Showing papers on "Voltage published in 1976"

Current sensing circuitry

Abstract: A current sensing circuit arrangement for controlling the response of a circuit electrically isolated from the circuit in which sensed current is flowing is disclosed. The input portion of the circuit arrangement provides paths for D.C. input current, one through a current sensing element and another through a light emitting diode circuit. The current-to-voltage characteristic of the current sensing element is such that changes in voltage across the element are substantially less than proportional to changes in current through the element. The light emitting diode circuit is connected in parallel with the current sensing element and produces light energy dependent on the voltage across the element. Light energy so produced is received by an electrically isolated light sensitive semiconductor device which device is for controlling the response of an output control circuit.

Constant output electrosurgical unit

Abstract: An electrosurgical unit which provides a voltage output to a load An oscator in the unit produces the output of a given frequency A switching circuit coupled to the oscillator provides an unmodulated RF carrier from the oscillator for use in cutting procedures and a pulse modulated RF voltage from the oscillator for use in coagulation procedures A feedback circuit is coupled from the output to the input of the oscillator to maintain the output voltage level from the unit at a substantially constant value independent of the load

A non-linear voltage dependent charge movement in frog skeletal muscle.

Abstract: 1. Voltage-clamp experiments were carried out using the three microelectrode technique. Using this method membrane current density at V1 is proportional to deltaV( = V2 - V1) where V1 and V2 are voltages at distances 1 and 21 from the end of a fibre. Voltage dependent sodium currents were blocked by tetrodotoxin, potassium by tetraethylammonium ions and rubidium. Contraction was blocked by adding sucrose, 467 mM. 2. The current deltaV (control) associated with a positive voltage step from a hyperpolarized conditioning voltage to the holding potential, -80 mV, showed two components, a capacitative transient which decayed rapidly and a maintained steady level...

An Improved Method of Resonant Current Pulse Modulation for Power Converters

Abstract: Presented is a converter philosophy for controlled transfer and transformation of electric energy through internal series resonant circuits at high internal power frequencies in excess of 10 kHz. Control of the continuously oscillating high Q series resonant circuit is attained by adjustment of the phase angle ? r between the exciting voltage and the resonant current. Only a very small fraction of the energy transferred to the load is absorbed by the resonant circuits to replace the power dissipated therein. Moderate and unconditionally predictable voltage and current stresses on components result from definite control of static and dynamic behavior of the system. This system is suited for construction of failsafe and highly efficient, low cost, submegawatt, single module converters with currently available components.

The use of charge pumping currents to measure surface state densities in MOS transistors

Abstract: A method is described for determining the surface-state density at the oxide interface in the channel of an MOS transistor from the charge pumping current flowing to the substrate when gate pulses are applied. From this simple measurement the surface state density can be determined as a function of gate voltage and if a quasi-static C-V characteristic is also measured for the gate of the transistor then the voltage distribution can be converted into an energy distribution. Representative results obtained on a set of commercial transistors show a large increase in the surface-state density near the middle of the band-gap after negative-bias thermal-stressing.

Medical electronic apparatus and components

Abstract: The apparatus includes a high frequency, high voltage generator, a therapeutic instrument for applying an electric current to a patient, a compound electrical power and control cable connected between the generator and the instrument, and a switch for selectively connecting at least one signal current conductor in the cable to a therapeutic current conductor in the cable to complete a circuit through an activating device for controlling the action of the generator. The cable includes a multiple strand bare therapeutic current conductor wire and preferably two single strand wires with film coatings of low voltage insulation, all of the wires being enclosed in a protective sheath of high voltage insulation. A high voltage is impressed on all of the wires but the voltage differential is very small so that the bare conductor is adequately insulated from the others by the film coatings, with a resulting savings in weight and cost of wire and insulation and improved flexibility. The cable passes into an instrument holder provided with a switch for selectively connecting the signal current conductors to the therapeutic current conductor for control purposes.

Electrochemical detector system

Abstract: An electrochemical detector has an electrochemical thin-layer flow cell whose operation is based on the so-called wall-jet principle, in combination with a controller unit. The controller unit can apply a periodically changing voltage having a square wave voltage formation to a sensor electrode of the electrochemical cell such that a first potential level of the square wave functions as a detecting potential and a second potential level of the square wave functions as a cleaning potential.

Method and device for checking a storage battery

Abstract: A battery of series-connected storage cells is checked by: Measuring the transient elementary open-circuit voltage at the terminals of each storage cell; Comparing the said elementary voltages with the average transient voltage of the said storage cells (i.e. with the total transient open-circuit voltage divided by the number of storage cells). The battery is rejected if the difference between the said average transient voltage and one of the said elementary transient voltage becomes greater than a predetermined threshold. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for checking a storage battery, more particularly a lead acid storage battery, charged and filled with electrolyte, this checking being effected in principle when the battery comes off the production line. 2. Description of the Prior Art Known means which are used at present for detecting electrical defects which have not been detected during checks made at intermediate stages of production are of two types: Firstly, devices for measuring the voltage of the batteries at the end of the forming and charging phase enable the rejection of the battery whose-end-of charge voltage is lower than a predetermined thereshold; and Secondly, rapid discharge devices require the rejection of batteries whose voltage is insufficient after a few seconds of discharge. These means are generally completely insufficient for detecting small or medium internal short-circuits and even large short circuits, which can be detected by conventional checking methods only after long storage or service periods. Preferred embodiments of the present invention enable electrical defects such as short circuits to be detected after charging ie; during battery finishing operations. SUMMARY OF THE INVENTION The present invention provides a method of checking a battery of series connected storage cells, comprising the following operations: An elementary transient open circuit voltage is measured at the terminals of each storage cell (ie; The said elementary voltages are compared with the average transient voltages of the said storage cells (ie with the total transient open circuit voltage devided by the number of storage cells); The battery is rejected if the difference between the said average transient voltage and one of the said elementary transient voltages is greater than a predetermined threshold. In the method according to the invention, the transient voltage of a storage cell to be tested is compared, not with that of a standard storage cell, but with the average transient voltage of all the cells of the battery to which it belongs; thus in each battery, the average theoretical cell is assimilated to a normal reference cell. The existence of an electric defect in a storage cell results in a difference in transient voltage which is greater in proportion the magnitude of the threshold value is chosen as a function of the least defect which it is necessary to detect. The measurement of transient voltages in an open circuit can be effected continuously or at predetermined instants in a period counted from the end of charging and ranging from a few tens of minutes to ten or so hours, a period of about one hour being preferable. The invention also provides a device enabling the implementing of the above method. Embodiments of the invention are described by way of example with reference to the accompanying drawings:

Charge movement in the membrane of striated muscle

Abstract: SUMMARY 1.Non-linear polarization currents apparently duetopermanent dipoles ormobile charges inthemembranecanbemeasured byappropriate comparison ofthetransient currents required toproduce small andlarge steps ofmembrane potential. Integration ofthese transient polarization currents estimates thecharge transfer associated withthemovementofmembrane dipoles orcharges. 2.Depolarization from-100to0mV requires a charge transfer of 35nC//tF inaddition tothecharge transfer predicted bylinear extrapolationofthecharge required forasmalldepolarization from-100mV. Depolarizations ofvarying sizegivea charge-voltage relation whichis sigmoid saturating beyond 0mV andwithamidpoint atabout-50mV. Therateaswellasthemagnitude ofcharge movementdepends steeply onthepotential. 3.Prolonged depolarization reduces orremoves charge movementdetected bycomparing currents forsmallandlarge voltage stepsfrom -100mV (Charge 1). However indepolarized fibres comparison ofcurrents froma smallpotential stepat+40mV anda large hyperpolarizing potential stepfrom-20mV reveals large movements ofasecond charge (Charge 2).MovementofCharge 2isless steeply dependent onvoltage thanmovementofCharge 1bothinmagnitude andinrate. 4.Insize andvoltage dependence these twokinds ofcharge movement correspond tomeasured voltage dependence ofcapacity innormally polarized anddepolarized fibres (Adrian & Almers, 1976).

Three phase load flow program

Abstract: The paper describes a general three phase load flow program developed for the steady state analysis of any electric transmission network under all possible imbalance conditions such as untransposed EHV lines, single phase loading, single pole switching, etc. Input data preparation and output data interpretation are made easy for program users by using both phase and symmetrical components quantities; however, the load flow problem formulation and solution are all done in phase quantities (A, B, C). The method of solution is the Newton-Raphson method, using optimally ordered triangular factorization to take advantage of the sparsity of network equations. The program has several new features to simulate real three phase operation of power systems and imbalance conditions. For example, the internal induced voltages of generators are balanced, while generator terminal voltages depend on internal machine impedances and the imbalance in machine currents. Also, the steady state performance of the voltage regulator is simulated to maintain some function of the machine terminal phase voltages constant, depending on the actual design of the voltage measurement. Another feature of the program is that it can handle all common transformer connections having two or three windings that are used in HV transmission networks.

Position Sensing by Charge Division

Abstract: A summary of a comprehensive analysis of theoretical and practical aspects of position sensing by charge division from resistive electrodes is presented. Properties of transformer decoupling of the resistive electrode from detection bias voltage are analyzed and compared to the usual capacitive decoupling methods. Optimization and limitation of signal shaping is discussed as a function of diffusion time constant, signal rise times, and noise.

A fast decoupled static state-estimator for electric power systems

Abstract: A new algorithm is described to solve the static, time-invariant weighted least-square state-estimation problem for large-scale electric power systems. The solution is obtained through P-θ and Q-V decoupling and alternately iterating the active and reactive equations using fixed, simplified submatrices of the information matrix. Thus, a much faster algorithm is obtained yielding the exact solution and requiring little computer storage. The new method is compared with the basic "Weighted-least-square" and the "Line-Only" algorithms on a practical HV network.

Level shift circuit

Abstract: A gating means couples excitation signals to the input of an inverter which is connected between first and second power terminals. Positive feedback means is connected between the input and the output of the inverter. In response to an excitation signal, whose level is intermediate the levels of the operating voltages applied between the first and second power terminals, the inverter output is driven to the potential at one of the first and second power terminals while the potential at the other one of the first and second power terminals is applied to the inverter input. The gating means, conductive during transitions of the excitation signals from one level to another, does not conduct in the steady state condition, whereby a potential at the inverter input of higher amplitude than the excitation signals is not coupled back to the source of excitation signals.

Electronic DC battery charger

Abstract: A battery charger receives direct current power from an external source through a power connector. Switch means receives the power from the power connector and supplies it to a boost circuit which is removably and conductively connected to a battery. A control circuit is connected to receive a battery voltage signal from the battery and a battery temperature signal from a temperature sensor positioned to detect battery temperature. The control circuit determines the state of charge of the battery from the voltage and temperature signals. The control circuit supplies (1) switching signals to the switch means to cause the switch to be conductive, and (2) boosting signals to the boost circuit to cause the boost circuit to charge the battery in accordance with a preselected charging program related to the state of charge of the battery. A safety circuit may also be adapted to sense unsafe battery and battery charger parameters and cause the control circuit to generate a switching signal to cause the switch means to be nonconductive upon the occurrence thereof. The battery charger is particularly adaptable for use with vehicles.

Adjustable speed A-C motor drive with smooth transition between operational modes and with reduced harmonic distortion

Abstract: Alternating voltage for energizing an adjustable speed a-c motor is derived from unipolarity input voltage by means of electric power inverting apparatus comprising at least one pair of alternately conducting controllable electric valves. The conducting states of these valves are periodically switched by control means responsive to frequency and amplitude command signals, whereby the frequency and the amplitude of the fundamental component of the alternating voltage are varied as functions of the respective command signals. The control means includes means for implementing a triangle interception mode of pulse width modulation (PWM) of the alternating voltage so long as the amplitude command signal does not exceed a predetermined reference value (which is less than 1.0 per unit) and the speed of the motor does not exceed a predetermined reference speed, and the control means additionally includes means for implementing a "transition" PWM mode of operation whenever the amplitude command signal exceeds its reference value or the motor speed exceeds said reference speed. As disclosed herein the transition PWM mode implementing means is a dual d-c level set scheme in which the lower level is varied as a function of the higher level so as to minimize selected harmonics of the alternating voltage and the higher level is varied as a function of the amplitude command signal thereby to vary the amplitude of the fundamental voltage component, and means is provided for smoothly transitioning to a square wave mode of operation as the amplitude command signal approaches 1.0 per unit.

Solar energy converter

Abstract: An improved solar energy converter comprising a plurality of electrically conductive, photoemitting electrodes geometrically arrayed so that light will strike only one surface of each to produce electron emission. The electrodes are in a spaced, generally parallel relationship so that electrons emitted by the illuminated surface of one electrode will travel to, and be collected by, a non-illuminated surface of a next adjacent electrode. A vacuum surrounds the electrodes so that only space conduction occurs. Each electrode has one surface which acts as a photoemitting cathode and one surface which acts as an electron collector, or anode, and thus each pair of adjacent electrode surfaces is analagous to a voltage cell, the plurality of electrodes forming a solar energy battery.

Charge movement in the membrane of striated muscle.

Abstract: 1. Non-linear polarization currents apparently due to permanent dipoles or mobile charges in the membrane can be measured by appropriate comparison of the transient currents required to produce small and large steps of membrane potential. Integration of these transient polarization currents estimates the charge transfer associated with the movement of membrane dipoles or charges. 2. Depolarization from -100 to 0 mV requires a charge transfer of 35 nC/muF in addition to the charge transfer predicted by linear extrapolation of the charge required for a small depolarization from -100 mV. Depolarizations of varying size give a charge-voltage relation which is sigmoid saturating beyond o mV and with a midpoint at about -50 mV. The ratnged depolarization reduces or removes charge movement detected by comparing currents for small and large voltage steps from -100 mV (Charge 1). However in depolarized fibres comparison of currents from a small potential step at +40 mV and a large hyperpolarizing potential step from -20 mV reveals large movements of a second charge (Charge 2). Movement of Charge 2 is less steeply dependent on voltage than movement of Charge 2 both in magnitude and in rate. 4. In size and voltage dependence these two kinds of charge movement correspond to measured voltage dependence of capacity in normally polarized and depolarized fibres (Adrian & Almers, 1976).

Long life cardiac pacer with switching power delivery means and method of alternately delivering power to respective circuit portions of a stimulus delivery system

Abstract: A pacer having a DC to DC converter for use with a relatively low voltage power source, and for providing a raised voltage supply to a load characterized by having a first circuit portion which is voltage sensitive and draws a low current, and a second circuit portion which draws a high current and is relatively insensitive to supply deviations, comprising a switching circuit alternately connecting said respective circuit portions through respective converters to the supply so that the voltage sensitive circuit is not affected by the loading of the high current circuit. A method is provided for alternately delivering power from a battery source to respective circuit portions of a stimulus delivery system.

Switching regulator power supply

Abstract: A switching regulator electronic power supply for 115 volt A.C. operation rectifies and filters to provide approximately 170 volts of unregulated D.C. to the primary winding of a power conversion transformer. In series with the primary winding is a transistor power switch controlled by a pulse width modulator whose ON-time is determined by the rectified D.C. voltage level, and whose OFF-time is controlled by an output voltage sensor and a current limiter that provide duty cycles that assure a constant D.C. voltage level from the rectified and filtered output of the power supply.

A mechanism for spike frequency adaptation.

Abstract: 1. Spike frequency adaptation was studied in large neurones of the marine molluscs Archidoris montereyensis and Anisodoris nobilis. These cells respond to a current step with a rapid rise in spike frequency followed by a gradual decline to a new steady level. 2. An exponentially declining current, Is, was measured when the cell was voltage clamped following an adapting spike train. The initial amplitude of this current depended on the preceding number of spikes and on the voltage to which the cell was clamped. A reversal potential (Vs) for this current was obtained by clamping to various potentials following a spike train. The time constant (τs) of decay of the current was dependent upon the clamping potential. 3. Clamping the membrane potential to a constant test level from various initial levels initiates an exponentially decaying current of similar time constant. The voltage dependence of the steady-state conductance (ḡsas(V, ∞)) associated with this current was determined using this technique. 4. Equations for neural repetitive firing (Connor & Stevens, 1971c) were modified by the addition of a term describing these slow membrane currents: [Formula: see text]. The solution to the modified equation was in good agreement with the spike frequency adaptation observed in these cells.

Charging system and method for multicell storage batteries

Abstract: A battery-charging system includes a first charging circuit connected in series with a plurality of battery cells for controlled current charging. A second charging circuit applies a controlled voltage across each individual cell for equalization of the cells to the fully charged condition. This controlled voltage is determined at a level above the fully charged open-circuit voltage but at a sufficiently low level to prevent corrosion of cell components by electrochemical reaction. In this second circuit for cell equalization, a transformer primary receives closely regulated, square-wave voltage which is coupled to a plurality of equal secondary coil windings. Each secondary winding is connected in parallel to each cell of a series-connected pair of cells through half-wave rectifiers and a shared, intermediate conductor.

Dual mode solid state inverter circuit for starting and ballasting gas discharge lamps

Abstract: A variable frequency ac source drives a gas discharge lamp connected as a damping element in an otherwise high Q L-C circuit. Commutation of the ac source voltage is initiated as the instantaneous current drawn from the source equals a predetermined reference current level. Prior to lamp ignition the ac source drives the L-C circuit at resonance causing a voltage buildup which initiates an ignition. After ignition the source limits lamp current to provide a ballasting function.

MOS reference voltage circuit

Abstract: An MOS integrated circuit for providing a stable reference voltage. The voltage thresholds of an enhancement mode transistor and depletion mode transistor are substracted to provide the stable reference potential. The reference potential is stable for both temperature and power supply variations, including variations in a substrate biasing potential.

Dynamic brake blending for an inverter propulsion system

Abstract: The stator terminals of an adjustable speed a-c induction motor are connected to a source of d-c electric power by means of an inverter, and a system is provided for blending both dynamic and regenerative electrical braking of the motor whenever it decelerates. The brake blending system comprises a plurality of braking resistors respectively coupled by a corresponding switch in parallel with the power source. The switches are controlled by a control circuit which responds to motor terminal voltage, motor angular velocity and the difference between the commanded and actual motor torques to determine the additional current which the motor could regenerate without exceeding commanded parameters. When the additional current corresponds to that current which can be absorbed by adding an additional stage of braking resistance, the control circuit actuates a switch to add a stage of dynamic brake resistance. The control circuit also monitors the voltage of the source and removes braking resistance in steps to maintain source voltage within selected limits in order to maximize the current fed to the power source and thus maximize regenerated energy. In an alternate embodiment the control circuit determines the admittance of the source and utilizes the admittance to maintain source voltage substantially constant by removal of dynamic brake resistance in order to force more regenerative current to the source.

InP/SiO2 MIS structure

Abstract: Metal‐insulator‐semiconductor (MIS) structures were produced by the pyrolitic deposition of SiO2 on InP. The insulating layers were hard and glasslike with a room‐temperature resistivity ≳1015 Ω cm at a field of 106 V/cm. Breakdown field strengths are typically between 5×106 and 107 V/cm. The electrical properties of the InP‐SiO2 interface were found to exhibit a strong dependence on the SiO2 deposition process parameters. For optimum conditions capacitance/voltage (C/V) measurements suggest that the average interface state density is ∼2×1011 cm−2 eV−1 with flat band occurring at a gate voltage of approximately −0.1 V. Triangular waveform bias sweep frequencies of ≲10−3 Hz are required to attain equilibrium C/V conditions.

Partial discharge characteristics of oil-immersed insulation systems under DC, combined AC-DC and DC reversed polarity voltage

Abstract: Breakdown characteristics of insulating oil, under combined ac-dc voltage and dc reversed polarity voltage, and partial discharge characteristics of oil-immersed insulation, under combined ac-dc voltage and polarity revesal of dc voltage Were made clear by elementary experiments. After that, a numerical dc field mapping method for electric field analysis of two-dimensional configurations which consist of composite insulation and field mapping methods under combined ac-dc voltage and dc reversed polarity voltage were proposed. Futhermore, partial discharge characteristics of transformer insulation under dc, combined ac-dc voltage were experimentally made clear by practical trial models.

Discharge lamp auxiliary circuit with dI/dt switching control

Abstract: A variable frequency AC source drives a gas discharge lamp which is connected in parallel with the capacitance of a series resonant circuit. The polarity of the voltage applied to the resonant circuit is commutated at such times as the rate-of-change of current flow in the resonant circuit is at or near zero. The source frequency is thus maintained at or near the circuit resonant frequency to maintain high output voltage when the lamp is starting or reigniting. The polarity is also commutated at such times as the current flow from the source reaches a predetermined level. Lamp current is thus controlled in the running mode.

Protection circuitry for insulated-gate field-effect transistor (IGFET) circuits

Abstract: The gate insulator of an IGFET, whose gate is connected to the input terminal of a circuit, is protected by limiting the potential difference between any two circuit terminals. Each input and output terminal of the circuit is connected via protective diodes to the power supply lines of the circuit and a high conductivity, low reverse dynamic impedance, diode is connected between the power supply lines. The reverse voltage across the high conductivity diode is less than that of any other diodes at a given current level, whereby only the high conductivity diode conducts substantial currents in the reverse direction.

Promotion and retardation of heat transfer by electric fields

Abstract: I REPORT here on the effects of an electric field on heat transfer. The effects depend on the applied voltage, the shapes, number and locations of the electrodes, and the frequency of the electric field1,2.