Abstract: Apparatus for selectively measuring voltage, resistance, and time duration f an event, each of which is associated with an electrical network, includes a device for providing a first train of digital pulses, the frequency of the pulse train being related to an analog voltage coupled thereto. The measuring apparatus also includes a clock for generating a second train of digital pulses of fixed frequency, and a constant current source to be coupled to a resistive element being measured by the apparatus. The apparatus further includes counters selectively receiving one of the digital pulse trains for counting the number of pulses received during a selected time period, and for providing a digital output in which the value of a quantity measured by the apparatus is encoded.

Abstract: The meter is primarily adapted to replace a standard analog panel meter and is designed to selectively receive different ranges of input signals such as DC input signals in ranges extending from 50 mVDC to 500 VDC. In the disclosed embodiment there are four ranges also adapted to receive AC input signals in ranges extending from 100 mVAC to 480 VAC. Preferably, a jumper is used to select the different ranges. The jumper is readily accessible at the rear of the meter. The meter circuitry comprises an analog to digital converter having three digit, seven segment display and input circuitry including a range circuit, an operational amplifier and filter circuitry coupling serially to the converter.

Abstract: A voltmeter for selectively indicating the polarity and magnitude of a peak value of voltage. The voltmeter comprises an ammeter, a diode bridge including positive and negative terminals and first and second probe terminals, a capacitor connected to the positive and negative terminals, and variable resistance switching means connected in series between one of the positive and negative terminals and the ammeter for selectively coupling the ammeter across the positive and negative terminals. Filter switching means are provided for selectively coupling the probe terminals to a single polarity of the voltage whereby the voltmeter affords charging of the capacitor so that the magnitude of the positive voltage differential between the positive and negative terminals is substantially equal to the magnitude of the peak value of the single polarity of voltage coupled to the probe terminals.

Abstract: In combination with a meter movement having a pointer movable over a variable value indicating scale having numbered variable value indicating marks forming respective scale segments having substantially different compression or expansion ratios and representing progressively increasing variable values over the entire extent of said segments, a meter control circuit comprising respective amplifiers for controlling the variation of pointer movement over said respective segments of said scale, each of the amplifiers being capable of producing an output which reaches a maximum possible output level when the signal fed to the input thereof is of a value which is to move the pointer of said meter movement to the uppermost point of the associated segment of the scale, means for summing the outputs of said respective amplifiers and feeding the same to said meter movement.

Abstract: A wide dynamic range, wide bandwidth, analog-to-digital conversion system d method. A plurality of overlapped analog-to-digital converters are utilized in conjunction with scaling amplifiers to provide a plurality of output ranges. Means for selecting the set of output bits which provides a magnitude representation of the input signal are provided along with means for outputting a digital representation of the appropriate range.

Abstract: A readout device connected to a parent metering system contains a digital display for circumventing the non-linearity of analog meter movement in the parent system. The readout device displays both numerical and dimensional information in a clear, legible form with both probe and range scale factors accounted for in the display itself. A "probe" switch on the front panel of the module encodes the logarithm of the scale factor associated with the probe in use to a two's complement binary number, and the full scale range information from the "range" switch is encoded in the same manner. This information, along with function information from the "function" switch, is processed by a scale computation circuit which positions the decimal point and causes the units of measurement to be indicated accordingly.

Abstract: A digital voltmeter for measuring an input voltage which can lie in any one of M successive ranges comprises an input scaling device which scales the input voltage to produce a voltage lying in a single predetermined range, and which also produces a range signal indicative of the range in which the input voltage lies. An analogue-to-digital conversion circuit then converts the scaled voltage to a corresponding digital signal which has up to N significant decade figures of resolution, where N<M. The voltmeter has a display unit with M decades, each of which represents a fixed order of magnitude of the input voltage, and control means responsive to the range signal to direct the digital signal to the group of N adjacent decades of the display means appropriate to the magnitude of the input voltage.

Abstract: An electrical system for measuring the relative level of protection afforded a structure against corrosion caused by electrochemical reaction where such structure is so protected by a system of sacrifical anodes. This instrument is constructed with a magnesium alloy anode and calibrated to read with reference to any of the three standard voltage reference half cells currently used in the industry, specifically copper-copper sulfate, silver-silver chloride, and saturated calomel.

Abstract: The automatic range selection circuit is particularly useful with a photomultiplier tube linear microphotometer and includes an amplifier, adjustable and switchable impedances coupled between an input and an output of the amplifier for adjusting the gain thereof, two comparators for comparing the output from the amplifier with upper and lower reference voltage levels, an integrator for integrating the output of the comparators, and an analog control circuit responsive to the output signal level at the output of the integrator for controlling the amount of impedance coupled between the input and output of the amplifier thereby to automatically adjust the gain thereof.

Abstract: An automatic ranging clamp-on ammeter includes an openable normally closed magnetic core for encircling an A.C. current carrying cable has a measuring winding and a sensing winding. A current meter, a diode rectifier and a pair of variable first and second resistors are connected in series across the measuring winding. A relay solenoid is shunted by a Zener diode and is connected in series with a variable resistor across the sensing winding. A sensitivity reducing shunt variable resistor is connected through the relay normally open contacts betwen the junction of the first and second resistors and the meter opposite terminal. An audible signal generator may be connected across the shunt resistor. When the measured current exceeds a predetermined value the relay closes and inserts the shunt resistor across the meter to reduce the measuring sensitivity and increase its range and energizes the audible signal generator.

Abstract: A combined electric meter for measuring AC and DC voltage and ohms is provided with read-outs having indicators progressively actuated for simultaneously indicating AC and DC voltages and for indicating ohms. The read-outs are in the form of light emitting diodes in which the lights are progressively illuminated to indicate a range of voltage or ohms. A pair of probes are manually connected to the circuit to be tested and provide a common connection for the voltage and ohm section of the meter. Should voltage be sensed by the probes, the ohmmeter section is automatically taken out of circuit to protect it from damage. A high speed switch transistor is responsive to an external voltage across the probes for opening the ohmmeter circuit before the external voltage can cause damage to the ohmmeter. The meter has an internal power supply for operating the read-outs and providing a regulated voltage for a resistance to be measured by the ohmmeter section.

Abstract: An input signal supplied to a signal measuring circuit is either amplified or attenuated as necessary to establish the magnitude of the input signal within the defined dynamic range of the measuring circuit and the output signal developed by the measuring circuit is subsequently readjusted through amplification or attenuation to develop an output signal which corresponds to the magnitude of the initial input signal.

Abstract: An expanded scale measuring circuit including a four-arm bridge having a pair of input terminals for connections to a source of input voltage to be measured and a pair of measuring terminals between which are connected a current responsive meter. Located in one pair of the bridge arms are a resistor and diode that establish a reference voltage at one of the measuring terminals. The other pair of arms are formed by a voltage divider network including a zener diode that establishes a fixed reduction in the portion of input voltage applied to the other measuring terminal and therefore in the voltage appearing across the meter. By appropriately selecting resistance values for the divider network, a zero meter current condition is established for an input voltage at the bottom of a range of interest.

Abstract: A method and circuit arrangement for changing the sensitivity of the measng range in a device employing delta modulation in a navigation system. The device uses an integrator for integrating a measured value from a sensor, a threshold detector following the integrator, a synchronizer responsive to the threshold detector and a pulse transmitter driven by the synchronizer. The pulse transmitter provides a reset pulse with appropriate release time to reset the integrator, the reset pulse being counted by a counter fed to a navigation computer. A switching arrangement at the input of the integrator operates to change the sensitivity or scale factor. Switching is controlled by logic circuitry which responds to the level of the measured value as well as the output of the integrator. The reset pulse release time is also employed as a switching criterion.

Abstract: A wide dynamic range, wide bandwidth, analog-to-digital conversion system and method. A plurality of overlapped analog-to-digital converters are utilized in conjunction with scaling amplifiers to provide a plurality of output ranges. Means for selecting the set of output bits which provides a magnitude representation of the input signal are provided along with means for outputting a digital representation of the appropriate range.

Abstract: An improvement is disclosed for use in a chromatographic system of the type including detector means providing a detector output signal indicative of the level of a component sought to be determined, detector output amplifier means for receiving the signal, an error signal balancing loop connected to the amplifier output to provide a balancing signal in feedback relationship to the amplifier, and means for adjusting the sensitivity range of the amplifier.

Abstract: A meter box assembly capable of displaying signal magnitudes. The meter box assembly is in the form of a housing which encloses therein a plurality of circuits, each of the circuits being connected to a display unit on the housing. Each meter box assembly circuit combines in a novel arrangement a meter, switch module, voltmeter circuit and strain gage circuit in order to display in an accurate fashion voltages external to the meter box assembly or to display the voltage output of a strain gage transducer.

Abstract: The invention contemplates tachometer apparatus which functions from an electric pulse input which is of frequency directly related to engine speed of an internal combustion engine. In application to a modern automobile assembly line wherein successively assembled vehicles may have various-sized engines in random succession, the particular feature of the invention is that with essentially the same rectifier circuit and associated indicating meter, and with the simplest of manipulation or connection of a single element, the meter can be direct-reading and fully calibrated whether the invention is applied to a four-cylinder engine, to an eight-cylinder engine or to a six-cylinder engine.

Abstract: A range switching circuit for a solid state electrometer, e.g., for use in radiacmeter, includes a substantially symmetrical circuit having an n-channel MOSFET and an NPN transistor in one branch and a p-channel MOSFET and a PNP transistor in the other branch. The electrometer includes an operational amplifier with two high value resistors in the feedback path. A latching reed relay selectively shorts out one of the feedback resistors when one of the transistors is gated on by the corresponding MOSFET.

Abstract: An electrical meter apparatus wherein the elements of construction of the meter are so constructed as to not warrant any significant amount of precision in manufacture. A selector knob is connected to a switch rotor with a switch rotor being mounted upon a panel bushing which is fixedly connected to the meter housing. A limited amount of canting movement is permitted along with the normal rotative movement between the switch rotor and the panel bushing. The switch rotor is connected in a non-precision manner with a socket and a plug. The plug is loose fittingly connected within an opening in the printed circuit board of the meter. A limited amount of canting movement of the plug is capable of occurring with respect to the printed circuit board.

Abstract: An electrical quantity measuring device is disclosed that includes a probe unit presenting high impedance, which device is suitable for measuring voltage. The components of the measuring device, except for the probe unit, are housed in a cabinet having a meter mounted thereon for external viewing. The probe unit has a contactor and provides an output signal indicative of the predetermined quantity of an element to be measured during contact of the element with the contactor and a ground lead. A high impedance between the contactor and the probe output is provided by a plurality of field effect transistors, and an operational amplifier, the gate of the first of which transistors is connected with the contactor and the gate of the second of which receives a feedback signal from the processing circuitry of the measuring device within the cabinet. A third field effect transistor is connected with the first field effect transistor and compensates for leakage current.

Abstract: An oscilloscope and a digital multimeter are combined in a single housing to provide a portable electronic measurement instrument wherein a substantial portion of circuitry is common to both measurement systems. A cathode-ray tube provides the display for both waveform and alpha-numeric information.

Abstract: For measuring and indicating phase voltage, phase sequence and other electrical values in a three-phase power system, and electrical values in single-phase and DC systems, a unitary instrument or apparatus includes a meter movement and three phase-resistors of equal value which are connected to a common juncture defining a neutral point, with a first phase-resistor connected in series with the meter. The three phases of the external circuit to be tested are connected respectively to the three phase-resistors through a three-pole three-position selector switch for selecting the three different phase to "phase-resistor" relationships. A switch connected between a third phase-resistor and the common juncture performs the alternative functions of opening or closing this circuit.

Abstract: An analog signal processor that is particularly suitable for measuring, igrating and holding a single or a pair of analog signals. The input signal to the analog signal processor may be sinusoidal of relatively low frequency and of low signal strength and slowly varying phase such as may be obtained from a pair of capacitive plates used in electric field measuring devices. The analog signal processor includes an analog current to voltage convertor, a synchronous rectifier and an integrate and hold circuit. In practice the analog signal processor may be mounted on a rotating shaft and converts the very low differentially alternating current input to a proportional d.c. voltage output. The analog signal processor includes timing and switching circuits to provide the desired information about vertical, horizontal and inclined electric fields.

Abstract: A scale modifying circuit for providing either expanded or compressed scale readings on a conventional electrical indicating instrument. The device includes a pair of input terminals adapted to be connected to a source of voltage to be monitored or measured, a voltage responsive network connected with one of said input terminals for supplying output voltage to output terminals of the device, and amplifier means driven from the input terminals and having an output connected to supply a driving voltage to at least one of the output terminals. Expanded scales (or compressed scales) can be provided at the lower, middle, or high end of a particular range of voltages being monitored, or at intermediate points. This results in higher resolution over the expanded scale portion, together with improved accuracy. An illustrated embodiment of the invention embraces a voltage-limiting diode, to effect a cut-off of an ascending applied voltage.

Abstract: An electrical test device and method for use in checking current carrying circuitry by an AC current measuring hook-on meter having a magnetic core for magnetic coupling to the circuit being measured. The test device includes the electrical current carrying conductor means to be tested and support means upon which the conductor means is wound and through which the magnetic core of the hook-on meter may be placed. The test device and method is utilized for more easily and accurately performing a checkout of the circuitry and is particularly useful in connection with appliances.

Abstract: An automatic gain control circuit functions to adjust the magnitude of an input signal supplied to a measuring circuit to a level within the dynamic range of the measuring circuit while a log-ratio circuit adjusts the magnitude of the output signal from the measuring circuit to the level of the input signal and optimizes the signal-to-noise ratio performance of the measuring circuit.

Abstract: A device is provided for automatically selecting from a plurality of ranges of a scale of values to which a meter may be made responsive, that range which encompasses the value of an unknown parameter. A meter relay indicates whether the unknown is of greater or lesser value than the range to which the meter is then responsive. The rotatable part of a stepping relay is rotated in one direction or the other in response to the indication from the meter relay. Various positions of the rotatable part are associated with particular scales. Switching means are sensitive to the position of the rotatable part to couple the associated range to the meter.

Abstract: A digital display electronic meter apparatus is disclosed which is capable of displaying amplitude ratio measurements directly in decibels over its entire amplitude operating range.

Abstract: A plurality of luminescent elements, such as light-emitting diodes, incandescent lamps or the like, are located adjacent each other, each connected to the output of a difference amplifier. The respective inputs of the difference amplifier are connected, on the one hand, to a voltage divider to have different reference voltages applied thereto and, on the other, in common to the input voltage to be sampled so that, as the voltage changes between the amplification ranges of the difference amplifiers, the output therefrom will change in accordance with input voltage so that the brightness of the respectively connected luminescent elements will also change, thus providing gradual increase in brightness of any individual element as the voltage changes. The difference amplifiers may be differentially connected operational amplifiers.

Abstract: The tester does not require any external power source as it derives its energy from the pulse being measured. It includes circuitry which produces a signal proportional to the energy without directly calculating the energy. This is accomplished by generating a current portional to E.sup.2 with a diode network and then integrating the current in a capacitor thus indirectly measuring the true energy. The results are read directly upon a linear meter or can be connected to an oscilloscope or the like for inspection or recording. A bridge rectifier can be used so that the circuit is responsive to both polarities of input pulse or it can be made responsive only to the unipolar signal.

Abstract: A multi-range electrical measuring or indicating instrument including a current sensitive movement adapted to provide an indication of an electrical signal. The movement is connected to contacts which make electrical connection with contact members on a printed circuit member. The printed circuit member includes circuit apparatus for controlling the sensitivity of the instrument, and is movable relative to the contacts to selectively connect the circuit apparatus to the movement.

Abstract: The faceplate of the display system carries the outlines of a sequence of computer compatible digits. Each digit consists of four binary weighted line segments, each segment is associated with a hole in the faceplate. Holes are in line and equally spaced. Behind the faceplate a slide bearing Leds moves along the line of holes. For each operating position the Leds appear behind a set of successive holes. The Leds receive the digital output of the instrument. The arrangement is such that movement of the slide by one position changes the scale by a factor of two. A switch associated with the slide causes the measuring range of an associated instrument to be simultaneously changed by that same factor of two.

Abstract: Centralized telephone circuit testing equipment with receptacles for selectively receiving a wide variety of electronic circuit modules, various modules being provided to make the equipment capable of performing a large number of commonly employed telephone tests. A scanning system is disclosed as part of the central measuring equipment for determining which of a plurality of remote testing stations has requested access to the central measuring equipment, one requesting remote station at a time being given complete control over a test function of the central measuring equipment for conducting tests on a telephone trunk.

Abstract: This invention relates to a range changing circuit that operates in conjunction with a digital panel meter of fixed sensitivity. The circuit decodes the output of the panel meter and uses that information to change the gain of an input amplifier to the panel meter in order to insure that the maximum number of significant figures is always displayed in the meter. The circuit monitors five conditions in the meter and responds to any of four combinations of these conditions by means of logic elements to carry out the function of the circuit.

Abstract: A level indicating system adapted to provide an indication of the peak-level or the volume unit level of an input signal. The system is comprised of an amplifier to receive the signal; a first changeable time constant circuit; a second changeable time constant circuit coupled to the first time constant circuit; an indicator connected to the second time constant circuit; and a control circuit for changing the respective time constants of the first and second time constant circuits. The indicator selectively provides an indication of the peak-level of the signal or the volume unit of the signal depending upon the particular time constants of the time constant circuit.

Abstract: A power meter having a remote power transducer is provided with a circuit for measuring the value of a resistor in the transducer to indicate and automatically adjust the power measuring circuitry for the sensitivity of the transducer used.

Abstract: An electronic device for amplifying, with automatic gain control by discr values, analogue signal samples and thereafter preferably effecting analogue-to-digital conversion of the samples, consists of an amplifier circuit, a comparator circuit, and a delay store circuit. The amplifier has a basic gain during a gain control or gain ranging operation, and supplies an output sample amplified with sufficient gain to bring it into the region of a predetermined voltage. The comparator circuit compares the output of the amplifier circuit with a reference and supplies an output in accordance with the result of the comparison. For analogue-to-digital conversion the amplifier circuit supplies for an input signal U an output signal 2U - VQ, where VQ is the quantification voltage, or, in other embodiments a signal 2U.