Electronic Capacitor Research Articles

Proposals for extending traceable impedance measurements to higher frequencies

Geometrical constructions are proposed which minimize residual impedances of four terminal-pair (4 T-P) capacitance, resistance and inductance standards together with adaptors to other terminal systems. Some standards whose measured frequency dependence is small (up to 10 MHz) have been made using surface-mounting electronic capacitors. These standards facilitate the traceable calibration of 4 T-P impedance-measuring instruments. A 4 T-P to single-port adaptor having small, measurable residual impedances bridges the gap in calibration traceability between low and microwave frequencies. The resistance standards usually used for ac/dc transfer up to 1 MHz can also be converted to a 4 T-P definition with another adaptor.

Importance of doc in sediments for contaminant transport modelling

Contaminants in the interstitial waters are not only dissolved but also associated with a filterable colloidal phase such as DOC. The DOC plays an important role regulating the distribution of chemicals between particulate and dissolved phases since it binds chemicals and makes them unavailable for vertical diffusive exchange. A three-phase partitioning model that consists of free-dissolved, DOC-bound, particulate-bound components of the chemicals involved is used for the contaminant transport model in order to include the effect of DOC on the partition coefficient. The contaminant model is linked to WASP modeling framework to predict remobilization of PCBs in sediments and the fate and transport of the contaminant in overlying waters of the New Bedford Harbor where the harbor has been contaminated with PCBs and heavy metals released from electronic capacitor manufacturers. Simulation of remedial controls indicates that if no action is taken, PCB concentrations will continue to be at elevated levels. Several scenarios for the removal of contaminated sediments have been performed to reduce the elevated PCB concentrations to background levels.

Pixel array detector for time-resolved x-ray scattering (invited)

This paper describes the development of a large area hybrid pixel detector designed for time-resolved synchrotron x-ray scattering experiments in which limited frames, with a high framing rate, are required. The final design parameters call for a 1024×1024 pixel array device with 150-micron pixels that is 100% quantum efficient for x-rays with energy up to 20 keV, with a framing rate in the microsecond range. The device will consist of a fully depleted diode array bump bonded to a CMOS electronic storage capacitor array with eight frames per pixel. The two devices may be separated by a x-ray blocking layer that protects the radiation-sensitive electronics layer from damage. The signal is integrated in the electronics layer and stored in one of eight CMOS capacitors. After eight frames are taken, the data are then read out, using clocking electronics external to the detector, and stored in a RAM disk. Results will be presented on the development of a prototype 4×4 pixel electronics layer that is capable of storing at least 10,000 12-keV x-ray photons for a capacity of over 50 million electrons with a noise corresponding to 2 x-ray photons per pixel. The diode detective layer and electronics storage layer along with the radiation damage and blocking layers will be discussed.

Technological progress in materials application for electronic capacitors in Japan

The technological development of the four main types of electronic capacitors-aluminum electrolytic capacitors, ceramic capacitors, tantalum electrolytic capacitors, and film capacitors-are discussed. Particular attention is given to the materials involved and the accompanying innovations in manufacturing techniques, which have enabled electronic capacitors to move steadily toward miniaturization, longer life, lower prices, and improved reliability.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A solid state switched power supply for simultaneous capacitor recharge and railgun operation

A capacitive power supply for driving a railgun load has been developed using solid-state electronic switchgear and computer-grade electrolytic capacitors. These choices provide relative ease of component orientation and insensitivity to field conditions. The circuit is constructed so that half the bank capacitance is initially charged while the other half is uncharged. both halves are connected in series with the load, and diodes across each prevent voltage reversal. When the discharge is initiated, the current passing through a railgun simultaneously charges the uncharged section of the capacitor bank. Modeled and actual circuit performance results from a four-module supply, with 7500 J and 30 kA per module, are presented. It is concluded that this type of supply is ideal for use with augmented and multiturn railguns. In these configurations the pulse-shaping inductance becomes part of the railgun itself. A feature of this arrangement which may be exploited is zero current crossing with projectile exit; this is required for flashless firing and reducing tip-off of the projectile upon launch. >

The dense part of the electrical double layer: molecular or electronic capacitor?

The electrical double layer (EDL), which arises at a metal-electrolyte interface, does not-only determine nost of the equilibrium properties of this interface (surface tension, zero-charge point potentials, capacitance, etc.), but also controls, to a large extent, the kinetics of electrode reactions. That is why the concept of the equilibrium EDL underlies almost an the branches of electrochemistry: corrosion and passivation of metals, catalysis and adsorption, galvanoplasties. The double layer consists of two parts: the diffuse part and the dense part. The diffuse part is of minor importance in all electrochenical processes. Even in dilute solutions the potential drop across this part is about one tenth of that across the dense part; in concentrated solutions the diffuse part virtually does not exist. However, the diffuse part of EDL has been studied to a higher degree than the dense part. At present, not only has the mechanism of the diffuse part formation been understood, but a reliable theory has also been developed that describes this part (the latter mainly due to the work of Gouy and Chapman). The situation is, however, much worse for the dense part; there is not even a comolete understanding of the factors responsible for the formation of this part. At least, there has been no common opinion in the literature concerning this point. Most of the authors stick to the molecular capacitor (MC) model proposed by Helmholtz. According to this model, the dense part of EDL is formed by a monolayer of solvent molecules adsorbed at the metal surface, the electrolyte ions being partially or comoletely “prohibited” from penetrating into this layer. The properties of the monolayer should, apparently, be determined by three different interactions: 1) between the metal and electrolyte ions; 2) between the metal and solvent molecules; and 3) between solvent molecules themselves. In any consistent theory of this phenomenon, all three interactions should be taken into account equally. At present, however, such a theory cannot be developed because of technical difficulties. One is, therefore, forced to construct various graphic models of the MC: the reliability and “heuristic power” of these models are very poor. Thus, most of the properties of the dense part of EDL (the mechanism of the formation of the zero-charge point potentials, surface tension, etc.) have not been explained within the framework of the MC theory. As early as in the time of Frenkel and Rice, another model of the dense part of EDL was known in which electrons of the metal, rather than solvent molecules, were assumed to play the major role. For a long time, this model did not attract the attention of electrochemists and was, in fact, completely forgotten. Quite recently, however, in connection with Ref. 1–10, in which the model was actually rediscovered, there has been a surge of interest in this model. Following Ref. 7, we shall call it the electronic capacitor (EC) model. At present, the concept of EC has enafcled a wide range of phenomena to be described not only qualitatively, but quantitativeliy as well (ref. 7–10). However, the theory developed in these papers is based on an approximation, rather than on straight-forward solution of the Schrödinger equation. It is always possible, therefore, to assert that the agreement between theory and experiment is accidental, and that a more rigorous theory of the molecular capacitor would better expalin experimental results. A thorough analysis of experimental data is needed to decide which of the two models (MC or EC) is “closer to the truth”. On the other hand, such an analysis is very difficult to perform without preliminary systematization of experimental data. The present review precisely deals with systematization and analysis of experimental results. At first glance, it would hardly seem reasonable to conduct a study with the sole purpose of choosing one model or another. It should not, however, be forgotten that electrochemistry is based entirely on the concept of EDL, so that any fact and any theory in the field has to be verified especially carefully. Furthermore, a simple systematization of experimental data reveals new laws and facts, which in itself is also interesting.

The electronic capacitor at a metal–electrolyte interface

A model for the dense part of electrical double layer is proposed using the concept that conduction electrons penetrate into a solution to form an electronic capacitor on the metal surface. The potential drop between the metal and solution, the charge of the metal, its surface tension, and the electron work function for a metal–solution interface are calculated within the framework of the model, and the formulae derived are compared with experiment. It is shown that for a metal–vacuum interface of 38 metals in the left-hand subgroups of the Mendeleev table the discrepancy between the theoretical and experimental values of surface tension and work function does not exceed the experimental error (i.e. it is less than 10%); for six metals in the right-hand subgroups and especially for semimetals the theoretical error is two to three times higher. The density of free electrons in a metal determined in terms of the concepts of the model is shown to vary monotonously with the element number for all 54 metals with available experimental data.A relationship, previously unknown, between surface tension and zero-charge potential is established, which enabled one to calculate the electronic capacitor charge for mercury (the theoretical value is 33 C/cm2, and the experimental value is 36–38 C/cm2). This paper also reports the calculated values of the integral capacity of a mercury electrode in water: the experimental value is 29 F/cm2 (at the zero-charge point), and the theoretical value is 28 F/cm2. The model predicts an increase of the capacity in the anodic region and a decrease in the cathodic region, in a good agreement with experiment. It should be stressed that although the theory includes only one fitting parameter, the density of free electrons in the metal, it correctly explains a wide range of phenomena.

Automatic Moisture Sensor for Measurement and Control of Cotton Ginning Processes

Cotton fiber moisture content is one of the most important factors that affects the operation of the cotton ginning process. A system has been developed that measures cotton’s dielectric constant and density with sufficient accuracy to indicate moisture content of the fiber during processing. An electronic capacitor and a pneumatic density sensor supply measurements to a microprocessor which combines them into a predicted moisture content. Tests showed that these predicted readings are more precise than conventional oven-moisture determinations and that they can be used for process control in the ranges from 6.5- to 12-percent moisture content.

Statistical methods in accelerated testing of electronic capacitors lifetime : Mieczyslaw Fracki and Eugeniusz Przybyl. Electron. Technol.13 (4), 31 (1982)

Statistical methods in accelerated testing of electronic capacitors lifetime : Mieczyslaw Fracki and Eugeniusz Przybyl. Electron. Technol.13 (4), 31 (1982)

Comparison of Single Instance and General Case Instruction in Teaching a Generalized Vocational Skill

Using a multiple baseline mirror design, the relative effectiveness of two instructional strategies for teaching the crimping/cutting of biaxle electronic capacitors was investigated. Four severely...

Integration of analog filters in a bipolar process

Monolithic analog filters are described which are based on the integration of electronic transconductors and capacitors. The method used allows simulation of inductor capacitor filters. The transconductors are voltage-controlled current sources provided with a scaling multiplier. The value of one external resistor and matching of integrated elements determine the transconductances. Capacitors are made with an oxide/nitride dielectric on the low-ohmic emitter diffusion and with an aluminium top electrode. Applications include PCM low-pass filters, viewdata modem filters, etc. The method is extendable from the audio band up to video frequencies. Simple breadboarding, no need for special CAD, and an extremely low supply power consumption are features of the filter type. The filters are on-chip compatible with analog and digital system parts.

Measurement Procedures for Characterization of High Voltage Spark Sources

Procedures are presented for calibration of electronic adjustable waveform capacitor discharge spark sources. Both individual component measurements and system measurements are discussed. Characterization of components and subsystems involved in capacitor charging, spark formation, and discharge current control is described. Specific measurement devices and techniques are discussed, and precision requirements for various degrees of characterization of both components and systems are given. Application of the characterization procedures to routine source monitoring and to source development are also presented.

Hight-power electronic capacitor for small radios

Hight-power electronic capacitor for small radios

Metallised plastics capacitors for electronics

Synthetic polymer films are now becoming widely used in the production of wound electrical capacitors with large capacitances, particularly in electronics applications. The advantages of metallised plastics capacitors are size, performance and cost. Future developments could include the encroachment of these devices into the fields of microminiaturisation and high power.

Rotor Balancing with an Electronic Capacitor Gauge

A variable air-gap capacitor is formed between an unbalanced rotating member and a stationary plate. The output of an oscillator is modulated in accordance with the variations in air gap, the modulated wave being displayed on the screen of a cathode-ray oscilloscope for continuous observation. Cyclic displacements at the periphery of the rotor of 0.0005 in. are easily detected. A contactor on the rotor shaft provides the means for locating the point of unbalance.