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Hamlet, J. F.

Publications and source records attributed to Hamlet, J. F..

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

LC-oscillator with automatic stabilized amplitude via bias current control

A stable excitation supply for measurement transducers is described. It consists of a single-transistor oscillator with a coil connected to the collector and a capacitor connected from the collector to the emitter. The output of the oscillator is rectified and the rectified signal acts as one input to a differential amplifier; the other input being a reference potential. The output of the amplifier is connected at a point between the emitter of the transistor and ground. When the rectified signal is greater than the reference signal, the differential amplifier produces a signal of polarity to reduce bias current and, consequently, amplification.

Hamlet, J. F.↗
NASA NTRS1974

Automatic quadrature control and measuring system

A quadrature component cancellation and measuring system comprising a detection system for detecting the quadrature component from a primary signal, including reference circuitry to define the phase of the quadrature component for detection is described. A Raysistor optical coupling control device connects an output from the detection system to a circuit driven by a signal based upon the primary signal. Combining circuitry connects the primary signal and the circuit controlled by the Raysistor device to subtract quadrature components. A known current through the optically sensitive element produces a signal defining the magnitude of the quadrature component.

Hamlet, J. F.↗
NASA NTRS1973

Automatic quadrature control and measuring system

Quadrature is separated from amplified signal by use of phase detector, with phase shifter providing appropriate reference. Output of phase detector is further amplified and filtered by dc amplifier. Output of dc amplifier provides signal to neutralize quadrature component of transducer signal.

Hamlet, J. F.↗
NASA NTRS1972

Slush hydrogen liquid level system

A discrete capacitance liquid level system developed is specifically for slush hydrogen, but applicable to LOX, LN2, LH2, and RP1 without modification is described. The signal processing portion of the system is compatible with conventional liquid level sensors. Compatibility with slush hydrogen was achieved by designing the sensor with adequate spacing, while retaining the electrical characteristics of conventional sensors. Tests indicate excellent stability of the system over a temperature range of -20 C to 70 C for the circuit and to cryogenic temperatures of the sensor. The sensor was tested up to 40 g's rms random vibration with no damage to the sensor. Operation with 305 m of cable between the sensor and signal processor was demonstrated. It is concluded that this design is more than adequate for most flight and ground applications.

Hamlet, J. F.↗