Abstract: A method and apparatus are disclosed for determining electrical properties of dielectric and semiconducting materials and devices by admittance measurement. According to the disclosed method, a sample contained between electrodes is subjected to an essentially sinusoidal radio frequency signal. Simultaneously, the sample is subjected to a perturbation as may be produced, e.g., by thermal, optical, or electron irradiation. Admittance is determined as a current-to-voltage ratio.According to the invention, signal-to-noise ratio in the output signal is enhanced by establishing a resonant circuit formed by the sample capacitor and an appropriately selected inductor element and pulsing the perturbation synchronous to the resulting resonant oscillation.

Abstract: An alarm circuit to monitor a periodic signal source for an occurrence of a short-circuit condition detects the entry of the instantaneous periodic signal magnitude into a predefined window bounded by an upper and lower threshold. The duration of the entry is timed to determine if a short circuit has occurred.

Abstract: A high resolution gaseous discharge display and/or memory device comprises a panel array of bistable charge storage areas designated gaseous discharge cells or sites, each cell having an associated pair of coordinate orthogonal conductors defining the cell walls which, when appropriately energized, produce a confined gaseous discharge in the selected sites. The conductors are insulated from direct contact with the gas by a dielectric insulator, the dielectric insulator being composed of a layer of refractory material having high secondary emission characteristics such as a Group IIA oxide doped with lithium a Group IA element, to prevent degradation of the dielectric during operation, to increase the static margin of the panel and improve the stability of the maximum and minimum sustain voltages, thereby providing stable operating voltages and extending the life of the gaseous discharge panel.

Abstract: An apparatus for inspecting for cracks under installed fasteners and the like using a multiple frequency digital eddy current system. A computer with a plurality of digital arrays generate drive signals which are converted to analog and applied to the test coil, a second set of digital arrays generate balance signals, are adjusted in amplitude and phase and drive signals so that the output of the test coil is zero in a test specimen, output signals from a work piece are processed in the computer giving phase-sensitive crack detection.

Abstract: A method is proposed by which defects in workpieces are detected magnetically, which method comprises the following steps being performed concurrently: scanning the test surface of a workpiece utilizing magneto-sensitive elements; magnetizing the workpiece perpendicularly to its test surface in the test zone; exciting magneto-sensitive elements; and measuring the tangential component of the magnetic field strength in the test zone. An apparatus for magnetically detecting defects in workpieces according to the proposed method comprises an electrical signal excitation/measuring unit and a detector. The latter has a housing which accommodates a core-type magnet rigidly fixed to it and adapted to be magnetized prependicularly to its working surface which mounts magneto-sensitive elements separated from each other and oriented in a prescribed manner. The elements connect each other and the electrical signal excitation/measuring unit as well.

Abstract: A system for detecting fluid-leak in a pipeline or tank is disclosed, which includes a sensing coaxial cable having an outer conductor divided into a plurality of sections and a continuous inner conductor, the coaxial cable being permeable to oily fluids so that the distributed capacity of the coaxial cable can be changed upon penetration by the fluids. Whether or not the change has occurred may be detected by supplying an oscillator signal to each section of the outer conductor to measure an output from the inner conductor at a low frequency signal operational amplifier.

Abstract: An improved watt-hour meter which permits time modulation of the power utilized wherein varying rates can be imposed upon the power user. The improved meter includes a substantially standard type watt-hour meter to which is added circuitry which alters the effective time during which the potential coil of the watt-hour meter is connected in circuit. Inasmuch as the power reading or indication by the meter is a function of the time during which the potential coil is connected in circuit, the effective power reading and, thus the rate structure can be selectively altered in this manner.

Abstract: A vacuum fluorescent display has a filament heated below incandescence and phosphor coated anodes. A foraminous charge-control electrostatic lens between the filament and the viewer both controls uniform illumination of the anodes and also comprises part of a contrast-enhancement element. An embodiment of the invention with a linear array of anodes and an analog-to-digital power supply forms a linear scale indicator.

Abstract: An electromagnetic sensing system is disclosed for sensing the linear distance between two elements and generating a signal related to the distance. The sensing system utilizes a magnetized initiator as one element, and a magnetic fluxgate as the second element. The magnetic fluxgate creates a flux "window" by locating a biased toroidal saturating coil inside a sensing coil, both of which are located inside a non-magnetic sleeve having an opening or "window" to magnetic flux, with the window being focused on the initiator magnet.

Abstract: A large bandwidth non-contacting voltage follower for detecting and following both static or d.c. and dynamic or a.c. data of an electrical field or potential being measured. A probe or sensor includes a pair of voltage sensitive electrodes which are vibrated or oscillated within a housing to vary the capacitive coupling between the electrodes and external field or potential in an inverse manner to induce signals on the electrodes having static and dynamic data from the field or potential. The signals are processed and applied to the input of a voltage follower amplifier, the output of which is coupled to the probe housing as a reference, so that the follower output follows the static and dynamic characteristics of the external field or potential.

Abstract: A plurality of eddy-current generators are angularly grouped about an axis within an inspection tool or probe. Each eddy-current generator presents a circumferentially extending test segment. Collectively, the test segments form a discontinuous test gap which extends circumferentially about the probe. In some embodiments, adapted for inspecting from the inside of tubing or fastener holes, the test gap is at the outer periphery of a probe. In other embodiments, adapted for inspecting from the outer surface portions of tubing, rods, etc., the test gap region extends around the inside of a central passageway formed through a support body. The eddy-current generators are supported for limited radial movement, enabling the tool or probe to adapt to differences in shape and dimension of the material being inspected.

Abstract: A device for detecting specific positions of a moving part, for example a rapidly rotating part provided with soft-magnetic projecting elements which alternately pass close to the detector device, which comprises a stationary magnetic exciter circuit for a Hall-effect crystal.The magnetic exciter circuit comprises a single permanent magnet having one pole face oriented towards the moving part, and provided with two symmetrical soft-magnetic pole pieces forming a narrow gap in which the Hall-effect crystal is disposed.

Abstract: Apparatus is disclosed for aligning brushes of a dynamoelectric machine such as a DC generator or motor to minimize arcing of the brushes. The alignment monitor processes electrical signals from brushes of a dynamoelectric machine during tests in which various levels of buck or boost current are superimposed on a preselected level of excitation current applied to the machine, and the monitor produces output signals which, together with the levels of applied buck or boost currents, are indicative of the brushholder rigging adjustment which is required to achieve the optimum rigging position for a wide range of arc-free machine operation. Included in the brush alignment monitor are filter networks for removing noise from composite signals input to the monitor, a rectifier for changing the sign of negative signal components, and networks which amplify and integrate selected high-frequency information signals to produce output signals.

Abstract: Apparatus for measuring a high voltage in an ignition circuit, in which voltage dividing means has a first arm for connection to a point of measurement in said circuit and a second arm connected to a rectifying means. The output of the rectifying means is connected to means for matching impedance at the rectifying means to a direct current voltage display means connected to the output of the impedance matching means such that a displayed voltage is related to the high voltage in the ignition circuit. Low voltage measuring circuitry is also present which is connectable directly to the display means without the use of an impedance matching circuit.

Abstract: A metal detector is disclosed. The detector comprises oscillator circuit means comprising a first transistor, a second transistor, adjustable resistor means coupled to the emitter of the first transistor, and inductor means arranged to control the conductive state of the second transistor. The oscillator circuit means is arranged to generate an electromagnetic field and the second transistor is arranged to provide an output signal in response to and corresponding to any disturbance of the electromagnetic field caused by the presence of a metal article in the electromagnetic field.

Abstract: Electronic signal processing circuitry for use in the ignition system of an internal combustion engine is disclosed herein. A signal generator which receives crankshaft position pulses from a sensor and produces periodic outut pulses which have durations equal to a constant percentage of the period of the input sensor pulses is disclosed. The generator includes a crankshaft position sensor feeding a bistable flip-flop which controls a dual slope integrator circuit having its output coupled to a comparator with the comparator output coupled back to the reset terminal of the flip-flop. The generator produces pulses at the output of the flip-flop which have durations equal to a constant percentage of the period of the crankshaft position sensor pulses.

Abstract: An automatic four-point probe mechanism, containing various sensors, motors, and precision machine parts necessary to accurately and repeatedly lower a four-point resistivity head onto a semi-conductor slice surface is ideally suited for operator independent measurements of semi-conductor resistivity. The automatic four-point probe finds application in quality assurance incoming-outgoing inspections, materials process control, epitaxial in-process control, diffusion in-process control, thin-film process control, and similar applications. In the preferred embodiment, all torsional forces are eliminated from the probe head, thus avoiding scratch damage to the semi-conductor surface and providing for uniform depth penetration of the probe into the semi-conductor surface and great repeatability of test readings.

Abstract: A vibrating coil assembly for mirror galavanometers, light-beam oscillographs and the like having a mirror and a moving coil suspended by taut wires or ribbons. The ends of the wires nearest the moving coil are provided with eyes and a mounting wire is brought through the eyes and a window in the moving coil to form a figure 8 and clamp the moving coil within it. A stiffening tube for receiving the mirror is pushed over a section of the wire adjacent to one eye. The stiffening tube is cast together with the moving coil and the mounting wire by means of a setting compound.

Abstract: Electric lamps having a gas-filled lamp envelope according to the invention have a hydrogen getter consisting of a coherent mixture of 65-90% by weight of zirconium powder having a particle size of 100-1,000 .mu.m and 35-10% by weight of nickel powder.

Abstract: Method and apparatus for non-destructively testing fabricated metal components with eddy currents. The apparatus includes a coil for generating a magnetic field and means for concentrating the magnetic field into a small inspection volume in the component being tested. The magnetic field induces eddy currents in the component. The coil and the field concentrating means are moved in a manner to scan the component in a predetermined manner with the concentrated eddy currents.