Abstract: A method and apparatus for testing circuit boards using two or a small number of probes for making resistive and radio frequency impedance measurements e.g. capacitive measurements. The combination of resistive and impedance measurements substantially reduces the number of tests required to verify the integrity of a circuit board. The impedance or capacitive "norm" values used in testing the circuit boards can be obtained by operating the system in a learning mode. Analysis of the data provides not only fault detection but also can indicate approximate fault location.

Abstract: A test device having a body including an electric bulb rated at 9 or 12 volts, illumination of the bulb being visible from outside the body; and at least two pairs of terminal stubs projecting from the body at regions spaced from each other, the members of each pair of terminal stubs being connected respectively to the terminals of the bulbs, the terminal stubs of one pair being spaced apart from each other by a first spacing of between 9 and 13 mm and the terminal stubs of the other or another pair being spaced apart from each other by a second spacing between 22 and 28 mm.

Abstract: An apparatus and method of sensing openings in a perforated sheet by means of electrical contact between electrically conducting surfaces positioned on opposite sides of the sheet.

Abstract: An apparatus and a method is provided for verifying electrical coupling between a first contact point of an electrical device on a circuit board and a first connection pin, on a board tester. Within the tester, a JK flip-flop is electrically coupled to the first connection pin through an amplifier. A Q output of the JK flip-flop is initialized to a logic 0. An electrical probe with an electrical voltage is stroked across the first contact point and any other contact points on the circuit. If the first contact point is electrically coupled to the first connection pin, a logic 1 will be held on the Q output of the JK flip-flop. If there is no electrical coupling, then a logic 0 will be held on the Q output. By reinitializing the JK flip-flop and electrically coupling it to another connection pin, electrical coupling between another contact point and another connection pin may be tested.

Abstract: A humidity sensor operates with a capacitive sensor element (C.sub.S) which is arranged in one branch of a free-running multivibrator (MV), whereas a reference capacitor (C.sub.ref) is arranged in the other branch of said multivibrator. Both output signals (U1, U2) of said multivibrator (MV) are averaged by means of RC elements (R3, C1; R4, C2) and supplied to a differential amplifier (DV), the output signal (Ua) of which changes the operating voltage (U.sub.B) of the multivibrator (MV), and therefore, linearizes the characteristic of the capacitive sensor element (C.sub.S).

Abstract: Moisture in wood veneer strips received from a drying oven is measured by passing the veneer strips on a conveyor between arrays of plates including a transmitting plate on one side of the veneer and a juxtaposed receiving plate on the other. Phase plates on either side of and on the same level as the transmitting plate are empowered by a signal having the reverse phase to that applied to the transmitting plate, and when wet veneer passes between the plate arrays, part of the transmitted signal is shunted, placing the veneer at virtual ground level and reducing the signal received by the receiving plate. A plurality of diagonal passages in the lower plate array receive air under pressure for conveying the veneer strips thereover.

Abstract: Circuit arrangement for fault locating in conjunction with equipment for the trunk feeding of electrical loads by means of dc series feeding in which the trunk supply circuit is equipped with cross branches conducting only for currents in the direction of a test current. In such a circuit arrangement it is possible to indicate the results of the fault locating in a simple manner. Towards this end, one window discriminator for each load is provided in the supply point. This circuit arrangement can be used advantageously in communications equipment having trunk fed waystations.

Abstract: A speed detecting apparatus having a detector (101) for generating two sine-wave signals (PA, PB) which are .pi./2 out of phase with each other and have a frequency proportional to the speed of rotation of a motor so that actual-speed voltages (V.sub.L, V.sub.H) can be produced which are proportional to the speed of rotation of the motor. The speed detecting apparatus includes a quadrupling circuit and a frequency-to-voltage converter 107. Also included is a first speed generator for generating the actual-speed voltage (V.sub.H) in a high-speed range and a second speed generator which includes a four-phase rectangular signal generating circuit (106), a differentiating circuit (109), and a synchronous rectifier circuit (110) for producing the actual-speed voltage (V.sub.L) in a low-speed range. The voltages generated by the first and second speed generators are selectively issued as an output depending on whether the motor rotates at a high speed or a low speed.

Abstract: A directional relay for providing indication of the direction of a fault on an electric power transfer network has an adder (9), a subtractor (10) and filters (11) which receive signals from voltage and current transformers (6,7) and derive signals related to fault-induced forward and backward transient waves on the network. To ensure reliable operation even when the relay is close to a low impedance element such as a generator (2), the forward wave related signal is delayed in a delay unit (12) by an amount equal to the propagation time of the wave along the section protected by the relay, before the difference between its square and that of the backward wave related signal are integrated (16) to derive the fault direction signal.

Abstract: A moisture analyzing system including an antenna coupled to a frequency-modulated voltage source and arranged to apply an alternating electric field to a material being tested for moisture content. An LC tank circuit is connected in parallel with the antenna and a resistance is connected between the source and the parallel combination of the antenna and the tank circuit. Detecting the level of resonant voltage peak output signals produced across the tank circuit is a measurement circuit which provides therewith a sensing signal indicative of the moisture content of the material being tested. The detection of resonant peak amplitudes produced by frequency sweeping a tank circuit eliminates many unstable variables that interfere with moisture measurements.

Abstract: An elongated carriage has a first capacitive probe disposed from its top surface opposite to an object surface, and a second capacitive probe disposed from its bottom surface opposite to a level reference surface. An arm is orthogonally disposed from the elongated carriage member to provide lateral support. The carriage is moveably supported at opposite ends of the elongated member and at the distal end of the arm by three rolling members which roll in corresponding grooves of supporting members as the carriage is moved in lateral increments with respect to the stationary object and reference surfaces. The first capacitive probe and the object surface comprise a first capacitor, and the second capacitive probe and the reference surface comprise a second capacitor. As the carriage moves laterally, the first probe is moved across the object surface while the second probe is moved across the reference surface. The capacitance of each probe is translated into a distance measurement.

Abstract: A fault point in a line section of a three-phase power transmission line, is determined by measuring currents and voltages at a measuring point arranged adjacent the near end of the section. The type of fault (single-phase/multi-phase ground fault/phase-to-phase fault) is determined and the parameters in a quadratic equation are determined using the relative distance (n) from the measuring point to the fault point as a variable. The equation is derived in advance from the electrical relationships between the complex values of the line impedance, the source impedances of the networks located ahead of and behind the fault, and measured currents and voltages following elimination of the fault resistance and possible zero sequence components. The parameters in the equation are determined by the type of the fault, by the measured voltages and currents and by said impedances. The equation is solved directly by means of a numerical square root method.

Abstract: An improved method and system that utilizes conductance values of cationic and anionic exchange resins classified as layers of a mixed resin bed to automatically detect interfaces between the layers is disclosed. The arrangement includes electrical circuitry which initially samples the conductivity of a passing resin slurry. The initial conductivity value is compared to subsequent conductivity values of the passing slurry and the flow of the passing slurry is automatically terminated when the subsequent conductivity value is a certain fraction of the initial conductivity value. Termination in response to this equality condition effectively detects the interface between classified layers of a mixed resin bed.

Abstract: The secondary ignition circuit of a spark ignited internal combustion engine is analyzed to identify the location of faulty portions of the circuit, the circuit having an induction coil for generating sparking voltage pulses repetitively, and a distributor for cyclically distributing the voltage pulses to respective spark plugs in a predetermined order. The peak amplitude of respective voltage pulses of one polarity developed at a single point in the secondary ignition circuit for respective spark plugs in each engine cycle is measured to produce measurement signals systematically related thereto. A comparison signal is derived that is systematically related to the average peak amplitude of voltage pulses of the one polarity developed for all spark plugs. Successive measurement signals are compared with the comparison signal, and a fault is indicated when a measurement signal differs from the comparison signal by more than a predetermined differential.

Abstract: The apparatus according to the present invention for inspecting the quality of electrodeposited electrically insulating coatings on electrically conducting parts comprises wetting means for producing a high pressure, low flow volume spray of an electrically conducting liquid and means for producing a low pressure, high flow volume column of the same conducting liquid. It further comprises a conveyor which carries the part to be inspected through the spray produced by the wetting means and through the liquid column, as well as means for applying a voltage between the part and the liquid column and for measuring the resulting current when the part to be inspected passes through the liquid column. The high pressure spray produced by the wetting means thoroughly wets the part to be inspected and prevents air bubbles from adhering to the part, air bubbles being an impediment to correct current measurement. The measured current is an indication of the quality of the insulating coating.

Abstract: An apparatus useful in determining the value of a capacitor includes a first bilateral switch for flowing a charging current through a resistive element to an initially-depleted first capacitor of known value. The first capacitor is thereby charged to the potential of a trigger reference over a resulting first time period. A second bilateral switch is provided for flowing a charging current through the same resistive element to an initially-depleted second capacitor, thereby charging it to the potential of the same trigger reference over a resulting second time period. A device such as an oscilloscope or frequency counter is used for determining these time periods and the value of the unknown second capacitor may thereupon be computed using disclosed formulas.

Abstract: A pair of uniquely designed spring clips are snapped onto existing elements of a visual indicator such as the dial of a utility meter. An encoder having attachment elements with a spacing therebetween corresponding to the spacing between the clips is attached to the clips to quickly, easily, and precisely attach the encoder to the dial in properly aligned position.

Abstract: An electrical circuit identification means for identifying a particular circuit while the latter is normally energized and functioning, said means being usable with a plurality of energized circuits leading to different remote locations in an electrical installation such as a building structure or other facility, where the circuits originate at an energy distribution network that has fuses, circuit breakers or the like adapted to render the circuits dead or unenergized. A portable electrical load device is provided, to be applied to a designated circuit at the remote location where it is to be worked on, said device including a circuit controller or interrupter activated and powered by current from the circuit, so as to periodically interrupt or vary the current passing through the load and thereby cause electrical pulses or surges therein.

Abstract: An improved method and apparatus for determining the dielectric constant of materials which flow using capacitive techniques, having an electrode device with at least two output terminals and three or more electrodes spaced at fixed distances from one another. At least two of the electrodes are connected through a switch so that first and second capacitances appear at the output terminals of the electrode device depending upon the position of the switch. The output terminals of the electrode device being connected to an oscillator which produces an output signal indicative of the frequency of the oscillator's oscillation which is proportional to the capacitance at the terminals of the electrode device. The output signal of the oscillator is connected to a bi-directional counter or microprocessor which is used to calculate a value proportional to the change in capacitance of the electrode device when the switch is closed and to thereby determine the dielectric constant of a material being tested.

Abstract: A detection signal of a frequency corresponding to a rotational frequency is applied to a frequency-voltage converter and its converted voltage signal is provided to a sine-cosine current generator, from which sine-wave and cosine-wave currents having sine and cosine values corresponding to the voltage value of the voltage signal are supplied to a cross-coil rotary magnet type indicator for providing an indication of the rotational frequency by a pointer. When the power source is cut off, interruption of the power source voltage supply to the frequency-voltage converter and the sine-cosine current generator is delayed by delay means and, in the delay time, the input to the sine-cosine current generator is reduced, returning the pointer to the zero point. The indicator further includes a zero-resetting magnet which interacts with the rotary magnet to force the pointer to move to said zero point.