Abstract: Disclosed is a wearable electric shock recognition device, which includes first to fourth variable resistors and a bridge resistor forming a bridge circuit; a resistance compensator compensating the first to fourth variable resistors in the bridge circuit so that the bridge circuit is in a balanced state. When it is determined that a magnitude of a current flowing through a bridge line exceeds a predetermined electric shock threshold, a determiner determines that an electric shock event has occurred.

Abstract: An electronic device includes a substrate, a Wheatstone bridge circuit, a power module, and a controller. The Wheatstone bridge circuit includes a first pressure sensing electrode disposed on the substrate. A resistance of the first pressure sensing electrode varies with pressure applied to the first pressure sensing electrode. The first pressure sensing electrode is coil-shaped. The power module is electrically connected to the Wheatstone bridge circuit. The controller is configured to control the power module to provide direct current (DC) to the Wheatstone bridge circuit within a first period of time, and to control the power module to provide alternating current (AC) to the Wheatstone bridge circuit within a second period of time.

Abstract: The problem addressed by the invention is that of providing a coil having advantageous properties for an oscillating circuit, in particular for a measuring device for electromagnetic signals. This problem is solved in that the coil comprises an electric conductor, the ends of which form the two terminals of the coil. Wound sections of the electric conductor are twisted together, that is to say wound helically around one another. The electric conductor is in principle surrounded by insulation, for example made of plastic or varnish. As a result of the twisting, increases in spacing between adjacent conductor sections within the windings are achieved. This results in an improved quality of the coil.

Abstract: A method and an apparatus for calculating an offset of a Wheatstone bridge type sensor are described. The offset calculation method includes measuring resistances between nodes of a Wheatstone bridge type sensor, calculating an offset of the sensor using the measured resistances and providing information on the calculated offset. Accordingly, the offset of the Wheatstone bridge type sensor can be rapidly and easily calculated independently from the size of a bias current, and ultimately. Furthermore, time required to measure can be reduced and thus a sensor fabrication cost can be reduced, and also, mass production can be enhanced.

Abstract: A multi-touch sensing system and a method for estimating a location of at least one touch point are provided. The multi-touch sensing system includes a panel, a grid of conductor disposed on the panel, a driver array connected to the grid, a receiver array connected to the grid, a signal processing system, and a controller. The method involves transmitting drive signals to the grid, receiving signals from the grid, estimating a capacitance, and transforming the capacitance into touch coordinates.

Abstract: Methods and apparatus to provide an integrated circuit having a magnetic sensing element and fault detection module coupled to the sensing element, the fault detection module including circuitry to detect a fault condition and to self-test operation of the circuitry for detecting the fault condition. In illustrative embodiments, a fault pin indicates the fault condition.

Abstract: A bi-directional bridge includes a forward bridge portion, and reverse bridge portion and a shared portion that enables the simultaneous measurement of power flowing in both directions while reducing insertion losses, providing better impedance matching and/or providing improved directionality. In some embodiments, additional attenuation is provided to reduce the common mode rejection requirements of detectors used with the bridge. In other embodiments, multi-tap attenuators and steering circuits may be integrated into the forward and/or reverse bridge portions to reduce common mode signal levels while still maintaining high levels of sensitivity for measuring small input signals.

Abstract: A thermal, flow measuring device and method for measuring the flow of a measured medium. During a heating phase of predetermined length a constant heating current of a first electrical current source flows through a first resistor. During a first measuring phase of predetermined length a constant measurement current of a second electrical current source flows through the first resistor. During the first measuring phase a first voltage falls across the first resistor, wherein during a second measuring phase of predetermined length during the first measuring cycle the constant measurement current of the second electrical current source flows through a second resistor.

Abstract: Disclosed is a circuit arrangement for determining a temporal change of an output voltage of a half-bridge circuit during a dead time. In one embodiment, the circuit arrangement includes a first input for applying the output voltage. A capacitive network includes a first and a second circuit node capacitively coupled to the input, and having a terminal for a reference potential. A recharging circuit during the switched-on phase of one of a first and second switching elements, adjusts electrical potentials of the first and second nodes, the electrical potentials each being different from the reference potential. A comparator arrangement, during the dead time, determines a time difference between such times at which the electrical potentials at the first and second node each assume a given potential value, the time difference being a measure for the change with time of the output voltage.

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 magnetic field sensor assembly for measuring an angular direction of a sensed magnetic field relative to the assembly is disclosed. The sensor assembly includes a sensor of a first type configured to sense an orientation of the sensed magnetic field, a sensor of a second type configured to measure an orientation and a direction of the sensed magnetic field and processing circuitry connected to each of the magnetic field sensors. The processing circuitry being configured to process output signals from the sensor of the first type to determine an uncorrected sensed magnetic field angle and to apply an offset angle to the uncorrected magnetic field angle dependent on a logical combination of signs of output signals from the sensors of the first and second types.

Abstract: A current sensor including a magnetic detecting bridge circuit which is constituted of four magneto-resistance effect elements with a resistance value varied by application of an induced magnetic field from a current to be measured, and which has an output between two magneto-resistance effect elements. The four magneto-resistance effect elements have the same resistance change rate, and include a self-pinned type ferromagnetic fixed layer which is formed by anti-ferromagnetically coupling a first ferromagnetic film and a second ferromagnetic film via an antiparallel coupling film therebetween, a nonmagnetic intermediate layer, and a soft magnetic free layer. Magnetization directions of the ferromagnetic fixed layers of the two magneto-resistance effect elements providing the output are different from each other by 180°. The magnetic detecting bridge circuit has wiring symmetrical to a power supply point.

Abstract: A field device, comprising a sensor, and a control/evaluation unit. The control/evaluation unit is implemented on an application-specific integrated circuit—an ASIC—which, in at least a first section and in a second section, is embodied as a dynamically reconfigurable logic chip. In each of the two sections, in each case, a measuring path composed of a plurality of function modules can be configured; wherein the individual sections are spaced apart from one another in such a manner, that a temperature and/or a voltage change in one of the sections has no influence on the other section or the other sections. The control/evaluation unit partially dynamically reconfigures the function modules in the measuring paths as a function of the particular defined safety-critical application, so that the field device fulfills the required safety standard.

Abstract: A touch-sensitive device includes a touch panel, a drive unit, a sense unit, and a measurement unit. A touch applied to a node of the panel changes a capacitive coupling between two electrodes (a drive electrode and a sense electrode) of the touch panel. The drive unit delivers a drive signal, which may comprise one or more drive pulses, to the drive electrode. The sense unit couples to the sense electrode, and generates a response signal that that is used to accumulate charge in a charge accumulator to provide an accumulated signal. The accumulated signal is responsive to the capacitive coupling between the electrodes, and is measured to provide an indication of a touch at the node.

Abstract: The disclosure comprises: linking a first terminal of the capacitance to the mid-point of a first voltage divider bridge, applying a first voltage to a second terminal of the capacitance, maintaining a voltage of a mid-point of the first divider bridge near a reference voltage, and discharging a mid-point of a second divider bridge with a constant current. When a voltage of the mid-point of the second bridge reaches a first voltage threshold, applying a second voltage to the second terminal of the capacitance, and measuring the time for the voltage to reach a second threshold.

Abstract: The disclosure relates to a method for characterizing or measuring a capacitance, comprising: linking the capacitance to a first mid-point of a first capacitive divider bridge, applying to the divider bridge a bias voltage, maintaining the voltage of the first mid-point near a reference voltage, discharging a second mid-point of a second divider bridge in parallel with the first by means of a constant current, and measuring the time for a voltage of the second mid-point to become equal to the voltage of the first mid-point. The disclosure may be applied in particular to the control of a touch screen display.

Abstract: A circuit arrangement for determining a temporal change of an output voltage of a half-bridge circuit during a dead time. In one embodiment, the circuit arrangement includes a first input for applying the output voltage. A capacitive network is provided having a first and a second circuit node capacitively coupled to the input, and having a terminal for a reference potential. A recharging circuit is configured, during the switched-on phase of one of a first and second switching elements, to adjust electrical potentials of the first and second nodes, the electrical potentials each being different from the reference potential. A comparator arrangement is provided that is configured during the dead time to determine a time difference between such times at which the electrical potentials at the first and second node each assume a given potential value, the time difference being a measure for the change with time of the output voltage.

Abstract: An apparatus for optimizing a Wheatstone bridge robust in a temperature change, the apparatus including; a voltage difference measuring unit which measures a voltage difference between a current input end and a current output end of the Wheatstone bridge, wherein the Wheatstone bridge comprises a first resistor, a second resistor, a third resistor and a fourth resistor and a tuning resistor; and a resistance tuning controller which detects a resistance ratio of a first distribution resistance and a second distribution resistance of the tuning resistor so that the voltage difference measuring unit measures a maximum voltage difference, and controls tuning of the tuning resistor according to the detected resistance ratio.

Abstract: A transducer, including: a housing; a bridge sensor circuit disposed within the housing and including at least one micro electro-mechanical systems (MEMS) sensing elements and first and second output ports; circuitry disposed within the housing; and an input/output (I/O) line electrically connected to the circuitry, accessible at an exterior of the housing, and adapted for receipt of input voltage or current. The circuitry is for generating a single data signal that combines respective outputs of the first and second output ports, and transmitting the DC-coupled single data signal on the I/O line. The circuitry is for generating and transmitting to the bridge sensor circuit an excitation current or voltage using the input voltage or current.

Abstract: A transmission line impedance compensation method includes the step of providing a measurement device that is adapted to source a test signal having a frequency to a device under test and to determine a corresponding impedance of the device under test using an auto-balanced bridge technique. A first transmission line, a second transmission line, a third transmission line, and a fourth transmission line are connected to said measurement device. An end of the first transmission line is connected to an end of second transmission line. An end of third transmission line is connected to an end of fourth transmission line. A combined phase delay of the connected first and second transmission lines, and a combined phase delay of the connected third and fourth transmission lines, are measured by the measuring device. The device under test is connected to the first transmission line, the second transmission line, the third transmission line, and the fourth transmission line after measuring the phase delays.

Abstract: A measuring bridge arrangement has a measuring bridge with a first supply terminal and first and second measuring signal terminals. The measuring bridge arrangement has a working point adjustment circuit formed to feed the measuring bridge via at least the first supply terminal in a measuring state of operation, and to apply a signal to one of the measuring signal terminals in the test state of operation in order to bring the measuring bridge to a test working point different from a measuring working point in the measuring state of operation. The measuring bridge has a test tap, wherein a test signal dependent on resistive properties of at least one element of the measuring bridge can be tapped at the test tap of the measuring bridge.

Abstract: A pressure sensing apparatus including: at least one deflectable diaphragm having a center, wherein each diaphragm supports: at least one positive piezoresistive gauge and at least one negative piezoresistive gauge coupled in series across a voltage differential in a half-Wheatstone bridge configuration having an output between the positive and negative piezoresistive gauges; and, a compensating piezoresistive gauge coupled in series with the half-Wheatstone bridge configuration across the voltage differential; wherein, the compensating piezoresistive gauge is nearer the center of the diaphragm than the negative piezoresitive gauge, the negative piezoresitive gauge is nearer the center of the diaphragm than the positive piezoresitive gauge, and the compensating piezoresistive gauge linearizes the half-Wheatstone bridge output.

Abstract: An air flow sensor includes a sensor element and a microcontroller, employing a PWM signal to drive the sensor element. Signals from the sensor element are processed by the microcontroller inside the sensor, resulting in continuous readings of air velocity and air temperature.

Abstract: An air flow sensor includes a sensor element and a microcontroller, employing a PWM signal to drive the sensor element. Signals from the sensor element are processed by the microcontroller inside the sensor, resulting in continuous readings of air velocity and air temperature.

Abstract: A vacuum gauge of the Pirani type for measuring the pressure of vaporized organic or inorganic material used in forming a layer of a device, comprising: an extended filament having a thickness of 5 microns or less and having a temperature coefficient of resistance greater than 0.0035/° C., the filament being subject to the vaporized organic or inorganic material; means for applying a current to the filament so that the temperature of the filament is less than 650° C. so as not to degrade the molecular structure of the organic material; and a structure responsive to a change in resistance or a change in current to determine heat loss from the filament, which is a function of the pressure of the vaporized organic or inorganic material.

Abstract: An RF bridge circuit without a balun transformer. The RF bridge circuit may include a resistive bridge and a differential detector. The resistive bridge may generate a differential signal that is indicative of a differential imbalance across the resistive bridge. Specifically, the differential signal may be indicative of the ratio of the impedance associated with a DUT and the impedance associated with a reference device. The differential detector may be connected directly to the resistive bridge and may sense the differential signal. The differential detector may convert the differential signal into a differential or single-ended IF signal. The RF bridge circuit may process the differential signal without the use of a balun transformer. The differential detector may include a balanced differential mixer, such as a diode ring, a FET quad, a Gilbert cell, and a harmonic mixer. Alternatively, the differential detector may include a balanced differential sampler, such as a harmonic sampler and a sampling bridge.

Abstract: A directional bridge for measuring propagated signals to and from a source device to a load device where both the source device and load device are in signal communication with the directional bridge is disclosed. The directional bridge may include a first bridge circuit network and a first sensing element in signal communication with the first bridge circuit network. The first sensing element may produce a first measured signal that is proportional to the propagated signals.

Abstract: A method for finding the impedance of a device under test using an impedance measuring apparatus having a modem-type auto-balancing bridge, two or more measurement signals, each of which has a different phase with respect to the reference signals supplied to the modem inside said auto-balancing bridge, are applied to a device under test; the impedance of this device under test is measured when each of the measurement signals is applied to the device under test; and the impedance of this device under test is found using the above-mentioned phase and the impedance measurement value of each of these measurements.

Abstract: A bridge sensor emulator includes a first emulation circuit programmable to emulate an output signal of the bridge circuit under 11 conditions each including a different combination of applied stimulus and temperature. A second emulation circuit is programmable to emulate the temperature-sensing device for 3 temperatures. An excitation signal is applied to the first emulation circuit. One rotary switch is coupled to the first emulation circuit to select from it and emulate a bridge output signal. An emulated common mode sensor output voltage is also generated. Another rotary switch is coupled to the second emulation circuit to select from it and emulate one of three temperature output signals. In another embodiment, a microcontroller, nonvolatile memory, and three digital to analog converters are utilized to emulate the bridge sensor for the 11 conditions.

Abstract: A pressure sensing apparatus including: at least one deflectable diaphragm having a center, wherein each diaphragm supports: at least one positive piezoresistive gauge and at least one negative piezoresistive gauge coupled in series across a voltage differential in a half-Wheatstone bridge configuration having an output between the positive and negative piezoresistive gauges; and, a compensating piezoresistive gauge coupled in series with the half-Wheatstone bridge configuration across the voltage differential; wherein, the compensating piezoresistive gauge is nearer the center of the diaphragm than the negative piezoresitive gauge, the negative piezoresitive gauge is nearer the center of the diaphragm than the positive piezoresitive gauge, and the compensating piezoresistive gauge linearizes the half-Wheatstone bridge output.

Abstract: A circuit for measuring the mass air flow rate through a duct is disclosed. The circuit includes a bridge circuit, a first amplifier, an oscillator, a comparator and a switch. The bridge circuit has a plurality of resistors arranged to output first and second bridge voltage signals. The first amplifier circuit receives the first and second bridge voltage signals and generates a differential bridge voltage signal. The oscillator provides an oscillating control signal. The comparator is in communication with the first amplifier circuit and the oscillator for comparing the differential bridge voltage signal to the oscillating signal to generate a pulse width modulated differential bridge voltage signal. The switch is in communication with the bridge circuit and the comparator. The switch selectively provides a power voltage signal to the bridge circuit at a frequency corresponding to the pulse width modulated differential bridge voltage signal.

Abstract: A bridge type phase detection device comprises one or more than one transformer, a plurality of tubes, a voltage-detecting protection circuit and a first, second and third impedance, wherein a first tube of said plurality of tubes has a phase opposite to that of a second tube of said plurality of tubes, and a first end of said first impedance coupling with a secondary side of said transformer and a first end of said first tube, a first end of said second impedance coupling with said secondary side of said transformer and a first end of said second tube, then a second end of said first impedance connecting to a second end of said second impedance to form a detection point, said detection point coupling with said third impedance and said voltage-detecting protection circuit; said detection point having a voltage value derived from calculating a sum of said phase of said first impedance and that of said second impedance, then an output voltage divided among said first, two and third impedance, resulting in appro

Abstract: An integrated circuit includes a first circuit component, a second circuit component, and an external terminal for making contact with the circuit. The first circuit component is connected to the external terminal via the second component. A bridging circuit connects the first circuit component to the external terminal and can be activated by a test mode signal. In the active state, the bridging circuit connects the external terminal to the first circuit component while bridging the second circuit component, while it is nonconducting in the deactivated state. Circuit components integrated in the semiconductor chip can be electrically measured nondestructively via activatable switches. Circuit components that lie between the external terminal and the device to be measured can be excluded from the measurement by bridging circuits. The method also makes it possible to measure a plurality of integrated devices in parallel or serially.

Abstract: In a method for detecting an offset drift in a resistive Wheatstone measuring bridge, a switch is made between a measuring mode and a testing mode without interfering in the internal structure of the measuring bridge. In testing mode, two sensor resistors that act in the same way and lie in different bridge arms in the measuring mode are connected in series, and a voltage level occurring in the connection of these sensor resistors is compared with a reference voltage. Preferably the sensor resistor that acts in a different way and lies between the two series-connected sensor resistors acting in the same way is bridged. The reference voltage is advantageously formed by resistive division of the voltage applied to the series connection of the sensor resistors. The testing mode may expediently be switched in such a way that the two pairs of sensor resistors acting in the same way are respectively tested in succession.

Abstract: In the method and circuit arrangement for offset correction of the measurement bridge, the full bridge signal and half bridge signal of the measuring bridge are measured; a self-adjustment of the half bridge signal path to an output signal of the full bridge signal bath is performed to adjust the half bridge signal to the full bridge signal for each measurement cycle between turn on and turn off of the measurement bridge; and an offset value of the half bridge signal path is determined at a time of turning on and the offset value is kept constant during a given measurement cycle.

Abstract: An output sensor apparatus, system, and method including a circuit having a plurality of bridge resistors and one or more connecting resistors coupled to the plurality of bridge resistors. Additionally, a programmable amplifier can be coupled to the connecting resistor, wherein the circuit produces an output signal that changes in a manner similar to that of an output of a Wheatstone bridge circuit sensor. Thus, a circuit can be provided, which can be effortlessly added to a readily available programmable integrated circuit (IC) chip.

Abstract: An impedance measuring apparatus comprising an automatic balanced bridge has four numerically controlled oscillators that supply sine-wave signals and cosine-wave signals to the quadrature detector and vector modulator of the narrow-band amplifier inside the automatic balanced bridge. The frequency or phase of the output signals of the four numerically controlled oscillators are updated by numeric control from the outside. The four numerically controlled oscillators of the impedance measuring apparatus are oscillators whose frequency or phase is changed a pre-determined time after they have been controlled from the outside. Furthermore, the impedance measuring apparatus has control means with which the change in the frequency or the phase of the output signals of the four numerically controlled oscillators is synchronized.

Abstract: A sensing device of the present invention includes a first resistive branch having first and second resistors connected in series, a second resistive branch comprising third and fourth resistors connected in series and arranged in parallel with the first resistive branch to form a bridge circuit, first and second feed wiring arrangements connecting the first and second resistive branches to a power source side, respectively, in parallel to each other, and a ground wiring arrangement connecting the first and second resistive branches to a ground side.

Abstract: An ASIC (14, 14′, 14″) conditions two independent outputs (VINM, VINP) of a full Wheatstone piezoresistive bridge (12) in separate conditioning paths. Each path is provided with a bridge supply voltage (VHB1, VHB2) which can serve as a temperature related input signal to respective offset and gain compensation control circuits. The half bridge outputs are inputted to respective amplifiers (U1, U2) along with a selected percentage of the temperature dependent bridge supply voltage. The outputs of the amplifiers provide a signal proportional to respective half bridge output voltage. In one embodiment, the output of the amplifier (U2) in one conditioning path of one half bridge is connected to the input of an amplifier (U4) in the other conditioning path to provide a signal in the one path proportional to the Wheatstone bridge differential output voltage and in the other path a signal proportional to the Wheatstone half bridge output voltage.

Abstract: A thermal conduction vacuum gauge using a Peltier tip is provided. The vacuum gauge for measuring the pressure in a vacuum chamber includes: a signal generator that drives an electric current; an ammeter connected to the signal generator for measuring the current; a bridge circuit consisting of junctions of thermocouple wires, which is connected to the ammeter, wherein one junction of the dissimilar metallic wires is made in the form of a Peltier tip inserted into the vacuum chamber; and a lock-in amplifier connected to the two symmetrical points of the bridge circuit for detecting a voltage signal due to the temperature oscillation at the Peltier tip and thus measuring the pressure in the vacuum chamber.

Abstract: A full Wheatstone bridge sensor has conditioning electronics of an ASIC connected thereto. Two independently controlled diagnostic switches (S1, S2) in the ASIC are commonly connected to one of the bridge output nodes. The first diagnostic switch connects first resistor between the bridge output node and bridge supply voltage and the second diagnostic switch connects a second resistor between the bridge output and bridge ground. The first diagnostic switch closes during a first diagnostic waveform phase and opens during all other phases of operation. The second diagnostic switch closes during a second and third waveform phase and opens during all other phases of operation. The diagnostic waveforms are used to test major signal conditioning and fault reporting paths of the ASIC.

Abstract: A sensor output processing device has an amplifier circuit for amplifying a sensor output signal of a sensor and a buffer circuit for limiting the amplified signal to a high limit level lower than a high side voltage of a power source or a low limit level higher than a low side voltage of the power source. This limited signal is normally produced as an output signal to an external circuit. When a self-diagnosis circuit determines an abnormality in the sensor or in the amplifier circuit and the buffer circuit, the output signal is fixed to a level higher than the high limit level or lower than the low limit level.

Abstract: A radio frequency bridge, useful for measuring complex values of an unknown impedance or associated complex reflection coefficient and VSWR value, which comprises an rf source, a novel asymmetrical bridge, a measuring device (comprising two logarithmic amplifiers, a difference amplifier and a phase detector), a computing device and a display or interface device. The complex impedance may be any two terminals of a general N-port network not to exclude an antenna with or without feed-line. The invention is more accurate than prior art when measuring complex impedance values having magnitudes from approximately five ohms to an upper value limited only by the dynamic range of the logarithmic amplifiers, normally greater than 4000 ohms. It has the great advantage of maintaining constant measuring accuracy over a wide measuring range and can be designed to operate over very wide bandwidths.

Abstract: A thermal conduction vacuum gauge using a Peltier tip is provided. The vacuum gauge for measuring the pressure in a vacuum chamber includes: a signal generator that drives an electric current; an ammeter connected to the signal generator for measuring the current; a bridge circuit consisting of junctions of thermocouple wires, which is connected to the ammeter, wherein one junction of the dissimilar metallic wires is made in the form of a Peltier tip inserted into the vacuum chamber; and a lock-in amplifier connected to the two symmetrical points of the bridge circuit for detecting a voltage signal due to the temperature oscillation at the Peltier tip and thus measuring the pressure in the vacuum chamber.

Abstract: A junction field effect transistor (JFET) RF oscillator-detector circuit generates an RF signal for an apparatus for conducting electrical measurements of particles contained in a carrier fluid passing through an aperture in a cytometer flow cell. The JFET oscillator includes a plurality of parallel-coupled JFETs having respectively different VDS vs. IDS characteristics, that are biased to operate at square law detection regions of their respective VDS vs. IDS characteristics. One JFET operates in Class C mode, while the other operates in Class AB mode. An RF resonant circuit is electrically coupled to the JFETs and to the measurement cell, and is operative to establish the frequency of an RF field applied to the measurement cell. An RF load change detection circuit is coupled to the RF resonator circuit and is operative to detect an RF load change associated with a modification of the RF field as a result of a particle within the measurement cell aperture.

Abstract: An in-range fault detection system for a full wheatstone bridge element (12) having piezoresistive elements (R1, R2, R3, R4) has bridge outputs (INP, INM) connected to measuring means in the form of a first circuit portion (13) to provide a common mode voltage (VCM). A second circuit portion (14) is used to provide a centering voltage (C*VBRG) equal to the common mode voltage at the time of sensor calibration and a third circuit portion (15) is used to provide a small window voltage (W*VBRG) which is a fraction of bridge voltage. The value (W*VBRG) is subtracted from (C*VBRG) at a first summing circuit (SUM1) and added to (C*VBRG) at a second summing circuit (SUM2) and the results are each compared to the common mode voltage by comparators (Q1, Q2) which are then determined to be within or without a window of valid values by an OR gate (Q3).

Abstract: A magnetic oxygen analyzer which employes a detector comprising a magnetic pole, heat generator arranged in a non-uniform magnetic field where the intensity of a magnetic field produced by the magnetic pole varies, and a magnetic wind sensor disposed to not be affected by heat produced by the heat generator. A change in electrical resistance of the sensor, caused by change in magnetic wind strength, is detected as the oxygen concentration of a mixed gas. The magnetic wind is caused by the magnetic field produced by the magnetic pole and by heat produced by the heater and is related to the oxygen concentration of the mixed gas exposed to the analyzer. Advantageously, the analyzer of the invention provides improved signal to noise ratio, is immune to ambient temperature, and eliminates the need for precise temperature control.

Abstract: A junction field effect transistor (JFET) RF oscillator-detector circuit generates an RF signal for an apparatus for conducting electrical measurements of particles contained in a carrier fluid passing through an aperture in a cytometer flow cell. The JFET oscillator includes a plurality of parallel-coupled JFETs having respectively different VDS vs. IDS characteristics, that are biased to operate at square law detection regions of their respective VDS vs. IDS characteristics. One JFET operates in Class C mode, while the other operates in Class AB mode. An RF resonant circuit is electrically coupled to the JFETs and to the measurement cell, and is operative to establish the frequency of an RF field applied to the measurement cell. An RF load change detection circuit is coupled to the RF resonator circuit and is operative to detect an RF load change associated with a modification of the RF field as a result of a particle within the measurement cell aperture.

Abstract: A combustible gas detector or sensor having catalytic coated resistance sensing elements that uses a wheatstone bridge to sense the presence and concentration of any combustible gases in a gas stream that chemically react with such catalytic coatings. Wherein there is a power supply node electrically coupling one end of a first and second bridge of the wheatstone bridge. There is a ground node electrically coupling the first and second bridge at another end. There is a first and second metered node located on the first and second bridge respectively. There is a first catalytic sensor element, located on the first bridge between the power node and first metered node. There is a second catalytic sensor element, located on the second bridge between the ground node and second metered node. There is a first reference sensor element, located on the first bridge and in series with the first catalytic sensor element, and coupled between the first metered node and the ground node.

Abstract: The circuit for feeding a Wheatstone Bridge (DMS 1 . . . DMS 4) with a rectangular waveform alternating voltage which is derived from a single DC reference voltage, consists of a first operational amplifier (V 1) whose positive input is connected to the DC reference voltage and whose negative input is connected via the switches (S 5 and S 6) alternately to the one (A) or to the other (B) feed point of the bridge, and a second operational amplifier (V 2) whose positive input is connected to ground potential and whose negative input is connected to one measuring input (C) of the bridge. The outputs of the two operational amplifiers (V 1 and V 2) are connected via the switches (S 1 . . . S 4) alternately to the one (A) and to the other (B) feed point of the bridge, and the output signal is taken off at the second measuring output (D) of the bridge.