Abstract: A logging-while-drilling system is disclosed which includes a pair of receiving antenna disposed between upper and lower transmitting antenna. The upper and lower transmitting antenna are energized successively to generate an electromagnetic wave which propagates through the formation surrounding the borehole. The amplitude attenuation and phase shift of the electromagnetic wave between the receiving antenna is measured. Measurements from both the upper and lower transmitting antenna can be combined to eliminate by cancellation system error components. In order to further improve the performance of the logging-while-drilling system, separate and dedicated driver circuits are provided proximate each transmitter. In addition, reference signals which are utilized to coordinate and synchronize the operation of the various components of the logging-while-drilling system are provided at frequencies which are substantially different from the interrogation frequency of the electromagnetic interrogation signal.

Abstract: A magnetoresistor (MR) and a non-magnetoresistor (NMR) are formed of indium antimonide or other magnetoresistive material in thermal proximity to each other on an integrated circuit substrate (100). Hall effect shorting strips (104) are formed on the magnetoresistor (MR) to make it much more magnetoresistive than the non-magnetoresistor (NMR). A current mirror (80) causes equal constant currents (I2) which do not vary with temperature to flow through the magnetoresistor (MR) and non-magnetoresistor (NMR), such that magnetoresistor and non-magnetoresistor voltages are developed thereacross respectively. The magnetoresistor and non-magnetoresistor voltages vary equally in accordance with temperature. The magnetoresistor voltage also varies in accordance with applied magnetic flux. A comparator (66) subtracts the non-magnetoresistor voltage from the magnetoresistor voltage to produce an output signal (Vout) with the temperature variation canceled, and which thereby varies only in accordance with magnetic flux.

Abstract: The vehicle has two groups 24, 26 of foils which transfer flux to and return flux from a wall 10 of a pipeline. The flux is from a coil 20 or from a permanent magnet or magnets. Each group is a single group of common foil members 59 interleaved with spacers 69; or alternatively each group contains sets of common foil elements such as six sector-shaped sets, for example. Each foil 59 and each spacer 69 is cut from steel for example stainless steel. Each foil 25 is an outwardly-directed resiliently-deflectable foil integral with the common foil member forming an array around the vehicle. The foils are separated by slots 63 preferably V-shaped. The sets are clamped together by retainers 73 and pins 71. In the pipe 10 the foils deflect as indicated by broken lines 32, 34. The length of each foil is at least 200 times its thickness. The foil separation divided by their thickness is at least unity. Sensors 28 detect leakage flux due to metal loss from the wall.

Abstract: The apparatus includes an array of azimuthal current electrodes (Aaz.sub.i) that are circumferentially spaced apart from one another on a body together with two annular guard electrodes (A2) disposed on opposite sides of the array of azimuthal current electrodes (Aaz.sub.i). Measurement currents (Iaz.sub.i) are emitted by the current electrodes (Aaz.sub.i) and focusing currents are emitted by the guard electrodes (A2). Azimuthal monitor electrodes (Maz.sub.i) are associated with respective ones of the azimuthal current electrodes (Aaz.sub.i). Two annular monitor electrodes (M3, M4) are disposed on opposite sides of the array of azimuthal current electrodes (Aaz.sub.i). For focusing purposes, a servo-control system controls the emission of the currents so as to substantially cancel the potential difference detected between the short circuited monitor electrodes (M3, M4) and each of the azimuthal monitor electrodes (Maz.sub.i). In response to the measurement currents (Iaz.sub.i), output signals (Raz.sub.

Abstract: A secondary ignition voltage peak meter provides an indication of ignition operation. A capacitive sensor picks up secondary ignition voltage, and an inverting amplifier reduces and inverts that voltage to a second signal. The second signal is conducted to first and second signal storage circuits and is respectively stored as third and fourth signals. Signal from the second storage device is provided to a second amplifier and converted to an on-off gating signal. The signal from the first storage device is provided to a first power terminal of a field effect transistor, and the gating signal is provided to the gate terminal. A third storage device is connected to a second power terminal of the FET, and a third amplifier is connected to the third storage device to provide an output which is moved by a capacitor and adjusted by a potentiometer. The output signal is delivered to a display driver, and the display driver converts the signal to a sensible signal of good, fair and poor ignition operation.

Abstract: The apparatus includes an annular current electrode (Ao) mounted on a body and guard electrodes (A2, A'2) disposed on the body above and below the annular current electrode. A first measurement current (Io) is emitted by the central current electrode (Ao) and focusing currents are emitted by the guard electrodes (A2, A'2). A first output signal representative of the deep resistivity of the formations is generated in response to the first measurement current (Io). One of the guard electrodes (A2) includes two longitudinally spaced-apart portions, and an array of azimuthal current electrodes (Aazi.sub.i) that are circumferentially spaced-apart from one another is disposed between these two portions. Second measurement currents (Aaz.sub.i) emitted by the azimuthal current electrodes (Aaz.sub.i) are focused longitudinally by the currents emitted by the said two portions of the guard electrode (A2). Second output signals are generated in response to the second measurement current (Iaz.sub.

Abstract: An eddy-current apparatus for measuring the conductivity of a conductive material and for reducing the influence of lift-off on conductivity measurements is provided. The apparatus includes a probe for inducing an eddy-current in a conductive material and a digital LCR meter for measuring the impedance of the probe when it is placed near the conductive material. A digital processor uses calibration impedance data obtained from a series of reference materials and an impedance measurement for a test material to produce a conductivity value independent of lift-off between the probe and the test material.

Abstract: A device for determining the position of an axially movable body wherein the position of the body is deduced from the inductance of a coil arrangement. A layer which has a layer structure containing less than 8% by weight of P, preferably up to 3% by weight of phosphorus, up to 2% by weight of an element of main group IV or V, in particular antimony, and up to 5% by weight of a transition metal element, in particular cobalt, is deposited on the body. The percentages by weight resulting from the sum are increased up to 100% with nickel. An axial movement of the body to which the layer is joined, modifies the magnetic flux in a coil arrangement comprising at least one coil. The changes in inductance resulting therefrom are measured and the position of the body is deduced therefrom.

Abstract: In the rolling probe, the measuring pole is designed as a rotating, rotationally symmetrical roller (4), such as a disk, cylinder or sphere, which directly contacts the surface of object to be measured (5) and is placed in the range of a sensor system. As a result, the maximum possible signal deviation can be fully used for the measuring. An increased measured value resolution and measuring accuracy especially in the measuring of thin sheets is achieved. Further, the actual thickness measuring takes place at the contact point with the layer to be measured. Thus, a true "one-point measuring" is involved.

Abstract: A synchronous position correction system for a self-controlled linear synchronous motor train includes a position detector for detecting a positional relationship between a propulsion winding provided on a track and a field pole provided on the train which is formed by a plurality of cars. A synchronous operation of the formed train is performed at a phase which is obtained by correcting a phase detected by the position detector on the basis of a difference between an average phase of the whole of the formed train and the phase detected by the position detector, at a phase which is obtained by correcting the phase detected by the position detector on the basis of a difference between the phase of a speed electromotive force of the whole of the formed train and the phase detected by the position detector, or at a phase which is detected by the position detector in conjunction with the position of a central car of the formed train.

Abstract: A detachable coils air core movement holder having aligned upper and lower holders defining a chamber therebetween for housing a magnet with a center shaft extending through the upper holder and coupled to a pointer of a meter. A plurality of horizontal projections extend from the periphery of the aligned upper and lower holders for mounting on each a bobbin having a coil wound thereon.

Abstract: A pointer intended for attachment to the digging arm of an excavator, is characterized by an elongated arm which can be pivoted on the digging arm using a drive whose driving movements are activated and controlled by the magnetic field generated by an underground cable, conduit or like conductor in a manner such as to cause the pointer to point towards the cable, conduit or like conductor independently of the position of the digging arm.

Abstract: An implement for removing from its socket and testing a Christmas light bulb which has a handle with two opposite ends. The handle has a cap secured to one of the ends. The cap has a socket in its distal end and the socket is adapted to loosely receive the base of a bulb. A cavity is formed in the other of the ends. The cavity has a top and a pair of opposite side walls that extend toward the other end, and a bottom. A bulb gripper is provided in the bottom for gripping the base of a bulb. A battery is housed in the handle. The battery is easily accessible so that it can be removed and replaced as desired. The battery and the cap are electrically connected. The handle cooperatively attaches the cap and the cavity and the gripper so that the bulb can be positioned in the cavity and the gripper can grip the base to the bulb from its socket without separating the bulb from its base. The bulb then can be loosely positioned in the socket and tested.

Abstract: A motion sensor for detecting and providing an indication of the direction of motion along a predetermined line of travel of a smooth, uninterrupted, generally flat or gently curved, ferromagnetic target surface of a movable member includes a permanent magnet, at least one active field sensor for sensing magnetic field intensity and mounting structure for positioning the magnet and sensor along the line of travel in fixed spatial relationship to the target surface and to each other. The magnetic field of the permanent magnet, upon movement of the target surface relative to the permanent magnet along the line of travel, creates asymmetric magnetic fields along the target surface on either side of the axis which are unequal in strength in a way which is dependent upon the relative direction of motion of the target surface. The sensed magnetic intensity permits determination of the direction of motion, where the target surface is ferromagnetic, and velocity, where the target surface is conductive.

Abstract: A portable hand held diagnostic tool which non-invasively detects an electric field when placed adjacent a component of a spark plug firing portion of an ignition system and provides a positive indication of the detected electric field. A printed circuit board containing a control circuit, a replaceable battery supply, an ON/OFF switch, an indicator such as an LED, and a pickup antenna, is slidably mounted within the hollow interior of a dielectric tubular case. The antenna is located adjacent a pickup end of the case and detects the electric field generated by an ignition system during firing of a spark plug which actuates the LED in response to the detected firing. The dielectric case is free of external metal parts adjacent the pickup end to help minimize arcing. A battery test circuit may be incorporated into the control circuitry to ensure an adequate power supply for operation of the control circuitry. A fixed or variable resistor enables the sensitivity of the firing pickup to be selected.

Abstract: A magnetic position sensor system including a magnetic medium divided into a plurality of areas of magnetization for producing a magnetic field with a variable intensity. The magnetic medium includes a first side, a second side and a longitudinal axis. A Hall cell is used for detecting the intensity of the magnetic field produced by the magnetic medium and for producing an electric signal which corresponds to the intensity detected. The magnetic medium is movable with respect to the Hall cell so that the Hall cell scans along the first side of the medium along the longitudinal axis and detects the intensity of the magnetic field at any given point along the longitudinal axis of the medium.

Abstract: An apparatus of sensing a magnetic field using a ceramic superconductor magneto-resistive element having a superconductor magneto resistive effect of non linear characteristic against the applied magnetic field, there is provided a coil for applying a bias magnetic field to the magneto-resistive element, the coil is connected to a feed back power source for supplying current for holding the output of the magneto-resistive element constant value, whereby the applied magnetic field is measured by the current supplied to the coil.There is disclosed also a device for sensing a magnetic field using a magneto-resistive element comprising a superconductor member having weak coupling grain boundaries, said device comprising means for applying A.C. bias magnetic field to said element, and means for taking out an output voltage of the element generated by application of the bias magnetic field as the signal representing the intensity of the applied magnetic field.

Abstract: A dual sensitivity stud sensor senses studs through both thick and thin surfaces. Studs are sensed by detecting a change in the capacitive loading of plates as they are moved along a surface and into proximity with a stud. The sensor informs the operator when the sensor has (incorrectly) been calibrated over a stud. The sensor also informs the operator if the sensor is placed against a surface either too thick or too thin for stud detection. Through use of a digital register, the sensor remains calibrated indefinitely while the sensor is powered on.

Abstract: Primary coils generate flux upon being excited by a predetermined ac signal. A stator is made in a plate-like configuration and has plural primary coils independently in the circumferential direction so that flux is generated by the primary coils in the direction of the axis of rotation. A rotor is provided displaceably relative to the primary coils to change reluctance with respect to the flux generated by the primary coils. Accordingly, as the rotor is rotated, reluctance change is produced due to the relative positional relation between the primary coils provided in the stator and the rotor. This reluctance change causes to change self-inductance of the primary coils and affects the exciting ac signal flowing through the primary coils and, therefore, by outputting the self-induced ac signal in the primary coils, the relative positional relation between the rotor and the primary coils, i.e., the rotational position of the rotor, can be detected.

Abstract: A gauge probe for a handheld combination coating thickness gauge allows the combination coating thickness gauge to measure both nonferrous coatings on ferrous substrate and nonconductive coatings on conductive nonferrous substrate. The gauge probe enables the combination coating thickness gauge to determine automatically, with a single probe, the substrate characteristics, and to effect a measurement of the coating thickness on that substrate. The technique used to measure coatings on a ferrous substrate utilizes a permanent magnet to provide a constant magnetic flux and a Hall sensor and thermistor arranged to measure the temperature-compensated magnetic flux density at one of the poles of the permanent magnet. The flux density at the magnet pole can be related to a nonferrous coating thickness on a ferrous substrate. The technique used to measure nonconductive coatings on a conductive nonferrous substrate utilizes eddy current effects.