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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Frequency shifting, commonly used in electronic signal processing, is applied in tuning, automatic frequency control, antenna element switching, phase shifting, etc. Frequency shifting can be accomplished economically and reliably with simple circuit comprising conventional resistor and solid-state switching device which can be equivalent to two capacitors, depending on switching state.
Capacitive integrator circuit using Silicon Controlled Switches /SCS/ insures output voltage linearly proportional to input pulse width. This circuit provides high input impedance and relatively low output impedance.
Solid state switch for commutating capacitors in an RC commutated network increases switching speed and extends the filtering or commutating frequency spectrum well into the kilocycle region. The switch is equivalent to the standard double- pole double-throw /DPDT/ relay and is driven from digital micrologic circuits.
Photon actuated solid state switch development
Seebeck effect solid state switch was developed eliminating thermoelectric generator switch voltage drops. Semiconductor switches were fabricated from materials with large Seebeck coefficients, arranged such that Seebeck potential is generated with such polarity that current flow is aided.
A compact high-current pulse-forming network capacitor bank using paralleled silicon controlled rectifiers as switches is described. The maximum charging voltage of the bank is 1kV and maximum load current is 20 kA. The necessary switch equalization criteria and performance with dummy load and an arc plasma generator are described.
Solid-state crossbar switch for automatic, analog computer patching
The design of a solid-state circuit breaker that can be interconnected to a second breaker to form a transfer switch is presented. The breaker operates on a nominal 270-V dc circuit and controls power to loads of up to 15 A. Automatic overload trip is provided as a function of excess energy measured through the breaker and/or excess current through the breaker. After an overload trip, up to nine preprogrammable attempts to reclose may be tried with programmable delays between each attempt. The breaker or switch is remotely controllable. Test data on performance in the laboratory over temperatures from -45 to 100 C are provided. The feasibility of solid-state switch gear has been established.
A class of power converters is described for supplying direct current at one voltage from a source at another voltage. It includes a simple passive circuit arrangement of solid-state switches, inductors, and capacitors by which the output voltage of the converter tends to remain constant in spite of changes in load. The switches are sensitive to the current flowing in the circuit and are employed to permit the charging of capacitance devices in accordance with the load requirements. Because solid-state switches (such as SCR's) may be used with relatively high voltage and because of the inherent efficiency of the invention that permits relatively high switching frequencies, power supplies built in accordance with the invention, together with their associated cabling, can be substantially lighter in weight for a given output power level and efficiency of operation than systems of the prior art.
Pressure switch, incorporating a semiconductor light-detector coupled to an electrically controlled actuating unit, provides accurate and reliable switching over a broad range of pressures and environments.
Bank uses commercially available high-energy-density capacitors for energy storage and silicon-controlled rectifiers for switching. Low voltage design employing solid-state switching is utilized in lieu of conventional gas discharge switching.
Cavity-dumped lasers employ electrooptic-effect cell to alternately block and release laser pulse. Cell requires high-speed switching circuit that can apply and remove high voltage. Solid-state circuit employs complementary transistor switches which can switch at rates greater than 5 kHz, eliminate warmup time, provide variable voltage wave-form, and allow polarity reversal.
Silver-cadmium battery sensing and switching circuit design for satellite electric power systems
Electrically controlled optical latch consists of a sensitive phototransistor and a solid-state light source. This design requires less current to activate an optically activated switch than in prior art.
A feasibility study to design and demonstrate solid-state switchgear composed of circuit breakers and a power transfer switch is described. The switchgear operates on a nominal 270 Vdc circuit and controls power to a load up to 15 A. One circuit breaker may be interconnected to a second to form a power transfer switch. Breaker or switch on-off and transfer functions can be remotely controlled. Automatic overload trip-out is provided through an ultimate current trip and an I squared t trip for transient overcurrents lower than the ultimate current trip level. A number of reclosures with variable time delay between trip-out and reclosure are programmed and controlled by integrated analog and COSMOS logic circuits. A commutation circuit that creates minimal transient disturbances to either source or load was developed to interrupt current flow through the main SCR switching element.-
Investigation into the uses of step-recovery diodes /SRD's/ leads to the development of necessary circuitry for using fast current-switching capabilities of SRD's in frequency multiplication, the design of solid-state X-band transmitters employing SRD multipliers, and the use of SRD multipliers in a phased-array receiving antenna.
Attitude controllers are used to guide roll, pitch, and yaw of vehicle in flight. Controllers enclose multitude of switches, gears, cams, and other hardware needed to transmit pilot's commands to attitude control systems. New design, using magnetic coupled transducers, eliminates many mechanical parts, improving reliability and reducing maintenance.
Circuit concepts for realization of highly reliable and efficient electronic subsystems and microminiaturization application - switching amplifier analysis