Abstract: A gas concentration detector for detecting a concentration of pollutant gas such as NOx or SOx contained in ambient air is composed of an oxide-semiconductor gas sensor heated by a heater and a controller for determining the gas concentration by comparing a concentration level detected by the gas sensor with a calculated comparison level. The comparison level is calculated so that it follows the detected level with a certain delay. The degree of the delay is set shorter in an unstable region of the gas sensor than in a stable region, thereby to effectively determine the gas concentration even in the unstable region.

Abstract: A bidirectional current sensor including a transformer having a primary winding arranged in a circuit likely to be run through by a current to be measured, a secondary winding, an impedance for demagnetizing the transformer, and a measuring resistor connected to the secondary winding via a switch controlled to be on when a current is likely to run through the primary winding. It applies in particular to the detection of currents in bidirectional voltage converters.

Abstract: Apparatus is described for generating a frequency-sweepable measurement signal and a local signal with a frequency separated from the measurement signal frequency by an intermediate frequency. The measurement signal and a local signal are generated by a simple structure, including a high-frequency variable-frequency signal source, a low-frequency fixed-frequency signal source, a first frequency divider and a second frequency divider. The variable-frequency signal source is a sweepable signal source. The first frequency divider divides an output frequency fa from the variable-frequency signal source by n and outputs a measurement signal with a frequency of fa/n. The signal of the variable-frequency signal source is also applied to the first input of the second frequency divider, and the signal of fixed-frequency signal source, with a frequency of fb, is applied to the second input.

Abstract: An ultra high accuracy voltage measurement system utilizes a Josephson junction voltage generator whose voltage is controlled by a high precision frequency.

Abstract: A technique and circuit for measuring direct current flowing through a conductor at a high voltage employs a capacitor connected in series with the conductor, and a neon lamp connected in parallel with the capacitor. The series connected capacitor and conductor are connected to a high voltage source such that the current flowing through the series connected capacitor and conductor charges up the capacitor. Since the capacitor and the neon lamp are connected in parallel, the voltage across the electrodes of the neon lamp follows the voltage across the capacitor. When the voltage across the electrodes of the neon lamp reaches the lamp's ignition voltage, the neon lamp fires, and discharges the capacitor until the voltage across the electrodes of the neon lamp falls to the lamp's extinction voltage. The light signal generated by the neon lamp is picked up by a fiber optic cable and transmitted to a remote receiver for processing.

Abstract: A circuit interrupter samples waveforms in a protected circuit by taking samples in pairs spaced 90 electrical degrees apart. The sum of the squares of samples in each pair, which is representative of the RMS value of the fundamental frequency of the waveform, is used for instantaneous protection by comparing a running sum of the squares for the two most recent pairs of samples to a threshold representative of the instantaneous trip pick-up value. This sum of the squares of successive two pairs of samples is also used for short delay protection. A delay between successive pairs of samples is varied to produce a selected equivalent sampling rate after a given number of samples. Samples accumulated at this equivalent sampling rate, which is sixty-four samples per cycle in the preferred embodiment, are used for long delay protection and metering.

Abstract: A battery pack (10) has a charge measurement circuit (12) for estimating the state of charge during use. The charge measurement circuit (12) includes a sense resistor (24), amplifier (26), at least one oscillator (28), counter (30), and a communications circuit (32). The battery pack powers a host device (16), which has a limited number of modes of operation, each mode requiring a different current level. The number of oscillators (28) equals the number of modes of operation of the host device (16). As current is drawn from the battery cells (18), the sense resistor (24) and amplifier (26) act to convert the current to a voltage level. The voltage level is fed to each oscillator (28) present. Each oscillator (28) provides a clock signal at a frequency corresponding to one mode of operation of the host device, and is activated when the voltage level is within a preselected range. The clock signal is fed to a counter (30), which counts at a rate determined by the frequency of the active oscillator (28).

Abstract: Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Abstract: The design of a current-to-voltage converter with a uniform transfer function in its feedback loop (12) is proposed. It employs a very large, double-shielded measuring resistance (13) and a two-stage setup to perform a fully linear I/V conversion with a conversion factor of 10.sup.10 V/A and a bandwidth of 1 MHz. With the low noise level attained, and with the bandwidth and conversion factor mentioned, it will be possible to monitor events involving as few as 300 electrons. The current-to-voltage converter comprises a differential input amplifier (8), a current source (11) for supplying said differential amplifier (8), at least one operational amplifier (10, 14), and a high-valued measuring resistance (13) the voltage drop across which is being taken as a measure of the current to be detected. The measuring resistance (13) is arranged in a feedback loop (12) associated with said differential amplifier (8).

Abstract: A current-to-frequency converter 12' (FIG. 3) for use with an accelerometer 10 comprises a storage capacitor 13 which receives the accelerometer current and develops a charging voltage, reset charging means 25 which delivers timed charges to offset the voltage by predetermined amount and voltage sensing means 14' which senses the charging voltage reaching positive or negative thresholds in order to initiate a reset and offsetting the voltage. The polarity of charging voltage at which reset is triggered determines that polarity threshold as being half the magnitude of the offset voltage but the opposite polarity threshold of greater magnitude so that the voltage on the reset capacitor avoids it.

Abstract: A single integrated circuit operable in either a single chip mode or a host dependent mode.

Abstract: A circuit arrangement for detecting an input voltage comprises an oscillator responsive to the voltage, the oscillator including a pair of transistors (8, 9) connected as an astable multivibrator, each of the transistors having a load which comprises a primary winding (16 or 17) of a current transformer (T) and a low resistance proof resistor (12 or 13). A current flows through a secondary winding (18) of the transformer the amplitude of which current is proportional to the input voltage.

Abstract: A transformerless line powdered digital AC voltmeter for selected voltage ranges is disclosed which takes a minimum of electrical power from the AC line being measured. The AC input is firstly directed to an AC/DC converter to furnish a source of DC operative voltage, the AC/DC converter possessing external electronic circuitry to assure that an adequate minimum voltage appears as its input for any selected voltage range the invention measures. The AC voltage input to be measured is first halfwave rectified, and then voltage divided and smoothed before directed to the input of an A/D converter. The A/D converter has specific external circuitry added to it to assure that the output is accurate over the range of the voltages to be measured. The output of A/D converter is directed to a liquid crystal display which visually indicates the AC voltage measured. A external electronic circuit determines the decimal point for the voltage range measured.

Abstract: An electronic circuit arrangement for producing an output signal representative of the average value of an alternating voltage in a power transmission system, composed of: at least one circuit unit composed of a pulse width modulator (6) connected to derive, from the alternating voltage, a train of pulses modulated in width as a function of the amplitude of the alternating voltage and with a defined phase relation to the alternating voltage, an electronic circuit (4,8) connected to derive, from the alternating voltage, an alternating signal which varies in frequency with the alternating voltage and which has the defined phase relation to the alternating voltage, and a signal multiplying device (14) connected to receive the train of pulses modulated in width and the alternating signal for multiplying the pulses and the alternating signal to produce a product signal having an amplitude proportional to the average magnitude of the alternating voltage; and a signal to frequency converter (16) connected to derive

Abstract: A digital integrator for sensors which takes a time varying current or charge flow signal and converts it into a proportional voltage varying signal. The voltage varying signal is then preferably passed through an active full wave rectification subcircuit to provide an absolute value of the time varying voltage signal. The voltage signal also is analyzed by a zero crossing detector. The absolute value signal is converted into a proportional frequency varying signal which is counted either positively or negatively to produce an integral of the current flow with time. The integrator can be used with sensors such as piezoelectric crystals to indicate force on a real-time basis. The integrator is described as part of an animal hoof force detection system.

Abstract: A digital voltmeter includes a display device surrounded by a variable color background area for indicating measured voltage in a digital format. The color of the background area is controlled in accordance with the significance of measured voltage.

Abstract: An electronic interface device is provided for use between a sensor and a display unit, including a controllable generator which delivers a signal to the display unit and is connected to an input of a comparator whose other input receives the output signal of the sensor. The output of the comparator controls the up counting or the down counting of an up-down counter of clock pulses. The sign output of the up-down counter controls the generator.

Abstract: A circuit layout for continuous display of power consumption of an electric device includes a light emitting diode actuated by voltage pulses, the frequency whereof corresponds to the current draw of the electric device. It is possible to determine directly whether the instantaneous power consumption of the electric device, in particular a household device, is low or high in case of varying loads as the frequency of the voltage pulses and thus the flashing frequency are below the flicker limit resolvable by the human eye. The power consumption display can be manufactured in a highly cost effective manner and in a compact configuration, so that it may be placed in an electric outlet housing.

Abstract: A traction load meter system for displaying information concerning the amount of current energizing electric motors which drive a locomotive. These motors have power and braking modes and have a continuous current rating. The system includes a current-to-frequency converter for providing an output signal having a frequency corresponding to the amount of current drawn by the motors. Electronic logic circuitry is included for receiving this output signal and being responsive thereto to provide outputs indicating whether the locomotive is in the power or braking mode, the amount of current being drawn, whether this amount is above the continuous rated current for the motors, and the period of time the above-rated condition has existed. Additionally, the meter system includes a display panel connected to the logic circuitry and adapted to be mounted in a cab of the locomotive for displaying to the engineer the aforementioned outputs of the logic circuitry.

Abstract: An atto amperemeter includes a shop tip (1) correctable to a voltage source (18) providing a known potential (U') via a sample conductor measured, the tip (1) faces a particle detector such as an electron multiplier (4). The count of the free electrons being emitted from the tip (1), multiplied by the electron multiplier (4) and counted by an electronic current (i) passing through the sample conductor (17). Calibration of the arrangement is performed by temporarily connecting the tip (1) to ground and applying a calibration potential (U cal) to a calibrated electrode (3) aligned with the tip (1) and the channel electron multiplier (4).

Abstract: In order to display a measured value, a digital measuring instrument is provided with a digital display and an analog display. The display value emitted by the digital display is fixed during a predetermined holding time. The analog display displays the difference between the current measured value and the particular display value of the digital display at the time. The current measured value may be read off at the beginning of a new holding time on the digital display, or it can be ascertained as the sum of the values of the digital and analog displays.

Abstract: Device for measuring voltage by sampling, including a voltage metering sampling means (2) driven by a pilot frequency generator (12), an amplifier (3) to amplify the sampled signal and a signal processing unit (6) to evaluate the amplified signal in accordance with the prescribed measuring task. The device, in accordance with the invention, contains an auxiliary oscillator (14) which produces an auxiliary signal, as well as an amplifier (3) with adjustable amplification, which is located between sampling unit (2) and signal processing unit (6), and a differential circuit (5). The auxiliary signal on one side, together with the voltage to be measured, is connected to signal input (17) of sampling unit (2), on the other side by means of a phase shifter (13) to an input (25) of differential circuit (5).

Abstract: A display signal generator device which allows the pulse width of a digital signal to be constant and the pulse repetition period to be proportional to the analog amount of an input signal so as to produce a signal to be displayed even by an analog or digital display unit 7 or 6, thereby obtaining a digital/analog common signal of average value proportional to the frequency even with the pulse signal. In order to maintain the pulse width constant, only a monostable multivibrator is, for example, added, thereby providing an inexpensive display signal generator device.

Abstract: A method and apparatus for converting an electrical signal into a proportional frequency is disclosed. Modulation of the output frequency resulting from polarity switching cycles having half-periods of unequal duration and capacitor voltages which might be non-zero at the time of polarity reversal are substantially avoided. This permits faster and more precise calibration.

Abstract: A light conductor has two sealed embedding elements molded to its ends, respectively containing a light emitter and a light receiver. The light emitter is connected to a likewise embedded Wiegand probe, the light receiver is connected to a likewise embedded amplifier and a pulse shaper. These signal transmission lines are used for data acquisition, the respective Wiegand probes are disposed to be responsive to measured conditions represented by variable magnetic fields. The transmission system is moisture-proof and insensitive to interfering electromagnetic radiation.

Abstract: A current to pulse-sequence transducer for transforming a current to be measured into a sequence of pulses which has a certain mark-to-space ratio, includes a first transforming device for transforming the current to be measured into a measurement magnetic field, a second transforming device for generating a reference magnetic field, and magnetic field comparison device including a magnetoresistive thin film comparator normally providing a zero output when the fields are equal, but generating an impulse when the strength of one magnetic field exceeds that of the other, and an impulse processing device. The impulse processing device includes a differentiator amplifier connected to the output of the magnetoresistive thin film comparator and a Schmitt trigger circuit postcoupled to the differentiator amplifier.

Abstract: The monitor system consists of a voltage controlled oscillator for produc an acoustic wave whose frequency is proportional to the voltage being measured. An acoustic waveguide is used for transmitting the wave to an electrically isolated acoustic to electrical transducer. The output of the transducer is amplified and then displayed on an appropriate readout calibrated in volts.

Abstract: A voltage measuring device includes a surface acoustic wave propagating medium and transmitting and receiving transducers coupled to the medium. An electrode that receives an unknown voltage is applied to the medium for effecting, when the unknown voltage is supplied, a frequency change in the acoustic wave propagating through the medium. A detector is provided for detecting the frequency change which is an indication of voltage supplied to the electrode.

Abstract: An apparatus for measuring varying current levels is particularly suited to the measurement of distinct current pulses. The apparatus couples by means of an inductive sensor to a current carrying conductor. A current pulse in the conductor induces a voltage within the sensor, which is then converted by a unipolar voltage to frequency converter to a sequence of electrical pulses, the total number of which is proportionate to the peak current value of the pulse. The number of pulses produced may be displayed as a measurement of the peak current pulse; in a preferred embodiment, the apparatus compares the number of pulses to a pre-set alarm value, enabling the apparatus to signal any occurrence of current pulses over a desired value.

Abstract: A watt/var transducer utilizing the pulse width-pulse height modulation type of multiplying scheme wherein a stable squarewave is generated by switching from one reference voltage to another reference voltage, the output thereof is integrated to produce a stable triangular wave output, the gain of which can be simply adjusted by shorting the output of amplifying means to various points in a resistive means contained in feedback means from the output to the input of said amplifying means. The frequency of the triangular wave output is high relative to any alternating signal which may pass upon the power line to be monitored by the transducer such that those portions of said alternating signal sampled by the multiplier portion of the transducer appear to be non-alternating signals thereby rendering the transducer capable of multiplying alternating signals as well as non-alternating signals.

Abstract: A test circuit for determining the current produced by a current source device with a predetermined, non-zero voltage at the output of the device. The circuit includes a current to voltage converter circuit for converting the current produced by the current source device, typically a digital-to-analog converter (DAC), into a corresponding voltage. A control voltage source is coupled to the output of the current source device and to the current to voltage converter circuit through a coupling circuit. The coupling circuit couples a predetermined portion of the control voltage to the output of the current source device and to the current to voltage converter circuit with the voltage produced by the current to voltage converter being proportional to the current produced by the current source device and independent of the control voltage.With such an arrangement, the compliance voltage range of a DAC may be accurately measured.

Abstract: An indicating device for measuring instruments having a voltage-frequency converter for converting measurement signals expressed as voltage values into frequency signals with a frequency proportional to the voltage values, a counter for counting the frequencies of the frequency signals sent from the voltage-frequency converter and sending the counted number to an indicator for digitally indicating the measured values corresponding to the counted number. A switch is connected between the voltage-frequency converter and the counter, and a controller for holding the switch in the closed state only during a predetermined time is connected to the switch. Analog signals sent from the measuring device can be indicated digitally and the digital values indicated can be held by a simple, inexpensive and miniaturizable construction.

Abstract: An arrangement which displays an indication of the amplitude level of digital audio signals. The arrangement includes an acquisition means which receives digital audio signals and determines the peak amplitude value of the signals received between successive interrogations by a control means, and at least this value is indicated by a display means. If the currently indicated value exceeds the last determined value, then the indicated value is caused to decay at a predetermined rate.

Abstract: Apparatus for detecting electric fields and providing an indication of their magnitude includes a glass bulb containing a gas such as neon. When the bulb is placed in a time varying electric field, pulses of electromagnetic radiation are generated within the bulb. The number of pulses is proportional to the magnitude of the variation in the electric field. The pulses are transmitted by a fibre optic bundle to detection and recording apparatus to provide an indication of the magnitude.

Abstract: Disclosed is an analog voltmeter which generates audible tones whose frequency is representative of the analog voltage being measured. Since voltage levels are detected through the sense of hearing, a user is not required to direct his visual attention to "read" the meter; but instead he can use his visual attention to place the meter's probe onto various nodes whose voltage is to be measured. Using the audio analog voltmeter on a five volt scale, frequency differences in the tone corresponding to 17 mv changes in the measured voltage are detectable.

Abstract: The output of each of a plurality of CMOS inverting amplifiers is connected to a corresponding one of a plurality of impedances to be measured. A stepping circuit is connected to the inputs of the amplifiers. A voltage supply is connected to the amplifiers and provides a signal to be measured which is directed via a corresponding one of the amplifiers to an impedance measuring circuit connected to the impedances to be measured in common. The impedance measuring circuit produces an output impedance proportional to the impedances to be measured.

Abstract: Two phase-locked loop (PLL) solid state devices are used in conjunction with a fiber optics transmitter-receiver link in order to derive at a remote location an analog signal which is a representation of an inputted analog signal. Frequency-modulation is used in an analog signal measurement context to provide a bandwidth extending from direct current to a frequency of the order of 125 kHz. The transmitter portion is integrated within the base enclosure of a high voltage coupling capacitor connected between a high voltage power line and ground to provide high voltage protection and measurement capability for high frequency high voltage transients or surges in relation to high voltage power lines from the remote location.

Abstract: A capacitance to be measured is connected between the input and output of an inverting amplifier. A bistable circuit has an input connected to the output of the inverting amplifier and an output impedance inversely proportional to the capacitance to be measured. A resistive feedback is connected from the output of the bistable circuit to the input of the inverting amplifier.

Abstract: Indicating devices for mounting on a test point in an alternating current distribution system provide a visual indication of either voltage level or fault occurrence in the system. The indicating devices are contained in a housing which includes an electrically-conductive rubber outer shell adapted to snap-fit over the test point, and a non-conductive inner housing within which the indicating devices are contained. The indicating devices include a bridge-type rectifier which is coupled to a conductor of the system through the test point terminal, and to ground through the electrically-conductive outer shell. In a voltage indicator application, the rectifier circuit charges a capacitor across which a neon lamp visible through a window in the end of the housing is connected, the rate at which the neon lamp flashes providing an indication of the voltage level on the conductor.

Abstract: Disclosed is a method and apparatus for the precise linear rectification and envelope detection of oscillatory signals. The signal is applied to a voltage-to-current converter which supplies current to a constant current sink. The connection between the converter and the sink is also applied through a diode and an output load resistor to a ground connection. The connection is also connected to ground through a second diode of opposite polarity from the diode in series with the load resistor. Very small amplitude voltage signals applied to the converter will cause a small change in the output current of the converter, and the difference between the output current and the constant current sink will be applied either directly to ground through the single diode, or across the output load resistor, dependent upon the polarity. Disclosed also is a full-wave rectifier utilizing constant current sinks and voltage-to-current converters.

Abstract: Electrical noise is suppressed on an input signal by squaring the input signal and any noise thereon, removing the sinusoidal terms in the squared output (as by averaging), subtracting the d.c. noise component, and taking the square root of the remainder, so as to produce an r.m.s. dependent, substantially noise free output. If desired, the noise suppression circuitry may be combined in a low signal measuring instrument in which the input signal is repetitively sampled and freed of noise in the manner described, the output then being measured on a d.c. meter.

Abstract: Apparatus for selectively measuring voltage, resistance, and time duration f an event, each of which is associated with an electrical network, includes a device for providing a first train of digital pulses, the frequency of the pulse train being related to an analog voltage coupled thereto. The measuring apparatus also includes a clock for generating a second train of digital pulses of fixed frequency, and a constant current source to be coupled to a resistive element being measured by the apparatus. The apparatus further includes counters selectively receiving one of the digital pulse trains for counting the number of pulses received during a selected time period, and for providing a digital output in which the value of a quantity measured by the apparatus is encoded.

Abstract: A dc measuring circuit for power rectifiers is described wherein primary line current is utilized to measure direct current output. In the measuring circuit, line current transformers are connected to a multiphase instrument rectifier through a phase shifting current transformer which is adjustable to compensate for differences between the primary and secondary line current phase shift characteristics of the power transformer and any phase shift in the line current transformer. By such compensation, the average value of rectified primary line current in the measuring circuit is maintained independent of the commutating angle of the rectified power current. The dc measuring circuit includes means for providing unity current transformation through the phase shifting current transformer. The dc measuring circuit also includes means for handling the presence of zero sequence current without causing measurement error or circuit damage.

Abstract: A test point cap provides a visual indication of the voltage level of an alternating current in the conductor of a connector on which the cap is installed. The test point cap includes a bridge-type rectifier circuit which is capacitively coupled to the conductor through a test point terminal on the connector. The rectifier circuit charges a capacitor across which a neon lamp visible through a window in the end of the cap is connected, the rate at which the neon lamp flashes providing an indication of the voltage level on the conductor.

Abstract: A circuit for determining on a half-wave cycle basis the maximum and minimum voltages of input cyclic line voltages for selected time periods in which the line voltages are rectified to half-waves, and an integrating voltage to frequency converter provides output pulses proportional to the voltage magnitudes of the half-waves with the pulses being counted and placed in a memory and then compared with minimum and maximum previous counts for previous half-waves, to provide an updated minimum and maximum voltage for such half-waves over a period of time or period of half-waves, with provisions for providing resetting strobe pulses at zero voltages of the half-waves and for providing accurate measuring of the pulse outputs in the integrating voltage to frequency converter by modulating the integrator sense voltage and achieving substantially accurate compensation for the effects of timing errors in the V/F converter.

Abstract: In the ion gauge system disclosed herein, the ion current obtained from an ion gauge tube is directly converted to a signal having a frequency proportional to the ion current so that a digital measurement of vacuum may be obtained. The ion current charges an integrating capacitor which is periodically discharged after reaching a preselected threshold. Preferably, the threshold is adjusted in proportion to the ion gauge emission current so that automatic compensation for variation in the emission current is obtained, the output frequency being proportional to the ratio of the ion current to the emission current. The variable frequency output signal generated by the integration and discharge process is counted by a scaling circuit which automatically changes the timing interval to provide the desired number of significant figures while incrementing the exponent value in a scientific notation display in keeping with the active time base.

Abstract: A microwave or other r.f. radiation detector in which a tunnel diode or other negative resistance device exhibiting the proper I-V (current-voltage) characteristics is biased in the positive resistance region near the voltage point at which the peak current occurs. Microwave or any other r.f. signal is picked up and detected by the tunnel diode such that an oscillation circuit connected thereto is caused to oscillate. The frequency of oscillation varies in accordance with the amplitude of the detected r.f. and is monitored with an earphone and/or a meter.

Abstract: A plurality of window comparators and voltage controlled oscillators are arranged to receive analog input signals which are converted to output frequencies that are linearly proportional to the analog signals over a substantially infinite amplitude range.

Abstract: A highly linear AC to DC conversion system comprises a variable gain amplifier via which an AC signal to be converted is applied to an AC/DC converter. The output of the AC/DC converter is compared with a reference level and a control signal dependent on the difference therebetween adjusts the gain of the variable gain amplifier so as to reduce the difference. The output of the AC/DC converter is also applied to one input of a comparator, whose DC output is applied via the variable gain amplifier to the other input of the comparator. The variable gain amplifier has exactly the same gain for both AC and DC signals. It can then be shown that the DC output signal produced by the comparator is very accurately linearly related to the magnitude of the AC input signal.

Abstract: A suspension insulator used on the tower of a high-voltage transmission line has a capacitive voltage dividing pickup plate placed thereon to capacitively pick up a low-power indication of the potential carried by the line. In order to detect the potential on the plate, the potential difference between the plate and the tower is limited, rectified and applied to a neon lamp in a photo coupler. A photosensitive element in the photo coupler responds to the light from the lamp to operate a relay to control remote indicators.