Abstract: An example circuit may include an inductor; a low-frequency sensor connected to the inductor; a high-frequency sensor connected to the inductor; and an integrator connected to the low-frequency sensor and the high frequency sensor, comprising one or more resistive devices and one or more capacitive devices, wherein the integrator is characterized by a time constant that varies as a function of the inductance of the inductor. The inductor may, for example, be part of a switched-mode power supply or an amplifier.

Abstract: Circuits and techniques for improving power converter efficiencies and controllability are disclosed. For example, a first converter stage includes a push-pull circuit topology and an isolating element including a magnetizing inductance for isolating a primary side of the first converter stage from a secondary side of the first converter stage. The magnetizing inductance may vary as a function of a current flowing in the primary side of the first converter stage. For example, the isolating element can be a transformer with a stepped gap core and have a varying magnetizing inductance profile.

Abstract: An electrical apparatus to sense current through a load includes a first input terminal having a first input voltage relative to a reference, a second input terminal having a second input voltage relative to the reference, a first load terminal of the load having a first load voltage relative to the reference, a second load terminal of the load having a second load voltage relative to the reference, a first current sensing element connected between the first input terminal and the first load terminal and a second current sensing element connected between the second input terminal and the second load terminal. A first sense voltage is determined by a relationship between the first input voltage and the second load voltage and a second sense voltage is determined by a relationship between the second input voltage and the first load voltage.

Abstract: An audio system including an audio power amplifier, a transducer electrically connected to the audio power amplifier, an enclosure coupled to the transducer, and a secondary resonant element coupled to the enclosure. An electrical feedback signal representative of the transducer current is negatively fed back to the audio power amplifier to synthesize a positive output impedance.

Abstract: An electronic assembly including a first heat producing device mounted on a first outer surface of a first portion of a circuit board. The first portion can deflect upwardly and downwardly relative to other portions of the circuit board. A first force element urges the first heat producing device against a heat sink. The force exerted by the first force element is variable with respect to time.

Abstract: An output filter for an audio amplifier includes a printed circuit board having at least one aperture extending through the printed circuit board. The output filter includes a first coil winding formed on a layer of the printed circuit board. The first coil winding substantially surrounds the first aperture. A magnetic core includes at least one leg. The at least one leg passes through the at least one aperture.

Abstract: An audio system including an audio power amplifier, a transducer electrically connected to the audio power amplifier, an enclosure coupled to the transducer, and a secondary resonant element coupled to the enclosure. An electrical feedback signal representative of the transducer current is negatively fed back to the audio power amplifier to synthesize a positive output impedance.

Abstract: A limited rotation motor optical scanning system is disclosed that includes a limited rotation motor scanner, a digital controller servo system, a position feedback unit, a wide angle compensation unit, a digital processor, and an adjustment unit. The limited rotation motor scanner element is adapted for directing an energy beam to at least one location within a field of view. The digital controlled servo system is adapted for controlling motion of the limited rotation motor scanner element in accordance with a servo command waveform. The position feedback unit is for providing a position feedback signal indicative of a rotational position of the limited rotation motor scanner element. The wide angle compensation unit is for receiving the position feedback signal and for providing a boost signal that is representative of a boost factor that compensates for torque constant variation with the rotational position of said limited rotation motor scanner element.

Abstract: An output filter for a switching audio amplifier includes a magnetic core having a gapped central leg and a first and a second outer leg. The central leg and the first outer leg form a first independent magnetic path and the central leg and the second outer leg form a second independent magnetic path. The first and the second outer leg together form a joint magnetic path. A first coil having a first plurality of turns is wound around the first outer leg. A first load current applied to the first coil generates a first magnetic flux in a first direction through the joint magnetic path. A second coil having second plurality of turns is wound around the second outer leg. A second load current applied to the second coil generates a second magnetic flux in a second direction opposite to the first direction through the joint magnetic path.

Abstract: A planar transformer is fabricated on a multilayer printed circuit board having more than two layers. A magnetic core includes a common leg and a first and a second return leg that form a first and second core window, respectively. A first coil includes a first coil winding formed on the circuit board. The first coil winding passes through each of the first and second core windows. A second coil includes a plurality of coil windings formed on the circuit board. Two or more of the plurality of coil windings include fractional turn windings. Each of the plurality of coil windings passes through at least one of the first and the second core windows and is interconnected such that the sum of ampere turn products from all of the coil windings passing through each of the first and the second core windows is substantially equal to zero.

Abstract: An improved servo system for galvanometers, scanners and similar devices which uses digital processing to increase the dynamic range and provide greater effective resolution. The system provides digital control of a reference point that directly influences the excitation, which in turn directly influences the gain of the circuit. A high and low resolution switching path is provided to optimize dynamic range. Wide angle torque compensation improves uniformity of response at large angular deflections from zero. Improved thermal protection allows safe operation near system thermal limits. A graphical user interface allows adjustments and changes response on the fly for tuning due to input conditions or user control.

Abstract: The invention provides a method and apparatus for directing a radiation beam (504, 606) in a desired direction. There is provided a movable member (10) supported for movement by a fixed member (40) and the movable member has an optical element, e.g a flat mirror (30) fixedly attached thereto. In one embodiment the mirror scans a radiation beam incident thereon in one plane. In a second embodiment, the radiation beam is scanned in two mutually perpendicular planes. A magnetic element (50) having a north and a south magnetic pole is fixedly attached to the movable member (10). A magnetically permeable stator element (70) that is stationary with respect to the movable member (10) and the magnetic element (50) is placed in the field of the magnetic element such that the stator element and said magnetic element mutually generate a magnetic traction force between them.

Abstract: A method and apparatus for supporting a movable member (10) with respect to a fixed member (40) is provided. The movable member (10) includes a magnetically permeable portion (81) contained therein and magnetic element (50) fixedly attached thereto and movable therewith. The movable member (10) is supported for rotation with respect to the fixed member (40) by an outer bearing surface (11) of the movable member and an inner bearing surface (20) of the fixed member (40). The fixed member (40) provides access to the movable member (10) from two sides thereof. A magnetically permeable stator element (70) is fixedly attached to the fixed member (40) and positioned within a magnetic flux field of the magnetic element (50) such that an air gap (73) is formed between the magnetic element (50) and the stator element (70).

Abstract: An optical element is disclosed for use in a scanning system. The optical element comprises a carbon-based substrate having a first specific stiffness, and a titanium carbide coating having a second specific stiffness. The carbon-based substrate and the titanium carbide coating form a composite having a desired shape. The composite has a third specific stiffness that is greater than the first specific stiffness and greater than the second specific stiffness.

Abstract: The invention provides a method and apparatus for directing a radiation beam (504, 606) in a desired direction. There is provided a movable member (10) supported for movement by a fixed member (40) and the movable member has an optical element, e.g a flat mirror (30) fixedly attached thereto. In one embodiment the mirror scans a radiation beam incident thereon in one plane. In a second embodiment, the radiation beam is scanned in two mutually perpendicular planes. A magnetic element (50) having a north and a south magnetic pole is fixedly attached to the movable member (10). A magnetically permeable stator element (70) that is stationary with respect to the movable member (10) and the magnetic element (50) is placed in the field of the magnetic element such that the stator element and said magnetic element mutually generate a magnetic traction force between them.

Abstract: A method and apparatus is provided for directing an optical beam by a movable optical element and especially in a free space optical switch. The control element (5) comprises a movable member (10) including an optical element such as a mirror (30) fixedly attached thereto and supported for movement by a fixed member (40). A magnetic element (50) is fixedly attached to the movable member (10) and a magnetically permeable stator element (70) is provided fixedly attached to the fixed member (40). The stator element (70) and the magnetic element (50) mutually generate a magnetic traction force between them for substantially holding the movable member (10) in a stationary position during periods when it is not moving. The stator element (70) is provided with current coils (60) wound around portions thereof and connected with a current driver (400) for providing a controlled current in the stator coils. The current in the coils is provided to induce an electromagnetic force in the stator element (70).

Abstract: A method and apparatus for supporting a movable member (10) with respect to a fixed member (40) is provided. The movable member (10) includes a magnetically permeable portion (81) contained therein and magnetic element (50) fixedly attached thereto and movable therewith. The movable member (10) is supported for rotation with respect to the fixed member (40) by an outer bearing surface (11) of the movable member and an inner bearing surface (20) of the fixed member (40). The fixed member (40) provides access to the movable member (10) from two sides thereof. A magnetically permeable stator element (70) is fixedly attached to the fixed member (40) and positioned within a magnetic flux field of the magnetic element (50) such that an air gap (73) is formed between the magnetic element (50) and the stator element (70).

Abstract: A position sensor comprises a capacitive transducer and an inductor connected in series with the transducer. The transducer is a differential capacitor whose total admittance is essentially independent of changes in the sensed position. The total capacitance and inductance resonate at the fundamental frequency of a generator that provides a drive voltage and the resulting voltage across the sensor is thus substantially greater than the drive voltage. This increases the current through the transducer, and consequently increases the sensitivity of the sensor.

Abstract: A reciprocating rotary action actuator consisting of a rotor and stator that can be added to a bi-directional rotary motor or galvanometer scanner, where the stator has a ring magnet and a pair of soft iron pole pieces that concentrate the flux of the ring magnet into a concentric set of narrow, uniformly spaced, axially oriented, magnetic flux fields intersecting the rotor's field of travel. The rotor has small permanent magnets embedded in the periphery of a nonconductive, nonmagnetic rotor core. The rotor magnets have the same number and spacing as the stator's magnetic flux fields. The magnet poles are oriented opposite the flux fields of the stator pole pieces, so that upon rotation, the rotor magnets encounter the stator flux fields at each end of rotor travel, creating an opposing force that reverses the angular direction of the rotor with minimal requirement for actuator current and generation of thermal losses.

Abstract: A capacitive sensing system for detecting the angular position of a rotatable member of a motor. The position detection system includes a cylindrical excitation pin attached to the housing of the motor and a tubular signal plate, having a plurality of sensing surfaces symmetrically arranged about the axis of rotation of the rotatable member, which surrounds the cylindrical excitation pin and, which is also attached to the motor housing. A lobed dielectric is attached to the rotatable member of the motor and inserted between the cylindrical excitation pin and the tubular signal plate. An electric circuit connected to the sensing surfaces of the tubular signal plate calculates the relative angular position of the rotatable member from the amount of energy detected at each of the sensing surfaces.