Abstract: A tomographic flow imaging system comprising three or more capacitance electrodes positioned around a pipe through which a flow to be monitored passes. The capacitance between each pair of the electrodes is measured, and an output is derived from the measured capacitances which is representative of the distribution of material within the pipe. A predetermined voltage signal is applied to one electrode at a time, and the electrodes other than said one electrode are connected to sources of equal fixed potential. The capacitance of each pair of electrodes is measured by measuring charge flowing between the said other electrode of the pair and the source of potential to which it is connected.

Abstract: In a hot gas turbine engine a capacitive probe clearanceometer is employed to measure the clearance gap or distance between the continuous surface of a compressor or turbine wheel such as, for example, a shroud ring turbine and its confining casing under operating conditions. The probe positions a capacitor electrode at the inner surface of the casing adjacent the continuous surface path. Electrical power is supplied to the probe through an oscillator having a tuned circuit in which the probe is a component. A high frequency signal of the oscillator is amplitude modulated by changes in electrical capacitance between the probe capacitor electrode and the passing continuous surface. The modulated oscillator signal is processed to provide an electrical signal which is proportional to the distance between the casing and the continuous surface. A preferred combination of high temperature and contamination resistant metal and ceramic materials are combined in an improved gas tight braze sealed probe tip.

Abstract: An apparatus for automatically testing multipin connectors is disclosed. A carrier frame contains connector cells of different configurations. Multiple groups of pins of the connector are connected together and to a source of high voltage. The resulting leakage current between energized pins and a remaining unenergized pin may be measured and compared with various stored test parameters. When the on-board computer detects a current which does not meet the stored test parameters, an error message is posted and displayed and also passed to a host computer connected to the on-board computer for storage and display.

Abstract: An apparatus for monitoring current through a lamp circuit that uses a series resistance shunt in the circuit with one end being connected to a current source and the second end being connected to the lamp. The circuitry includes a comparator that is connected across the shunt and has a threshold switching voltage such that a voltage across the shunt that is larger than the threshold voltage will switch the comparator on (as in the case where the lamp is not functioning) and a voltage across the shunt that is smaller than the threshold voltage (as in the case where the lamp is in the circuit and functioning) will switch the comparator off. In a preferred embodiment, the shunt is actually a portion of the printed circuit board trace.

Abstract: Monitoring state of charge of an electric storage battery (18) is done by deliberately inducing eddy currents, specifically using an induction coil (70) in conductive metallic constituents of negative plate material (74) of the battery concerned, and detecting effects representative of said eddy currents, specifically by detecting (76, 78) amplitude or frequency effects on energizing signals (72).

Abstract: The apparatus for measuring the comparative output power of each cylinder of a multi-cylinder engine comprises a digital signal processor 1 and a phase locked loop detector 2. By inputting instantaneous current measurements from (e.g.) a current transformer attached to an alternator output of an engine under test and analysing same in the processor 1, instantaneous engine speed may be measured. This measurement may be processed to determine comparative measurements of compression and power output of each of the cylinders.

Abstract: Testing apparatus is coupled to the plug used to connect the electrical system of a towed or trailer vehicle with a main or powered vehicle. The plug typically has terminals which connect related trailer vehicle electrical components with components in the main vehicle, e.g., the back up lights of the trailer vehicle are coupled to the back up lights (or transmission reverse gear) of the main vehicle. After coupling the testing apparatus to the plug portion attached to the trailer vehicle, switches can be used to activate selectively the trailer vehicle components. Instruments in the testing apparatus measure the electrical response to each activation and can be used to determine when the components are operating correctly. Similarly, when the portion of the plug coupled to the main vehicle is coupled to the testing apparatus, the response to activation of the main vehicle components can be monitored by the same instruments.

Abstract: A pH-measuring system using a Barnacle electrode (e.g. Ni--NiO.sub.2) in an electrolyte to abstract hydrogen from a metal electrode in the same electrolyte, and produces data as to the time t.sub.max required for the current density at the exposed surface of the metal electrode to reach its maximum value j.sub.max after an external circuit between the two electrodes is closed. From t.sub.max and j.sub.max the pH in the bulk of the electrolytes is determined, for display or for control purposes.

Abstract: A transducer system and method of use thereof by sequentially operating a comparator to produce a series of pulses in which the time distribution of the pulses is representative of the transducer value, and is used to normalize the sensed value in the event that the total transducer value varies due to environmental influences. The transducer is adapted to monitor the substantially linear movement of the level (fuel-air interface) of fuel in a tank and the angular positon of an input shaft.

Abstract: A transducer system and method of use thereof by sequentially operating a comparator to produce a series of pulses in which the time distribution of the pulses is representative of the transducer value, and is used to normalize the sensed value in the event that the total transducer value varies due to environmental influences. The transducer is adapted to monitor the substantially linear movement of the level (fuel-air interface) of fuel in a tank and the angular position of an input shaft.

Abstract: A flame ionization detector comprises a housing forming a flame chamber for burning a mixture of hydrogen, oxidant and a sample gas. The flame chamber includes: a nozzle in which the sample gas and hydrogen are intimately mixed prior to injection, an igniter for igniting the gas emitted from the nozzle, inlets for hydrogen and oxidant, and an exhaust outlet through which the burnt gases are removed. A collector electrode is electrically insulated from the housing of the flame chamber. The nozzle and flame chamber housing are electrically grounded, and the collector electrode is maintained at a predetermined potential relative to ground. A pre-chamber is disposed adjacent to the flame chamber to provide a substantially constant pressure input of the sample gas to the nozzle.

Abstract: A circuit and method for measuring resistance in an active and high temperature environment is provided using a low frequency square wave as an input. The square wave input is fed through the unit under test into a full-wave rectifier and RMS circuit. The full-wave rectifier and averaging circuit cancel out errors caused by the Seebeck effect and noise. The resulting d.c. signal is proportional to the resistance of the unit under test and can be displayed.

Abstract: An apparatus for and a method of measuring capacitance employs a charge measuring system. While a capacitive element, which may be an unknown capacitor, is charged completely to a predetermined voltage, a charge proportional to the capacitance of the capacitive element is accumulated on the feedback capacitor of an integrating operational amplifier. Thereafter, the charge is measured by measuring the time required to completely remove the charge from the feedback capacitor using the same predetermined voltage as a reference. In a preferred embodiment, the present invention is manifested as a capacitance measurement feature in a hand-held multimeter wherein a largely conventional dual-slope analog-to-digital converter is employed as the charge measuring system.

Abstract: A low cost and portable scalar network analyzer for the simultaneous measurement of forward and reflected scalar scattering parameters of devices under test. Plural UHF oscillators of similar construction are mixed to produce a wideband test instrument having good stability characteristics. A dual-diode biased RF detector with feedback, including an in-loop adjustable gain buffer stage, provides enhanced linearity, over a wide dynamic range, and at low cost. The forward transfer parameter measurement arrangement further includes a selectable attenuation/gain PIN-diode switched stage to accommodate the widely varying gain/attenuation characteristics of devices under test.

Abstract: An electric coil to be tested for interturn and/or interlayer faults is coupled into a series resonant circuit. A measurement of the quality-factor (Q-factor) is carried out by measuring the overshoot voltage in circuit resonance. Through the selection of a suitable capacitance in the series resonant circuit, the resonant frequency can be placed in a range in which the quality-factor of the coil attains its maximum value. The coil to be tested is therefore a component of a series resonant circuit. The measuring system for determining the quality-factor of the coil is low capacitively coupled into the resonant circuit. Because the interturn resistance of the test coil must be measured in any event, since this value is also obtained during Q-factor measurement, the necessary operating and measuring periods can be optimized.

Abstract: An improved swept frequency domain reflectometry instrument has an input/output terminal coupled to one end of a cable. A radio frequency at the input/output terminal is converted to an intermediate frequency using a swept local frequency. The radio frequency is derived from the swept local frequency and a variable offset frequency. A controller controls the variable offset frequency, monitoring the amplitude of the intermediate frequency. A period counter counts the intermediate frequency at a first maximum response of the intermediate frequency and further counts the offset frequency at a second maximum response of the intermediate frequency. The location of a discontinuity in the cable is calculated from the counted frequencies.

Abstract: A method and apparatus of developing a stabilized power firing event signal for a cylinder in a wasted spark ignition system having pairs of complementarily connected cylinders, each with a spark plug connected to an opposite end of an independent ignition coil. The first and second firing event signals are developed for each spark plug upon firing of the ignition coil. The first and second signals are combined with like polarity in a summation circuit for eliminating common mode signal portions. The combined signal, which is now stabilized and accurately indicates spark duration, is used for capturing secondary ignition data and may be visually displayed for analysis.

Abstract: An automotive electrical system including a wiring harness incorporates a dedicated test line passing through critical connectors and components for allowing detection and isolation of improperly connected connectors. The dedicated test line can feed through expansion connectors, termination connectors, and junction blocks. A respective impedance is connected between the dedicated test line and ground at each respective connector. Connector fault detection and isolation is achieved by measuring the total impedance presented at the beginning of the test line. The measured impedance uniquely identifies the locations of any improperly connected connectors.

Abstract: A digital isolation monitor comprises a signal processor operating in conjunction with a measuring circuit to perform a first no-load measurement and a second load measurement of a zero sequence signal delivery by a toroid of a differential transformer, followed by synchronous demodulation, A microcontroller computes the tangent of the angle of phase difference introduced by the toroid by computing the relationship between the load and no-load components, and determines the true values of the leakage resistance and stray capacitance of the power system.

Abstract: A ground fault detector has a neon bulb connected between a rectangular copper plate connected to an antenna wire and a resistor connected to one arm of a double-pole double-throw relay with the stationary contacts cross coupled to hot and neutral wires of a three-wire A.C. line. A photocell detector is optically coupled to the neon bulb and provides a signal to a live wire detector circuit when the neon bulb is illuminated to disable operation of the relay. A timer circuit causes the live wire detector circuit to operate the relay when the neon bulb is not illuminated after a predetermined time. A network is photo-optically coupled to a ground status detector that controls a contactor that selectively connects power to the equipment being monitored. The junction of a Y network is also coupled to the input of the ground status detector. The input of the photo-optical coupler is connected between a leg of the Y circuit and the enclosure of the equipment being monitored.