Abstract: The present invention provides a method for testing performance of thin-film encapsulation. Through different combination designs of film layers, lateral water vapor intrusion paths of various thin films or encapsulation structures are formed, thereby obtaining a means to inspect a lateral water vapor and oxygen barrier capacity of thin films and provide a highly effective inspection means for encapsulation of display panels.

Abstract: A magnetoresistive Wheatstone bridge includes two bridge branches connected in parallel between a supply potential Vb, wherein two series-connected resistor arrangements R1 and R3 or R2 and R4 are arranged in each bridge branch with an interposed measuring potential Vout. The resistor arrangements of the two bridge branches are situated diagonally opposite one another and at least two magnetoresistive resistor arrangements have a magnetically sensitive preferred direction. The preferred directions of diagonally opposing resistor arrangements of the bridge branches R1 and R4 or R2 and R3 differ by an angle other than 0° or 180°. An angle sensor includes at least two of the Wheatstone bridges offset by a predefined angle for determining an angular orientation of a magnetic field by a sine bridge and a cosine bridge. The measuring bridge reduces harmonics and optimizes resistance values, improving the accuracy of a phase-angle sensor signal and the sensor resolution.

Abstract: A control method of measuring an internal resistance of an electric power accumulator 19 of a hybrid-type construction machine 100 comprises: a pattern generating step of generating an internal resistance measurement pattern in a non-operation status in which there is no operation for the hybrid-type construction machine from an operator; an output changing step of changing an output of a generator 12 based on the pattern generated in the pattern generating step in the non-operation status; an electric current, etc., detecting step of detecting electric current values and voltage values in the electric power accumulator 19 before and after the change of the output of the generator 12 in the output changing step; and an internal resistance measuring step of measuring the internal resistance of the electric power accumulator 19 based on the electric current values and the voltage values detected before and after the change of the output of the generator 12 in the electric current, etc., detecting step.

Abstract: Methods and structures are described for determining contact resistivities and Schottky barrier heights for conductors deposited on semiconductor wafers that can be combined with combinatorial processing, allowing thereby numerous processing conditions and materials to be tested concurrently. Methods for using multi-ring as well as single-ring CTLM structures to cancel parasitic resistance are also described, as well as structures and processes for inline monitoring of properties.

Abstract: A diagnostic method and system is described for diagnosing an operating condition of a conductive particulate matter sensor. The sensor has a substrate with electrical resistance that varies with temperature and two electrodes on the substrate adapted to collect particulate matter between the electrodes, thereby establishing an electrically conductive path through collected particulate matter between the electrodes that can be detected by measuring electrical resistance between the electrodes, Relect. The diagnosis is performed by heating the substrate in the area between the electrodes and using the resistance between the electrodes to determine detecting whether contamination is present on the surface of the sensor. Heat may be maintained on the sensor to attempt to burn off a detected contaminant, and a subsequent resistance reading may be used to determine if the contaminant was successfully burned off.

Abstract: Systems and methods for compensated barrier permeability testing are provided. In one embodiment, a method for testing water vapor penetration through a barrier material comprises: obtaining a first series of resistance measurements from a first moisture sensor located on a substrate surface of a test card, wherein the first moisture sensor is exposed to a testing chamber sealed onto the substrate surface of the test card; obtaining a second series of resistance measurements from a second moisture sensor, wherein the second moisture sensor is isolated from the testing chamber, wherein the testing chamber is defined by a cavity within a spacer element that separates the first moisture sensor from a test barrier; and determining a measurement of water vapor penetration through the test barrier by adjusting the first series of resistance measurement based on the second series of resistance measurement.

Abstract: Methods and structures are described for determining contact resistivities and Schottky barrier heights for conductors deposited on semiconductor wafers that can be combined with combinatorial processing, allowing thereby numerous processing conditions and materials to be tested concurrently. Methods for using multi-ring as well as single-ring CTLM structures to cancel parasitic resistance are also described, as well as structures and processes for inline monitoring of properties.

Abstract: A readout apparatus and a driving method for sensor are provided. The readout apparatus includes an adjustable bias unit, a sensor unit, a signal converting unit, a checking unit and a control unit. The sensor unit senses physical energy and outputs a sensing result by using a bias voltage outputted from the adjustable bias unit. The control unit controls the adjustable bias unit according to the sensing result, so as to adjust the bias voltage. Therefore, the readout apparatus can reduce continuous power loss caused by long-term detection.

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: Provided is a current sensing signal comparing device and current sensing signal comparing method. The current sensing signal comparing device includes a current sensing circuit for detecting a current signal of a switching circuit and thereby generating a current sensing signal, a control unit for outputting a control signal, and a compensating circuit for compensating the current sensing signal according to the control signal. The compensated current sensing signal is compared with a constant current reference signal in order to issue a constant current control signal. The device can also be provided to configure the compensating circuit to compensate the constant current reference signal, such that the current sensing signal is compared with the compensated constant current reference signal in order to issue a constant current control signal.

Abstract: A method of measuring resistance in each of a plurality of resistors in a resistor matrix is provided. Each resistor is located at a different intersection between a column conductor and a row conductor. The, the method includes determining an offset error row current of each row conductor, scanning each row conductor to identify if that row conductor is connected to a column conductor by one of the plurality of resistors, if that row conductor is connected to a column conductor by one of the plurality of resistors, scanning each resistor connected to that row conductor to determining if that resistor is connecting a column conductor to that row conductor, and if that resistor is connecting a column conductor to that row conductor, outputting an offset compensated resistance of that resistor calculated from the row current measured for that resistor less the offset error row current for that row conductor.

Abstract: A diagnostic method and system is described for diagnosing an operating condition of a conductive particulate matter sensor. The sensor has a substrate and two electrodes on the substrate adapted to collect particulate matter between the electrodes, thereby establishing an electrically conductive path through collected particulate matter between the electrodes that can be detected by measuring electrical resistance between the electrodes, Relect. The diagnosis is performed by detecting whether water vapor condensate may be present between the electrodes and if it is, then measuring resistance between the electrodes while subjecting the sensor to conditions sufficient to evaporate any water vapor condensate and diagnosing a validation that the sensor is in proper operating condition if resistance increases in a manner consistent with evaporation of condensate.

Abstract: A control method of measuring an internal resistance of an electric power accumulator 19 of a hybrid-type construction machine 100 comprises: a pattern generating step of generating an internal resistance measurement pattern in a non-operation status in which there is no operation for the hybrid-type construction machine from an operator; an output changing step of changing an output of a generator 12 based on the pattern generated in the pattern generating step in the non-operation status; an electric current, etc., detecting step of detecting electric current values and voltage values in the electric power accumulator 19 before and after the change of the output of the generator 12 in the output changing step; and an internal resistance measuring step of measuring the internal resistance of the electric power accumulator 19 based on the electric current values and the voltage values detected before and after the change of the output of the generator 12 in the electric current, etc., detecting step.

Abstract: Subsystems and methods for use in patch clamp systems are provided. For example, in certain embodiments, compensation circuitry is used to compensate for non-idealities present in the patch clamp system. The accuracy of this compensation may be verified by employing, for example, circuitry that models the patch clamp system.

Abstract: A semiconductor integrated circuit (IC) acts as a controller of a heating-controlled device or appliance. A heating body has a positive temperature coefficient and acts as both a heating element and a temperature sensor. A Silicon-Controlled Rectifier (SCR) switches AC current to the heating body to increase its temperature. When the SCR switches off, temperature sensing is performed using a sampling resistor, isolation diode, voltage comparator, and switch for a low-voltage DC supply are formed on an integrated circuit that has a first circuit branch and a second circuit branch. A compensation diode and a compensation resistor can be added in parallel to reference resistors. The compensation diode compensates for the forward voltage drop of the isolation diode that would otherwise create an inaccurate temperature measurement. The diodes have the same temperature response, allowing for a more accurate temperature measurement over a full temperature range of the sensorless appliance.

Abstract: In some embodiments, the arrangement includes a sense element to convey a current from a source to a load and a compensation element located proximate to the sense element. The compensation element has a resistance that changes proportional to a change in temperature of the sense element. In several embodiments, the arrangement further includes an operational amplifier having a first input connected to the sense element, a second input connected to the compensation element and an output that provides an output signal that biases a current through the compensation element in response to a voltage across the sense element. In such embodiments, the bias current provides an output signal proportional to the conveyed current and the compensation element provides temperature compensation for the output signal. Other embodiments are also disclosed.

Abstract: In one embodiment, a method for detecting contaminants in a liquid comprises: contacting a sensor with a liquid, generating electrical information based upon a concentration of the contaminant in the liquid, transmitting the electrical information to a controller, and determining the concentration of a contaminant in the liquid. The sensor can comprise a film, a purge chamber, and a transducer, which are configured such that a first surface of the film is in fluid communication with the liquid and the purge chamber is in fluid communication with a second surface of the film that is opposite the first surface, and wherein the transducer is in fluid communication with the purge chamber.

Abstract: A structure and method for monitoring extrusion failures. The structure includes: a test wire having first and second ends; first and second vias contacting first and second ends of the test wire; a first monitor structure electrically isolated from the test wire and surrounding a periphery of the test wire; and a second monitor structure over the test wire, the second monitor structure electrically isolated from the test wire, the second monitor structure extending over at least the first end of the test wire.

Abstract: A resistance compensation circuit and a method thereof for tuning frequency, includes several resistors serially connected to one another, several transistors, each of which connects across one of the corresponding resistances, and a register electrically connected to the gates of the transistors. A control signal controls the switching of the transistors either to compensate the process variation of the resistance through the register or to tune the working frequency of the Integrated circuit.

Abstract: A method for improved cable resistance measuring is provided including coupling a measurement test device including a master unit and a remote unit, via at least one connector, to at least one network cable and determining a terminating impedance using field calibration. The method additionally including transmitting an AC signal across the network cable for determining a resistance of the network cable, and measuring a length of the network cable. The method still further including measuring a capacitance of the network cable, and measuring an impedance of the network cable terminated by the measurement test device. The method additionally including extracting the resistance of the network cable from the impedance measurement, and correcting for error in at least one of capacitance, termination resistance, and nominal cable effects for a corrected resistance value.

Abstract: A sensing system, comprising: a sensing assembly, the sensing assembly having: a trim resistor integrally formed with the sensing assembly, the trim resistor having a resistance value; a first sensing element for providing a first signal in response to a first sensed condition; a second sensing element for providing a second signal in response to a second sensed condition; and a controller removably secured to the sensing assembly and receiving the first signal and the second signal, the controller being configured to determine the resistance value of the trim resistor; a database associated with the controller, the database having a plurality of resistance values, each resistance value in the database identifies a pair of compensation values; a microprocessor associated with the controller, the microprocessor receiving the resistance value of the trim resistor, the first signal and the second signal, the resistance value of the trim resistor being used to define a selected pair of compensation values from th

Abstract: A resistance compensation circuit and a method thereof for tuning frequency, includes several resistors serially connected to one another, several transistors, each of which connects across one of the corresponding resistances, and a register electrically connected to the gates of the transistors. A control signal controls the switching of the transistors either to compensate the process variation of the resistance through the register or to tune the working frequency of the Integrated circuit.

Abstract: A chemiresistor sensor system that compensates for changes in resistance caused by changes in ambient temperature, thereby increasing the accuracy of the sensor system's ability to detect target analytes. The sensor system generally includes a first resistor, a second resistor, and a load regulator or switch that is sensitive to changes in ambient temperature. At least one of the first resistor and the second resistor is a sensing element having a resistance that changes in response to the presence of one or more of the analytes. The switch manages an electrical load across the first resistor and the second resistor. The switch prevents passage of the electrical load across the first and/or second resistor when the ambient temperature is at a first value. The switch permits passage of the electrical load across the first and/or second resistor when the ambient temperature is at a second value.

Abstract: A range resistor, for deployment with a low voltage AC measuring instrument as a voltage range multiplying attenuator, provides increased accuracy in the measurement of high AC voltages at frequencies up to 1 MHz, particularly when large attenuation ratios are needed. Passive guarding and neutralizing structure permits the use of higher value resistors for a given frequency response accuracy and an intrinsically lower input capacitance than is obtainable with conventional structure. Very low drift and voltage coefficients are achieved by a coordinated thermal design. Applications include high accuracy voltage measurement in the 10 to 1000 volt range with low input signal current when attenuation is resistively scaled to match the operating input level of the measuring device to be used, typically a thermocouple and/or digital or analog precision voltmeter.

Abstract: A digital eddy current proximity system including a digital impedance measuring device for digitally measuring the proximity probes impedance correlative to displacement motion and position of a metallic target object being monitored. The system further including a cable-length calibration method, an automatic material identification and calibration method, a material insensitive method, an inductive ratio method and advanced sensing characteristics.

Abstract: A voltage probe includes a first signal lead configured to receive a first signal from a device under test, a first probe-tip network that is coupled to the first signal lead and that has a frequency response that includes a first transmission zero, a first compensation network that is coupled to the first probe-tip network and that has a frequency response that includes a first transmission pole, a second signal lead configured to receive a second signal from the device under test, a second probe-tip network that is coupled to the second signal lead and that has a frequency response that includes a second transmission zero, a second compensation network that is coupled to the second probe-tip network and that has a frequency response that includes a second transmission pole, and a differential amplifier circuit that is coupled to the first compensation network and to the second compensation network, and that is configured to provide a third signal that is responsive to the first signal and to the second sign

Abstract: A system and method for measuring the alternating current series resistance of a conductor when transporting large currents on the order of several thousand amperes. The system comprises a current sensor, a current/voltage converter, a voltage divider, a voltage sensor, a null indicator, and a voltage meter. The alternating current series resistance is measured by measuring a real component of a voltage drop over a predetermined length of the conductor, deriving a measurement current from the conductor, converting the measurement current into a measurement voltage, withdrawing an adjustable portion of voltage from the measurement voltage, comparing the adjustable portion of voltage with the voltage drop, adjusting the adjustable portion of voltage to balance the voltage drop, measuring the alternating current, and determining the resistance of the conductor as a function of the value of the adjustable portion of voltage that balances the voltage drop and the measured alternating current.

Abstract: A system (20, 30, 40, 50) and method for canceling a leakage current is provided that uses line voltages (L1, L2) that are out of phase with each other to produce a counter leakage potential that cancels leakage current. In one embodiment of the invention, the actual potential of the phases is measured (42, 52, 54) and used to determine the counter potential that is to be applied to the line voltage (L1 or L2) that is generating the leakage current. The counter potential is applied to the appropriate line voltage by way of a transistor circuit (Q1, Q2). The transistor circuit (Q1, Q2) is controlled through standard electronic circuitry (28), or by way of a microprocessor device (32).

Abstract: Apparatus and method to identify chafing of a conduit, thereby reducing the failure of any system which would be damaged or whose function would be impaired by abrasion of the conduit. Such a system may carry electrical power, fuel, other fluid, hydraulics, pneumatics, optical, or electromagnetic signals. Wear caused by rubbing against external structures is detected by wrapping the conduit with a sensing element, which may be a conductive wire, waveguide, fiber optic cable, or a tube (wound around the conduit or enclosing it) that holds a fluid under pressure. The sensing element is positioned so that chafing on the conduit electrically contacts, breaks, or punctures the sensing element well before the conduit fails.

Abstract: The output voltage of a Wheatstone bridge type electrical circuit compris four main resistances (J.sub.1 to J.sub.4) having substantially the same ohmic value, R, and substantially the same temperature coefficient of resistance, .alpha., is made independent of temperature differences existing between the branches of the bridge by addition, in each of the branches, of a compensation element (r.sub.1 to r.sub.4) in series with the main resistance, each compensation element being physically located very close to a main resistance situated in one of the adjacent branches of the bridge so as to have the same temperature as that main resistance. The compensation elements have the same ohmic value r and the same temperature coefficient of resistance .beta., with R.alpha.=r.beta., r being less than R and, preferably, r/R.ltoreq.1/2, so as to limit the loss of sensitivity of the Wheatstone bridge to variations in the resistances of the bridge.

Abstract: A power supply voltage (Vcc) is applied to a dummy capacitor having a capacitance identical to that of a bypass capacitor to generate an excessive current. The excessive current is subtracted from a current flowing through an IC and the bypass capacitor to obtain a power supply current (Icc) of the IC. The time required for measuring power supply current (Icc) of the IC is reduced since it is not necessary to wait for attenuation of the excessive current of the bypass capacitor.

Abstract: The invention consists of a system to compensate for the parasitic signal induced by a parasitic impedance in the signal path. An auxiliary signal, outside of the frequency band of the desired signal, is introduced to evaluate the effects of the parasitic impedance. A compensating signal is then generated by simulating the effects of the parasitic impedance on the desired signal. Those simulated effects are then superimposed over the normal signal path with a phase adjusted to eliminate the effects of the parasitic impedance on the total resulting signal.

Abstract: A circuit arrangement for air quality measuring having at least one sensor element which has resistors the resistance of which changes depending on the air composition. The circuit arrangement has an evaluation circuit for the sensor signals and includes a logarithmic circuit.

Abstract: Sensing apparatus is disclosed which allows for the determination of the presence, absence or percentage of a conducting medium such as water, by electronic means. The inventive apparatus negates the effect of a false signal generated by contamination of the sensing apparatus. The inventive sensor comprises three or more sensing members attached to a non-conducting substrate with electronically significant distances between pairs of sensing members. An appropriate electrical circuit is connected to the sensing members which converts signals output from the pairs of sensing members into readings which indicate the presence or absence of a conducting medium, notwithstanding the presence or absence of contamination between the sensing members.

Abstract: The apparatus includes a first transmitter for transmitting a first test signal from a first end of the cable and a second transmitter for transmitting a second test signal from a second end of the cable. The first test signal is transmitted on a first conductor pair at a first frequency and the second test signal is simultaneously transmitted on a second conductor pair at a second frequency. The apparatus also includes a first receiver for receiving a first coupled signal at the first end of the cable and a second receiver for simultaneously receiving a second coupled signal at the second end of the cable. The first coupled signal exhibits the first frequency and is received on a third conductor pair, while the second coupled signal exhibits the second frequency and is received on a fourth conductor pair. The transmit frequencies are offset such that interference and noise are not detected by the receivers as coupled signals.

Abstract: A differential voltage monitor is shown using a resistive bridge to produce a sample value representing that differential voltage. A portion of the resistive bridge is located on an IC and a portion is external to the IC. The object is to compare the differential voltage with a reference, producing a logic signal at a threshold level. The threshold level serving as a reference and the sample valve representing the differential voltage are made to be equally dependent on the bridge components located on the IC. In this way, any changes in the IC located bridge resistors compared to the bridge resistors located outside the IC are prevented from affecting the measurement.

Abstract: A system for testing the integrity of critical circuitry, lines and wires employs a differential amplifier having an input resistance R.sub.in and a feedback loop with a resistance R.sub.fb. The critical wires being tested must be a signal wire series connected to a resistance R.sub.S, which is in turn series connected to a return wire. A test voltage source is connected to the noninverting input of the differential amplifier. The signal wire is connected to the inverting input of the differential amplifier. The test voltage source is activated by a test control unit. When activated, the test voltage source provides two distinct outputs allowing computation of a test gain in the presence of other functional signals. The test control unit measures the output V.sub.out of the differential amplifier and computes the value of the test gain. A break in either the signal wire or the return wire will result in a test gain of 1. If the signal and return wires are shorted, the test gain will be 1+R.sub.fb /R.sub.in.

Abstract: A measuring circuit obtains desired characteristic values of a device under test by accurately measuring a voltage and a current. Errors are eliminated that originate from the transmission characteristics of cables used in measurements at high frequencies and measurements using long cables. The errors are eliminated by connecting resistors that are equal in resistance to the characteristic impedance of cables, to the inputs of the cables which connect the device under test to a measuring device.

Abstract: Apparatus to measure the crosstalk between pairs of conductors in a cable. The measurements are affected by the crosstalk inherent to the connectors that are part of the apparatus. The improvement consists of adding a compensating signal which equals that from the connector crosstalk in magnitude but has opposite sign.

Abstract: A circuit for generating a linear current proportional to the displacement of the movable member of a transducer receives an undetermined supply voltage from a monitoring circuit which has a relatively high internal resistance. The circuit is provided with two parallel current paths with one path including a resistive potentiometer strip and other path including a transistor and resistor connected in series. The movable member of the transducer has an electrical contact member attached thereto with the contact member having one end making contact with the resistive potentiometer strip and with the other end thereof making contact with a conductive strip which is connected to the gate of the transistor so that the current drawn by the circuit will be linearly related to the movement of the movable member.

Abstract: With a view to enabling errors in the space potential to be automatically corrected by detecting a floating potential in each of a plurality of probes and to remove the errors in measurement based on the corrected space potential to thereby realize the accurate measurement of the space potential, there is provided a triple-probe plasma measuring apparatus, which comprises: a circuit for measuring electron temperature and electron density of a plasma with use of triple probes; a circuit for detecting and holding a floating potential difference; a differential voltage adding circuit; a fixed voltage source; and a change-over switch, the apparatus being capable of determining a difference in the floating potentials at the position of said probes, and superimposing the potential difference determined on the fixed voltage.

Abstract: A device for adjusting sensor signals, and, in particular, signals supplied to a sensor for detecting an operating parameter of a motor vehicle having an internal combustion engine. The device has adjustment elements and a current divider, which includes at least one adjustable resistor and a second resistor, coupled in series with the sensor.

Abstract: An instrument and method for measuring chemical properties, the instrument having electrodes suitable for immersion in a chemical solution. A voltage source and a current-sensing circuit are connected to the electrodes to measure the current produced in the solution in response to a voltage applied to the electrodes to determine a value of the chemical in the solution. The instrument and method further include background compensation for offsetting the value of the analyte by an amount which is reflective of the background value of the solution. The background value is stored in an internal memory of the instrument so that when new experimental measurements are taken, the measurements are immediately offset by the background portion of the new experimental measurements. This allows operation of the instrument at high gain levels, resulting in a broad dynamic range and greater useful precision in the output signal.

Abstract: A humidity detection circuit includes a bridge circuit containing temperature sensing elements. The bridge circuit is connected in series to a current limiting resistance, a current controlling element and a power supply. There is a set of resistances arranged in parallel with the current limiting resistor and the bridge circuit. A voltage comparing circuit is operatively connected to the bridge circuit the current limiting resistance and the set of resistances. A control section is provided to detect the potential of a junction between the bridge circuit and the current limiting resistance. Based upon the detector potential, the humidity detection circuit changes resistance value of a resistor in the set to an optimal level so that temperature drift does not occur.

Abstract: A heater control device for an air-fuel ratio sensor which comprises: an air-fuel ratio sensor comprising a sensor element which detects an air-fuel ratio state of exhaust gas of an engine, and a heater which heats the sensor elements; a heater current flow control means for controlling a value of a resistance of the heater to be a target resistance value; a harness having a couple of couplers at both ends thereof which connects between the air-fuel ratio sensor and the heater current flow control means; and a current detecting resistance which is incorporated in the coupler on the air-fuel ratio sensor side, or provided adjacent to said coupler on the air-fuel ratio sensor side, and which is connected to the heater in series and detects current of the heater.

Abstract: A circuit element measuring apparatus for measuring a parameter of a device under test (DUT) includes a signal source, a voltmeter, a zero detection amplifier, and a compensation network all of which are coupled to the DUT by four shielded lines. The compensation network is also coupled to a range resistance. The compensation network provides two independent sets of correction data. One is based on the length of the shielded line and the other is based on the range resistance used. The parameter being measured can then be adjusted by the appropriate set of correction data to provide a more accurate measurement. A method of operating the circuit element measuring apparatus for measuring the parameter of the DUT by generating the two sets of correction data and adjusting the parameter accordingly.

Abstract: The arrangement serves to process sensor signals furnished by a sensor which when fed with a supply signal in response to the action of a physical measured quantity. The sensor generates a measuring effect representing the dependence of an electrical characteristic quantity on the physical measured quantity. The arrangement also includes a signal processing circuit which operates by the principle of quantized charge transport by means of switch-capacitor structures. The signal processing circuit establishes a charge balance by opposite integration of measuring charge packets dependent on the measuring effect and compensation charge packets independent of the measuring effect and furnishes an analog output signal corresponding to the integration result. The analog output signal also provides a feedback input to the sensor. By this feedback the analog output signal is regulated so that it is proportional to the measurement result.

Abstract: A heater control device for an air-fuel ratio sensor which comprises: an air-fuel ratio sensor comprising a sensor element which detects an air-fuel ratio state of exhaust gas of an engine, and a heater which heats the sensor elements; a heater current flow control means for controlling a value of a resistance of the heater to be a target resistance value; a harness having a couple of couplers at both ends thereof which connects between the air-fuel ratio sensor and the heater current flow control means; and a current detecting resistance which is incorporated in the coupler on the air-fuel ratio sensor side, or provided adjacent to said coupler on the air-fuel ratio sensor side, and which is connected to the heater in series and detects current of the heater.

Abstract: A precision bridge measurement circuit connected to a current source providing a linear output voltage versus resistance change of a variable resistance (resistance temperature transducer) including a voltage follower in one branch of the bridge so that the zero setting of the transducer resistance does not depend upon the current source or upon an excitation voltage. The zero setting depends only on the precision and stability of the three resistances. By connecting the output of an instrumentation amplifier to a feedback resistor and then to the output of the voltage follower, minor nonlinearities in the resistance-vs-temperature output of a resistance-temperature transducer, such as a platinum temperature sensor, may be corrected. Sensors which have nonlinearity opposite in polarity to platinum, such as nickel-iron sensors, may be linearized by inserting an inverting amplifier into the feedback loop.

Abstract: An electrical conductivity measuring apparatus for measuring the electrical conductivity of liquid has a plurality of electrodes disposed in the liquid contained in a measuring cell, with an a.c. voltage being applied between the electrodes, thereby measuring the electrical conductivity by measuring a current flowing between the electrodes. The apparatus includes a reference a.c. voltage source including adjustment means for varying the magnitude and phase of the signal current, and is designed to cancel the conductivity of background by adding the current from the reference a.c. voltage source to the current from the electrodes.