Showing papers on "Bridge circuit published in 1972"

Conductive elastomeric extensometer

Abstract: An extensometer for measuring surface area changes of the human body caused by expansion and contraction of the body comprising a relatively thin and wide strain responsive conductive elastomeric band adapted for application to a part of the body, such as around a limb or the trunk of the body. The elastomeric band is incorporated as a resistor in a balanced bridge circuit. Expansion or contraction of the portion of the body on which the elastomeric band is applied causes a change in the resistance of the band and a resultant imbalance of the bridge circuit generating an output that is fed into an amplifier. The output of the amplifier in volts is suitable for providing the desired reading through a recorder, oscilloscope or voltmeter.

Fluid pressure transducers

Abstract: A fluid pressure transducer is disclosed, said transducer includes a differential capacitor with one plate movable by a pressure sensing device. This capacitor is part of a resonant radio frequency a.c. bridge circuit, which produces an a.c. signal, and dependent on the displacement of the movable plate. A phase discriminator circuit is coupled to the bridge circuit to produce a d.c. signal the polarity and magnitude of which depend on the position of the movable plate. The output of the phase discriminator circuit is used to drive an electromagnetic force applying device which is mechanically coupled to the movable plate and to provide an output signal dependent on the position of the movable plate.

Capacitive-inductive bridge type electrical suspension

Abstract: An electrical suspension for positioning an element with respect to a frame of reference without mechanical connection to the reference. The suspension includes a bridge circuit having opposite bridge leg impedances vary together in response to the gap between an armature attached to the element and a stator attached to the reference frame. The bridge includes a diagonal impedance which acts to redistribute bridge current when the bridge impedances vary with displacement of the element from a centered position. The redistributed current results in an increased current flow through the legs corresponding to the increased gap and the increased current is used to create a restoring force on the element.

Vehicle weighing device with a balanced electrical bridge

Abstract: A weighing device particularly suited for vehicles, comprising strain gauges placed on a structural member of a vehicle, such as an axle of a truck in optimum orientation thereto, to compensate for certain inclinations of the vehicle when it is being weighed. The vehicle weighing device comprises strain gauges placed in a unique configuration on special mechanisms, and on the axles of a vehicle positioned laterally and angularly with respect to each other. The strain gauges are connected to and form a part of a constant current cross balanced bridge circuit which forms a portion of this invention. The circuit incorporates certain amplifiers analogous to operational amplifiers, and balancing techniques in a configuration creating a novel balanced bridge. Thus, this invention comprises a novel balanced bridge configuration and a novel weighing device and forms a new circuit and strain gauge combination, as well as mechanisms for optimum utilization of the gauges.

Device having a bridge circuit for detecting faults in an electric network

Abstract: A device for detecting faults such as burning-out, earthing, short-circuiting taking place in each of a plurality of fundamental elements in an electric network in which said fundamental elements each constituting at least one kind of circuit element such as a resistor are connected in series or in parallel to each other, said device being provided with a bridge circuit connected between two equipotential points a and b, and other two equipotential points c and d in the network, and with a comparator connected between two equipotential points in the bridge circuit to thereby detect an unbalanced load produced from the bridge circuit.

An Improved ac Bridge Circuit for Use in Four‐Terminal Resistance Thermometry

Abstract: Details are given of an improved version of the ac Kelvin bridge first described by Ekin and Wagner [Rev. Sci. Instrum. 41, 1109 (1970)]. Battery‐operated operational amplifiers with highly superior noise performance at 33 Hz were used for the voltage followers required to make the bridge compatible with four‐leaded germanium resistance thermometers. A discussion of bridge operation, accuracy limitations, and final performance characteristics is presented, including a confirmation of the design objective to accurately measure a ΔT of 0.5 mK at 4.2 K, with a 1 mV germanium sensor excitation and a 1 Hz detector bandwidth.

Electric motor controlled fluid valve

Abstract: An electric motor controlled hydraulic or pneumatic valve including a valve housing having a main spool positioned to control the flow of fluid from a pressure port to a fluid circuit, the spool including a threaded bore at one end, a high speed low torque reversible electric motor mounted on said housing and being connected to the spool by a threaded rod to provide high torque output to the spool and an electric control circuit including a bridge circuit having a manually controlled variable resistance, a feed back variable resistance mechanically connected to the spool, and a pair of solid state switches or relay circuits connected across the bridge circuit to provide an electric signal to the electric motor in response to movement of the manually controlled variable resistance.

Proximity probe with output proportional to target distance

Abstract: A proximity probe circuit is disclosed which is responsive to the distance between a proximity probe and a conductive or an inductive target, and has an output directly proportional to the distance between the probe and a conductive target. An amplifier is connected as an oscillator in a bridge circuit with the probe in one arm of the bridge and variations of probe to target distance change the input to the amplifier. An output circuit is connected to the output of the amplifier and has a variable negative feedback to decrease the input to the amplifier as the output of the amplifier increases. This is accomplished by light emitting diodes and light sensitive resistors in one embodiment of the invention and the output circuit provides a means for determining an output voltage proportional to the probe to target distance.

Proximity circuit with active device feedback

Abstract: A proximity switch circuit is disclosed which is responsive to the distance between a proximity probe and a conductive or inductive target. An amplifier is connected as an oscillator in a bridge circuit with the probe as one arm of the bridge and variations of distance between the probe and the target change the balance point of the bridge to change oscillation output. If the target is close, the oscillator will tend to cease and this is detected by an auxiliary detector to partly turn on an auxiliary energy pump which sustains oscillation output of the amplifier. This output is fed to a window detector which determines if the output is between lower and upper threshold values, and if it is, then there is an output from an output circuit. If the detector circuit determines that the amplifier output is below the lower threshold or greater than the upper threshold, then there is no output. This establishes a fail-safe operating condition by terminating the output should the oscillator cease to function for reasons such as short-circuiting or open-circuiting of the proximity probe.

Automatic battery polarizing circuit

Abstract: Disclosed is and automatic battery polarizing circuit employing transistors in the arms of a bridge circuit configuration wherein the transistors are operative to couple a battery connected to the input thereof in a manner that the bridge output voltage will always be of the same polarity regardless of how the battery is connected to the bridge input with respect to polarity.

Corrosion measuring bridge circuit having automatic controlled constant source of energy and temperature compensation

Abstract: A controllable source of alternating current signals, for excitation of a bridge circuit used in apparatus such as corrosion analyzers and the like, includes an automatic amplitude control circuit to maintain the amplitude of the alternating current signals applied to the bridge circuit substantially constant for wide variations in the impedance of the bridge circuit. By maintaining the bridge circuit excitation substantially constant, the amplitude of the bridge circuit unbalance signals now provides an accurate indication bridge circuit unbalance and therefor the corrosion of a probe element connected in the bridge circuit.

Air leakage detector

Abstract: A pneumatic circuit for testing articles for leaks which includes means for measuring the size of the article and testing the circuit for operability. A conventional bridge circuit is provided with means for varying the effective volume of one side of a bridge circuit for accomplishing these ends.

Rectifier bridge assembly comprising stack of high-current pn semiconductor wafers in a sealed housing whose end caps comprise ac terminals of the bridge

Abstract: An integrally housed bridge circuit including a plurality of high power semiconductor rectifiers. The rectifiers are disposed within a hermetically sealed insulative housing and are electrically interconnected therein to form a bridge circuit having a pair of A-C terminals and a pair of D-C terminals.

Apparatus for controlling the energization of a load

Abstract: A plurality of condition responsive impedances, such as PTC thermistors are each connected to reference impedances to form voltage dividers which form half of a bridge circuit. The voltage divider junctions are coupled through diodes to the base of an NPN transistor in the detector of the bridge circuit, the emitter-collector circuit of the transistor being connected across the gate cathode circuit of a silicon controlled rectifier which is used to control the energization of a serially connected relay coil. In the absence of a predetermined condition, such as excessive temperature in a load, the silicon controlled rectifier is gated on each half cycle thereby allowing current to flow through the relay coil to energize the load. On the occurrence of the predetermined condition, i.e., excessive temperature, the impedance value of the condition responsive impedances change and cause conduction of the transistor which shunts current away from the gate of the silicon controlled rectifier thereby deenergizing the relay coil. Differential between the temperature at which energization and deenergization of the system occurs is provided by a reset impedance with contacts coupled thereacross, the contacts being closed when the relay coil is energized. Bypass diodes are connected across the reset and reference impedances to increase the temperature differential and to effect a longer delay before reenergization.

Inverting bridge circuit

Abstract: A power inverting bridge circuit for a highly regulated direct current power supply to provide high efficiency and increased current handling capacity. The inverting bridge circuit includes at least one pair of series-connected gate elements, preferably power transistors, connected across the leads of a DC power source and having a series-connection point between the gate elements defining one bridge output point. An alternating current path is provided between each power source lead and a second bridge output point. The primary coil of a transformer is connected across the two bridge output points. The gate elements are controlled by a high frequency square-wave generator to produce an alternating current in the primary coil of the transformer. A high frequency alternating current signal is produced in the transformer secondary coil which is easily rectified and filtered to produce the highly regulated output. An anti-crossconduction transformer ensures that each gate element ceases conducting before the other gate element is permitted to conduct. The anti-crossconductiontransformer includes feedback from the transformer to the gate elements anti-crossconduction transformer ensure the gates are not overdriven by the squarewave generator. In addition, anti-crossconduction transformers are included to prevent the switching gate elements from conducting at the same time. For regulating the power supply output, a DC source boosting circuit is provided to raise the DC voltage to the inverting bridge circuit as the output voltage varies due to load or AC power source fluctuations.

Light coupled loop current detector

Abstract: This loop current detector includes four light-emitting diodes and a bridge circuit electrically isolated therefrom with two photoresponsive arms and two resistive arms. Two light-emitting diodes are connected in parallel in opposite polarities and inserted in series with each conductor. Each photoresponsive arm is optically coupled to the light-emitting diodes that respond to loop current of a respective sense. Longitudinal currents therefore cause both photoresponsive arms to be illuminated, thereby leaving the bridge in balance; loop currents cause only one photoresponsive arm to be illuminated, thereby providing bridge output.

Electrical flow meter

Abstract: Fluid flow rate determined by measuring the displacement of distributed electrical resistance along a flow conduit through which fluid is conducted The flow conduit is heated by current simultaneously induced therein and in a fluid storing tube of the same structural and electrical configuration The resistances of the flow conduit and the fluid storing tube form the resistive branches of a balanced bridge circuit through which changes in the resistance distribution are measured

Circuit arrangement for attenuation compensation in telecommunication subscriber stations

Abstract: The invention is related to a circuit arrangement for centrally supplied subscriber stations in telecommunication installations. In the inventive circuit the recieving amplifier is connected into a bridge circuit used for side-tone attenuation. The signal input of the receiving amplifier is located in the one diagonal of the bridge, and the output of the transmitter is located in the other diagonal of the bridge circuit. A variable resistance element is connected in parallel with the bridge diagonal across which the signal input to the receiving amplifier appears for compensating for the different attenuation affects of transmission lines having differing lengths.

Method and apparatus for analyzing blood properties

Abstract: Method and apparatus for determining the hematocrit and related properties of blood samples by determining the electrical conductance thereof. A sample probe is employed which has two spaced electrodes in the form of capillary tubes on either side of a nonconducting capillary tube. The probe forms an electrical resistivity measuring leg of an A-C bridge circuit and the unbalance of the circuit caused by replacement of a portion of a diluent by the blood sample is measured and transformed into the desired analysis.

Sensing element response time measuring system

Abstract: A resistance temperature detector, which is one arm of a bridge circuit, is heated by an electric current separate from the bridge exciting current, to a temperature higher than its environmental temperature. The time required for the RTD to cool through a predetermined temperature range after the heating current is removed is measured to determine the response time of the RTD.

Apparatus for line supervision for wire breaks in data transmission systems

Abstract: Apparatus for monitoring data transmission lines for wire breaks in systems which utilize D.C. modulation is described. The transmitting and receiving devices in a subscriber station are equipped, respectively, with low and high internal impedances. The transmitter and receiver are connected in shunt with a bridge circuit to, respectively, different opposed pairs of junctions in the bridge circuit. The bridge includes a balancing network and the transmission line as ratio arms. A first voltage source may be connected in series with either the transmission line or in the shunt circuit containing the transmitter unit, and a second voltage source is connected in series with the balancing network. These voltage sources generate a monitoring current on the subscriber line upon the inverting of the polarities of the transmitter voltages in the two connected subscriber stations.

Voltage regulator for synchronous generators

Abstract: An accurate, stable, and inexpensive voltage regulator for single or multiple phase synchronous generators. A monolithic integrated circuit comprising reference and error amplifiers establishes a stable output reference voltage. A comparator amplifier compares the reference voltage with a sensed output voltage of the generator and provides an excitation signal to a charging circuit in response thereto. Upon reaching a predetermined charging level, the charging circuit discharges through a unijunction transistor triggering circuit and enables the input gates of a pair of silicon controlled rectifiers configured in opposite legs of an AC bridge circuit. When enabled, each silicon controlled rectifier will conduct during that half cycle of the bridge AC excitation signal in which it is forward biased and will thereby energize the field or the exciter windings of the generator. A voltage or current feedback network from the generator or exciter field winding to the integrated reference circuit stabilizes the reference circuit against hunting.

Weighing device for movable conveyors

Abstract: A weighing device used an eddy current sensing device wherein lines of flux are passed in one direction through a stainless steel membrane. The membrane is specially heat treated such that it collimates and permits passage of generated lines of flux yet provides an effective environmental shield that will allow operation even when the device is subjected to temperatures of up to 1,400*F. and pressures of up to 3,000 p.s.i. An impedance comparator circuit, including measuring and reference coils having virtually identical characteristics, is used to operate a meter to thereby indicate proximity and/or characteristics of conductive materials spaced along the undersurface of an endless conveyor belt. The magnetic flux of the measuring coil is shielded and collimated to provide localized sensing and reflected impedance variations between the two coils, which comprise legs of a bridge circuit, are detected and translated to weighing measurements, as represented by the output signal of the sensing device.

Ground protection apparatus for electrical equipment with y-connected windings

Abstract: Apparatus for the detection of grounds occurring at or near the neutral point of Y-connected windings of electrical equipment is disclosed. Between the neutral point and ground a load resistor is connected as part of a bridge circuit. A bias voltage source having a frequency different from that of the system is connected to one diagonal of the bridge circuit. A potentiometer is connected across the second bridge diagonal and its voltage is evaluated by a time measuring device to determine the spacing between the zero voltage crossings of the potentiometer. The time measuring device transmits a signal indicating a ground if the time intervals between two successive zero crossings of the voltage in the potentiometer differ from each other by a predetermined amount or if a predetermined time interval between successive zero crossings is exceeded.

Bridge circuit changing fault location method and device

Abstract: A device and method for locating faults in electrical conductors, said device comprising a bridge circuit adapted to be connected to operative and faulted conductors with a jumper connecting their remote ends, and switch means associated with the bridge circuit selectively movable to a first mode setting to provide a first balance condition reading corresponding to the length of the conductors and a second mode setting to provide a second balance condition reading representing a percentage of the first reading at which the fault is located from the device. A modified form of the device includes switch means with three mode settings to provide a single reading corresponding to the distance to the fault without computations. The device provides a convenient method for locating faults without necessarily knowing the size or resistivity of the operative conductor.

Photosensitive control apparatus with movable light control member

Abstract: A novel control device for use in a servo apparatus of the type employing a galvanometer movement connected in a servo feedback loop arrangement. The device comprises a photosensitive transducer having an expansive sensing surface, means providing a beam of light to strike said surface, and a movable, tapered light-control member disposed in the path of the light beam to produce illuminated areas disposed on either side of an elongate shadowed area on the sensing surface. The relative size of the illuminated and shadowed areas changes in response to movement of the member, thus varying the transducer response. The control device is employed in a servo apparatus comprising a bridge circuit, one leg of which includes the photosensitive transducer and the other leg of which contains a condition-responsive transducer. Amplifying means are provided, having input terminals connected with the bridge to receive signals therefrom and having output terminals connected to a galvanometer to drive the latter. The light control member is directly carried by the galvanometer movement. Any change in the output of the condition-responsive transducer is sensed by the amplifiers, which drive the glavanometer upscale (or downscale), thus changing the position of the light control member in such a way as to direct more (or less) light on the photosensitive transducer and thereby re-establish balance of the bridge. In this way, changes of the condition-responsive transducer are reflected by a corresponding change in the position of the galvanometer, which can be calibrated in convenient units intended to form the basis for the particular measurement desired.

A radio-frequency moving-boundary detector

Abstract: A new type of moving-boundary detector is described in which boundaries are detected at platinum ring electrodes situated on the outside of a moving-boundary tube. These rings are part of a bridge circuit operating at radio frequencies. Impedance changes in the region of the rings are converted by a phase-sensitive detector to a voltage output which, when operating in the differential mode, takes the form of a sharp peak as a boundary passes through the rings. Boundary displacements of less then 20 μm can be detected, and a precision of better than 0.02% is obtained in the measurement of boundary velocities in typical transference measurements. The fact that only three electrical leads are required in the detecting circuit gives this detector a decided advantage for high-pressure work. Equally important is the elimination of electrode polarization problems associated with other types of electrical detectors.

Thermal stabilization device using a temperature sensing device and an electrical heating means especially for field probes for measuring magnetic field strength in sectoral field mass spectrometers

Abstract: A device for thermal stabilization of a field probe using a temperature sensing device and an electrical heating element disposed in the gap of the magnet of a sectoral field mass spectrometer. The probe is disposed between bipartite NTC (negative temperature coefficient) resistance means which are coupled in a bridge circuit.

Device for measuring a defined force component

Abstract: A defined component of the force acting on a body is measured by wire strain gauges located in the path of the force component and providing the input for a bridge circuit. The strain gauges are located on a member which fits between the elements which create the force. This member also includes a region which is isolated from the force and which carries a device subjected to the same temperature as the strain gauges and connected in the bridge circuit to act as a temperature compensator which compensates for temperature variations experienced by the wire strain gauges.

Battery charging system supplied from a polyphase generator

Abstract: To provide for reverse polarity protection without substantial, additional components in star-connected polyphase generator battery charging systems, in which a pair of diodes are connected to the center, star point of the generator and direct current for battery charging is obtained from a polyphase bridge circuit, the protective fuse is interconnected in the additional diode circuit, preferably with the positive output terminal of the generator (in a negative-ground system) to simultaneously protect against over current and reverse polarity.