Abstract: Amounts of electric charges in a semiconductor wafer are measured by using a non-destructive measuring device. First and second flat-band voltages before and after a specific charging process are measured with a non-destructive C-V measurement device. A gap between a test electrode and a surface of a semiconductor wafer is also measured before and after performing the charging process. The electric charge accumulated proximate the surface of the semiconductor wafer is determined according to measured values of the gap and the flat-band voltages before and after performing the charging process.

Abstract: A method and a circuit arrangement having a device for measuring the depletion layer temperature of a GTO are specified. In this case, a measurement current (I.sub.M) is impressed in the gate circuit, and the voltage (U.sub.GR) between the cathode and gate is measured, with an applied measurement current (I.sub.M), after the transient turn-off processes have decayed. This voltage (U.sub.GR) is at this time dependent on the depletion layer temperature of the GTO. It thus becomes possible to measure the depletion layer temperature directly on the element, that is to say without circuitous routes via a heat sink temperature and calculation of the thermal resistance or the like, and during operation, continuously, and in consequence to monitor and control the stress level on the GTO precisely.

Abstract: A waveguide and pressure barrier for use with devices for measuring fluid parameters of fluids passing in a pipe under high temperature and pressure conditions and utilizing microwave energy for making the measurements, the device including a pair of substantially identical members adapted to be mounted in spaced opposition on the pipe. Each member has an axial bore with a transverse bore for receiving a microwave antenna. The axial bore is substantially filled with a ceramic glass material providing the pressure and temperature barrier.

Abstract: A test fixture is provided for testing the resistance associated contamination material on the surface of electrical contacts mounted to a printed circuit board. An elongated probe is provided which has an axis perpendicular to X and Y planes. A mechanism is provided for maintaining the probe in a precise perpendicular orientation to the X and Y planes while permitting movement of the probe along its axis in the Z plane to engage an aligned contact. A predetermined bias force is exerted by the probe along its axis while engaging the contact to be tested.

Abstract: A method for improving accuracy of estimating natural frequency of a distribution system. The estimation is performed in order to identify a rectifier load that generates harmonics due to commutation oscillation. It includes the steps of measuring a charging current flowing into a power factor improving capacitor to obtain first data, removing fundamental frequency from the first data to obtain second data, determining, from the second data, a first time at which the amplitude of commutating oscillation components takes a maximum value, picking up third data in the interval beginning from the first time and ending at a second time later than the first time by T/N, where T is the period of the fundamental frequency, and N is the number of rectifier phases, performing frequency analysis on the third data to form fourth data by expanding the third data into a Fourier series, and determining a local peak frequency, that is, the natural frequency in the fourth data.

Abstract: In order to permit rapid, high-resolution measurement of the frequency of an electrical signal using a digital device, the electrical signal is fed to two linear-phase non-recursive digital filters (3, 20) with symmetrically distributed filter coefficients (a(n), t(n)), one of which is developed as an all-pass filter (3) and the other as a low-pass filter (20). Following the all-pass filter (3) there is a circuit unit (4) in which a logic signal (r(.OMEGA.)) is formed by means of two transverse filters (5, 6) time-delay member (7, 9), multipliers (8, 10) and a difference former (11), said logic signal being dependent on the quantity frequency responses of the transverse filters (5, 6) and the square of the scanned values of the all-pass filter (3). A further logic signal (s(.OMEGA.)) is generated by a circuit device (21) which is designed in a manner corresponding to the circuit unit (4) and is arranged following the low-pass filter. By quotient formation of the logic signals (r(.OMEGA.)), s(.OMEGA.

Abstract: A resistance measuring method and device for a thermal head, and a thermal printer using the resistance measuring device. From among a plurality of parallel connected heating elements of the thermal head, the heating element whose resistance is to be measured is set ON, while other heating elements are set OFF. A capacitor connected in parallel to the heating elements is discharged through the conductive one of the heating elements, while being disconnected from a power supply for charging the capacitor, and a discharge time required to discharge the capacitor down to a predetermined voltage level is measured. A resistance value of the heating element is calculated based on the measured discharge time.

Abstract: A cathodic protection measurement apparatus including a coupon made of similar material as a buried metal pipeline to form an artificial holiday, where the coupon is buried near and electrically connected to the pipeline to receive the same level of cathodic protection current as the pipeline. A test wire is connected to the pipeline and routed to a normally-closed contact switch located at an access point of a test station. The switch is also connected to a coupon wire, which is routed and connected to the coupon to complete the electrical connection. A reference electrode having a measuring surface contacting the soil close to the buried coupon includes an electrode wire provided to the access point. A voltmeter is connected between the switch and the reference electrode wire, and the switch is then opened to electrically isolate the coupon from the pipeline.

Abstract: A system monitors the stability of fats and oils especially having the capacity of simultaneous analysis of a multitude of samples making it convenient for use to monitor a production plant. A plurality of probes (made from a metal taken from a group consisting of nickel, chromium, rhodium, titanium and stainless steel) have spaced parallel electrodes immersed in a liquid carrier (deionized water) through which an effluent of heated fats or oils is bubbled. A common conductivity meter responds to signals from each of the probes, in turn, for measuring the induction time of the fats or oils samples. The instrument features a power failure recovery system that utilizes a battery-power clock, so that short duration power failures do not cause a loss of data. A long duration power failure does not cause loss of data to the point of failure, however incomplete analyses are stopped.

Abstract: A capacitive measuring device or apparatus; in particular, a length-measuring apparatus, which incorporates a scale portion and a scanning unit which is movable relative to the former and which supports transmitting electrodes and at least one receiving electrode. Herein, a transmission circuit applies transmitting signals at a basic frequency to the transmitting electrodes, and with the receiving electrode being connected to a reception circuit, to the output side of which there is connected an evaluating circuit for the receiving signals. The transmitting signals are applied to the transmitting electrodes through a pulse width modulator and a synchronous modulator and the receiving signal is conducted through a demodulator.

Abstract: A device for testing for leakage of electronic equipment has a female AC connector for receiving the male AC connector of the electronic equipment to be tested and a male AC connector for attaching the test device to a source of AC power. The device also includes an electrically conductive probe and a meter for detecting a voltage on a surface contacted by the probe. Within the device are first and second switches which connect the male AC connector and the female AC connector in four successive configurations for applying AC power to the connector of the piece of equipment to be tested. A sequencing circuit in the device operates the two switches to apply all four test configurations within an interval of 1.033 seconds. The probe and the meter for detecting a current in the probe is used to contact the conductive surfaces of the piece of equipment being tested to detect a voltage while the four tests are applied to the power connector.

Abstract: A method and apparatus for sensing proximity of an object using near-field effects. Modulated radio frequency energy is fed to an antenna. The antenna radiates this modulated radio frequency energy to charge the surface of an object. When the position of the object changes, the impedance of the antenna due to near-field effects changes. This impedance change is detected to provide an indication of the object's movement. The sensing device may be packaged to be inserted into a wall to provide a sensor having a leak-free seal.

Abstract: In an apparatus for determining the material moisture of a medium by measuring the dielectric coefficient of the medium around a measuring probe, wherein the apparatus includes a signal generator providing to one end of the probe a pulse signal, the echo of which, when returning from the other end of the probe, is received by a receiver, and a timing device determining the time elapsed between the introduction of the pulse signal and the return of the echo, the probe consists of a body structure which has electrical signal conductors disposed on its surface.

Abstract: A system for measuring the gap between two surfaces is disclosed. The sensing apparatus comprises an actuator, an active sensor and a display. The actuator actuates operation of the sensing apparatus. The active sensor includes a transmitter for transmitting a wave signal beam reflectable off one of the surfaces and a receiver for receiving the reflected wave signal beam by the sensing apparatus. A signal processor is in electrical communication with the actuator, the transmitter and the receiver, for processing the reflected wave signal beam to determine the gap between the two surfaces. The display is in electrical communication with the signal processor for displaying the amount of gap between the two surfaces.

Abstract: An electrode structure of a metallic particle detecting sensor capable of detecting with high efficiency metal powders floating in a wide range in an oil tank. The electrode structure is formed by opposing, on a substrate, a pair of electrodes (1, 2), formed of thin film metals of such as Ta, W, Pt, Cr, Au or the like, having combed (toothed) structures with their respective teeth being meshed or interdigitated with each other.

Abstract: A method and an apparatus are provided for safely testing an autotransformer of power distribution lines which has an identified centre tap ground connector, a primary winding terminal and a secondary winding terminal. The method for safely testing the autotransformer includes the steps of disconnecting the terminals and connector of the autotransformer from the distribution lines, applying a first testing AC voltage having a maximum value of substantially one volt only between a first of the terminals and the ground connector, measuring a first value of an AC voltage between the first terminal and the ground connector, and measuring a second value of an AC voltage between the second of the terminals and the ground connector.

Abstract: The present invention is a device for measuring the electric surface charge density on each surface of a sheet. The sheet can either be moving or non-moving. If the sheet is non-moving a pliers-like device having a pair of electrodes aligned opposite with each other is used. The sheet is placed between the electrodes and the surface measurement is made by either one or two electrometers. For a moving web, the apparatus includes a first and second roller each having a charge measurement segment electrically isolated from the roller shell wherein the charge measurement segments periodically engage the web running through the two rollers. Two grounded shields which periodically shield the charge measurement segment are provided. Two electrometers are provided and from this surface charge density measurement and net charge density measurement on the moving sheet are obtained.

Abstract: A motor assembly (A) cyclically moves a sample (34) longitudinally through the longitudinally aligned central bores (16, 18) of a pair of hollow electrodes (12, 14). One of the electrodes (14) is connected with a Faraday shield (10) which electrically shields the electrodes and the sample and the other electrode (12) is electrically insulated from the Faraday shield. Preferably, the Faraday shield structure further serves as a hermetic seal for sealing the hollow electrodes against adverse effects of the ambient atmosphere. An electrical instrument (C) is connected across the two hollow electrodes to measure the induced charge transfer or potential difference as the sample cyclically moves back and forth between the hollow bores of the two electrodes.

Abstract: An apparatus and a method are provided for determining solution resistance and corrosion rate of a metal surface contained in a solution such as an electrode. The signal is applied to the metal surface of interest and the current response is monitored from the applied signal. A peak detector is provided for detecting the peak of the current response. From the peak, the resistance of the solution is ascertained. Following independent determination of the solution resistance, polarization resistance of the metal surface in the solution may be determined. The corrosion rate of the metal surface may be calculated from the polarization resistance.

Abstract: A method and apparatus for detecting the possibility of transfer of material through a protective barrier between a worker and an external object and warning the worker of that possibility is provided. In one embodiment, an electronic leak alarm module is electrically connected to the worker and to the external object. In another embodiment, the module is connected to the worker and a conductive layer on or within the protective barrier.