Showing papers on "Bridge circuit published in 1982"

Rotational angle detection device having two magnetoresistive sensing elements

Abstract: A rotational angle detection device having two magnetoresistive sensing elements positioned at a 45° angle with respect to each other senses the rotary position of a permanent magnet. Sine and cosine waves are applied to first and second bridge circuits respectively incorporating the two sensing elements. The resulting bridge circuit outputs are differentially combined to provide an output whose phase relative to either of the input sine or cosine waves is dependent upon the rotational position of the permanent magnet. The phase difference is detected and the rotational position is calculated therefrom.

Bridge circuit compensation for environmental effects

Abstract: A method and apparatus are described for using a computer to compensate for zero point and span errors as well as other non-linearities in the operation of strain gauge transducers. The apparatus comprises a semiconductor strain gauge transducer with a quasi stable voltage supply, two strain gauges and two precision resistors which form a voltage divider network; a scanner for scanning the strain gauges and precision resistors; an analog-to-digital converter for digitizing the output of the scanner; and a microprocessor for calculating a corrected output representing the phenomenon that is monitored by the strain gauge transducer. The microcomputer contains a memory in which are stored a set of bridge completion constants, a table of correction constants and a set of temperature compensation and signal conditioning algorithms. The bridge completion constants are a set of values representative of the bridge supply voltage and the resistances of a set of bridge completion resistors which are selected during factory calibration to provide two point temperature and two point span compensation for the pair of strain gauges used in the transducer. One group of correction constants provides for zero point compensation over the operating temperature range of the transducer, a second group provides for span compensation and a third group compensates for other input to output non-linearity.

Touch sensitive liquid crystal switch

Abstract: A touch sensitive switch with a liquid crystal cell and a circuit for measuring capacitive changes when the cell is deformed by touch The cell has a layer of a liquid crystal material between slides bearing electrodes Capacitive changes are detected for example by a comparator or by a bridge circuit which includes one or more cells Touching one cell unbalances the bridge The area of cell that is touched may be coincident with or separate from a display area For some types of cells extra sensitivity is achieved by maintaining a voltage across the cell between a critical and saturation value

Multi-phase transistor/diode bridge circuit

Abstract: A three-phase bridge circuit includes two sets of transistor/diode assemblies in which the diode of each assembly is connected in reverse current mode across the main current path of its transistor. Each diode of one set has its cathode connected to a positive d.c. input bus bar and its anode to a respective a.c. output bus bar. Each diode of the second set has its cathode connected to a negative d.c. input bus bar and a respective a.c. output bus bar. An input terminal has a plurality of electrical contacts, each connected to the control electrode of a respective transistor in the transistor/diode assemblies. A heat sink has its electrically insulating layer on one major surface thereof and in thermal contact therewith. Each transistor is in thermal contact with the heat sink by way of a bus bar part, and each of the bus bar parts is secured to the insulating layer so as to be in thermal contact with the heat sink.

Gear tooth position and speed sensor with four, bridge circuit connected, magnetic resistance tracks

Abstract: To simplify a field plate effect speed and position sensor, particularly for association with the starter gear of an automotive-type internal combustion engine, four meander-arranged permalloy resistance tracks are located on a substrate at the corners of a rectangle, spaced, in circumferential direction, by about half the pitch distance of the teeth (2) of the starter gear. The resistances can be connected in a voltage divider (FIG. 4) configuration, or in form of a bridge circuit (FIG. 5) supplied from a constant current source (CC) to eliminate temperature variation affects, and providing alternating current output voltages within the wide range of temperature of essentially uniform level as the teeth (2) scan the sensor, a special marker tooth (10) providing an output signal of different level. Preferably, the resistances (5-8) are formed as meander-shaped thin film vapor deposited tracks on a silicon substrate (4), a permanent magnet (9) providing bias magnetization, the direction of which changes with respect to the orientation of the meander tracks--preferably 45° with respect to the direction of rotation (11) to cause the resistance elements to either have high, or low resistances (FIG. 3).

Manual muscle tester

Abstract: A portable manual muscle tester has an external actuator, a case capable of being held in one hand and a digital display indicating peak force applied to the actuator. Strain gages connected in a bridge circuit are located on a flexure contacted by the actuator. The flexure is a cantilever beam shaped to fit the small case and to prevent reflected or mounting stresses being registered in the force display. The circuit from the strain gage bridge to the display includes an instrumentation amplifier followed by a peak freeze circuit that includes operational amplifiers and a peak freeze capacitor. The peak freeze capacitor provides a voltage that is read by a digital volt meter. A further operational amplifier connected as an integrator feeds back from the peak freeze circuit to an input of the instrumentation amplifier to reset the meter to zero after the displayed force reading has been noted.

Fluid leakage detecting apparatus

Abstract: An apparatus for detecting leakage of fluid comprises a bridge circuit composed of a heat generating resistance element connected in one arm and installed at a location where leakage of fluid may possibly occur and other resistor elements inserted in other arms, respectively, an input power supply source connected to the input of the bridge circuit and a differential amplifier connected to the output of the bridge circuit for amplifying an unbalance voltage produced by the bridge circuit, wherein the resistor elements inserted in the other arms of the bridge circuit are so dimensioned that the heat generating resistance element is maintained in a heat generating state.

Fuse loss indicating circuit

Abstract: The present invention relates to a fuse loss indicating system for monitoring the condition of a plurality of fuses in an electric circuit. The indicating system includes a plurality of individual indicator circuits, one for each fuse to be monitored. Each indicator circuit includes an optical isolator for electrically isolating the indicator circuit from the monitored circuit. When a monitored fuse blows, the associated optical isolator triggers a flip flop to generate a fuse loss signal to cause a warning LED to light and alert an operator as to which fuse has blown. In its preferred embodiment, the fuse loss indicating system is utilized to monitor the fuses in an SCR motor bridge circuit. In this embodiment, the fuse loss system also generates a bridge disable signal when a fuse blows to cause a bridge lockout circuit to disable the gating signals to the SCR's, thereby disconnecting power from the motor.

Fluid level measuring system

Abstract: A system for measuring the level or volume of a fluid within a fluid storage vessel which comprises: a multi-capacitor fluid level sensor formed of a pair of capacitors of fixed and substantially like capacitive value and a pair of capacitors having like open dielectric spaces for receiving varying levels of the fluid within the vessel. The four capacitors of the sensor are connected together to form the four capacitive sides of a Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across the bridge circuit to a first set of bridge terminals at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor. A detection circuit is connected across the bridge to a second set of bridge terminals (independent of said first set of terminals) and at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor. The current value in the detection circuit is measured and indicates the value as a fluid level or fluid volume measurement in direct linear relationship with the current value. The system may be used for volume measurement with respect to a wide variety of multi-component fluid systems as long as the dielectric constants for the two or more components are different.

Circuit arrangement for determining the polarity and magnitude of the load current in a reversible d-c controller or chopper

Abstract: A circuit arrangement for determining the polarity and the magnitude of the load current in a reversible d-c controller includes a bridge circuit comprising two pairs of bridge arms connected to opposite terminals of the voltage supply bus. Each pair of bridge arms connected to the same side of the supply bus form a bypass circuit connected across the load. Two diagonally disposed bridge arms each contain a primary winding of a current transformer having two primary windings connected in opposite winding phase. Load current normally flows through either pair of diagonally disposed bridge arms, but during pauses in the load drive, circulates in one of the two bypass circuits. Electronic switches in each of the bridge arms are controlled so that the load current circulates in successive bypass periods in an alternating pattern in the two bypass circuits. When current flows in a bypass circuit, a phase sensitive voltage is induced in the single secondary of the current transformer. Signals from the electronic switches in one of the bypass circuits are fed via digital logic circuitry to a further electronic switch which causes an operational amplifier to invert pulses from that bypass circuit alone. A pulse train having a polarity corresponding to the polarity of the load current is thereby obtained. In a further embodiment, a sample-and-hold stage for determining the magnitude and polarity of the load current is provided.

Adaptive corrector of facet errors in mirror scanning systems

Abstract: A beam deflection system is provided with electrical circuitry for adaptively correcting the deflection of a beam of radiant energy in a scanning system incorporating a rotating scanning mirror to compensate for misalignment in facets of the mirror. With the use of an acousto-optic modulator providing a deflected beam at an angle dependent on the frequency of an acoustic drive signal, the orientation of the beam can be altered to compensate for the misaligned facets by varying the acoustic frequency. A sensor and bridge circuit signal the position of a beam scan. A memory stores the value of the frequency for scans by each facet, the value being altered with each scan to optimize the frequency. A drift compensation circuit provides for an averaging of the parameter values, and provides a voltage to adjust the balance of the bridge to drive the average value towards a reference value.

Brushless D-C motor system with improved commutation circuit

Abstract: To provide for reliable commutation of a single-strand or single-line winding (25) connected in the diagonal of a transistor bridge circuit (40, 40') having four transistors (70-73) which are alternately rendered conductive in accordance with a Hall-IC rotor position sensor (32) affected by the field of a permanent magnet rotor (13), time delay capacitors (64, 66; 87) are connected to charge current sources, for example high-resistance resistors (59, 63; 88, 90, 95) to delay turn-ON of respective transistors of the bridge permitting current flow through the winding in a first direction after commutation from the other transistors (71, 72) of the bridge which are being turned OFF or blocked, so that a finite time interval or gap of no current flow is provided to reliably prevent possible short-circuit currents across the power supply buses (44, 45) if the inherent switching characteristics of the transistors are longer than the commutation interval. The capacitors are connected to a rapid-discharge circuit, for example through diodes (62) or the inherent semiconductor, such as a transistor (54) in a Hall generator-integrated circuit combination. If transistors of inherent sufficient capacity, and switching delay for switching ON are used, external capacities (87) may not be needed, the internal capacity of the transistor switching providing for sufficient time delay, with the switching-OFF being assisted by the aforementioned diode or discharge circuit (54, 89).

Method and apparatus for using spring-type resistive elements in a measurement bridge circuit

Abstract: A method for converting a movement into an analog or digital variable, in particular into an electrical voltage, and an apparatus for performing the method are proposed. The apparatus includes at least one measuring spring element having windings and fabricated of electrically conductive material, which is disposed together with a supplementary spring element of identical structure and serving as a supplementary resistor in a bridge branch of a carrier-frequency measurement bridge. A deformation of the measuring spring element by a movement causes a change in the spacing between windings and thus causes a change in the inductive resistance of the measuring spring element which serves as a standard for the movement.

Temperature control system

Abstract: A temperature control system is disclosed wherein a heater of a gas sensor and a plurality of reference resistors cooperate to form a bridge circuit. The temperature control system comprises a comparator means for monitoring a balancing voltage of the bridge circuit and generating a control signal indicative of the balancing voltage and an electric power amplifier means responsive to the control signal for varying a voltage applied to the bridge circuit in such a manner to reduce the balancing voltage. The gas sensor has mounted therein at least one of the plurality of reference resistors, which reference resistor having a resistance resulting from multiplying the resistance of the heater with a constant.

Three phase square wave welding power supply

Abstract: In a three phase welding power supply, the three phase power is connected to a welding arc by a power control circuit having three conducting paths for straight polarity current and three conducting paths for reverse polarity current. The power control circuit comprises a three phase bridge rectifier circuit having eight bridge arms each including a silicon controlled rectifier with the bridge circuit being connected between the three phase power source and the welding arc which is in turn connected to the three phase power supply neutral. An inductor is connected across the direct current terminals of the bridge circuit so that arc current flows in one direction through the inductor regardless of the polarity of the arc current. The conducting paths are selectively activated at non-zero voltage points to conduct repetitive sequences of independent numbers of straight polarity half cycles of arc current followed by independent numbers of reverse polarity half cycles of arc current to the welding arc. Pulses are generated in synchronism with each of the three power phases and counted to determine the activation sequences of the conducting paths. By controlling the generation of the pulses and the counts of the pulses at which the paths are activated, a variety of sequences are generated.

Multiphase inverter drive circuit with synchronized switching delay feature

Abstract: A synchronized switching delay circuit including an oscillator and multivibrator for generating a synchronized delay pulse. The oscillator is divided into three waveforms shifted in phase by 120°. A 4-16 decoder receives the three waveforms and the delay pulse outputs a series of blanking pulses that blank a portion of the leading edge of each of the pulses in each of the three waveforms and their complements to provide a leading edge delay. The resulting delayed waveforms are input to a three phase bridge circuit comprised of three pairs of complementary switches. The delay enables one of the switches in each pair to completely turn off before the other switch turns on.

Gas detecting and monitoring device

Abstract: A gas detecting and monitoring device comprises a bridge circuit including a gas detecting element and a constant-current circuit for feeding a constant current to the gas detecting element. The device further comprises a compensating bridge circuit including at least a part of the gas detecting element. The compensating bridge circuit produces a signal corresponding to the variation of the resistance value of the gas detecting element depending upon the variation of the ambient temperature and feeds the signal to the constant-current circuit to automatically control the current fed to the bridge circuit thereby maintaining the resistance value of the gas detecting element at a constant value. The device may further comprise a correcting circuit including a temperature sensor for sensing the variation of the ambient temperature disposed near the gas detecting element. The correcting circuit feeds the output of the temperature sensor corresponding to the variation of the ambient temperature to the compensating bridge circuit thereby compensating for the variation of the respective circuit components owing to the variation of the ambient temperature.

Temperature compensation circuit for strain gauges

Abstract: A temperature compensation circuit for strain gauges fixed to an object to be measured and adapted to take out an output conforming to a strain by being fed with a constant voltage, wherein a compensation resistors in the form of a combination of two or more kinds of resistors each made of a pure single metal material having a resistance versus temperature characteristic equivalent to the output voltage versus temperature characteristic of the bridge circuit of strain gauges are inserted and connected at a predetermined position on the voltage supply side or output take-out side of the bridge circuit of strain gauges thereby compensating for variations in the strain gauge output due to temperature variations with high accuracy. The temperature compensation circuit for strain gauges according to the present invention not only has very high accuracy of temperature compensation but also can be produced with high yield.

Non-contact inductive coupling circuit - has primary and secondary stages with band-pass filters for handling two-way transmissions of different frequencies

Abstract: The non-contact inductive coupler is designed to allow information to be transmitted across a variable gap between two units. The primary unit has an oscillator (S) that is coupled to a band pass filter consisting of a capacitor (C1) and inductance (L1) that transmits a frequency (f1) signal across the gap to a secondary unit filter (C2,L2). The transmitted signal is rectified in a bridge circuit (B) and is amplified (V1). A second frequency (f2) signal is produced over a secondary unit filter (C3,L3) and this is received and is filtered (C4,L4) by the primary unit to control an amplifier (V3) coupled to the transmitting oscillator. The system operates in a self regulating mode to maintain operating voltages within the working range.

Bi-directional driver system for electrical load

Abstract: A bi-directional driver system for an electrical load operable in response to two independent logic command signals provides a means for selecting the direction of current flow in the load when driven by the external command. A bridge circuit employs inputs to dual transistor switches operating in the saturated mode in series with the electrical load, cooperating with common emitter transistor linear amplifiers and diodes, and biased by the input logic signal so as to drive the load current in a predetermined direction. The circuit provides protection from undesired power supply current surges when logic command signals are applied to both inputs, and from transients due to failure of a saturated transistor switch at one input to cease conducting before the application of a command signal to the second input. Embodiments for inductive loads and annunciator lamps are described.

Frequency-scanning marginal oscillator for ion cyclotron resonance spectroscopy

Abstract: A number of ion cyclotron resonance applications have arisen in the past few years which require a frequency‐scanned detection system. Since the traditional marginal oscillator detector has always been a fixed‐frequency detector, alternative detection techniques such as bridge circuit detectors have become widely used. In this paper we present an alternative to the bridge detector, namely, a frequency‐scanning marginal oscillator. Requirements and modifications necessary to convert a marginal oscillator to frequency scanning operation are discussed in detail and the necessary circuit diagrams presented. Finally, a theoretical comparison is made between bridge circuit and marginal oscillator sensitivities.

Gas pressure measuring circuit

Abstract: In a circuit for controlling the temperature of a filament in a Pirani gauge head, secondary temperature compensation is provided by mounting an auxiliary resistor adjacent the temperature-compensating arm of a bridge. The auxiliary resistor forms part of a potential divider which provides a preset offset voltage to an associated output amplifier. This offset voltage is added algebraically to the variable voltage driving the bridge circuit so as to provide additional temperature compensation.

Optical reproducing device having focus servo system

Abstract: An optical reproducing device for reproducing information from a rotating record medium includes a focus control system for displacing a focusing lens perpendicular to the plane of the record medium. A light beam is conducted through the focusing lens on to the record medium. A capture range search system is provided to move the focusing lens at a substantially constant speed from a rest position until it is positioned within the capture range of the focusing control system. The capture range search system includes a bridge circuit for sensing the moving speed of the focusing lens. The bridge circuit includes a moving coil of a drive motor for said focusing lens and a variable impedance element. The bridge circuit is balanced by controlling the variable impedance element when the lens is at the rest position.

Pressure detecting device

Abstract: PURPOSE:To realize high accuracy and a low cost in the titled device by digitally performing the temperature compensation of a gage element of a pressure sensor by an operation processing circuit. CONSTITUTION:A current is supplied to a bridge circuit comprising gage element G1-G4, whose resistance values are equal and temperature characteristics are approximately equal, from a constant current circuit comprising resistors R1-R3, transistors Tr1 and Tr2, and an operation amplifier OP1. The resistance values of the elements G1 and G3 vary in proportion to the pressure variation, and the resistance values of G2 and G3 vary in inversely proportional to the pressure variation. Therefore, the voltage variation at one end of the bridge circuit, which is detected via the operation amplifier OP1 gives a temperature sensing signal Vot, while an output signal Vop is given pressure signals at connecting points P1 and P2 which are detected through an operation amplifier OP3. Vot and Vop are stored in RAM. The pressure wherein temperature is compensated by CPU via data of ROM is obtained. Thus the high accuracy and the low cost in the device are realized.

Superconducting fault-current limiter and inductor design

Abstract: A superconducting fault current limiter (SFCL) that uses a biased superconducting inductor in a diode or thyristor bridge circuit was analyzed for transmission systems in 69, 138, and 230 rms kV utility transmission systems. The limiter was evaluated for costs with all components--superconducting coil, diode and/or SCR power electronics, high voltage insulation, high voltage bushings and vapor cooled leads, dewar, and refrigerator--included. A design was undertaken for the superconducting cable and coils for both diode and SCR 69 kV limiter circuits.

Multiple capacitor transducer

Abstract: A capacitive type pressure, force or displacement sensing transducer comprised of a mating pair of spaced dielectric elements each carrying a pair of capacitive elements forming two like capacitors of variable capacitance value depending upon the variable spacing distance between the dielectric elements and two like capacitors of fixed capacitance value. The pair of variable value capacitors and pair of fixed value capacitors comprise all of the capacitance elements of a Wheatstone bridge circuit in a single structural unit in which such capacitive elements are all subjected to the same temperature and pressure environment and which is not sensitive to stray capacitances. Each pair of capacitors forms opposing sides of the Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across a first set of bridge terminals at opposite corners of the bridge and a current detection circuit is connected across a second set of bridge terminals independent of the first set of terminals and at opposite corners of the bridge. Detection and measurement of the current value of the bridge circuit is translated into a value of force, pressure or motion applied to the transducer unit in direct linear relationship with the current value as determined by the separation distance between the spaced dielectric elements of the transducer.

Reference voltage source

Abstract: Band gap voltage regulator employing a self-balancing bridge circuit for controlling current flow through two parallel branches. Voltage points in each branch are alternately sampled and applied to one input of a comparator in a delta modulator circuit. The output of the delta modulator circuit is applied to the other input of the comparator. The output of the comparator is applied to a control circuit which controls a current source in each of the two branches. The voltages at each voltage point are alternately compared with the voltage at the other input of the comparator, and the result is employed to control the current sources so that the voltages at both points are equalized despite any offset voltage in the comparator.

Transducer for dynamometer

Abstract: The measuring element for a dynamometer consists of a band-shaped substrate of amorphous metal The band-shaped substrate has one or two necked-down sections on which strain gauge resistors are arranged in the direction of load application The resistor or resistors may be connected in a bridge circuit together with reference resistors The load-dependent elongation of the resistors unbalances the bridge circuit to create the desired output measuring signal Use of a suitable alloy of amorphous metal results in good mechanical characteristic of the measuring element Specifically, there is a high resistance to creep and to hysteresis effects, while relatively high loads may be measured Further, such a measuring element is also immune to temperature variations