Abstract: A differential pressure monitoring device utilizing two crystalline frequency sensors exposed to different pressures for generating two signals which are combined by a frequency mixer. Two offset based frequency crystal sensors are each exposed to different pressures and the resulting frequencies are mixed to measure the pressure differential between the two crystals. When the crystals are exposed to a common pressure, the crystals have an offset based frequency response that is consistent with pressure. When the two crystals are exposed to pressures, the offset frequencies are mixed together to create a differential frequency that is precisely related to the differential in the pressures placed on the two different crystal sensors.

Abstract: A capacitive differential pressure sensor comprises two end pieces and a central diaphragm all of the same type of electrically non-conductive material, such as quartz. As the central diaphragm moves relative to the end pieces in response to pressures applied through the end pieces, capacitance changes are sensed through one pair of facing electrodes on one end piece and the diaphragm and another pair of facing electrodes on the other end piece and the diaphragm. A method of measuring differential pressures at an oil or gas well with such a sensor is also disclosed.

Abstract: A dual crystalline resonator package comprises either (1) two crystalline bodies, in adjoining cavities of which bodies a crystalline temperature resonator and a crystalline reference resonator are respectively connected and which bodies are directly connected together, or (2) such two crystalline bodies in conjunction with a third crystalline body which is connected directly between the two first-mentioned bodies and to opposite sides of which third body the resonators are connected so that the resonators extend therefrom into the cavities of the two first-mentioned bodies. Either of these embodiments can be used for generating temperature data signals in a high pressure, high temperature well wherein the respective embodiment is lowered and exposed to such high pressure and high temperature. A modification of the second embodiment eliminates one of the resonators and the respective body having the cavity into which the eliminated resonator would otherwise extend.

Abstract: An apparatus and method for sensing temperature in an oil or gas well use an AC-cut temperature crystal connected to a Z-cut crystalline member contained in a crystalline housing that can be subjected to high pressures and temperatures.

Abstract: A pressure transducer comprises a quartz crystal having an orientation within a range of angles between about -25.degree. and about -45.degree. relative to the Z axis of X, Y and Z crystallographic axes. Such a pressure transducer provides a useful pressure response at pressures and temperatures above those of the operating ranges of pressure transducers using AT-cut or BT-cut quartz crystals.

Abstract: A self-contained electrical energy source, particularly embodied as a linear array of interconnected battery cells, includes a housing having the cells linearly disposed therein. At the two ends of the housing, mechanical connectors are provided for coupling with the apparatus to be energized by the energy source and for coupling with additional energy sources in a selectable electrical series and/or electrical parallel configurations. The electrical potential provided by the batteries within the housing is connected to both connectors through separate conductive paths which include folded conductors that permit the conductors to be deformed in response to forces that might act upon the conductors.