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8129981 |
Apparatus for detecting a fault in the balancing unit
An apparatus can be coupled to at least two lines for transmitting a differential signal, which is substantially symmetrical to a predefined reference potential, and/or for receiving such a...
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7957844 |
Device and a method for power balancing
A method for stabilization of the power balance in an electric power system including a number of nodes. An instantaneous value of the mains frequency of the electric power system is sensed. In...
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7884596 |
Self-balancing frequency determining bridge
A self-balancing Wheatstone bridge that provides frequency and power information. The frequency information obtained can be applied to correct the power measurement to provide excellent match,...
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7769497 |
Method of super super decoupled loadflow computation for electrical power system
A method of performing loadflow calculations for controlling voltages and power flow in a power network by reading on-line data of given/specified/scheduled/set network variables/parameters and...
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7706991 |
Alternator tester
An alternator tester is provided for testing an alternator of a vehicle while the alternator is coupled to the vehicle. A sensor is configured to couple to the vehicle and sense a signal related to...
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6747205 |
Device for assisting in the measurement of the earth resistance
The invention relates to a device for assisting in the measurement of the earth resistance comprising a ground rod with a wire coiled up on a reel or the like, and electrical connecting means for...
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6714881 |
Time reference compensation for improved metering accuracy
A method for time reference compensation in a power metering system, the method comprising monitoring a time-dependent characteristic of incoming AC power over a predetermined local time interval,...
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6657442 |
Micromechanical alternating and direct voltage reference apparatus
An AC/DC voltage reference system has at least one micromechanically fabricated electrode pair having first and second electrodes facing each other so that the electrodes are disposed at a distance...
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6582840 |
Fuel cell stack coolant conductivity sensor using differential voltage measurements
A method and apparatus for detecting leakage current in the coolant of a fuel cell stack. The invention eliminates the use of a conductivity sensor by using a voltmeter to measure the voltage...
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6118409 |
Method and device for inspecting at least one antenna branch, in particular in a vehicle
In order to inspect at least one antenna branch (A1, A2, . . . An), in particular in a vehicle, a power level to be radiated is initially fed into the antenna branch, after which a power level...
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5877619 |
Battery-operated hand field-strength meter and method of null balancing same
A method of null balancing a hand field-strength meter is described in which the effect of the measurement probe on the balancing is suppressed by short-circuiting the measurement probe by two...
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5461322 |
Autonulling DC bridge for real-time sensor transduction and voltage measurements
A feedback operated DC bridge circuit for monitoring the voltage variations in a voltage divider circuit using a voltage controlled resistance component to reach a null balance across the bridge....
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5313165 |
Temperature-compensated apparatus for monitoring current having controlled sensitivity to supply voltage
An apparatus for monitoring current through a lamp circuit that uses a series resistance shunt in the circuit with one end connected to a current source and the second end connected to the lamp....
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5291073 |
Thermal power sensor
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...
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5264798 |
Autonulling AC bridge using differential and integration feedback
A self-contained autonulling bridge circuit based on phase-sensitive deteon of an impedance to be measured is described. The system utilizes a feedback structure to control a variable impedance in...
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4795965 |
Capacitance to voltage conversion circuit including a capacitive bridge and a capacitive offset
A capacitance to voltage conversion circuit for converting changes in capacitance of a capacitive bridge-type probe to voltage includes a detector for detecting changes in an excitation signal...
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4786859 |
RMS measuring apparatus for AC/DC voltages
A true RMS instrument using a multijunction thermal converter with two beaters automatically determines and displays the RMS value of an unknown voltage using two steps or modes. In an AC mode, the...
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4782285 |
Variable resolution control system
A variable resolution system for a potentiometer converts the analog output of the potentiometer to digital steps which are multiplied to provide a number of digital output steps dependent upon the...
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4628257 |
Wattmeter
A differential thermal wattmeter of the type disclosed in U.S. Pat. No. 4,045,734 is modified to remove undesirable in-phase a.c. ripple at the fundamental frequency in the feedback path. This...
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4580062 |
Safety shield control device
An electrical interlock to prevent unauthorized access to potentially hazardous equipment and an associated detection circuit to detect if a safety shield or closure member is open, not securely...
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4420745 |
Security system
A security system of the bridge circuit type has in one of its arms a conducting element whose impedance is to be monitored and in its other arms reference and/or compensating elements, for...
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4375616 |
Non-loading digital voltmeter
A substantially non-loading circuit for measuring voltages in a range with relatively high upper limit uses a resistive voltage divider for scaling down these voltages for application to a digital...
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4263583 |
Digital alarm system with variable alarm hysteresis
A digital alarm system for monitoring a variable process signal utilizing a variable, digitally controlled alarm hysteresis capability. The system includes a means for establishing a preselected...
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4213088 |
Voltage measuring circuit
A voltage indicating meter is connected between the outputs of two high impedance operational amplifiers, the first of which receives an input signal to be measured through a range setting...
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4206404 |
Vacuum fluorescent indicator
A vacuum fluorescent display has a filament heated below incandescence and phosphor coated anodes. A foraminous charge-control electrostatic lens between the filament and the viewer both controls...
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4177423 |
Bridge circuits
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...
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4165653 |
Signal ratio indicator
A pressure measuring system which includes a variable reluctance pressure transducer energized from an alternating voltage source, wherein the ratio of the output voltage to the source voltage is...
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4156180 |
Apparatus and method for detecting metabolic activity
An apparatus and method for detecting metabolic activity in a medium which includes an electrical circuit suitable for passing electrical current through a medium which contains a suspected...
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4110685 |
Standing wave ratio measurement instrument
The output voltages produced by two directional couplers are applied to analog circuitry for generating a voltage that is directly proportional to return loss. An analog meter scale is calibrated...
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4091381 |
Digital indication for selectable impedance circuit
A digital indication for a selectable impedance circuit consisting of a plurality of serially connected impedances and a selector which is connectable to a common junction of any of them is...
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4071819 |
Device for sensing the real part in a complex impedance
A device for accurately measuring the quantative value of the real part of complex impedance without the measurement affecting or being affected by the reactive component of that impedance. The...
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4028642 |
Circuit for converting a temperature dependent input signal to a temperature independent output signal
A bridge circuit for combination with a variable resistance sensor whose resistance may vary as a function of a sensed variable and also as a function of a parasitic variable such as, for example,...
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3975669 |
Electronic damper motor control
There is disclosed a motor control circuit that is particularly useful for the control of a damper motor in a heating and ventilating system. The control circuit comprises a bridge circuit having a...
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3970930 |
Current meter
The invention relates to the supervision of a measuring circuit which is connected to a load by way of measuring leads. This load is connected to a generator via supply leads. The load is bridged...
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3928799 |
Automatic balancing DC comparator voltmeter
An apparatus for measuring potentials with great accuracy using a self-balancing current comparator. The comparator includes a variable primary winding and a secondary winding wound on a magnetic...
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3923403 |
Circuit for light measuring devices and method
Circuit and method of use thereof in light measuring devices and, particularly, devices for measuring optical density and the calibration of neutral density filters. The basic circuit includes a...
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3921068 |
Indicating potentiometer
An indicating potentiometer with a potentiometer having an input rotor rotatable through ten revolutions between internal limit stops of the potentiometer for setting the potentiometer output...
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3908165 |
Field strength meter
A signal strength meter indicates signal level directly in dBmV. The signal under test is attenuated to a level which centers a meter indicator, and the attenuator movement is translated into...
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3879662 |
Differential amplifier sliding reference
A tolerance detector circuit comprising a differential amplifier circuit comparing a signal to be measured with a reference voltage, a level sensor to indicate when the signal level differs from...
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3872386 |
TEST DEVICE
The disclosure relates to a test instrument of compact size, operable with a battery source and capable of measuring with high precision voltages in the millivolt and low voltage ranges, milliamps,...
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3852727 |
MULTIPLE VOLTAGE MONITORING APPARATUS
A multiple voltage monitor includes individual sensing networks for each source with respect to a common reference connected by a logic network for detecting a voltage failure and transmitting a...
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3842349 |
AUTOMATIC AC/DC RMS COMPARATOR
This invention is directed to an improved apparatus for the accurate comparison of an ac voltage with an accurate dc voltage standard to obtain the RMS value of the ac voltage. The voltages are...
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3825918 |
IMPACT SENSITIVE SECURITY WINDOW SYSTEM
A security window system having a transparent structure having high resistance to penetration is described. A transparent conductive layer is provided over most of the area of the window and the...
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3825920 |
LAMINATED SECURITY WINDOW SYSTEM
A security window system having a transparent structure having high resistance to penetration is described. A transparent conductive layer is provided over most of the area of the window and the...
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3799681 |
VARIABLE COMPUTING RESISTOR
A variable computing resistor is disclosed for representing non-linear curves in null or bridge circuits. A flexible resistive rod is used or resistor components are placed in end-to-end sequential...
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3725782 |
POTENTIOMETRIC MEASURING DEVICE WITH MULTIPLE STAGE COUNTER MECHANISM
In a potentiometric measuring counter assembly comprising rotary counters corresponding to successive orders of integers, the transfer means from each lower order counter to the next higher order...
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3711773 |
PHASE JITTER METER
A system is disclosed for monitoring short term amplitude and phase variations and measuring average and peak-to-peak phase jitter experienced by a test signal transmitted through a system under...
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3710240 |
CIRCUIT ARRANGEMENT FOR THE DETECTION OF FAULTS OR POINTS ON INHOMOGENEOUS ELECTRIC LINES OR CABLES ACCORDING TO THE IMPULSE REFLECTION METHOD UTILIZING AN ADJUSTABLE BALANCING NETWORK
A circuit arrangement for the detection of faulty or inhomogeneous points on electrical lines or cables, according to the impulse-reflection method, in which test impulses are applied to the line...
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3710249 |
SLIDEBACK PEAK CIRCUITS WITH CONSTANT TONE INDICATIONS
A peak detector measuring apparatus having an audio output tone which is abruptly cut-off when a DC voltage is manually adjusted to be equal to the peak value of an input signal voltage wave. The...
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3702939 |
FAIL-SAFE COMPARATOR
This disclosure relates to a fail-safe comparator circuit having an input transformer, the primary of which is fed by an a.c. signal voltage. The secondary winding of the first transformer is...
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