Pulse Circuit Research Articles

Voltage Recovery Time of Small Spark Gaps

A two-pulse method is used to determine how fast and to what degree a small spark gap can recover its voltage holdoff capability after breaking down. The first pulse is used to overvolt and break down the gap. The second pulse is used, after a time delay, to determine the voltage recovery of the gap. By varying the time delay to the second pulse, a recovery voltage versus time plot can be obtained. Time delays from 10 ?s to 100 ms have been recorded. The spark gap discharges millijoules of energy with a gap spacing of less than 1 mm. Recovery has been measured at breakdown voltages of up to 10 kV in argon, hydrogen, and a mixture of the 2 gases. The experimental setup, pulse circuits, and data collection methods are described. Percent voltage recovery versus time plots for various parameters (gas species, gap spacing, and pressure) are discussed.

微小エネルギによる放電加工の研究 放電加工による鏡面の形成

This study covers the mirror surface machining by planetary electro discharge machining (EDM). In the process of this EDM, a mirror surface is created in a micro-energy condition where an independent pulse circuit is used, and its gloss is affected by the electrode polarity, storage capacitance, discharging energy and planetary motion.It has been found as the result of our three-dimensional analysis of a single discharge crater by using a scanning electron microscope and contouring device that the mirror surfacing depends upon the profile of the discharge crater. Also the gloss can be effectively calibrated by the analysis in which the laser diffraction is adopted.Our study on mirror surfacing by EDM has made clear the following:(1) In micro-energy conditions using independent pulse circuit where any storage capacitance is eliminated, an extremely flat discharge crater with smaller undulation is obtained when the electrode is negative.(2) The mirror surface is realized by both the microscopically smooth surface formed by such flat discharge craters as overlapped, and the macroscopic smoothing adopting the elimination of undulation by means of planetary motion.(3) The gloss of mirror surface has no relation whether or not the workpiece has been subject to heat treatment, but depends upon the small cracks occurring because of the carbide or stressed condition of machined surface due to the composition of material.(4) The gloss of mirror surface is affected by the capacitance formed between electrodes; as the machining area increase, the gloss will be degraded, and the surface will change from mirror to dull surface.

Voltage and current measurements for fast pulsed high current discharges

A method for correcting for the inductance in a fast pulsed discharge circuit yields accurate discharge voltage and power input waveforms. An economic fast current shunt is described.

A digital random pulser for testing nuclear instrumentation

A digital random pulser circuit based on a linear feedback shift register is described. The circuit provides a wide range of discrete output rates and exhibits very little deadtime. The testing of this circuit and its use with a neutron coincidence counter electronics circuit is discussed.

A dynamic model of the p- n- n+ step recovery diodes for the numerical analysis of pulse circuits

A new p- n- n + diode model for circuit transient analysis is developed. In contrast to existing circuit models, this model reflects all step-recovery diode (SRD) effects during switching on and off, including “ramp” of slow recovery phase. It is accomplished by taking into account the dynamic physical phenomena in the p- n- n + diodes when switched. A non-linear dynamic diffusion capacitance of the diode model is determined by the dependence of the instantaneous base charge on the instantaneous diode voltage. The accuracy of the presented model is verified by comparison of the calculated and measured wave forms of some pulse circuits. The present model has been proved to be more accurate than SRD models previously published.

Sequential Machines Having Quasi-Stable States

This correspondence investigates a model of description for sequential systems having state-transitions among any number of stable states, quasi-stable states, and unstable states. The quasi-stable states are typically seen in the so-called astable and monostable multivibrators in pulse circuits.

Improved touch operated capacitance switch circuit for an electronic organ

Disclosed is a touch operated capacitance switch which may be used in connection with a digital arpeggio system for an electronic organ that through the use of digital techniques permits arpeggios, note sequences as well as strum, multi, organ, and normal modes of operation to be played automatically. Two counters scan by counting through an 8×8 matrix of 64 words covering the 61 notes of an organ in rapid sequence upon the playing of one or more organ keys. Each word is fed to a corresponding one of 61 decoders, one for each note of the keyboard. If a corresponding key has been played, the decoder provides a signal to a corresponding pulser circuit which enables a corresponding keyer to transmit an audio signal from an audio oscillator corresponding to the played key to an output system and loudspeaker. The two counters are stopped by a clock control while the note is sounded and then the counters are enabled by the counter control to continue counting through the matrix until the next actuated key is located. The two counters can be controlled to count up only, or up and down so that both and up and an up-down arpeggio can be sounded. A sequence control is also provided so that the sequence of the sounding of the played notes can be varied by changing the pattern of the words supplied by the two counters so that the notes can be sounded out of their normal chromatic order. The system also permits normal mode of operation so that the notes are sounded as the keys are played, multi mode so that octavely related notes are sounded or a strum mode simulating the strum of a guitar or banjo strings. The touch operated capacitance switch provided is so that the organist can change the mode of operation rapidly during playing by maintaining physical contact with the capacitance touch switch.

Precision stress measurements in severe shock-wave environments with low-impedance manganin gauges

We describe new techniques that permit the use of low-impedance manganin stress gauges in chemically reacting shock waves in the 1.0–40.0 GPa range. The rugged, small, and fast response gauge has reproducibility better than 2% when used in conjunction with a pulsed bridge circuit and adjustable, current-regulated power supplies. Techniques are presented for fabricating the transducer package, calibrating the bridge circuit and oscilloscopes, designing the drive system, and reducing the data. Data are presented for planar impact experiments performed with a 102-mm gas gun on high-explosive samples. In particular, we directly measured the Chapman-Jouquet pressure in the explosive RX03-BB [92.5% triaminotrinitrobenzene (TATB)/7.5% polychlorotrifluoroethylene (Kel-F binder)] as 28.2±0.6 GPa. These new developments open the possibility of applying low-impedance manganin gauges in chemically reactive hydrodynamic flows such as the evolution of a shock wave into a detonation wave.

A Compact, High Speed Ion Beam Chopper

A simple, compact pulse circuit was designed for use as an ion beam chopper with both synchronous and asynchronous triggering. The rise and fall times of the beam-on pulse are 60 ns and 320 ns, respectively, with a beam suppression potential of 180 V. The beam chopper was interfaced to a spark-source mass spectrometer for which the precision of analyses can be improved by reducing effects of sample or spark inhomogeneities. Additionally, the synchronous mode of chopping provides a means for temporal analysis of the spark.

Digital arpeggio system

First Page

Magnetic field-pulsed ELDOR spectroscopy

A preliminary account is given of attempts to perform ELDOR spectroscopy utilizing a pulsed EPR spectrometer that operates in the saturation-recovery mode for measurements of electron spin-lattice relaxation times. The procedure is to saturate one of the hyperfine lines with a pulse of high microwave power, shift the magnetic field at the end of the microwave pulse within a time shorter than the electronic T 1 to the resonant value of another hyperfine component, and measure the saturation transfer that has taken place by monitoring the EPR signal intensity as a function of time as in a conventional saturation-recovery experiment. The saturation transfer has been measured as a function of the microwave pulse width and the peak power of the saturating microwave pulse in order to establish that the extent of saturation transfer is related to the extent of saturation of the transition which was directly saturated in the first instance. The studies are carried out on 2,5-ditertiary butyl p-benzosemiquinone ion in ethanol. The lack of signal-averaging techniques in these preliminary experiments forces the use of a high free radical concentration (10 −2 M) leading to considerable overlap between hyperfine components-the spectral overlap aiding saturation transfer. However, these preliminary experiments have demonstrated the feasibility of the field-pulsed ELDOR method in the investigation of saturation transfer. By a minor modification of the pulsing circuit, it has been possible to obtain linear magnetic field scans of the order of 6 G at the maximum rate of 1 G/μsec. Since the spectrometer has a response time of the order of 3 μsec, it should be possible to obtain EPR spectra of transient species with lifetimes of the order of 10 μsec or longer by such rapid scan techniques.

Krypton entrapment in pulse-biased sputter-deposited metals

A supported gas discharge sputtering system was constructed to investigate krypton entrapment in high rate sputter-deposited thick films. Krypton entrapment was studied as a function of substrate and target voltage for nickel, aluminum, titanium and iron deposits. Control of the substrate and target voltages was achieved with pulse circuits capable of adjusting the pulse duration and repetition rate. A water-cooled cylindrical copper substrate 15 cm in diameter was used to collect the sputtered metal from a cylindrical target 9 cm in diameter. To observe the immediate effect of changes in the sputtering parameters on gas trapping, as well as to measure the total gas trapped, a sensitive mass flow indicator was installed in the krypton supply of the dynamically pumped system. Data relating krypton content to substrate bias conditions and deposition rate are discussed. Krypton contents of more than 2 at.% were found in the metals studied, all of which were deposited at rates exceeding 1 nm s -1.

An isothermal displacement calorimeter for positive excess enthalpies

An isothermal displacement calorimeter has been constructed on the basis of the successful design of the Armidale group. (1,2) The most important changes in the design are (a) a stainless-steel construction was used instead of a glass one, (b) the dead space has been elimiated by introducing the stirrer shaft from below, (c) the degassed liquids are injected without any contact with air, and (d) the energy is measured by using a pulsed heater circuit instead of the conventional time-switching method. Calibration was carried out using benzene + carbon tetrachloride and benzene + cyclohexane at 298.15 K. The standard deviation are 0.10 and 0.45 J mol −1 respectively. Our results are in good agreement with those obtained by other investigators.

Subnanosecond pulsing of a 3-MV Van de Graaff electron accelerator by means of a passive coaxial pulse shaper

A passive coaxial pulse shaper has been developed which produces a subnanosecond duration pulse with short rise and decay time from a long pulse with short rise time. The mechanical construction of the pulse shaper is a modified coaxial air line T-section. The pulse shaper has been incorporated in the pulsing circuit of a 3-MV Van de Graaff accelerator. The form of the resulting electron beam pulses was monitored both as the charge collected by a coaxial target and as the Cerenkov light emitted by a quartz plate. In both cases sequential sampling techniques were used. The electron beam pulses were found to have rise and decay tiems of approxiamtely 100 ps and a half-width as short as approximately 200 ps could be obtained. An advantage of this method of producing subnanosecond beam pulses is that it does not interfere with normal nanosecond pulsed operation of the Van de Graaff.

Effect of dissociation pulse circuit inductance on the CuCl laser

The performance of the double-pulsed CuCI laser is improved by a decrease in the inductance of the dissociation pulse circuit. Higher efficiency is obtained due to a larger ground state copper atom population and lower optimum dissociation energy.

WT4 Millimeter Waveguide System: Regenerative Repeaters

The electronic circuitry and physical structure of 12 two-phase repeaters made for use in a field evaluation test are described. The repeaters consist of four kinds of circuitry; millimeter-wave circuits covering the 40 to 110 GHz range, if circuits at 1.2 to 1.6 GHz, pulse circuits for the 274Mb/sec pulse stream, and power supply circuits. All repeaters have been successfully operated over the trial repeater link in northern New Jersey. The results of this repeater development effort are the basis for an estimate of the performance obtainable in future four-phase repeater performance. This estimate has been used in the system repeater spacing calculations.

Book reviews - Digital integrated electronics

This book represents the third generation of textbooks coauthored by H. Taub covering the general topics of pulse,switching, digital, and integrated circuits. The progression to the present book started in 1956 with Pulse and Digital Circuits, a textreating digital and switching circuits almost exclusively with vacuum-tube devices. A decade later the highly acclaimed and well-recognized book, Pulse.Digital, and Switching Woveforms, was issued in the second generation. In this volume, the importance of the transistor was emphasized and vacuum-tube circuits were presented only incidentally.

Pulse Width Multiplication Using a Monostable Multivibrator

A modified monostable multivibrator circuit that acts as a Pulse Width Multiplier (PWM) is described. Applications of PWMs, in many pulse and digital circuits, are given.

64 Stage BCD (Bulk Charge-Transfer Device) Analog Memory with Differential Integrated Clock Pulse Generator

A 64 stage BCD (Bulk Charge-transfer Device) with a new differential integrated clock pulse generator is developed. The device effectively eliminates problems of interference from external clock pulse circuits to a picture tube, and of output voltage variation in varying clock pulse frequency of a conventional device. The BCD consists of two clock pulse circuits fabricated differentially to drive two arrays separately. Experimental results show good matching of the two arrays. In addition, the device requires only one TTL level master pulse and two power supplies, thus enhancing its application to practical video delay lines.

Improved versatile gigahertz pulse generator

The high-speed pulse circuit investigated, which mainly consists of a broadband magic T with two step-recovery diodes shunted to opposite ports, is shown to generate versatile pulse trains at gigahertz frequencies (upper limit at about 5GHz). Owing to the availability of two output signals, simple pulse patterns can be produced.