Abstract: Controlled bending movement of a flexible elongate rod or filament in response to a bend signal indicative of a desired amount of bending is effected by a strip of shape-changing material disposed on a first side of an elongate rod element, the shape changing material changing shape in response to an actuation signal, thereby causing the filament element to bend, and a sensor including a strain gauge disposed on the rod element on a second side opposite the first side, said sensor sensing the amount of bend in the rod element from strain indicated, and a feedback control comparing the amount of bend of the filament sensed to a desired amount of bend defined by said bend signal and altering the actuation signal as required to make the amount of bend sensed the same as the amount of bend desired.

Abstract: An improved isolated current sensing device. The invention consists of two magnetizable cores which surround the conductor carrying the current to be measured. The two cores are cyclically saturated in opposite directions by a high-frequency excitation current counter-wound around the two cores. The device then detects through an output winding the asymmetry in the core magnetic fluxes caused by the current-carrying conductor. The output signal is passed through a phase-sensitive detector tuned to twice the original excitation frequency. Negative feedback is used to stabilize the device.

Abstract: A current sensor operating according to the compensation thereon which is particularly suited for acquiring high currents has a secondary winding of the current transformer is divided into at least two sub-windings that are supplied by different amplifiers in an amplifier arrangement. This results in symmetrical loading of the supply voltage so that twice as high a compensation current is enabled given the same internal resistance of the sub-windings and same resistance of the terminating resistor as in known current sensors of this type.

Abstract: An analog isolation barrier data acquisition system comprises a plurality of satellite sampling modules which are referenced to remote grounds for sensing direct current (dc) voltages which are referenced to these remote grounds. The satellite sampling modules are capable of monitoring several signals which are referenced to its local ground system, and are comprised of three functional blocks: a signal selection block which allows proper selection of the dc voltage signal to be monitored; a modulation block which modulates the selected dc voltage signal to produce a modulated waveform; and a barrier coupling block which transfers waveform information contained in the modulated waveform from the local floating ground reference system to an analog ground reference system.

Abstract: A thermal power sensor for providing an output signal that is linearly related to the amount of power derived from a power source over a first range and that is square law related to the amount of power derived from a power source over a second range which may overlap the first range. The apparatus comprises a pair of matched transistors connected in a common emitter configuration. Each of the matched transistors is thermally coupled to a matched resistor so that heat generated in the resistor is transmitted to its respective transistor to cause temperature variations therein. The current through each transistor is a function of the temperature of the transistor. The matched transistors are connected in series with a pair of cascode transistors. The cascode transistors are connected to a first differential amplifier which senses and amplifies the differential voltage which results from any difference in current flow through the matched transistors.

Abstract: A high voltage measuring system with very high input impedance. The system measures a high voltage source under test by developing a control signal which is proportional to the differential voltage between the high voltage source being tested and an adjustable high voltage reference. This control signal is fed back into a controller which adjusts the reference source so as to match the reference source with the source under test. When the controller detects that matching has occurred, it measures the reference source. By measuring the reference source, as opposed to measuring the source under test directly, the system avoids loading down the source under test.

Abstract: A range selecting impedance is switched into or out of a parallel range-selecting network by connecting the impedance across the network through an n-channel and a p-channel FET connected in parallel output configuration. The n-channel FET does the switching if the drains are negative with respect to the sources. The p-channel FET does the switching if the drains are positive with respect to the sources. Each FET is controlled by a gate drive whose output waveform is varied to select the rate at which the FETs switch. In cases of several different switched range impedances, the FETs are used to switch the smallest impedance into the network, another range impedance is selected, and then the FETs used to switch the smallest impedance out of the network. In this way, fast glitch-free range switching is achieved.

Abstract: A current measuring method in which a magnetic sensor is a torodial core having a conductor for carrying a current to be measured passing through the hollow portion of the toroid. A coil on the core is excited with an AC voltage such that the positive and negative voltages induced in the coil are equal in amplitude when the conductor is not carrying current. Current in the conductor generates a change in magnetic flux which change is measured by detecting the algebraic sum of the amplitudes of the positive and negative voltages. Simultaneously, the amplifier output is applied to the input side of the AC voltage or a second coil disposed in the magnetic sensor so as to establish a magnetic equilibrium. Current measuring apparatus according to this invention include two types of apparatus composed of hardware to which the above-mentioned current measuring method is applied.

Abstract: An active current transformer has a primary conductor in which a current is to be measured and a secondary conductor in which a measuring current is generated in use. A feedback sensor provides an induced voltage and an amplifier receives a signal induced in the feedback sensor and generates the measuring current in the secondary conductor. The primary and secondary conductors are located in first and second magnetic circuits respectively, the first and second circuits having a common path over at least a part of their respective lengths. The feedback sensor is disposed on the common path of the first and second magnetic circuits so that, in use, the magnetic flux in the second path can be made substantially equal to that in the first path by operation of the amplifier in response to the voltage in the feedback sensor.

Abstract: A magnetic circuit is coupled with a primary conductor in which flows the current to be sensed. The magnetic circuit has at least one air gap with a magnetic field detector and is coupled with at least one measuring coil producing a magnetic flux for compensating the flux generated by the primary current. The necessary current in the measuring coil to achieve such flux compensation is a measure for the primary current. A magnetic shielding part is provided in the vicinity of the air gap inside the measuring coil.

Abstract: A fluctuating voltage to be monitored is fed to the non-inverting input of a first op amp via a first input resistor; a reference voltage is fed to the inverting input of the second op amp via a second input resistor. The inverting input of the first op amp is taken from a first voltage divider connected between the reference voltage and ground; the non-inverting input of the second op amp is taken from a second voltage divider connected between the fluctuating voltage and ground. The power inputs of both op amps are connected to a positive voltage and ground. The output of both op amps is tied together, with a first feedback loop feeding the tied output voltage to the non-inverting input of the first op amp via a first high-resistance gain-setting resistor, and a second feedback loop feeding the tied output voltage to the inverting input of the second op amp via a second high-resistance gain-setting resistor.

Abstract: A current measuring circuit for an integrated circuit comprises an operational amplifier (22), the non-inverting input terminal of which is grounded through a first resistor (23) having a value R.sub.B and a second resistor (21) having a value R.sub.2, the junction of those two resistors receiving the current (I.sub.NL) to be measured, and the output of which is connected by an inverter (26) to a MOS transistor (27). The biasing voltage of the operational amplifier and the characteristics of the inverter are chosen so that the MOS transistor is biased at its threshold in the absence of a current to be measured, whereby the output voltage V.sub.s is correlated with the current to be measured by a linear relation independent of the temperature.

Abstract: A current sensor for use with a conductor with known cross-sectional characteristics is an electronic circuit having a monolithic Hall-effect element disposed substantially perpendicular to the conductor first major surface. A conductive loop substantially encircles the element and is oriented such that its flux is substantially orthogonal to the element surface. An amplifier sets current flow in the loop responsive to minimization of the differential Hall voltage across element. The loop current, at null, will be related to the conductor current by the ratio of the conductor flux path length to the loop flux path length.

Abstract: A computer automated method and system is used to time transformers to produce a resonant circuit for matching elements to a circuit is disclosed. The modeling method uses a computer to select discrete values for resistive and capacitive loads to be connected to the secondary of a transformer. For each combination of resistive and capacitive load connected to the secondary, the circuit is measured for phase angle. This data is used by the computer software to predict the tuning of the transformer to a load combination that is not actually connected to the transformer. This is done by determining two load lines for actual values of resistance and capacitance connected to the transformer secondary and then interpolating between the two load lines using a logarithmic equation. An option provided to the operator is to specify the value of the load capacitance or not. If the load capacitance is specified, the computer computes the phase angle for that value of load capacitance.

Abstract: For measuring voltage sources with capactive internal impedance (Z.sub.G) the voltage source is connected to a charge amplifier (7) whose input capacitance comprises a vibrating capacitor (C(t)). The output of charge amplifier (7) is connected in series with negative feedback via a regulator to the input of the measuring circuit. The frequency response of this transmission line (7, PID) is designed so that a closed regulating circuit has a good follower behavior, at least up to signal frequencies corresponding to the exciting frequency of vibrating capacitor (C(t). The vibration of the capacitor causes an amplitude-modulated alternating signal with the voltage across said capacitor to appear at output (A). This signal is filtered out (13), amplified (15), and amplitude-demodulated (17). The demodulated signal is filtered, and supplied through a high-ohmage resistance (R) as a current to the current summation node of charge amplifier (7).

Abstract: An ammeter is used for measuring the current flowing through a lead on a printed circuit board having a four point probe contacting the printed wire under test. Each probe points is spring loaded and approximately one millimeter separates adjacent probe points. The center two probe points are coupled to the inputs of a high gain chopper stabilized operational amplifier which provides a signal related to the voltage between the center two probe points as a result of the line resistance. The operational amplifier must have a very low and stable input offset voltage. The amplifier signal is applied to the base electrodes of a bipolar current driver circuit, such as two opposite polarity Darlington circuits, which respectively have a source of positive and negative voltage coupled to flow through the collector emitter electrodes when the signal applied to the base renders the collector emitter conductive.

Abstract: An adaptive line hybrid for digital telecommunications including a bridge circuit for connection to the telecommunication line the bridge circuit having automatically adjustable components in two arms of the bridge to compensate for variations in the characteristics of the telecommunications line.

Abstract: A parameter, such as the current flowing through a conductor, is measured by initially passing an energizing magnetic flux through a hall element to produce a hall voltage proportional to the sensed parameter. To eliminate temperature, aging and non-linear effects normally associated with a hall element, the amplitude of the hall voltage is effectively ignored and only its polarity is detected and employed to control the operation of an integrator to develop a cancelling current to establish an equal, but opposite direction, cancelling flux in the hall element. With a zero net flux, the integrator will hold the cancelling current at the level required to balance out and cancel the initial energizing flux. Since the cancelling current needed to null the energizing flux will be proportional to that flux, the current may be used to produce a control voltage to represent the measured parameter.

Abstract: An RF wattmeter is disclosed of the type using an "insertion-type" pick-up element to produce a voltage wave signal corresponding to the measured power in the coaxial transmission line. The induction loop in the pick-up element is connected to a principal detector, and a secondary detector is connected in opposition to the principal detector. Both detectors are located in close proximity to each other and are subject to the same thermal environment. A sine wave generator supplies a wave signal to the secondary detector in opposition to the wave signal supplied to the principal detector from the inductive loop. The d.c. portion of the resulting signal representing the difference between the opposed signals is integrated, and the integrated output is used as the amplitude in the generated sine wave. When the circuit is in balance, the integrated output matches the amplitude of the inductive wave form and can be used as an output indicating measured power in the coaxial transmission line.

Abstract: A precision circuit for measuring electrical currents, of the order of only a few pico-amperes, in the individual ionic channels of biological membranes, comprising a pipette engaging a membrane and having an internal electrode connected to a current-to-voltage converter; the converter output is integrated and fed back to a reference potential source for the converter to control that reference potential so that the average pipette electrode is maintained at zero over a predetermined time interval. In the preferred construction the time constant of the feedback integrator is adjustable between a "slow" value and a "fast" value; at the "slow" setting the long-term average of the pipette current is forced to be zero, whereas at the "fast" setting it is possible to measure the potential at the pipette tip at zero current.

Abstract: A method and device for the contactless measuring of direct and alternating current, in particular current instantaneous values, by using a magnetic circuit having an air slot and a magnetic field dependent resistor through which a control current flows and a winding through which a measuring current flows. In order to provide a large measuring speed for picking up a rapid instantaneous value, for example, generated high current peaks, at least a further winding is mounted on the magnetic circuit, the voltage drops on the magnetic field dependent resistor are picked up and stored at the peak values or other typical values of the current to be measured. After completing the measuring current, the current in the equivalent current winding is increased and the already stored voltages corresponding to the measuring current are compared consecutively with the voltage drops on magnetic field depending resistor, corresponding to the increase in the amount in the equivalent current winding.

Abstract: N-(.beta.-aminoethyl)-3-hydroxy-1,1,6,6-tetramethyl-piperidine and certain of its N- and O-substituted derivatives are useful as light stabilizers for polymeric materials, particularly for thermoplastic polymers and automotive finishes. Preferred compounds include the N-, O-diacyl derivatives.

Abstract: A tuning aid for tuning musical instruments, particularly keyboard instruments, includes a sensor unit (12) which has an elongate capacitative sensor probe which is capable of extending across one octave of the instrument, and an octave switch (22) and a tone switch (20) on which are manually set the nominal octave and note of the string being measured. Amplifiers (16,24) including an AGC amplifier and controlled band-pass filters (18,26) are responsive to the octave and tone switches to select the measured tone. A divider (32) responsive to the octave switch divides the measured frequency by a power of two. A divider (38) is connected to the output of a crystal oscillator (36) to divide by a factor dependent upon the tone switch setting. The outputs of the two dividers are compared in a discriminator (34) which compares the two frequencies. A meter (50) displays the sense and magnitude of the discriminator output so as to display in terms of cents the amount by which the frequencies differ.

Abstract: A circuit for providing a signal proportional to the RMS value of a periodic input waveform having either a variable or fixed frequency. The input waveform is applied to a rectifier. The output from the rectifier is squared and integrated at least once each period of the periodic waveform. The integrated voltage is sampled and a voltage equal to the sampled voltage is applied to a divider circuit. The output of the divider circuit is applied to a square root circuit until the integrated voltage is again sampled, at which time the voltage provided to the square root circuit is updated. The output from the square root circuit is a voltage proportional to the RMS value of the input waveform. The circuit can be coupled to an AC generator to provide RMS regulation of the AC voltage wherein the voltage proportional to the RMS value of the input waveform is applied to the exciter winding of the generator for control thereof.

Abstract: Apparatus for monitoring and controlling the operation of a dual platen press used in the manufacture of nuclear fuel pellets is disclosed. The apparatus includes means for indicating the displacements of both platens and imposing the displacements of the platens on orthogonal axes such that the displacements jointly control the motion of a point which traces a lissajous figure representative of the displacement and relative velocity of the press platens. A second lissajous figure representing the desired platen movements and relative velocity may be superimposed on the first lissajous figure, differences between the first and second lissajous figures indicating deviations from the desired operation of the press. Alternately, a press operator may simply use the first lissajous figure constructed from the actual platen displacements to analyze the operation of the press. The completion of preselected portions of the first lissajous figure may be detected and used to trigger subsequent press operations.

Abstract: A bridge circuit for measuring or use in a temperature-responsive servo-mechanism. A chain of four or alternatively five resistors is connected between power supply rails, an inner two resistors of the chain being shunted by the track of a potentiometer. A balancing potentiometer is connected directly across the supply rails and has its wiper connected to one side of a balance detector through a high value resistor. The signal to be measured is applied between the chain of resistors and the other side of the balance detector. There is a resistive connection from the wiper of the first-mentioned potentiometer and the resistor chain to the end of the high value resistor nearer the detector. The signal to be measured is derived from a resistance-type or thermo-couple temperature sensor. Reference junction compensation for the latter is described.

Abstract: An arrangement for the determination of the effective value and/or the performance or power and, for example, also the cross-power of electrical signals, in particular those Doppler signals which are received in ultrasonic-Doppler blood flow measurement. The arrangement includes an amplifier for the present electrical signal regulatable in amplification which, on the one hand, is connected into a control loop or circuit for regulating the degree of amplification for the purpose of producing constant amplifier power outputs and, on the other hand, connected into a measuring circuit for determination of the degree of amplification which adjust itself at the current power constant-regulation of the amplifier.

Abstract: A recording device which utilizes a closed loop servo system including a limited rotation motor, i.e. a moving coil galvanometer wherein the moving coil is activated by an input signal such that the rotational movement of a shaft supporting such coil may be translated into a graphic display for recording of the input signal. The device has specific utility in the recording of medical information wherein the input signal is created by the patient's body functions but has widespread alternate utility. The device further includes a transducer construction utilizing a rotational resistance mechanism including a rotating hub to which a contact arm is attached that creates a signal proportional to the position of the coil shaft and utilizes this signal for comparison with the input signal such that the coil position and thus that of the shaft may be corrected.

Abstract: An electrical indicator is disclosed of the type including a housing with an elongated window therein, and an elongated scale and an adjacent, relatively-translatable index carried on an elongated tape loop, both viewable through the window. The indicator provides increased resolution over such indicators known to the prior art by placing the elongated scale also on a tape which is made translatable past the window but in a direction opposite to that of the tape carrying the index. Both tapes are driven by the same drum forming part of a DC torque motor, but are taken off a peripheral surface of that drum in opposite directions to achieve opposite translations of the tapes past the window. An electrical circuit for controlling the DC torque motor is disclosed, as are details of the DC torque motor and associated components of the electrical indicator.

Abstract: An unknown voltage to be measured is applied to the input of an automatic servo-actuated potentiometer which when unbalanced by an unknown voltage is servo-actuated to restore a balanced condition with the extent of the displacement necessary for such restoration being indicated on a scale as an analog measure of the input voltage. The absolute value of the voltage across the potentiometer is measured and is supplied to a balance detecting circuit which upon a change in said absolute value actuates a control gate to transmit pulses from a pulse generator to a set of binary counters which have their output signals applied through a binary-decimal converter to a digital display. The counter output signals are also converted to an analog voltage which is fed to the balance detecting circuit and when the converted analog voltage equals the absolute detected voltage, the pulse count is terminated.

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: The average amplitude of an incoming signal voltage of variable frequency is measured by half-wave rectification of that signal voltage to produce a pulsating current which is subtracted from a continuous current in the input of an integrating amplifier. The fluctuating output voltage of this amplifier is periodically sampled, once per cycle of the signal voltage, to provide a train of corrective pulses. These pulses are accumulated to provide a reference voltage fed to a differential amplifier which controls the continuous current in response to differences between this reference voltage and a feedback voltage proportional to that current to compensate for changes in average signal amplitude. The magnitude of the continuous current, read by a meter, is therefore a measure of the desired amplitude. The voltage samples may be weighted, in proportion to signal frequency, by a variable-gain amplifier or a sampling switch closed for different periods in the output of the integrating amplifier referred to.

Abstract: A limited-displacement device is provided with an extended frequency range by critically damping it and compensating its frequency characteristics with a pair of series lead compensation circuits whose break-point frequency matches the natural frequency of the mechanical parts of the system.

Abstract: An arrangement for the determination of the effective value and/or the performance or power and, for example, also the cross-power of electrical signals, in particular those Doppler signals which are received in ultrasonic-Doppler blood flow measurement. The arrangement includes an amplifier for the present electrical signal regulatable in amplification which, on the one hand, is connected into a control loop or circuit for regulating the degree of amplification for the purpose of producing constant amplifier power outputs and, on the other hand, connected into a measuring circuit for determination of the degree of amplification which adjust itself at the current power constant-regulation of the amplifier.

Abstract: A voltage level display circuit for providing a display of the magnitude of the reference voltage level to a comparator circuit. A microprocessor is responsive to an input command signal to generate a digital reference voltage level which is converted by a digital to analog converter to an analog signal which is coupled to a reference voltage input of a comparator which compares the reference voltage level with an applied signal. A digital display is coupled to the output of the microprocessor to simultaneously provide a visual indication of the output of the microprocessor while generating the digital reference voltage signal.

Abstract: A carrier wave compensator includes a novel sampling filter connected between a null amplifier and a compensation potentiometer to suppress interference voltages without deteriorating the dynamic response of the system. The sampling filter includes a multiplier, an integrator and a sample and hold circuit which is reset during zero passages of the carrier wave.

Abstract: In an automatic polarization analyzing device which employs the extinction detecting method using a light amplitude modulating system, two sets of converter means are provided for converting into an angle a positional deviation electrical signal corresponding to a dead zone present in the control system.

Abstract: A method and an apparatus are described for indicating and/or recording electrical quantities, the desired and actual values being converted into pulses whose repetition frequencies are proportional to the actual and desired quantities. The difference between the two pulse frequencies controls a stepping motor, whose shaft drives the indicating or recording element.

Abstract: An electronic method and apparatus for measuring temperatures by means of a thermistor in one arm of an electrical bridge, bridge output being varied by the on and off duty cycle of a shunting impedance selectively switched into and out of the balancing arm of the bridge in accordance with the relative states of a counting display register and a cyclically scanned counting register, the display register state being altered by gated pulses, under the control of bridge output, to provide a digital indication of measured temperature. Bridges of both the nulling and non-nulling types are disclosed using either a dual ramp integrator or conventional detector acting upon bridge output to provide an impedance measurement subsystem independent of reference supply voltage and also enabling non-linear analog to digital conversion to compensate for a non-linear thermistor temperature vs. thermistor resistance characteristics, without sacrificing measurement sensitivity.

Abstract: A multi-range, self-balancing instrument using a Zener diode circuit and a phase compensating circuit is disclosed. The Zener diode circuit is capable of generating a white noise, which is effectively applied to the self-balancing system whereby the dead zone is maintained constant irrespective of the range. The phase compensating circuit, comprising a non-inverting input amplifier, is capable of compensating for the phase lag of the self-balancing instrument by adjusting the amplification factor of the amplifier without affecting the stability of the servo amplifier system.

Abstract: A torque motor incorporating a permanent magnet rotor and winding therewith for providing the indicating mechanism of a servoed indicating unit. The circuitry for use with the indicating mechanism first applies a reference feedback-producing pulse, then provides the signal for application of torque to the indicator to move it toward the desired position, and then has a quiescent period to clear the stator windings of the mechanism of currents before recommencing the voltage reference and torquing cycle.