Abstract: Multiple deflections of a structural member (SM) can be measured at multiple locations thereof, which deflections can be used to monitor changes in stiffness over time, using an antenna to measure the resonant frequencies at different harmonic frequency numbers of a predetermined radio frequency spectrum. The antenna includes a plurality of coils providing at least a first coil region that has a maximum sensitive to a first resonant frequency harmonic number and a second coil region spaced from the first coil region and that has a maximum sensitivity to a second resonant frequency harmonic number that is different from the first predetermined resonant frequency harmonic number. Using different harmonic resonant frequency numbers, deflections at multiple regions of the SM can be determined concurrently using a single antenna.

Abstract: A monitoring method and system include an antenna disposed spaced from a structural member (SM), which itself can be the target object or attachable to a target object, without using any in-dwelling strain sensor. The antenna is arranged to not touch the SM in at least the no load condition. As the target object undergoes displacement and/or deformation, the SM undergoes displacement and/or deformation. The SM is juxtaposed, partially contained with, or fully contained within a magnetic or electromagnetic field and electromagnetically coupled to the emitting antenna. Characteristics of the electromagnetic field coupling between the antenna and the SM shift over time due to the displacement and/or deformation applied to the SM. The shift in the characteristics of the electromagnetic field coupling between the antenna and the SM over time can be used to determine the temporal change in deformation and/or displacement of the SM over time to enable diagnosis of the target structural object being monitored.

Abstract: Provided is a sensor circuit which can amplify a sensor signal at high speed and with a high amplification factor without increasing the current consumption. The sensor circuit includes a primary amplifier for amplifying in advance a differential output signal which is a current signal of a sensor element, a secondary amplifier for amplifying the amplified differential output signal, a constant voltage generating circuit for maintaining a sensor element driving current to be constant, and a feedback circuit for feeding back a feedback signal to adjust an amplification factor. Most of the currents which pass through the primary amplifier are bias currents of the sensor element.

Abstract: A capacitance sensing circuit comprises a capacitive device having a capacitance, the device initially being at a first voltage level. The capacitance sensing circuit is capable of applying one or more pull-up currents to the device during one or more corresponding pull-up periods of time, for changing the first voltage level into one or more corresponding pull-up voltage levels; applying a measurement current to the device; and measuring a measurement period of time, during which one of the pull-up voltage levels changes into a second voltage level. A method of sensing a capacitance of a capacitive device comprises applying a first voltage to the device; applying one or more pull-up currents during corresponding pull-up times, for changing the first voltage into corresponding pull-up voltages; applying a measurement current; and measuring a time, during which one pull-up voltage changes into a second voltage.

Abstract: An arrangement for operating a sensor, in particular a bridge sensor, comprises a sensor input (Vin1, Vin2) for connecting the sensor (Brdg) and a clocked signal generator (Osc), which is coupled to the sensor input (Vin1, Vin2). Furthermore an amplifier (Amp) is provided for detecting sensor signals (Sn, Sn+1), which is connected on the input side to a signal input (IN+, IN?) for connecting the sensor (Brdg), wherein the detection takes place depending on the clock pulse of the signal generator (Osc). A signal processing device (PROC) is connected to an output (AOUT+, AOUT?) of the amplifier (Amp) and is arranged to demodulate the sensor signals (Sn, Sn+1) that follow one another according to the clock pulse.

Abstract: A circuit for simulating an electrical load at a terminal of a test circuit having at least one first switch and at least one second switch includes a third switch connected to the first switch of the test circuit via a first external connection point. A fourth switch is connected to the second switch of the test circuit via a second external connection point. The first switch and the second switch are connected via a shared, first internal connection point to the terminal of the test circuit and the third switch and the fourth switch are connected via a shared, second internal connection point such that that the first switch, the second switch, the third switch and the fourth switch form an H-bridge circuit. A voltage source is configured to provide the first and second external connection points with a supply voltage. A controllable voltage source is connected in a transverse bridge branch between the terminal and the second internal connection point. An inductance is active in the transverse bridge branch.

Abstract: An electrical circuit identification means is revealed. The electrical circuit identification device includes a signal generator connected directly to an AC power socket and a signal receiver set in a power control panel. The signal generator blocks a half cycle of sine waves and produces a short off-and-off signal at an interval. The signal receiver includes a signal sensor receiving signals from the signal generator and connected to both a control voltage divider and a signal strength switch for modulating and amplifying signals received by the control voltage divider, and a signal integration module that is connected to the signal strength switch and a microcontroller for outputting digital signals with different waveform. An identification system in the microcontroller cross checks the digital signals and the identification accuracy is determined according to the position of a light lit up in an indicator light module.

Abstract: A device for use with a conduit having a first conduit end and a conduit second end, into which conduit a cable can be installed using a flow of air into the first conduit end, the device being suitable for confirming that the air is flowing out from the second conduit end. In an embodiment, the device includes a housing, means to enable connection of the device to the second conduit end, a detector arranged to detect an electrical property change, and an actuator for causing an electrical property change detectable by the detector, wherein in use, the air flowing into the device causes the detector and the actuator to move relative to each other, causing an electrical property change detectable by the detector.

Abstract: The invention provides a method and a circuit arrangement for measurement of the current through an inductive load L wherein the current is fed into the inductive load L with the aid of a full-bridge circuit. By way of example, full-bridge circuits such as these are used to feed a current in a pulse-width-modulated form into a winding of a direct-current, stepping or plunger coil motor. A respective measurement device (Ra, Rb) is provided for each half-bridge. In this case, a respective measurement device (Ra, Rb) is arranged between in each case one series circuit of switching elements and ground (VSS) or the supply voltage (VDD), respectively, at which a respective voltage is tapped off, which is a measure of the current through the respective measurement device.

Abstract: Apparatuses and methods for measuring stress or strain in a conductive material without physical contact with the material are provided. The device comprises an inductor circuit configured to induce an alternating current into the material along a first path; and a detector configured to detect a signal representative of the stress in the material along the first path when current is induced in the material.

Abstract: The disclosure relates to a touch sensing device and method. An embodiment of the disclosed method includes starting to count with a counter while charging a sensing point which has distributed capacitance periodically, then transferring the charge on the sensing point to a second capacitor. Next, the voltage on the second capacitor is compared with a reference voltage, and if the former exceeds the latter, the counter stops counting and saving the value. If the voltage on the second capacitor is less than the reference voltage, the sensing point is judged to determine whether it is in touching state or in non-touching state according to the saved count value while discharging the second capacitor, clearing the counter after the discharge, then restarting the method. Using the device and method of this disclosure, the touching sensing action can be tested accurately.

Abstract: A differential reflection bridge is provided for a 100 Ohm load, the bridge not being compromised by a translation to a 50 Ohm system. The reflection bridge uses two transmission line baluns. The first traditional balun T1 connects the input signal source to a resistor bridge. The second balun T2 connects between a central node of the resistor bridge and an output OUT as well as a second test port that eliminates a path to ground. With no ground path the bridge is immune to common mode impedance disturbances.

Abstract: An electromagnetic stimulator circuit has a precharge power supply, a capacitor, a set of switches, and a stimulator coil. The switches, which can be implemented using a variety of devices, enable flexible control over the coil current waveform without requiring the physical reconfiguration of circuit elements. The shape of the output current pulse is controlled by the modulation of the switches, and much of the energy applied to the coil is returned from the coil to the capacitor for reuse on the succeeding pulse. Less power is required and less heat energy is generated.

Abstract: A wireless liquid sensing system includes a beverage container and a table top for holding the container. Embedded in the walls and bottom of the container are two electrically conductive plates coupled to a transponder wire coil. A reader radiates an RF signal at a predetermined frequency through a reader antenna. A microprocessor, also coupled to the transponder coil and the two plates, is powered by a rectifier circuit that gains power from then radiated RF signal. The microprocessor amplitude modulates the RF signal in accordance with the amount of liquid in the container. The reader can then detect this modulation with a peak detector to sense the amount of the substance in the container when the transponder antenna is inductively coupled to the reader antenna at the predetermined frequency.

Abstract: A circuit capable of detecting natural gas at a wide range of concentrations is disclosed. The gas detection circuit includes a catalytic Wheatstone bridge circuit and an analyzing Wheatstone bridge circuit. A circuit for detecting natural gas, which includes placing a device containing the circuit described above in an area in which the air has a potential of containing natural gas, and monitoring the output signal for indications of the presence of natural gas is also disclosed.

Abstract: A device for charging batteries is comprised of a mobile electrical device MD and a charging unit CU and inductively transmits electrical power by means of a alternating magnetic field from at least one primary winding W1, W2 to at least one secondary winding W3, W4 in the mobile device MD. According to the invention, the alternating magnetic field is generated by a self-oscillating push-pull oscillator which contains switches Q1, Q2 that are reciprocally connected with positive feedback and in each push-pull branch, contains a resonance circuit with the effective inductance of at least one primary winding W1 or W2 and with a circuit capacitance C1, C3 or C2, C4, wherein the primary windings W1 and W2 in the charging unit CU are disposed spatially separate from each other so that each generates a magnetic alternating field in a different spatial region and the secondary windings W3, W4 in the mobile device are disposed so that each spatial region is equally loaded.

Abstract: A device for measuring residual stress in ferromagnetic and non-ferromagnetic metal objects. The device having four electrically identical induction coils which form a four terminal alternating current bridge circuit. There is a fine wire shield formed of fingers for shielding the coils from stray capacitance. The bridge having four coil terminals. Two diagonally opposite coil terminals are connected to a variable frequency constant voltage generator. The other two diagonally opposite coil terminals are connected to a low noise broad band preamplifier. The preamplifier amplifies any unbalance in the bridge. There is a double pole double throw switch connected to two coil terminals which are diagonally opposite each other. Connected to the preamplifier is an amplifier. The amplifier is connected to a phase detector which is connected to a computer. The phase detector detects in phase and quadrature component signals.

Abstract: The inductance-change detection apparatus comprises an inductance-change converter that converts inductance-change in coils into voltage to output, a reference-voltage generator that generates and outputs a predetermined reference voltage, a frequency characteristic adder that adds a frequency characteristic similar to that of the converted voltage converted by the inductance-change converter to the reference voltage, a reference-voltage compensator that varies and compensates the frequency spectrum of the reference voltage containing the added frequency characteristic, in parallel in the direction of amplitude, corresponding to a parallel variation of the frequency spectrum of the converted voltage in the direction of amplitude, and an inductance-change detector that compares the converted voltage with the compensated reference voltage to detect inductance changes in the coils.

Abstract: An ice detector and deicing fluid effectiveness monitoring system for an aircraft is disclosed. The ice detection portion is particularly suited for use in flight to notify the flight crew of an accumulation of ice on an aircraft lifting and control surfaces, or helicopter rotors, whereas the deicing fluid effectiveness monitoring portion is particularly suited for use on the ground to notify the flight crew of the possible loss of the effectiveness of the deicing fluid. The ice detection portion comprises a temperature sensor and a parallel arrangement of electrodes whose coefficient of coupling is indicative of the formation of the ice, as well as the thickness of the formed ice. The fluid effectiveness monitoring portion comprises a temperature sensor and an ionic-conduction cell array that measures the conductivity of the deicing fluid which is indicative of its concentration and, thus, its freezing point.

Abstract: A measuring circuit (MS) for measuring the value of an impedance in an impedance network includes an oscillator device (OSZ1), a second oscillator device (OSZ2), a phase-controlled rectifier (PG), a reference/actual value comparison point (AG) and an integrator.The first oscillator device feeds a first alternating voltage of constant amplitude and constant frequency to a first output connection (A1). The second oscillator device feeds a second alternating voltage of the same frequency, but with adjustable amplitude and with phase shifted by 180.degree., to a second output connection (A2). The amplitude of the second alternating voltage depends on the phase of the signal which is transmitted to the phase-controlled rectifier via an input connection (E). If the input signal is in phase with the second output signal, the amplitude of the second output signal is reduced. However, if the input signal oscillates in opposite phase to the second output signal, the amplitude of the second output signal is increased.

Abstract: A DC current-comparator-based circuit generates an adjustable output proportional to an input signal, i.e. an input voltage or current. One use of the circuit is in the formation of a DC resistance bridge that can be controlled automatically by a microprocessor. The ends of a pair of test resistors (the resistances of which are to be compared) are connected to respective ratio windings of the current comparator. The same potential is applied across these resistors by a master power supply. A microprocessor is alternately supplied with two voltage signals, a first being proportional to the current in a variable one of the ratio windings of the comparator, and the second being proportional to any inequality between the current in the other ratio winding and the test resistor to which it is connected. The microprocessor controls a slave power supply that receives both the first signal and a third signal that is indicative of any unbalance in the bridge.

Abstract: The present invention relates to a method and apparatus for remotely detecting impedance. It is specifically adapted for use on a polishing machine wherein the end point of polishing for removing a surface layer during the processing of semiconductor substrates is detected. A first, or stationary coil having a high permeability core is wound having an air gap and an AC voltage is applied to the stationary coil to provide a magnetic flux in the air gap. A second coil is mounted for rotation on the polishing table, in a position to periodically pass through the air gap of the stationary coil as the table rotates. The second coil is connected at its opposite ends to contacts which are embedded in the surface of the polishing wheel. The contacts are positioned to engage the surface of the substrate which is being polished and provide a load on the second or rotating coil.

Abstract: An oscillator (10) supplies via a first feeding path a fixed frequency signal to the fixed inductance (L.sub.o) connected in series with a variable inductance (L). The signal at the common connection point of the two inductors (RW1) is used to provide an output signal (U.sub.act) and a control voltage (V) for controlling the amplification of an inverting amplifier (B3) in a second feeding path from the variable oscillator (10) to the inductance (L). The signal from the common terminal (RW1) is processed in a differential amplifier (30) and an amplification control circuit (40) comprising a rectifier (B4, S), a delay element (VZ1), an integrator (I) and a sample-and-hold circuit (S & H) controlled by a synchronization output of the oscillator stage (20). The controllable amplifier (B3) is the part of a multiplier (50), which may comprise analogue or digital components.