patent
06 May 1974
TL;DR: In this article, an improved regulated DC power supply using a ferroresonant power transformer is presented. But the transformer is not designed to handle a large number of loads and the voltage across the secondary winding is rectified to obtain the regulated DC output.
Abstract: An improved regulated DC power supply using a ferroresonant power transformer. The transformer includes a primary winding which is separated from a secondary winding and a resonant winding by a magnetic shunt on a transformer core. A ferrocapacitor is connected across the resonant winding. A control circuit operates an electronic switch for connecting a linear inductor across at least a portion of the resonant winding at a predetermined time in each half cycle for regulating the voltage across the secondary winding. The voltage across the secondary winding is rectified to obtain the regulated DC output. Circuitry is provided for advancing the operation of the electronic switch during each half cycle when power is initially applied to the transformer primary winding to initially reduce the DC output voltage. Operation of the electronic switch also may be advanced if the load current demands exceed a predetermined maximum.

Patent
James S. Irwin1
16 Dec 1974
TL;DR: In this article, an improved inductor arrangement is proposed for ferrite antenna structures intended to operate at relatively higher frequencies, where a spiral inductor or coil is divided into a plurality of wire segments, respective pairs of which are interconnected by individual capacitance elements to form a series-resonant circuits at a particular frequency or range of interest.
Abstract: An improved inductor arrangement suitable for a wide variety of applications, but particularly advantageous for use in the design of ferrite antenna structures intended to operate at the relatively higher frequencies The disclosed inductor arrangement includes a spiral inductor or coil divided into a plurality of wire segments, respective pairs of which are interconnected by individual capacitance elements to form a plurality of series-resonant circuits at a particular frequency or range of interest The capacitance elements may be provided in the form of discreet components or by a suitable electro-deposition process in the interests of further optimizing size factor The number of individual wire segments and resonating capacitance elements may be selected to provide a given terminal impedance for the inductor arrangement within a certain limited design range

Book ChapterDOI
31 Dec 1974

Journal ArticleDOI
TL;DR: In this article, a dynamical model is described which permits calculation of the excitation current I as a function of time in a laminated grain-oriented (G-O) steel transformer core.
Abstract: A dynamical model is described which permits calculation of the excitation current I as a function of time in a laminated grain-oriented (G-O) steel transformer core. The independent variable is the magnetic flux density or, equivalently, the coil voltage less the IR drop associated with the resistance R of the windings. Recent observations on flux reversal mechanisms in GO steel indicate that, in the range of magnetic field intensities typically present in transformer cores, the important reversal processes are the motion of long 180° domain walls continuous across grain boundaries and the motion of 90° walls within individual grains. These processes are represented in the model by two subcircuits connected in series. Each subcircuit consists of an inductive element in parallel with a linear resistor which accounts for the eddy current losses accompanying the flux change. The properties of each inductive element (flux vs. current) reflect the two wall motion mechanisms, respectively, in the limit of zero frequency. This model is capable of faithfully simulating minor loop behavior as well as the response to complex waveforms; e.g., the superposition of two or more frequencies. The circuit equations are solved, and some results of computer calculations using a program that implements this model are presented.

Patent
05 Jun 1974
TL;DR: In this article, a pulsewidth modulated DC-to-DC converter with first and second windings is described, which includes a plurality of switching devices and a transformer having plurality of primary windings, selectively coupled across a DC source through first and/or second inductor windings.
Abstract: A pulsewidth modulated DC to DC converter is disclosed which includes an inductor having first and second windings. A transformer having a plurality of primary windings is selectively coupled across a DC source through first and/or second inductor windings by a plurality of switching devices. The first and second inductor windings provide a low current through first and third paths in first and third transformer windings during first and third periods of a cycle. The first inductor winding provides a high current through second and fourth paths in second and fourth transformer windings during second and fourth periods of a cycle, respectively.

Patent
14 Jun 1974
TL;DR: In this paper, a two-stage amplifier with zero phase shift and a capacitor between the output of the amplifier and earth is used to detect a flaw in a surface under test.
Abstract: A flaw detecting device responding to variations in eddy currents induced in a surface under test includes an oscillatory circuit comprising a tuned detector circuit including a detector coil. The detector circuit is in series with an inductor and preferably capacitors are in parallel with the detector coil and with the detector coil and inductor respectively. The oscillatory circuit includes also a two stage amplifier with zero phase shift and a capacitor between the output of the amplifier and earth. The oscillatory circuit operates to successively decrease its output amplitude when the detector is moved from free air to adjacent a flawless surface and then adjacent a flaw in the surface.

Patent
15 Feb 1974
TL;DR: In this article, a rotary assembly comprising a hollow shaft containing the inductor, a passive screen for protecting the inductors against rapid variations in field due to disturbances in the armature.
Abstract: The machine comprises a rotary assembly comprising a hollow shaft containing the inductor, a passive screen for protecting the inductor against rapid variations in field due to disturbances in the armature. An auxiliary winding borne by the shaft creates a rotary magnetic field of intensity and frequency such that it completes the compensation of the magnetic fields created by the armature. The machine is useful for synchronous power alternators.

Patent
08 Nov 1974
TL;DR: In this paper, the inductance value of the inductor was chosen such that minimum transducer insertion loss is achieved at the center frequency of the midband channel, subject to the constraint that the insertion losses of all the remaining channels, measured at their respective center frequencies, lie at or near the above optimum value within an acceptable prespecified margin.
Abstract: The input transducers of a multichannel surface acoustic wave device are electrically connected in a series or series-parallel circuit arrangement and are connected to a single channel electromagnetic wave transmission line through an inductor. The inductance value of the inductor is chosen such that minimum transducer insertion loss is achieved at the center frequency of the midband channel. The circuit arrangement is selected which achieves optimum coupling to the midband channel subject to the constraint that the insertion losses of all the remaining channels, measured at their respective center frequencies, lie at or near the above optimum value within an acceptable prespecified margin.

Patent
Eckart G1
08 Oct 1974
TL;DR: In this paper, a system of ground fault sensors and signal interlocked ground fault relays operating in a multi-zone power distribution system is also disclosed, where one of the phase lines is coupled to ground through a first inductor which is transformer coupled with a second inductor connected across two other phase lines.
Abstract: The disclosure is directed to apparatus for sensing a ground fault in a normally ungrounded, polyphase power distribution system. One of the phase lines is coupled to ground through a first inductor which is transformer coupled with a second inductor connected across two other phase lines. A current sensor responses to current flow in the ground circuit including the first inductor resulting from a ground fault on any of the phase lines by signaling a ground fault relay to either provide a fault indication, interrupt the ground circuit or interrupt the phase lines. A system of ground fault sensors and signal interlocked ground fault relays operating in a multi-zone power distribution system is also disclosed.

Patent
22 Apr 1974
TL;DR: In this paper, a parallel-connected inductance and capacitor are connected in parallel with a normally closed switching device and in series with an electric power distribution system, and means are provided to produce a high arcing voltage in a pressurized liquid medium.
Abstract: A parallel-connected inductance and capacitor are connected in parallel with a normally closed switching device and in series with an electric power distribution system. The capacitive reactance of the capacitor is substantially higher than the inductive reactance of the inductor at the power line frequency. The normally closed switching device is opened in response to a predetermined level of fault current in the system so that the reactor is inserted into the power distribution system to effect limitation of current level. The switching device is springbiased to a closed position and the current path through the switch contacts forms a blow-open magnetic circuit, whereby the contacts are blown open against the closing force of the biasing springs when the predetermined current magnitude is reached. Means are provided to produce a high arcing voltage in a pressurized liquid medium.

Patent
09 May 1974
TL;DR: A voltage regulation control circuit for a magnetically-coupled inductive discharge switching regulator suitable for use in an automotive electrical system provides a regulated output voltage isolated from an unregulated input potential source and controls the rate of energy transfer from an inductor to a capacitor as discussed by the authors.
Abstract: A voltage regulation control circuit for a magnetically-coupled inductive discharge switching regulator suitable for use in an automotive electrical system provides a regulated output voltage isolated from an unregulated input potential source and controls the rate of energy transfer from an inductor to a capacitor in accordance with the unregulated potential source and the regulated output voltage.

Patent
16 May 1974
TL;DR: In this paper, an electric induction furnace has an inductor coil formed from a tubular conductor through which cooling water may be flowed, and which is made with an inner layer of corrosion-resisting copper or copper alloy and an outer layer of aluminum or aluminum alloy and which, although oxidizable in air, forms an electrically nonconductive oxide layer eliminating the risk of short-circuiting between the coil convolutions.
Abstract: An electric induction furnace has an inductor coil formed from a tubular conductor through which cooling water may be flowed, and which is made with an inner layer of corrosion-resisting copper or copper alloy and an outer layer of aluminum or aluminum alloy and which, although oxidizable in air, forms an electrically nonconductive oxide layer eliminating the risk of short-circuiting between the coil convolutions. Material costs are reduced by making the aluminum layer considerably thicker than the copper layer. The two layers are integrated under high mechanical pressure during the manufacture of the conductor, the electrical resistance between the interfaces of the two layers being negligible.

Patent
10 Jun 1974
TL;DR: In this article, a temperature control apparatus comprising an electric heater, switching means connected between the heater and an AC electric power source, and a thermo-detector means thermocoupled with the heater means to turn on and off the switching means below and above a predetermined temperature.
Abstract: A temperature control apparatus comprising an electric heater means, switching means connected between the heater means and an AC electric power source, and a thermo-detector means thermocoupled with the heater means to turn on and off the switching means below and above a predetermined temperature, in which a thyristor is employed for the switching means, the thermodetector means being a transformer which has a primary winding connected to the power source through a resistor means, a secondary winding connected to the control terminal of the thyristor and a core of magnetic materials having a Curie point of the predetermined temperature, a low coercive force and a high differential permeability at a magnetic field strength equal to the coercive force. Outputs on the transformer secondary winding fire the thyristor at each zero voltage of the AC voltage to permit the heater means to be excited below the predetermined temperature. No output is present on the secondary winding above the predetermined temperature so that the thyristor is not fired. An inductor having a winding and a core of similar magnetic materials as above may be substituted for the transformer to perform the same purpose, in which case the self-induced voltage on the inductor winding is coupled to the control terminal of the thyristor.

Patent
27 Feb 1974
TL;DR: In this paper, a saturable transformer has three windings, one being in series with a horizontal deflection coil to introduce a parabolic reactance variation to correct for side pincushion distortion.
Abstract: In a television receiver, a saturable transformer has three windings, one being in series with a horizontal deflection coil to introduce a parabolic reactance variation to correct for side pincushion distortion. An adjustable correction circuit includes a transistor integrator for producing in another winding of the saturable transformer a vertical parabolic current. The last winding of the saturable transformer is coupled through a pair of switching diodes to a pair of variable inductors. The diodes conduct alternately at the beginning and end of the vertical scanning period. The variable inductors may be mounted coaxially with a common movable core to allow inverse side correction, or may be mounted separately with separate movable cores to allow independent side correction.

Patent
05 Aug 1974
TL;DR: In this article, an auxiliary polyphase winding parallel to the track and wound so as to create a sliding field, synchronous with the field of the inductor, is arranged mechanically so that relative motion between it and the axis of the induction in translation along the track is absent.
Abstract: The motor has a passive conductive track, comprising an inductor winding intended to be traversed by a direct current, of superconducting material, placed in a cryostat, rotary with the cryostat around an axis parallel to theplane of the track and perpendicular to the direction of relative movement of the track and of the inductor. An auxiliary polyphase winding parallel to the track and wound so as to create a sliding field, synchronous with the field of the inductor, is arranged mechanically so that relative motion between it and the axis of the inductor in translation along the track is absent. The auxiliary polyphase winding may be flat and comprise coils whose separation increases from its medium plane, in line with the axis of the inductor.