Electronic analog divider

Advantage is taken of the current-exponential voltage characteristic of a diode over a certain range whereby the incremental impedance across the diode is inversely proportional to the current through the diode. Accordingly, a divider circuit employs a bias current through the diode proportional to the desired denominator and applies an incremental current to the diode proportional to the numerator. The incremental voltage across the diode is proportional to the quotient

Sustained arc ignition system

Circuitry for maintaining an arc or spark across a spark gap for a desired length of time is disclosed. A high voltage, direct current source is connected in series with a secondary winding of a high voltage, stepup transformer or coil and a spark gap such as a spark plug for example. The high voltage source may be on continuously or may be turned on and off by a control circuit such as a solid state switch which is, in turn, responsive to a timing device such as a set of ignition contact points or a magnetic pulse generator operating in synchronism with a spark ignition engine. The timing device also provides signals to a current switching circuit which interrupts, current flow through a primary winding of the high voltage coil at the prescribed time that a spark is desired at the spark gap

Ac-coupled ultrahigh input impedance amplifier

Input impedances of several hundred megohms and input capacitances of less than one picofarad are achieved with a conventional unity gain are buffer amplifier modified by addition of positive feedback. The circuit is stable over a temperature range of 25 to 70 deg C

Analysis and test of a 16-foot radial rib reflector developmental model

Analytical and experimental modal tests were performed to determine the vibrational characteristics of a 16-foot diameter radial rib reflector model. Single rib analyses and experimental tests provided preliminary information relating to the reflector. A finite element model predicted mode shapes and frequencies of the reflector. The analyses correlated well with the experimental tests, verifying the modeling method used. The results indicate that five related, characteristic mode shapes form a group. The frequencies of the modes are determined by the relative phase of the radial ribs

Digital phase-locked-loop speed sensor for accuracy improvement in analog speed controls

A digital speed control that can be combined with a proportional analog controller is described. The stability and transient response of the analog controller were retained and combined with the long-term accuracy of a crystal-controlled integral controller. A relatively simple circuit was developed by using phase-locked-loop techniques and total error storage. The integral digital controller will maintain speed control accuracy equal to that of the crystal reference oscillator

Performance of the electrical controls for the Mini-Brayton system

The design theory and performance of a breadboard of the proposed Mini-Brayton electrical control system is presented. The Mini-Brayton is a nuclear isotope powered dynamic power conversion system. Testing was performed with an electronic simulation of a turbine alternator. Data on the voltage regulation, speed control, power consumption, reliability and transient response are presented for the breadboard

Coulometer battery state-of-charge indicator

Mercury-column electrochemical coulometer is a linear ampere-hour integrating device consisting of a sealed glass tube containing two columns of mercury separated by a gap containing an electrolyte. The drive circuit uses operational amplifier techniques to match nonlinear charge-discharge characteristics of an alkaline battery

The application of laser measurement techniques to the pneumatic transport of fine particles

The application of laser anemometry techniques to the measurement of local velocities and turbulence intensities is now well established for gas and liquid flows. In these situations, light from a low powered laser is scattered by seeding particles in the fluid which are small enough to follow the flow. The resulting Doppler shift of the scattered light is proportionate to the velocity of the particles and hence, to the velocity of the fluid. When solid particles are conveyed pneumatically, for example in transport chemical reactors, in drag reducing flows, and in certain heat transfer processes, the particles are generally much larger than the usual seeding particles, and thus do not travel at the same velocity as the carrier fluid. During this investigation, local particle velocity and axial turbulence intensity measurements using a laser anemometer have been made in an upward flowing gas-solid suspension and some of the limitations of the method have been found. The measured velocity profiles were used to evaluate the mean solids velocity and these mean values were compared with the results obtained using a technique developed by the author, which measures the mean solids velocity directly. Solids loading ratios up to 2.0, and conveying velocities up to 56 m/s, have been analysed and it has been confirmed that all the alumina particles (size range 5 to 45 microns) contributed to the analysed signal. Measurements have also been made of the particle velocity in the wall region of the two-phase flow, using a back-scattered light collection method. The pneumatic conveying imposed an upper limit on the loading ratio of 4 for these experiments. However the measuring system itself suffers no such restriction. The results of the "back-scatter investigation" are discussed by reference to particle wall velocity curves which can be used to indicate that 'choking ' is imminent. Further work examined the 'clean' air velocity and axial turbulence intensity profiles obtained by seeding the flowing air with sub-micron particles of titanium dioxide. Finally, measurements of axial pressure gradient in the fully developed region of the gas-solid flow were made simultaneously with the particle velocity measurements

Design and operating experience on the US Department of Energy experimental Mod-0 100-kW wind turbine

The experimental wind turbine was designed and fabricated to assess technology requirements and engineering problems of large wind turbines. The machine has demonstrated successful operation in all of its design modes and served as a prototype developmental test bed for the Mod-0A operational wind turbines which are currently used on utility networks. The mechanical and control system are described as they evolved in operational tests and some of the experience with various systems in the downwind rotor configurations are elaborated

Vibration tolerance of a mercury-column coulometer

Vibration tests on mercury column coulomete