Showing papers on "Voltage drop published in 1985"

Anomalous voltage distribution of random resistor networks and a new model for the backbone at the percolation threshold.

Abstract: We develop a new approach for studying the random resistor network by focusing on the distribution of voltage drops across each bond We introduce a simple model which provides a useful description of the percolating backbone, and which shows that the voltage distribution is log normal, with an infinite set of exponents required to describe the voltage moments. This latter prediction is verified by simulations of a resistor network on the square lattice.

Protection apparatus for patient-implantable device

Abstract: An electrical circuit is connected in series with a lead of an implantable heart pacemaker between the pacemaker and the heart to protect the pacemaker against high voltages and currents produced by defibrillators and other sources. The electrical circuit has a sensing resistor arranged between two normally conducting field effect transistors (FETs) all in electrical series with the pacemaker lead. When the voltage drop across the sensing resistor exceeds a predetermined positive or negative amplitude, a transistor becomes conductive and turns off the normal conduction channels of the FETs. An alternate, electrically conductive high-impedance path is switched in to limit the current flow to the pacemaker until the magnitude of the voltage across the sensing resistor drops to a safe level. The transistor then becomes non-conductive and the FETs become conductive re-establishing the normal low-impedance conduction path and effectively switching the alternate high-impedance path out of the circuit.

Arc resistance of laser‐triggered spark gaps

Abstract: In the use of spark gaps as switching devices, it is desirable to maximize the power delivered to the load and to minimize the power deposited in the switch; that is, it is desirable for the resistance of the switch to be negligible as compared to the load. The hydrodynamic time scale for expansion of the arc in a spark gap and hence for the reduction in its resistance to a small value is tens to hundreds of nanoseconds. Therefore, with current pulses of duration of a few hundred nanoseconds or less, the resistance of the spark gap may be a significant fraction of that of the load. In this paper, we report on measurements that determine the resistance of the arc in a fully diagnosed laser‐triggered spark gap. The spark gap switches a 100‐ns, 1.5‐Ω waterline into a 1.5‐Ω load resistor. A capacitive voltage divider housed within the switch enclosure measures the voltage drop across the switch, a current‐viewing resistor measures the current, and an interferometer measures the diameter of the plasma column, ...

Auto-reset circuit breaker

Abstract: Prior art generally cannot handle large currents. This automatic solid state circuit breaker protects both the circuit and the breaker from large current surges. A current sensing device (15) is used to generate a voltage drop proportional to the current flowing through the device. When the voltage drop reaches a predetermined level, resulting from an over-current condition, it trips a control circuit (22) that opens a solid state switch in the line. After a defined delay interval the time delay circuit (26) will automatically reset to close the solid state switch (15). If the over-current condition still exists, the control circuit (22) will again open the solid state switch (16). This cycle is repeated at the delay interval until the over-current condition has subsided. Circuits also provide overvoltage protection, through detectors (34) which trigger the control circuit (22) when an over-voltage condition is detected. The application of the invention is to lightning or surge protection, for single line and multiline environments.

Motor control circuit with automatic restart of cut-in

Abstract: A control circuit (10) is provided for automatically re-applying starting torque to a single phase AC induction motor by reconnecting the auxiliary or starting winding (2) to the AC power source (3) if the motor has not accelerated to a given cut-out speed, or otherwise begins to stall. Multiple reconnections of the auxiliary winding (2) are automatically provided as needed, without external intervention, to provide multiple bumping action. The auxiliary winding (2) is connected to the AC source (3) during initial energization of the motor, and is disconnected after a given starting interval. Induced voltage in the auxiliary winding (2) is sensed and compared against a reference voltage (17) for reconnecting the auxiliary winding (2) when the sensed auxiliary winding voltage drops below a given value relative to the reference voltage. The disconnecting, sensing and reconnecting functions are accomplished with a minimum number of components.

Direct indication technique of plasma potential with differential emissive probe

Abstract: We present a new method of plasma potential measurement with a differential emissive probe. The dc heated probes are combined with a feedback loop control circuit to measure plasma potential automatically. In addition, it is shown that connecting to the central point of the filaments reduces the effect on the emissive currents of voltage drops across the filaments. The decay time constant of half‐cycle heated emissive probe current during the off heating cycle is shown to depend on the initial emission current and on the bias voltage.

Color liquid crystal display element

Abstract: A color liquid crystal display element in which a liquid crystal (14) is contained between a first clear substrate (11) and a second clear substrate (12), a plurality of display electrodes (15) and thin-film transistors (16) connected thereto are formed on the first clear substrate (11), color filters (1R), (1G) and (1B) are formed on the second clear substrate (12) in a manner to be opposite to the display electrodes (15), and a common electrode (17) is also formed on the whole surface thereof. When light is transmitted through the gaps in the color filters (1R), (1G), (1B), contrast decreases. Further, voltage drop on the common electrode (17) leads to uneven contrast. With this invention, therefore, gaps among the color filters are covered with a metallic light-shielding layer (37) to interrupt the passage of light. The light-shielding layer is further superposed on the common electrode (17) and is electrically connected thereto.

Current-sensing scheme for switched reluctance motor drives

Abstract: By using the on-state forward voltage drops of the power switches to measure phase currents, and by using diode logic to sense the voltage drops, it is possible for a single voltage comparator to perform the current regulation function for an entire power converter. Current regulation is obtained in drives using either overlapping or nonoverlapping current conduction for excitation of the motor phases. A thermistor compensates for offsets and for temperature sensitivity of the power switch voltage drops.

Spontaneous transfer of magnetically stored energy to kinetic energy by electric double layers

Abstract: Current disruptions may be excited spontaneously in a laboratory plasma when the electric current density along the magnetic field is large. This phenomenon is investigated in the plasma column of a triple plasma device with an inductive external electric circuit. Each current disruption then gives an inductive voltage pulse of several hundred volts over the plasma, and this potential drop is found to be concentrated at an electric double layer which forms in the plasma during the pulse. Most of the magnetic energy, initially stored in the circuit inductance, is transferred to the double layer during the period of current decrease and released there as particle energy. Simultaneously as the current decreases the potential level at a local potential minimum in the plasma is found to decrease. Reflection of electrons at this minimum is conjectured to cause the decrease of the current during a disruption.

Analyzer for comparative measurements of bulk conductivity

Abstract: Circuit for measuring the relative change in conductivity between two cells which include a test biorigion and a control biorigion as the test cell biorigion conductivity changes as a result of analyte modecules binding to receptor sites in the test cell biorigion. The invention includes circuitry for driving a current through each of the cells and for measuring the voltage drops across the test and control cells as a function of time. A novel two-stage ac analog-to-digital convertion circuit in which the initial conductivities are measured via a successive approximation process, while the relative conductivities are monitored during a test interval via a tracking technique is included. The circuitry is controlled by a digital controller which can vary the parameters of the measurement processes so as to make the circuit adaptable to the measurement of a wide variety of substances using different cell configurations and/or electrolytes.

Ultrasonic coagulation monitor and method

Abstract: @ An ultrasonic coagulation monitor for measurement of prothrombin times and related coagulation times includes at least one piezoelectric crystal (24) operated at a fixed frequency near its resonant frequency. A sample (38) of material to be analyzed is placed in acoustic communication with the crystal (24). The voltage across the crystal is monitored in order to detect a voltage change, preferably a drop, that occurs upon coagulation of the sample. A timer is included that is turned off at a predetermined voltage drop corresponding to a particular stage of coagulation desired to be timed. In an alternative embodiment of the invention a second crystal is included and is mounted a predetermined distance from the first crystal to define a cavity therebetween. One crystal is driven by the frequency oscillator circuit and the material the coagulation of which is to be measured is placed in the cavity. A voltage sensing device senses the voltage across the second crystal and controls a timer as in the first embodiment. A method of monitoring prothrombin times and related coagulation times is also described. The method includes placing coagulating material in sound absorbing relationship with at least one piezoelectric crystal, driving that crystal at a fixed frequency using a fixed frequency oscillator circuit, measuring the voltage in the circuit and determining the amount of time required for the voltage to reach a predetermined voltage level.

Current sensing circuit

Abstract: A current sensing circuit senses current and signals if such current exceeds a predetermined level within an etched circuit board. The circuit comprises a conductive trace of a predetermined resistance within a metallization layer of the board and a reference voltage circuit and comparator coupled to the trace. The reference voltage circuit senses voltage at first sense point on the trace and offsets the voltage a predetermined amount to form a reference voltage. The comparator senses voltage at a second sense point on the trace and compares it to the reference voltage. So long as the second voltage exceeds the reference voltage, the comparator indicates that the current is below the predetermined level. If the second voltage drops below the reference voltage, the comparator generates an output signal indicating that the current has exceeded the predetermined level.

Method and apparatus to operate a high-voltage DC transmission system (HVDC) with automatic control of the converters

Abstract: In a first station operating as the rectifier, a fault indication quantity can replace the measured value of the HVDC voltage which regulates a control voltage. In normal operation in a second station of an HVDC transmission system operating as an inverter, a fault indication quantity is calculated from a control angle and the inductive D.C. voltage drop is calculated from the D.C. current and the A.C. voltage. In the second station operating as the inverter, the overlap angle can be precalculated from a fault indication quantity so that by automatic control of the control angle a preset extinction angle can be assured. Thereby stable, quickly controllable operation without any remote control signals is assured and rapid resumption of operation following a malfunction facilitated.

The Construction of Minimal Area Power and Ground Nets for VLSI Circuits

Abstract: This paper deals with the problem of sizing power and ground nets in integrated circuits composed of modules, where the nets are routed in the channels between the modules. Constraints are assumed on allowable voltage drops between the chip's power and ground pads and the module's power and ground pins. Maximum current drain into each module is also assumed to be known. A procedure for determining the width of each branch in the power and ground trees is presented, where the objective is to minimize the area of the power and ground nets subject to several constraints, such as IR voltage drop and metal migration.

Circuit for generating a substrate bias

Abstract: A substrate bias generator in which the junction point of the capacitance and the diode of the charge pump is connected to the earth point of the circuit (and of the further circuit on the substrate for which the bias is generated) via two or more series-connected transistors. During the charging period of the capacitance the transistors are (fully) conductive, hence the capacitance is optimally charged as the conductive transistors cause no (or hardly any) voltage drop. During the pumping cycle all transistors are diode-connected, bringing about a negative voltage with respect to the earth point at the junction point, which negative voltage is limited by the sum of the threshold voltages of the diode - connected transistors.

On state modeling of power JFET structures in the bipolar mode

Abstract: An analytical model for the on-state operation of the bipolar-mode power JFET is proposed. A closed-form solution in the low-voltage rnage of the output characteristics is obtained as a function of device parameters. The model shows that the hole-reflecting properties of the high-low drain transition are very important in order to achieve a lower on-state voltage drop. This allows us to explain the presence of an offset voltage in the output characteristics due to the recombination velocity effect at this transition. The effects of device parameters on the on-state operation, such as epi-thickness, lifetime and extent of heavy doping of source and drain are analyzed in detail and found in good agreement with experimental results.

An analytical one-dimensional model for lightly doped drain (LDD) MOSFET devices

Abstract: An analytic one-dimensional model for lightly doped drain (LDD) MOSFET devices is presented. This model decomposes the LDD device into an intrinsic MOSFET in series with n-source and drain diffusion. A conventional charge control model with a pseudo two-dimensional approach was used to calculate the current flow in the intrinsic MOSFET. The voltage drops in the n-source and drain, including both IR drops and voltage drop across the depletion region of the drain were calculated analytically. By reconstructing all the voltage drops across contact, source/drain, and channel regions, the calculated drain currents as a function of terminal voltages agree well with experimental data. Device optimization is also presented by using this analytical model for "full" LDD and As-P double diffused LDD structures.

Monitoring device for detecting faults in an electrical device, particularly in an LC filter circuit in an AC voltage network

Abstract: A monitoring device connected to an LC filter circuit for determining the occurrence of faults therein includes sensors for measuring the voltage drop across the LC filter circuit and the current flow therethrough. The monitoring device includes simulation circuits for estimating the voltage drop and current flow in response to the actual values of the current flow and voltage drop, respectively. In one position of the double-throw switch, the actual value of the current is compared with an estimated value thereof while in another position of the double-throw switch, an estimated value of the voltage drop is compared with the actual value thereof. Differences between the compared values are detected by a multiplicity of Y-connected limit and counting stages activatable by voltages of different magnitudes and directions for indicating different kinds of faults and for selectively disconnecting the LC filter circuit from a power supply network.

Voltage-current converter having reference resistor spread compensation

Abstract: The invention relates to an integrated voltage-current converter circuit for generating a current which produces a voltage drop across a reference resistor, which voltage drop is determined by an input voltage. In order to compensate for the spread in width of the reference resistor formed in the integrated circuit, this reference resistor is formed by two parallel-connected resistors having the same resistance per unit area, the same length and different widths, and the compensated output current is formed by the difference between the currents which flows through these resistors.

Method and apparatus for detecting faults in a structure by measuring voltage drop between surface points thereof

Abstract: A method for monitoring structures by measuring electrical quantities including subjecting an electrically conducting component to an a-c current with a predetermined frequency in a given direction generating a magnetic flux in a given direction, tapping a voltage drop across two measurement points mutually spaced apart by a given distance at individual partial regions of the component with two measuring lines contacting the component, forming a first conductor loop from the measuring lines and the component with an inductively effective area being as small as possible, forming a second conductor loop being substantially parallel to the given direction of the current and perpendicular to the given direction of the magnetic flux, tapping an induction voltage from the change of the magnetic flux as close as possible to the measuring points with the second conductor loop, feeding the voltage drop and the induction voltage to an electronic evaluation circuit, and deriving the local resistance of the component at the measurement points from the voltage drop and the induction voltage with the evaluation circuit and an apparatus for carrying out the method.

Protective switching device against undervoltage in a motor vehicle electric circuit

Abstract: 1. Protection circuit against undervoltages in the electrical system of a motor vehicle equipped with an anti-lock system that is divided into subsystems capable of independent operation, each of which subsystems acts on some of the wheels of the motor vehicle, characterised by the following features : a) a voltage comparator (1) is provided for identifying a voltage drop in the electrical system below a first threshold (Us1 ), b) a switch-off device controlled by the comparator (1) is provided which effects separate switching off of a sub-system (6) of the anti-lock system when the first threshold (Us1 ) is passed.

Multiple output switching power supply

Abstract: A compact multiple output switching power supply having a series connection of a D.C. input power supply (E), a switching device (0) and a primary winding (np) of a transformer (T1) which supplies currents to loads during an on period of the switching device, and supplies constant output voltages Vi (i = 1, 2, ..., m) from m (m ≧ 2) secondary windings ni (i = 1, 2, ..., m) of the transformer by turning on and off the switching device, includes means (T2) for storing a magnetic energy during the on period of the switching device and discharging the stored energy to the loads during on off period, connected in series with the primary winding of the transformer. The output voltage V, (j = 2, 3, ..., m) is represented by where kj is a voltage drop in the circuit.

An analytic model to estimate the avalanche breakdown voltage improvement for LDD devices

Abstract: An analytic model is presented to estimate the avalanche breakdown voltage improvement for various lightly doped source-drain (LDD) structures. In this model, the voltage drop across the lightly doped drain region is assumed to be responsible for breakdown voltage improvement. The voltage drop is calculated by assuming a two-dimensional potential distribution in the rectangular section of the n − region. This section is treated as a volume obeying Gauss' law, thereby enabling the mobile and immobile charges contained in it to be related to the electric fields normal to its surface without considering the detailed distribution of the charges inside. The calculated results agree well with experimental and two-dimensional simulation data for a wide range of processing parameters.

Temperature compensation injector control system

Abstract: A temperature compensation injector control system as used in an electronic fuel injection system for motor vehicles utilizes the value of the voltage levels across the coil (18) to determine the coil's (18) temperature. A multiplexer (20) responds to the value of the source of power (14) and the voltage drop across the coil (18) created by a small leakage current to generate digital signals to a microprocessor (10) for modifying injector control signals.

Using Parameter Estimation Techniques with a Simple Model of a Diaphragm-Type Electrolyzer to Predict the Electrical Energy Cost for NaOH Production

Abstract: Predictions of the electrical energy cost for NaOH production are determined as a function of the independent operating variables and diaphragm characterizing properties. The predictions are based on data fro a statistically designed experiment, a simple model of a diaphragm-type electrolyzer, a simple model of the cell voltage losses, and parameter estimation techniques. The data were obtained over a sufficiently large range of operating conditions so that the resulting design equation may be industrially useful. The simple model of the diaphragm is based on the mass transport of the hydroxyl ion, a linear potential gradient, and is presented in terms of measurable diaphragm properties. These properties are the thickness of the diaphragm (t) and a resistivity ratio, p/p /SUB o/ , where p is the resistivity of the diaphragm filled with electrolyte and p /SUB o/ is the resistivity of the electrolyte (this ratio may com to be known as the MacMullin number, N /SUB M/ ). It is shown that, according to the model of the cell, the caustic yield or current efficiency of the diaphragm cell depends on the product of N /SUB M/ and t and not on each separately. The simple model of the cell voltagemore » considers the diaphragm voltage drop, anode and cathode kinetics, and the bubble-filled brine-gap voltage drop. Parameter estimation techniques are used to determine the best values of the diffusion coefficient, average specific conductivity, exchange current densities, and transfer coefficients; these parameters and the simple models provide a design equation for the electrical energy cost of NaOH production using a diaphragm cell. The design equation is used to predict a minimum electrical-energy cost at a particular N /SUB M/ t.« less

Screened-space-charge transferred-electron oscillators

Abstract: We describe a novel form of a monolithic semiconductor oscillator in which the space-charge field of a drifting charge packet is modified, by means of the electrostatic boundary conditions of the device, so as to produce no voltage drop across the packet. Under these conditions, we predict that a sequence of narrow, identical, contiguous packets can be formed producing extremely high-frequency oscillations in the 30-300-GHz range, independent of the length of the drift region. This is in contrast to conventional transferred-electron oscillators in which the space-charge-induced voltage drop across either an accumulation region or a dipolar domain limits the drift region to, at most, a single packet at any time, thereby limiting the frequency achievable to packet-transit, -formation, or -decay times. Computer simulations and analytical solutions indicate that the frequency can be tuned electronically over a broad band by controlling the charge-injection level, while the oscillator center frequency depends upon the specific device geometry and the electron transport properties at the applied field. In theory, oscillations as high as 2 THz are not inconceivable.

Improvement of a proposed model for heat conduction in an electrode submitted to an electric discharge: Application to the indirect determination of the anodic and cathodic voltage drops

Abstract: We present an improved version of a heat‐conduction model which leads to better‐computed values of the anodic voltage drops for electric discharges in a liquid dielectric, with a short interelectrode gap (about 50 μm) and short duration (10–1000 μs). The results obtained show monotonic variations according to the duration of the discharge and peak current, and correspond to the measured value of the total interelectrode voltage drop.

Controlled-potential bias circuit for electrochemical cells

Abstract: A bias circuit (13) for an electrochemical fuel cell (15) serving for example as a carbon monoxide or hydrogen sulfide detector, including an operational amplifier tied to the anode and reference terminals (21,23) of the fuel cell (15), and a zener diode (50) arrangement for maintaining a predetermined voltage drop between the output and negative inputs of the operational amplifier (33).

Method and ohmmeter for measuring very low electric resistances

Abstract: An ohmmeter for measuring very low electric resistances, for example the very low resistance of a very high current electric joint, which ohmmeter comprises a source for establishing a measuring current through the joint to thereby create a voltage drop proportional to the magnitude of the measuring current and to the resistance to be measured. A first integrator integrates a signal respresentative of the magnitude of the measuring current in order to produce a first integration signal, while a second integrator integrates the voltage drop proportional to the measuring current and to the very low resistance in order to produce a second integration signal. The two integrators are simultaneously reset to zero so that they both start their respective integrations at a same instant. The first integration signal is compared to a reference signal through a comparator. When the amplitude of the first integration signal reaches the amplitude of the reference signal, the comparator delivers a signal which stops the integration carried out by the second integrator. The second integration signal is then stored, this signal having an amplitude constituting a measure of the very low electric resistance. A display device receives the stored integration signal for displaying the value of the measured resistance.

Controller for elevator

Abstract: PURPOSE:To keep off any malfunction due to a voltage drop in a microcomputer performing various types of control over a call registration, a drive motor, a safety circuit and so on by resetting a central processing unit when detecting a drop in supply voltage in this central processing unit. CONSTITUTION:In a signal input circuit 2 where each signal of various detecting switches is inputted, voltage is impression its power terminals 5, 6, transmitting the output to a central processing unit 7 of a microcomputer, and it performs various types of control over an elevator's call registration, a drive motor, a safety circuit or the like via a memory 8. Here, when a voltage drop detector 11 detects a voltage drop in the power source 4, its detecting signal is inputted into a reset terminal 12 of the central processing unit 7. Since this voltage drop detector 11 detects the voltage drop earlier than other signal input circuit 2, its detecting level is made higher in advance, and when it once detects a drop in the voltage or momentary power failure, the output signal is stored as long as the specified time. Thus, any malfunction due to a supply voltage drop is preventable.