Showing papers on "Capacitor published in 1971"

Theoretical performance of voltage multiplier circuits

Abstract: An expression for the equivalent source resistance of the capacitor diode voltage multiplier circuit is derived. The source resistance is found to increase as the cube of the multiplication factor, explaining the poor regulation observed with large multiplication. The distribution of capacitors that minimizes source resistance is presented. Good regulation is shown to be necessary for high efficiency, and to require relatively larger capacitors than needed for ripple filtering.

Atmospheric pressure CO 2 lasers giving high output energy per unit volume

Abstract: Two electrode designs are described that are capable of producing high output energy densities from pulsed atmospheric pressure CO 2 -N 2 -He lasers. In both cases a uniform volumetric excitation is obtained by the use of an auxiliary discharge. The first system uses a mesh cathode and has produced 4.8 J from an excited volume of 800 cm3(6 J.1-1). The second system uses a solid cathode and has produced 2 J from an excited volume of 110 cm3(18 J.1-1). Results of a parametric study of the solid cathode system are given. The output pulse energy, peak power, and pulse shape have been studied as functions of the energy-storage capacitor value, charging voltage, and gas composition. Partial self-mode-locking and the effect of single-mode operation on the pulsewidth have been observed.

Surface-state density and surface potential in MIS capacitors by surface photovoltage measurements. I

Abstract: A simple method is described for the measurement of surface-state density and surface potential in a MIS capacitor. It is similar in principle to the low frequency capacitance method in so far as a dc relationship is established between the surface potential and the voltage applied to the gate electrode. This is achieved by measuring the saturation surface photovoltage. The method differs from the low frequency capacitance method in that it measures the surface potential directly, requiring no additive constant. Experimental results are presented which agree well with those obtained by the low frequency capacitance method. The present method is complementary to a second method to be described by Lam and Rhoderick (companion paper) in that the surface-state density measurable by this first method has a lower limit while that by the second method has an upper limit, the two overlapping at the value of the space-charge capacitance.

Marx generator and triggering circuitry therefor

Abstract: A compact working Marx generator consisting of a stacked plurality of chargeable capacitors and normally open switches between successive capacitors, and a second Marx generator, having a rapid self-erection rate, for triggering the closing of at least some of the switches at a rate substantially faster than the compact generator self-erection rate, necessarily slow because of its large interstage stray capacitance resulting from its compactness. The illustrated switches are spark gaps, each having a third electrode between its two principal electrodes, and the switches are closed by pulses fed thereto from successive stages of the triggering generator through isolating means such as inductors to minimize any effect of the firing of the switches on the erection of the triggering generator. One or more additional working generators may be paralleled with the first working generator, both as to their switch closing circuitries and their outputs. Because triggering of the working generator does not directly depend on the voltage of its capacitors, its output voltage may be varied over a wide range.

Solid state induction cooking appliance

Abstract: A cooking appliance for inductively heating a cooking utensil comprises a flat induction heating coil mounted beneath a nonmetallic support with a substantially unbroken utensil supporting surface The induction heating coil is driven with an ultrasonic frequency wave generated by a static power conversion circuit typically formed of a rectifier and an inverter The inverter is a series capacitor commutated sine wave inverter with a variable output frequency, variable input voltage, or variable commutating components to adjust the utensil heating level The inverter is also controlled in on-off mode by a utensil temperature sensor

The Prediction and Control of Self-Excited Oscillations Due to Series Capacitors in Power Systems

Abstract: This paper covers the analysis of the problem of self-excited current oscillations which may occur when synchronous machines are closely coupled to transmission lines which are highly compensated with series capacitors. A mathematical analysis is made. Corrective measures are suggested and the results of confirming tests are discussed. Two typical system configurations which would be likely to produce these self-excited oscillations are used as examples for detailed calculations.

Dielectric Breakdown in Electrolytic Capacitors

Abstract: Starting with the known but unexplained fact that high‐voltage electrolytic capacitors need operating electrolytes of high resistivity, breakdown (sparking) voltages of aluminum and tantalum anodes have been examined. If interfering side reactions are eliminated, breakdown voltage increases linearly with the logarithm of electrolyte resistivity and is insensitive to variations in electrolyte composition and to changes in temperature between 65°C and 95°C.

Double layer capacitor with liquid electrolyte

Abstract: A capacitor utilizing the space charge polarization effect is described. The device employs a liquid electrolyte, resulting in a high capacitance-to-volume ratio, and a higher voltage than usually found in such devices. The capacitor is intended primarily for use in filter applications in transistor circuits.

Lumped-circuit elements at microwave frequencies

Abstract: Details are given of lumped capacitors, inductors, resistors, and gyrators. Active combinations of these components and encapsulated semiconductor chips include a 4-GHz tunnel-diode amplifier, a varactor-tuned X-band Gunn oscillator, a degenerate S-band parametric amplifier and an X-band Doppler radar. It is concluded that the techniques described here are useful at microwave frequencies up to X-band.

Adjustable hospital beds

Abstract: An electrical control system comprising a selector switch and a control switch in circuit with each other, said selector switch being movable to and from a position establishing a circuit between said control switch and said actuating means, said actuating means being a reversible electric motor, said electric motor having opposed windings, each of which is connected to the secondary of a transformer, the control circuit from each winding to the transformer, including a bi-directional gate, said gate being in circuit with a high frequency generator and with at least one capacitor interposed between said gate and said control switch.

Electrical conduction in thin metallic, dielectric and metallic-dielectric films

Abstract: This review is concerned with the structure and resultant electrical conduction properties of three types of film, defined as metallic, dielectric and discontinuous metallic; it is shown that the behaviour of the last one can be discussed as extensions of the first two. The review commences with a brief discussion of the type of structure that can be observed. In the light of this, both metallic and dielectric films are considered in detail and the current limiting phenomena in each discussed. Island-structure films (i.e. discontinuous metallic) are then considered and it is shown how dielectric theory can be extended to give an understanding of the mechanisms by which electrons get from one island to the next. A survey is made of the preparation techniques involved, and also of the devices that depend on electrical conduction. Thus it is shown how practical components such as capacitors, resistors, conductors, and to a certain extent active devices, are dependent on metallic or dielectric conduction processes.

Versatile cycloinverter power converter circuits

Abstract: A family of high-frequency-link solid state power converters having an input and output switching circuit that function as a high frequency parallel capacitor commutated control inverter and a cycloconverter output circuit to supply variable frequency and variable voltage power to a load. The tuned commutation circuit for the inverter switches, preferably thyristors, includes commutating inductance in parallel with the commutation capacitor. By operating the inverter at a variable frequency greater than the resonant frequency, the commutating energy or commutating angle changes as a function of the load. The cycloconverter switches are phase controlled with respect to the high frequency inverter voltages. Depending on the circuit configuration, a-c or d-c supply voltage is converted to polyphase a-c, single phase a-c, or d-c output voltage, and power flow in either direction can be obtained. An application is a variable speed a-c motor drive.

Three-terminal capacitive apparatus for remotely responding to a condition or dielectric properties of a material

Abstract: Three-terminal capacitive apparatus are disclosed which provide information concerning a condition of a material by responding to the dielectric properties of the material. A three-terminal capacitor, which may be a cell or probe, may be used, for example, to measure the dielectric constant of a material, to determine the level of a material in a container, to determine the interface between liquid materials in a pipeline, or the proximity of a material to the probe. Each cell or probe includes a conductive driven element connected to a regulated square wave source, and a conductive receptor element connected to the input of a high gain amplifier with a capacitor in the feedback loop which maintains the receptor element at virtual ground. The output of the feedback amplifier is proportional to the feed through capacitance of the capacitive probe or cell. A synchronous demodulator, synchronized by the drive signal or a signal in phase with it, is connected to the feedback amplifier output and is used to produce a DC output signal used for display or control. The cell or probe is connected to associated electronics through shielded cables and may be remotely located from the electronics. Suitable mechanical apparatus is associated with a particular three-terminal capacitor cell or probe for mounting it in position to respond to a particular condition being monitored.

Broadband circuit for minimizing the effects of crystal shunt capacitance

Abstract: A crystal controlled oscillator circuit having broadband circuitry for balancing out the effects of the static shunt capacitance of a crystal. A broadband phase inverting network is connected across the crystal to cancel the signal flowing through the crystal as a result of capacitive coupling between the plates. The phase inverting network may include a transformer, a center tapped inductor or a broadband inductance-capacitance network. A capacitor having a capacitance value related to the value of the static shunt capacitance is used in conjunction with the phase inverting network to determine the magnitude of the phase inverted cancellation signal.

Differential methods and apparatus for measuring dielectric constant to determine a condition of a material

Abstract: Method and apparatus responsive to conditions such as the moisture content or ingredients ratio of a material are disclosed in which the dielectric constant of a standard sample of such material of a reference moisture content or ingredients ratio is compared in a three-terminal differential capacitive device including two three-terminal capacitor probes with the dielectric constant of a test sample of such material of unknown moisture content or ingredients ratio. The comparison provides an electrical output signal proportional to the differences in moisture content or ingredients ratio of the test sample and the standard sample. For example, the differential capacitive device may be mounted in a differential capacitive cell which includes a standard sample cavity in which the standard sample is placed around the electrodes or conductive elements of one threeterminal capacitive probe and a test cavity in which the test sample is placed around the electrodes or conductive elements of a second three-terminal capacitive probe. Each probe of the differential capacitive device includes a conductive driven element, a conductive receptor element connected to an amplifier and maintained at virtual ground, and suitable shielding connected to a ground terminal. The test cavity is maintained at the same temperature as the standard sample cavity and the feed through capacity of each probe is a function of the dielectric constant of the material between their electrodes.

Trapezoidal waveshape defibrillator

Abstract: A trapezoidal waveshape, which is known to be the best waveshape for defibrillating the heart, is produced by charging a capacitor, and by starting to discharge it through a silicon controlled rectifier to the load, namely, the body of the patient. Subsequently, a second SCR is used to short circuit the first SCR and load circuit to effect termination of the trapezoidal waveshape rapidly, i.e., effectively dumping the remainder of the charge.

Temperature compensator for capacitive pressure transducers

Abstract: A pressure transducer of the capacitor type having a body of dielectric material has a thin film resistor deposited on the body for sensing the temperature of the body. The resistor is of a material having a suitable temperature coefficient of resistivity to provide a signal corresponding to the temperature of the body for temperature correction.

Broad-band lumped-element directional coupler

Abstract: A broad-band lumped element directional coupler for measuring either the forward or reflected power in a coaxial transmission line. A resistive voltage divider is coupled to the center conductor of a transmission line with a capacitor to keep the phase of the voltage sampling circuit equal to the phase of the current sampling circuit. Capacitors shunting the resistors make the voltage ratio of the resistive voltage divider independent of frequency over a large frequency range. Directivity greater than 50 dB is achieved over a large frequency range for coupling ratios of 30, 40 and 50 dB.

Thick film feed-through capacitor

Abstract: A feed-through capacitor deposited in a thick film on a flat, thin alumina substrate having an active circuit and a capacitor. The capacitor includes a bottom electrode of metallized film on the surface of the substrate, a layer of dielectric having a high-dielectric constant, and a top electrode of metallized film deposited on the dielectric. The bottom electrode film has a terminal portion for connection to ground reference potential and a lead film connected to the active circuit, the same extending around the edge of the substrate with the active circuit on the opposite side thereof. The top electrode film may be singular or multiple in nature, having an external terminal at one edge of each electrode and a lead film at the opposite edge connected to the active circuit, the same extending around the edge of the substrate with the active circuit on the opposite side of the substrate.

Characteristics of RF sputtered barium titanate thin films

Abstract: Results of a study on the deposition of thin-film barium titanate (BaTiO 3 ) by RF sputtering are discussed. BaTiO 3 was deposited onto Pt foil and onto thin-film electrodes on various substrates, and counterelectroded to form metal-dielectrio-metal structures. Dielectrics were deposited at substrate temperatures from 23° to 1000°C, some of the dielectrics fired in air at temperatures up to 1400°C after deposition. On bulk Pt, the BaTiO 3 film matrix indicated an average grain size of 2000 A after heat treatment Constant Ba/Ti ratios were measured for the films deposited over the entire substrate temperature range. Dielectric constants ranged from 16- 1900, the tan δ of the capacitors varying from 0.005 for amorphous films to 0.065 for polycrystalline films with highest dielectric constants. Effects of temperature and frequency on the capacitors and the charge-voltage and field dependence of the dielectric constant are described. Current-voltage relationships, breakdown strengths, and processing conditions indicate the potential of the capacitor structures for practical applications.

Analog to digital converter

Abstract: An analog to digital converter of the dual slope type, employing a high gain input amplifier as both a buffer and integrator and a second high gain amplifier as a comparator. The input voltage is coupled to the non-inverting input terminal of the integrator through a capacitor. A programmed switching circuit provides for switching of the coupling capacitor either to the input voltage or to an input common terminal and also provides for opening and closing a direct feedback loop from the comparator output and for switching the second input terminal of the integrating amplifier between a reference level and ground. The converter operates to charge the integrator capacitor for a fixed time at a rate proportional to the input voltage and then to discharge this capacitor at a rate proportional to the reference voltage, while a counter accumulates time base pulses, until the capacitor reaches its initial level, the accumulated counts being a digital representation of the input voltage.

Electronic flashlamp power supply

Abstract: A flash system power supply for charging a storage capacitor employed in operating a flashlamp. A battery-powered multivibrator-type converter is coupled to the storage capacitor through a transformer-rectifier circuit, with the multivibrator being triggered into oscillation by a start circuit comprising a relaxation oscillator. Multivibrator operation is squelched by a negative voltage pulse from a stop circuit controlled by a relaxation oscillator-type voltage detector which senses a predetermined charge on the storage capacitor. The stop circuit is also controlled by a current-sensing resistor which detects discharge of the storage capacitor. Operation of the start circuit is clamped to the stop circuit through a diode, with the stop circuit having a time constant sufficient to delay restarting of the multivibrator beyond the deionization period of the flashlamp.

On the motion of space charge in a dielectric medium

Abstract: A general relation is derived which describes the spatio-temporal behaviour of space charge in an ideal dielectric medium. (Diffusion effects are neglected.) This result is used to determine the behaviour of a parallel plate capacitor which contains space charges near its electrodes. Expressions are derived for the variation with time of the potential difference between the plates following the removal of an applied voltage and for the external current which flows when the plates are connected together. Symmetrical and asymmetrical charge distributions are considered.

Shark repelling device including pulse generator producing electrical field in water between widely spaced electrodes

Abstract: A sealed, water-proof housing encloses an inverter which is energized from a direct current source, such as a relatively low voltage battery in the housing, and has a secondary winding connected to opposite input terminals of a full wave rectifier, also enclosed in the housing. One DC output terminal of the rectifier is connected directly to an output terminal for a first electrode, and the other DC output terminal is connected to an output terminal for a second electrode. The first and second electrodes are spaced widely apart in the water, as by being trained along opposite edges of a trawl net or ''''bag.'''' Preferably, two pairs of electrodes are used, with corresponding polarity electrodes being connected to the same output terminal. The housing is attached to the net at a midpoint, with one pair of electrodes extending forwardly and the other pair extending rearwardly. A power capacitor is connected across the DC output terminals, and a variable resistor is connected between one AC input terminal of the rectifier bridge and the gate of the SCR. The SCR, during each alternate half cycle of AC potential applied to the input terminals of the rectifier bridge, is gated conductive through the variable resistor to discharge the power capacitor through the electrodes and the body of water therebetween to establish an electric field in the body of water. The potential across the power capacitor rapidly decreases to a value at which the SCR becomes non-conductive to interrupt the electric field. The charging of the capacitor and the discharge thereof is repeated cyclically. The battery in the housing is rechargeable.

Current measuring and automatically resettable fault indicating means

Abstract: A capacitor is charged through a capacitive coupling to a high voltage alternating current electric power conductor and is discharged when the charge reaches a predetermined value to reset fault indicator that previously had been operated by flow of fault current in the conductor. The magnetic circuit employs a demagnetizable low coercive force core in the form of a bifurcated yoke or a ring having magnetizing windings energized on discharge of the capacitor. A manually resettable fault indicator employing a demagnetizing winding on a low coercive force ring also is disclosed.

High frequency fluorescent tube lighting circuit and a-c driving circuit therefor

Abstract: A sinusoidal voltage source in series with a fluorescent, mercury vapor, sodium vapor device, etc. is pulsed at a given pulse repetition rate with the pulse having a given conduction time. Two or more tubes can sequentially conduct pulses with the current input being a continuous sinusoid. A particular pulsing circuit contains a modified pulse-forming network consisting of one or more stages of a closed series connection of a choke and two capacitors. The chokes of each stage are connected in series. The modified pulse-forming network is used as a frequency converter per se, as a d-c to a-c converter, or specifically is in parallel with a fluorescent tube load.

Some design aspects concerning input filters for DC-DC converters

Abstract: Various DC-DC converter input filter requirements as applied in spacecraft power processing equipment, are reviewed with respect to the spacecraft, its power source and filter loads. The conflicting implications arising from the requirements are noted. A filter configuration capable of providing a satisfactory overall compromise is presented. Various design aspects for converter input filters are analyzed. These include minimum weight toroid inductor design, the possibility of non-linear oscillation developing through the interaction of an input filter and a negative impedance regulator and problems in using paralleled capacitors to supply switching regulator loads.

Arc Extinction Phenomena in Vacuum

Abstract: Experiments have been performed to study the manner in which an arc between copper electrodes in vacuum extinguishes. In an ac circuit where current is limited to less than 1000 A peak, resistively, the extinctions are often prolonged over a period of many microseconds by successive reignitions of the arc caused by circuit‐recovery voltage. These reignitions tend to be suppressed by capacitance paralleling the discharge thus raising the current at which the arc is extingusihed. In a similar circuit where the current is limited by inductance, the extinction most often occurs at a minimum in high‐frequency oscillations of discharge current superimposed upon the 60‐Hz arc current near the end of the half‐cycle period. These oscillations occur at a frequency determined by the capacitance in parallel with the gap and the inductance of the wires used to connect the capacitors to the gap. For the inductive circuit with low values of capacitance, the oscillations are not apparent and extinction times of 10−7 to 1...

Current limiting interruption of currents at high voltages

Abstract: An improved circuit for the current limiting interruption of alternating or direct currents in a power main at high voltages of the type wherein an energy absorbing circuit and a capacitor are each connected in parallel with a circuit path including a commutation or interrupter switch so that upon opening of the switch the current flowing therein will be commutated into the parallelly connected circuits wherein the current will be reduced to a residual value which is switched off by a subsequently connected circuit breaker. A further commutating switch is connected in series with the first mentioned commutation switch and an ohmic resistance connected in parallel therewith so that the total series resistance of the ohmic resistance and the arc resistance of the first mentioned commutation switch will be sufficient to cause the commutation of the main current into the energy absorbing and capacitor circuits.

Process control simulator

Abstract: A process control simulator contains electronic circuits for modifying set-point control signals by summing, integrating, differentiating and introducing step functions on continuous, single or periodic bases to determine off-line the behavior of a process control system. Provisions are made for several interacting control loops, for dead-time delays and for faster than actual response times to speed up simulation. The dead-time delays are provided by scanning a set of storage capacitors with a variable speed scanning motor through a scanning control cycle of operation.