Abstract: A nonlinear load circuit, consisting of a transistor and a resistor in series, is provided for the photovoltaic array under test. Base bias for the transistor is supplied via the source-to-drain path of a field effect transistor (FET). A ramp signal is fed to the gate of the FET. As a result of the nonlinear relationship between the gate voltage and source-to-drain current of the FET, equal ramp steps result in a nonlinear effective load for the array under test. This produces a very gradual change in load impedance for each ramp step in the regions of high current output from the array ("current mode"), and relatively greater changes in load impedance for each ramp step at output levels of lower current and higher voltage from the array ("voltage mode").Advantageously, the array is illuminated by a pulsed flash lamp. A photosensor detects the light level incident on the array, and comparison circuitry provides a "sample" pulse each time that the incident light level is at a selected value.

Abstract: The wide-band nuclear magnetic resonance spectrometer is used for determining the NMR frequency of a sample in an external magnetic field and comprises a transmitter for generating a signal having a frequency equal to the NMR frequency of the sample. A receiver receives the signal from the sample and a probe is provided for applying the signal from the transmitter to the sample and from the sample to the receiver. The probe comprises a detector in the form of a tank circuit for detecting the signal of NMR frequency from the sample and for coupling the detector to the receiver and for substantially matching the impedance of the receiver.

Abstract: A high current field test set is electrically connected to pass test currents of overcurrent proportions through a single pole of a multipole static trip circuit breaker. The normal electrical connections between the breaker phase and neutral current sensing transformers and the static trip unit are made via a ground fault defeat cable which serves to automatically route the phase current monitoring signals produced by the test currents and fed to the appropriate trip unit phase overcurrent signal processing network through two primary windings of the ground fault sensing differential current transformer in opposite directions, thereby inhibiting a ground fault trip function.

Abstract: Optical apparatus for extending a light curtain, using a light beam shifted periodically laterally parallel to itself onto an array of plane mirrors at an angle to the beam, the span of the array normal to the emergent reflected beam being greater than its span normal to the incident beam.

Abstract: The rise of an intermittently incoming pulse modulated wave is detected to open a gate circuit by the detected output to supply therethrough a clock pulse of a frequency higher than the carrier frequency of the incoming pulse modulated wave to a counter and a pulse decay detector for counting with the former and resetting the latter every carrier cycle of the pulse modulated wave. While the pulse modulated wave continue, the pulse decay detector is repeatedly reset to be prevented from overflowing. Upon interruption of the pulse modulated wave, the pulse decay detector overflows to provide an output after the elapse of predetermined time selected to be longer than one carrier cycle. By the overflow signal, the gate circuit is closed to stop the counting operation of the counter and the numerical value corresponding to the predetermined time is subtracted from the count value of the counter, thereby obtaining the pulse width of the pulse modulated wave.

Abstract: A scanning mirror position sensor operable from the back side of a scanning mirror which utilizes the front side of the mirror for scanning a scene to be interrogated or displayed. A rectangular uniformly distributed light source is reflected from the back surface of the scanning mirror across a plurality of parallel photo voltaic diode structure bars which may have a gray coded aluminum mask thereon. The outputs of the diode structure bars energized through openings in the aluminum mask may energize sense amplifiers and output logic to provide a continual and accurate mirror position value.

Abstract: A magnetic field detector for determining the presence of a magnetic field disturbance in the vicinity of the apparatus senses the difference in magnetic fields at two spaced-apart locations. A pair of field sensors, each including a body of polarizable liquid and a probing coil, are connected in series and provide an output signal that is produced in the coils by the free precession of the protons of the liquid bodies in the earth's magnetic field. A timer circuit controls a relay to alternately connect the magnetometer coils to a source of polarizing current during a polarizing period, and to detection circuitry during a listening period. The detection circuitry includes a high gain signal channel comprising a multi-stage, high input impedance preamplifier and a bandpass amplifier tuned to the frequency range of the signals generated in the probing coils.

Abstract: A method of viewing nuclear magnetic resonance, wherein a test sample is immersed into a unidirectional polarizing magnetic field and subjected to the effect of a radio-frequency magnetic field directed at a perpendicular to the unidirectional polarizing magnetic field. The amplitude of the radio-frequency magnetic field is selected so as to exceed the average local magnetic field set by the gyromagnetic nuclei of the test sample, and the component of magnetization of the test sample longitudinal to the unidirectional polarizing magnetic field is viewed at a frequency of nuclear magnetic resonance in an effective magnetic field in a frame of reference rotating about the sense of the unidirectional polarizing magnetic field at a frequency of the above radio-frequency magnetic field in the direction of natural Larmor precession of the gyromagnetic nuclei in the test sample.

Abstract: A circuit is provided for monitoring a signal generated by an oscillator and producing a digital display of the sign and magnitude of the deviation of the actual frequency of the oscillator-generated signal from a preselected desired frequency. Alternating sampling and display period pulses are produced in the circuit and, during the period of a sampling pulse, clock pulses are produced at a rate proportional to the actual frequency of the oscillator-generated signal. A plurality of counters in the circuit count the number of clock pulses produced during the period of a sampling pulse and hold the count during the period of a display pulse succeeding the sampling pulse. Read only memory devices sense the count held by the counters and decode the count to drive display units either to display the magnitude and sign of the deviation when it is within a predetermined range or to display an out-of-range indication.

Abstract: A dosimeter for measuring accumulated dosage of noxious gases, such as carbon monoxide (CO), oxides of nitrogen, (NO.sub.x), etc., incorporates a gas-sensing electrochemical cell which utilizes an electrically biased, hydrated, solid polymer electrolyte (SPE) sensing cell. CO and other noxious gases are oxidized at the sensing electrode and the cell current is a measure of the gas concentration. The cell output current is applied to an electrically resettable current integrating device, which is basically an integrating coulometer in which metal is plated onto a working electrode in response to the cell output current. A fixed, reverse calibration current is driven through the coulometer during dosage readout to deplate the metal from the coulometer working electrode. An accurate timing device measures the time required to deplate the working electrode of the coulometer. This product of the fixed calibrating current and the time required to reset the coulometer, i.e.

Abstract: A calibrated unipolar signal is used to deviate a frequency modulator by a predetermined amount .DELTA.f from a carrier f.sub.2. An automatic frequency control circuit operates to bring the carrier back on frequency and a meter connected in the control circuit will read this departure from normal. During the test for correct deviation, a frequency shifter compensates for the predetermined frequency deviation and the meter would so indicate, e.g., would not change reading from that of carrier alone, if the deviation caused by the calibrated unipolar signal is equal to that incorporated in the frequency shifter. If the reading does change, the modulation sensitivity of the frequency modulator is adjusted until the readings before test (using carrier only) are the same as those under test.

Abstract: Carrier lifetimes and bulk diffusion length are qualitatively measured as a means for qualification of a P-N junction photovoltaic solar cell by alternately applying high frequency (blue) monochromatic light pulses and low-frequency (red) monochromatic light pulses to the cell while it is irradiated by light from a solar simulator, and synchronously displaying the derivative of the output voltage of the cell on an oscilloscope. This output voltage is a measure of the lifetimes of the minority carriers (holes) in the diffused N layer and majority carriers (electrons) in the bulk P material, and of the diffusion length of the bulk silicon. By connecting a reference cell in this manner with a test cell to be tested in reverse parallel, the display of a test cell that matches the reference cell will be a substantially zero output.

Abstract: A uniform magnetic field generating device for generating a uniform magnetic field such as that required in a nuclear magnetic resonance device is disclosed. In prior art devices, in order to obtain a highly uniform magnetic field space, a parallel gap has been formed between pole pieces which were magnetically homogenized and mounted on magnets coupled by a yoke. In place of such pole pieces, a magnetically homogenized pole block or a pole block sandwiched by pole pieces is inserted between the magnets and a cylindrical hole or space is formed in the pole block, a sectional area of the space taken in parallel with the direction of a magnetic field due to the magnets and perpendicular to the axial line of the space being of circular, ellipse or rectangular shape, whereby a highly uniform magnetic field space is established.

Abstract: A twisted nematic liquid crystal device contains a liquid crystal material having dielectric anisotropy .DELTA..epsilon. which is positive for certain values of temperature and frequency of an electrical signal applied across the material and negative for other values of these parameters. The device includes a heater and a test area (separate from the display area of the device) at which transmittance of light is monitored by a heater control circuit. A test frequency chosen to give .DELTA..epsilon..apprxeq.0 at the minimum desired operation temperature of the device is applied across the test area and the light transmittance is monitored to assure that the temperature is high enough. When the temperature is too low, the heater element is automatically energized to increase the temperature of the liquid crystal device.

Abstract: A method and apparatus for detecting whether the phase difference between a first and a second signal is constant or not. A Q output and Q output are derived from a set-reset flip-flop circuit by imparting thereto a first and a second trigger pulse which are respectively obtained on the basis of said first and second signals. Subsequently, on the basis of said Q and Q outputs, there are produced two pulse signals the fall portions of which correspond to those of said Q and Q outputs respectively but the rise portions of which are caused to occur while being delayed by a period of time corresponding to the duration of said trigger pulses. Thereafter, there are produced logical products of said first and second pulse signals with respect to said first and second trigger pulses. Thus, it is detected whether the phase difference between said first and second signals is constant or not, according to whether the outputs of said logical products are present or not.

Abstract: A phonograph cartridge is provided for use on a programmable phonograph turntable or changer. The cartridge includes a housing for mounting an electro-mechanical transducer on the end of a phonograph tone arm and a stylus connected to the electro-mechanical transducer for the reproduction of audio information contained in the groove of a record carrier. A sensor including a light source and a photodetector is mounted on the housing in a position in close proximity to the stylus to provide a unitary cartridge and sensor assembly. The stylus and sensor elements are mounted on a subframe portion which is removable from the housing to facilitate replacement of the stylus or sensor without requiring replacement of the entire phonograph cartridge.

Abstract: Methods and apparatus are disclosed herein for measuring the electrical conductivity of unknown fluid solutions. A constant current DC pulse having a very fast rise time is supplied to a test cell containing the unknown solution. By sampling the voltage across the test cell just prior to the application of the pulse and at a predetermined time during the application of the constant current pulse, a voltage difference is obtained which may be interpreted in terms of the conductivity of the unknown solution.

Abstract: In a four electrode conductivity sensor, each pair of electrodes is coupled to a respective one of two operational amplifier circuits that establish a fixed potential relationship between the two potential electrodes so that current flow between the two current electrodes is maintained directly proportional to the conductivity of the solution. Specifically a direct or alternating excitation voltage is applied to the positive input of one operational amplifier, while the other receives a fixed reference potential input. The operational amplifiers supply a unity gain, noninverted output to the respective current carrying electrodes, while the potential electrodes are directly connected to the feedback input of the respective amplifier.

Abstract: A system for automatic monitoring of a communication signal in the RF or IF spectrum utilizes a superheterodyne receiver technique with a VCO to select and sweep the frequency band of interest. A first memory is used to store one band sweep as a reference for continual comparison with subsequent band sweeps. Any deviation of a subsequent band sweep by more than a predetermined tolerance level produces an alarm signal which causes the band sweep data temporarily stored in one of two buffer memories to be transferred to long-term store while the other buffer memory is switched to its store mode to assume the task of temporarily storing subsequent band sweeps. Each alarm signal alternates the roles of the two buffer memories. In a second embodiment, the roles of the two buffer memories are switched at the end of each heterodyne receiver band sweep for display of successive band sweeps at a faster rate and for automatic long-term store of any band sweep producing an alarm.

Abstract: A lightning detection system utilizes a gated magnetic direction finder for determining the range and direction of lightning discharges to ground. Logic circuitry is provided for controlling gating circuits within the direction finder so that the direction measurement is made during the initial few microseconds of the return stroke waveform, thereby minimizing errors caused by nonvertical lightning channels to ground, branches and intracloud discharges. Distance measurements are made by analyzing the amplitude of the detected return stroke waveform, or by utilizing two or more geographically separated direction finders and triangulation techniques. The waveforms of the signals received by the direction finder are analyzed to determine whether the discharge is ground stroke or another type of discharge, or background noise. Further circuitry can be used to distinguish between various types of ground strokes, such as first strokes or subsequent strokes in a flash.