Showing papers on "Voltage drop published in 1974"

Theory of a membrane‐voltage clamp with discontinuous feedback through a pulsed current clamp

Abstract: We present a voltage clamp (potentiostat) for biological membranes which works on a new principle. Its feedback loop contains a current clamp which drives a train of brief current pulses through the membrane (typically 8 μsec duration and 8 μsec intervals). In each interval between two current pulses, the difference between membrane voltage and command voltage is sampled and determines the amplitude of the next current pulse. Since the membrane capacitance acts as an analog store between current pulses, the membrane voltage oscillates near the desired value in a triangular waveform. It is independent of resistive voltage drops at electrodes or fluid layers developing in series to the membrane (or the electrode) to be clamped. The clamp does not tend to oscillate, in contrast to clamps with continuous feedback after compensation for series resistors. A precise measurement of membrane capacitance is possible.

Thermocouple system having a PN junction for cold junction compensation

Abstract: A thermocouple system for catalytic controllers uses a PN junction at the cold junction for cold junction compensation. The linearity of the voltage drop across the PN junction permits accurate scaling for direct reading of the temperature at the output of the system. A switching circuit is described wherein the desired switching temperature is electrically entered into the circuit and when the compensated temperature signal is equal to the entered signal, the output of the switching circuit is switched.

Highly sensitive gate-controlled pnpn switching circuit

Abstract: A PNPN switch having substantially a fourlayer structure has at least its first, third and fourth layers, which have respectively P,P and N conductivity types, provided respectively with a first, third and fourth electrodes. The source and the drain of a field effect transistor is connected with the third and fourth electrodes, respectively. The third electrode is further connected with one end of a voltage drop element while the other end of the voltage drop element is connected with the gate of the field effect transistor. The gate of the field effect transistor and the other end of the voltage drop element, connected together, serve as a gate trigger terminal of a highly sensitive gate-controlled PNPN switching circuit.

Binary circuitry including switching elements utilizing superconductive tunneling effects

Abstract: Two Josephson gates are connected in series to a low impedance voltage source. Each junction is bridged by a load impedance. The feed voltage is maintained in the order of the gap voltage which corresponds to the voltage drop across a Josephson junction when it is in its single-particle-tunneling state. Therefore, only one out of both Josephson elements can exist in the voltage state at a time, and the other junction is forced to assume the superconducting pair-tunneling state. In its symmetric form, the basic circuit can be used as flip-flop or storage means. If asymmetric, the basic circuit shows monostable switching behavior, and it can be used as logic gate. Circuit asymmetry can be caused either by design using different junction areas or electrically by proper bias control currents applied to either or both gates of the basic circuit. The degree of symmetry or asymmetry can even be shifted with electrical means. AND and OR gates and inverting embodiments which perform logic NAND and NOR functions are shown.

Monitor and controller for heating a resistive element

Abstract: Apparatus for controlling the heating of an electric element which repeatedly disconnects the electric element from the heating power supply and connects a resistor in series with the electric element and an electric potential across the series combination, when the voltage drop across the electric element is above a predetermined level, heating power is not reconnected to the electric element. The controller utilizes an adjustable time delay for providing the time period for which heating power is applied to the electric element. After each heating cycle the voltage drop across the electric element is monitored. The length of the monitoring cycle is controlled by a time delay and a voltage sensitive contact connected across the electric element. The monitoring cycle will terminate after a time delay, unless the voltage drop across the electric element is above a predetermined value, in which case it will continue until the voltage drop falls below the predetermined level. In other words when the electric element is heated its resistance increases thereby increasing the voltage drop across the electric element when a fixed potential is applied across the electric element and resistance in series. When the voltage drop across the electric element is above a predetermined value, the electric element remains isolated from the heating power supply.

Circuit device for secondary electron multipliers

Abstract: A circuit device for electron multipliers, especially photomultiplier tub in which the amplification is varied by switching the number of active dynodes. Sensitivity ranges from diode-mode up to a multiplier with full number of dynodes. The signal is taken from the last active dynode, and from the cathode in diode-mode. Any switchable dynode is provided with its own load resistor inserted between the relevant dynode and a dynode voltage divider. An amplifier connected to the last active dynode and to the dynode voltage divider provides a feedback that compensates for voltage drops at the next lower dynodes due to the finite impedance of the dynode voltage divider. The circuit device features fast signal risetime, high linearity and wide dynamic signal range together with high DC-current capability and clean transient response. Applications are transient-spectrophotometers where high signal-to-noise ratios are needed, accurate pulse-height-analysis, etc. The device may be constructed as a self-contained unit.

Apparatus for testing multiconductor cables for continuity, correct connections, and the absence of short circuits between conductors

Abstract: Apparatus is disclosed for testing a cable by connecting Zener diodes or similar acting structures between terminating contacts at one end of the cable and then selectively connecting a series connected DC voltage source and resistor between terminating contacts at the other end of the cable. The diodes introduce unique voltage drops which determine the current flowing from the voltage source. The magnitude of the current is indicative of the condition of the cable with respect to continuity, correct connections, and interconductor short circuits.

Arrangement for controlling the gain of two-way amplifiers in accordance with loop lengths

Abstract: An arrangement is provided for controlling the gain of two-way amplifiers, in accordance with loop lengths. The voltage drop caused by a constant current device impressed on a variable length loop is used to control the gain of the two-way amplifiers by applying the variable voltage as a control for a voltage controlled resistance such as a field effect transistor coupled with an attenuator which is part of the gain-determining network of the amplifiers. Since the voltage drop across the constant current device is inversely proportional to loop lengths, and hence directly proportional to the desired additional loss, this voltage is used to reduce the effective feedback resistance of the amplifiers and hence their overall gain. The amplifier outputs thus are compensated for different loop lengths.

Speed control circuit for permanent magnet D-C motors

Abstract: To obtain in a brushless d-c motor a speed control signal which is dependent both on rotational speed and on armature current in a predetermined mix, each of n armature winding has a diode connected thereto with one terminal, all terminals of the diodes being connected together to provide a first control voltage which coupled out from the windings during current flow therethrough and is representative of a composite of the emf induced by the field of the rotor in the n armature windings and of resistance voltage drop due to the current flow through the respective armature windings; resistors have one terminal, each, connected to the same n respective armature windings and the other terminals together to provide a common resistor junction at which a second control voltage is derived representative of 1/n of the resistance voltage drop due to current flow through said n armature windings. The two control voltages are normalized or weighted with respect to each other, compared, and the comparison is applied to a speed control circuit which will be responsive to armature current and to induced voltages. Positive or negative feedback can be introduced, in dependence on armature current, by affecting the normalization or weighting ratio.

Measuring bridge circuit

Abstract: The present measuring bridge circuit is especially suitable for a plurality of measuring points. One measuring bridge branch is provided for each measuring point. Selectively operable switching means interconnect each measuring bridge branch, and if desired also at least one compensating bridge branch, to a voltage supply source. In order to compensate for any voltage drops across these selectively operable switching means, supply voltage control means are provided which regulate or continuously adjust the output voltage of the supply voltage source in response to said voltage drop. In an alternate embodiment of the invention, a high impedance complementary half bridge circuit is connected through selectively operable further switching means to the other bridge branches. A control of the supply voltage may be accomplished by means of an amplitude comparing circuit.

Electronic control system for battery chargers

Abstract: An electronic control system for battery chargers in which the charging current is switched on and off at predetermined intervals of time, and the magnitude of the charging current during the ON periods is controlled from a signal produced from the electronic control system On switching OFF the charging current at each cycle of operation, the rate of decay of battery voltage is utilized to form a control signal, having first removed the voltage drop on switch off due to the ohmic resistance of the battery, known as the ''''IR Drop'''' Having extracted the ''''IR Drop,'''' the remaining rate in decay in voltage representing the ''''Gas Drop'''' due to potential changes in the layer of gas on the active surfaces of the electrode, is compared with a standard reference voltage, the result of said comparison being utilized to vary the magnitude of the charging current in accordance with the state of charge of the battery as determined by the rate of decay of battery terminal voltage, due to the ''''Gas Drop

High speed low power schottky integrated logic gate circuit with current boost

Abstract: A high speed low power Schottky integrated logic gate circuit of a quadruple two input NAND gate type provides an adequate input voltage threshold even under increasing ambient temperatures by providing an additional transistor Vbe drop to the existing 2Vbe voltage drop circuit but yet maintains the high speed of the circuit by use of an additional current boosting transistor.

Ballast unit for gas discharge lamps such as fluorescent tubes or the like

Abstract: The disclosure relates to a ballast unit for gas discharge lamps, particularly fluorescent lamps, by which a substantially constant burning current is supplied to the lamp. The ballast unit includes a transformer mounted on a core having a defined air gap. The transformer is provided with a leakage inductance having a value resulting in a voltage drop of between approximately 15 and 30 percent of an input voltage applied thereto. One or more capacitors are connected in series with the transformer output supply to the lamp. The one or more capacitors provide a capacitance in series with the lamp substantially equal to the ratio of the burning current to the angular frequency of the input voltage multiplied by the secondary no-load voltage supplied to the secondary circuit.

Resistance measuring circuit - three wire circuit is used to balance line influences

Abstract: The resistance measuring circuit is especially for temperature measurement by resistance thermometers. It comprises a constant current source (IC) supplying the resistor (RT) to be measured through two of the three wires (L1, L2, L3). At least one amplifier (V1), has inputs (E1, E2) with practically infinite input resistance connected with one of the current carrying wires (L1, L2) and with the third wire (L3), in order to measure voltage drop in one of the current carrying wires (L1, L2). The amplifier's output voltage is inverted with respect to the input voltage, and its value corresponds to the voltage drop in one of the current carrying wires (L1, L2). It is used to compensate the voltage drop in both current carrying wires.

Low voltage monitor circuit

Abstract: A simple and inexpensive circuit for monitoring one or more current sources and producing an active output signal whenever one of the monitored sources fails. Current from the monitored sources is applied to respective transistors to hold them in saturation so long as the sources operate normally. The transistors are connected in series with each other and with the input of an optical coupling device. An annunciator device is connected in series with a control transistor across a current source that is independent of the monitored sources, and the output of the optical coupling device holds the control transistor cut off so long as the monitored sources remain normally operative. When one of the monitored sources fails, or suffers a significant voltage drop, current applied at the input of the coupling device is reduced causing the control transistor to conduct, thereby to energize the annunciator.

Cell for measuring electrical resistivity of a liquid

Abstract: A cell for measuring the electrical resistivity of a liquid contains four aligned and linearly spaced electrodes. A current source is connected to the end electrodes and an amplifier is connected directly to the inner electrodes. The amplifier has a high input impedance characteristic sufficient to limit the current carried by the inner electrodes to a small value which renders it essentially independent of any fouling of the inner electrodes. The amplifier is connected to the current source to control the current output thereof so as to maintain a constant predetermined voltage drop across the inner electrodes whereby the output of the amplifier is independent of any IR drop due to the fouling of the outer electrodes. A reference and a measuring cell may each be connected as above with the high input impedance amplifier of the measuring cell controlling the current sources for both cells and the corresponding amplifier of the reference cell driving a suitable output indicator.

Electronic monitoring system including contactless motion detector

Abstract: A contactless motion detector, including an oscillator and an amplifier, has an energizing circuit connected across an electronic breakdown device lying in series with a contant-current unit, this series combination receiving pulsating direct current from a supply circuit in parallel with an output thyristor which bridges either the entire series combination or only the constant-current unit. The output thyristor is controlled by a switching transistor responding to an output signal from the motion detector; even when the output thyristor fires to actuate a load in the supply circuit, a sufficient voltage drop is maintained across the breakdown device to keep the oscillator and the amplifier operating.

Voltage distribution systems for integrated circuits

Abstract: A technique for damping unwanted power system oscillations present in an integrated circuit package is disclosed. A very low d.c. impedance is achieved at any point in the voltage distribution system by a reduction in inductance, and increase in capacitance and an increase in a.c. resistance. The resistive voltage drop is achieved only at higher frequencies near the resonance frequency of the oscillations where it is needed. The scheme can be implemented on an integrated circuit chip by locating highly doped closed diffusion loops under the voltage supply lines or by placing metal layers on top of it. Further, a highly doped substrate has the same effect.

Electronic variac surge current limiting circuit

Abstract: A circuit having a gated, symmetrical switch is provided for insertion between an AC source of power and a load, and prevents a surge current from entering the load when the AC input is initially applied. A symmetrical negative resistance device that begins conducting at a prescribed voltage and remains on as a constant voltage regulator until the AC input voltage drops below a sustaining value is connected to provide the prescribed voltage to the gate control of the gated symmetrical switch. An RC circuit controls the length of time required for the AC input voltage to reach the prescribed voltage at the input to the symmetrical negative resistance device. At least part of the resistance in the RC circuit is of the negative temperature coefficient type, resulting in the resistance value decreasing as the temperature of the negative temperature coefficient device increases, thereby shortening the time after which the prescribed voltage to the symmetrical negative resistance device is applied.

Controlled current filaments in pnipn structures with Application to magnetic field detection

Abstract: Stable biasing of multiterminal PNIPN structures to support controlled current filaments is proposed. A filament forms when base layer spreading resistance is sufficiently high for lateral base voltage drops to shut off injection at all but a small interior portion of the structure. For elongated parallel stripe emitter-base configurations, application of a magnetic field normal to the current filament and stripe axes results in lateral displacement of the filament which is detectable through a change in the external circuit current flow pattern. This displacement can be significantly larger than that of a single-pass Hall deflection, yielding high sensitivity. Analysis of an ideal model confirms a substantial improvement in performance over that of conventional Hall devices, viz., a manyfold increase in the ratio of short circuit signal current to drive current, similar improvement in signal-to-offset ratio, and controllable high output impedance making large signal voltages available. Solutions for the ideal model are presented for carrier transport in the I region both without and with lateral diffusive spread. It is argued that departures of actual device behavior from this model are not apt to be important. Possible circuit connections and a sample calculation of parameter values for a realizable structure are also given.

High slew rate monolithic operational amplifier using compatible complementary P-N-P's

Abstract: An internally compensated monolithic operational amplifier, fabricated using only junction-isolated bipolar processing, slews in excess of 500 V//spl mu/s, and settles to within 0.1 percent in 200 ns as a pulse inverter. Performance in the noninverting mode is only slightly degraded in comparison with the inverting mode. In addition, the following performance levels have been achieved: 50-MHz unity-gain bandwidth with 96-dB open-loop gain, 30-mW quiescent power at /spl plusmn/3 V, /spl plusmn/50-mA output current capability, and output voltage to within 0.5 V of either supply. In order to achieve the above performance, the following innovations were made: 1) a process for junction-isolated compatible complementary p-n-p transistors with low collector series resistance, 2) a high-speed class-B output stage, 3) push-pull middle stages, 4) driven internal reference voltages locked to the noninverting input, and 5) very small voltage drops across large internal shaping capacitors which permit use of high-capacitance junctions.

Discharge Voltage of Arrester Connecting Lead Wires

Abstract: In order to provide adequate surge protection for underground cable circuits, particularly at system voltages above 13.2 kV, the riser pole arrester discharge voltage must be held to relatively low values. The surge impedance voltage drop of lead wires connecting arresters between line and ground adds to the arrester discharge voltage, and as a consequence influences the total transient voltage that can enter the cable circuit. Because of this it becomes essential to know, quantitatively, the effect of lead wire lengths on total voltage.

Overcurrent sense circuit

Abstract: An overcurrent sense circuit for sensing an overcurrent condition at the output of a power supply uses inherent D. C. resistance and the voltage drop associated with current flow through that resistance to generate a logic signal indicating the overcurrent condition. A current source offsets the maximum allowable voltage drop across the equivalent resistance for normal operation. The offset voltage and voltage drop across the equivalent resistance are fed into a comparator. When the voltage drop across the equivalent resistance exceeds the maximum allowable voltage drop due to an overcurrent condition, the comparator switches and thereby provides an output indicating the overcurrent condition.

Exponential resistance material and method of manufacturing same

Abstract: A voltage drop across a resistance element, wherein the resistance varies exponentially with the voltage, is expressed by the equation: E B X I1/n WHEREIN I is the current through the element, B is a constant and is equal to the voltage value at which the current through the element is equal to 1 Ampere, and E is the voltage drop. To achieve a variable B-value based on the resistance material itself and furthermore to achieve a greater dependence of the resistance on the voltage drop, the value of n can be selectively raised by varying the composition of the resistance element as follows: 50 - 90% ZnO 0.1 - 40% ZnF2 0.1 - 40% MeO wherein MeO is an oxide selected from the oxides of magnesium, calcium, strontium, barium, iron, cobalt, lead, boron, aluminum, bismuth, manganese, chromium, nickel, antimony, and mixtures thereof. An improved method of manufacturing such a resistance material is also described.

Control circuit for sequential energization of plural loads from an AC power source

Abstract: Control circuitry for solenoid type power units and the like, such as employed as pump means in oceanographic monitoring apparatus and the like. In an illustrative embodiment two power units oscillate 90 DEG out of phase through two sets of two solenoids, one set for each power unit, with distribution of successive half waves of the alternating current power being supplied to the solenoids in sequence. Each solenoid is energized through an electronic valve (e.g., an SCR) receiving gated power through another solenoid, the gating being through a capacitor and diode whereby the capacitor is initially rapidly charged and then discharges slowly enough to prevent or block regating until occurrence of a subsequent half wave, the blocking action being reinforced by the voltage drop occurring across the other solenoid, which in the meanwhile has been preferentially gated. A series connected capacitive means optionally provides series resonance with the mean net effective inductance of the solenoids to optimize power efficiency.

Voltage drop warning apparatus with negative-resistance device

Abstract: A series connection comprising a transistor (4) and a light-emitting diode (3) is connected across a D.C. power source (+Vcc), and one end of a negative-resistance device (1) is connected to the base of said transistor (4) and the other end thereof is connected to an end of said light-emitting diode (3), which last-mentioned one end is connected to the D.C. power source (+Vcc). The circuit constituted as above memorizes an occurence of voltage drop which enables bistable switching in the negative-resistance device, thereby energizing the light emitting diode to light. The circuit can be used to indicate voltage lowering or interruption of an A.C. power supply, or weakening of a battery.

Wide dynamic range logarithmic amplifier arrangement

Abstract: The arrangement conventionally comprises a high gain differential amplifier with a negative feed back transistor; a compensating circuit with resistors compensates for the voltage drops occurring due to the parasitic resistances of the transistor; a limiting circuit, comprising a unidirectional conduction device, brings to a minimum threshold value those values of the input signal which lie below this threshold value.

Loop current detector

Abstract: A loop current detector for detecting current flowing in a pair of telephone wires comprises: A. a saturable reactor having first, second and third windings, the first and second windings adapted to be connected in a loop circuit to pass DC current, B. resistance connected with the third winding to form therewith a voltage divider, and an oscillator having an AC output connected with the divider, characterized in that the AC voltage drop across the third winding is relatively high when no DC current flows through said loop circuit, and said drop is relatively low when DC current flows through said circuit, and C. switching means having first and second modes of operation with associated outputs, and connected with said voltage divider to be responsive to said oscillator output when said AC voltage drop is relatively high to be switched into said first mode of operation with one associated output, and to be non-responsive to said oscillator output when said AC voltage drop is relatively low to be switched into said second mode of operation with a second associated output.

Bridge circuit for measuring resistances

Abstract: A bridge circuit for measuring resistance of a pair of four-terminal resistances having their current terminals serially connected to an ac source comprising: a voltage follower connectable to each voltage terminal of the pair of resistances; a ratio transformer coupled across the output of the first and second of the voltage followers; a first pair of series resistances connected between the outputs of the second and third voltage followers; and a second pair of series resistances connected across the output of the fourth voltage follower; phase matching means across either of the four-terminal resistors and an adjustable tap on the transformer; the centre points of the first and second pairs of series resistances adapted to be connected across a null detector for indicating when the voltage across the input to the third and fourth voltage followers is equal to the voltage between the tap and the output of the second voltage follower.

Performance of a Faraday Rare Gas Alkali MHD Generator

Abstract: The performance of the IPP rare gas alkali MHD generator was theoretically and experimentally investigated. The open-circuit Faraday voltage, the short-circuit Hall voltage, and the load characteristic were measured at different segmentation ratios s/h and various magnetic field strengths. Furthermore, the current streamline pattern in the generator duct was determined from the equipotential lines measured by means of a movable probe. From these measurements it could be concluded that the generator is practically free of any leakage currents and internal plasma short-circuits. This conclusion was further supported by the reasonably good agreement between theory and experiment regarding the current voltage characteristic of the generator. In the calculation allowance was made for the influence of ionization instabilities, segmentation effects, and voltage drops at the electrode, but mechanisms producing leakage currents or internal plasma short-circuits were not considered. N rare gas alkali MHD generators the electron density and hence the electrical conductivity attain equilibrium in accordance with the electron temperature elevation. This "nonequilibrium ionization" in conjunction with the fact that the electron temperature elevation in the generator may show strong local variations and occurs in a medium flowing at high velocity through the generator duct gives rise to a number of complications which are not so pronounced in the case of an equilibrium generator or not even present there. The most important ones are: elongation of the current paths due to relaxation and convection effects particularly pronounced at the generator entrance, inhomogeneities in the current density distribution produced by the electrode configuration, axial leakage currents and ionization instabilities. All of these phenomena impair the performance of the generator. It is therefore necessary to investigate them, and if possible, lessen their influence. The performance of "nonequilibri um" MHD generators has already been investigated in a variety of test rigs. It was possible to achieve high power densities and electron temperature elevations in short-time MHD generator systems1'2 with operating times of up to a few milliseconds. The test rigs working in continuous operation3'4 involved technical problems which prevented the theoretically predicted power output from being attained. Better, but still not quite the ideal values of the power density and electron temperature elevation were obtained in the "blow-down facilities."5"7 Whereas this deviation is accounted for in Ref. 5 by assuming external leakages strictly associated with the duct technology, it is ascribed in Refs. 6 and 7 to the presence of highly conducting layers along the electrode walls which impair the generator performance. This paper reports investigations on a generator working in continuous operation. These were concerned not only with the measurement of the Faraday voltage across the duct, the Hall voltage between the electrodes, and the current flowing through one electrode pair, but also with the local distributions of the various plasma parameters, viz., the potential and current density distributions, the velocity profile, and the electron and gas