A precision bridge measurement circuit connected to a current source providing a linear output voltage versus resistance change of a variable resistance (resistance temperature transducer) including a voltage follower in one branch of the bridge so that the zero setting of the transducer resistance does not depend upon the current source or upon an excitation voltage. The zero setting depends only on the precision and stability of the three resistances. By connecting the output of an instrumentation amplifier to a feedback resistor and then to the output of the voltage follower, minor nonlinearities in the resistance-vs-temperature output of a resistance-temperature transducer, such as a platinum temperature sensor, may be corrected. Sensors which have nonlinearity opposite in polarity to platinum, such as nickel-iron sensors, may be linearized by inserting an inverting amplifier into the feedback loop.
Method Of Making Electrical Connections To Thin Film Coatings And The Electrical Connector Formed Thereby
Electrical connections to thin film coatings, especially useful in a fluid flowmeter, have a conductive coating pressed against a rigid, relatively long, connector bar by conductively coated pads of elastomeric material at a selected controlled pressure, with the electrical connections to the film coating being made through the bar and pads. Utilizing this method, localized high stress areas which cause damage to the thin film are avoided, and low current densities are accomplished by the controlled contact pressure over a large area of the film coating.
Acoustical Wave Flowmeter With Increased Density Capability
In a flowmeter system having a transducer assembly defining a path for confining the flow of fluid medium there through and with first and second acoustic transducer elements disposed along said flow path for generating and receiving acoustic compression waves in the fluid medium, a phase-locked loop transmitter/receiver system including a voltage-controlled oscillator for adjusting the frequency of the acoustic compression waves to maintain the compression wavelength constant, together with circuitry for measuring the phase difference of the received acoustic compression waves relative to the applied electrical signal and circuitry for producing a signal representative of both the velocity of sound in the fluid medium and the direction and magnitude of the flow, the improvement in the circuitry which enables operation over a wider range of fluid density by causing the operating phase of the system phase-locked loop to vary in a continuous manner according to a previously determined relationship of phase-versus-resonant frequency, and the loop acquisition frequency to vary in a continuous manner according to a previously determined relationship of amplitude-versus-resonant frequency, of the transducer due to the density of the fluids being measured. Disclosed are three embodiments of the improved circuitry which vary the phase-locked loop operating phase and acquisition frequency, either nonlinearly or linearly, depending on the density range of the gases to be monitored.
Electro-Optical Ion Detector For A Scanning Mass Spectrometer And Method Of Making Same
An improved electro-optical ion detector comprising a channel electron multiplier assembly located at the angled focal plane of the magnetic sector of a scanning mass spectrometer with a twisted fiberoptic window with a means for precisely optically coupling the assembly to the twisted fiberoptic window. Means are provided for precisely spacing the entrance end of said twisted fiberoptic window in the form of a foil of a selected thickness. Also disclosed is a method for making an improved electro-optical ion detector.
Bruce E. Mount - Diamond Bar CA David E. Burchfield - Rancho Cucamonga CA John M. Hagey - Alta Loma CA
Orbital Sciences Corporation - Dulles VA
A gas bubble detector having a modulated IR source focused through a bandpass filter onto a venturi, formed in a sample tube, to illuminate the venturi with modulated filtered IR to detect the presence of gas bubbles as small as 0. 01 cm or about 0. 004" in diameter in liquid flowing through the venturi. Means are provided to determine the size of any detected bubble and to provide an alarm in the absence of liquid in the sample tube.
Conductance Measurement Circuit With Wide Dynamic Range
Bruce E. Mount - Diamond Bar CA Myron Von Esch - Chino CA
Orbital Sciences Corporation - Dulles VA
A conductance measurement circuit to measure conductance of a solution under test with an output voltage proportional to conductance over a 5-decade range, i. e. , 0. 01 uS to 1000 uS or from 0. 1 uS to 10,000 uS. An increase in conductance indicates growth, or multiplication, of the bacteria in the test solution. Two circuits are used each for an alternate half-cycle time periods of an alternate squarewave in order to cause alternate and opposite currents to be applied to the test solution. The output of one of the two circuits may be scaled for a different range optimum switching frequency dependent upon the solution conductance and to enable uninterrupted measurement over the complete 5-decade range. This circuitry provides two overlapping ranges of conductance which can be read simultaneously without discontinuity thereby eliminating range switching within the basic circuitry. A VCO is used to automatically change the operating frequency according to the particular value of the conductance being measured, and comparators indicate which range is valid and also facilitate computer-controlled data acquisition.
Respiratory Co.sub.2 Detector Circuit With High Quality Waveform
Bruce E. Mount - Diamond Bar CA Douglas P. Becker - Walnut CA
Marquette Gas Analysis - St. Louis MO
A respiratory CO. sub. 2 detector (10) comprising an infrared lamp source (44) and an infrared detector (50) responsive thereto forming an optical path for detecting the change in CO. sub. 2 concentration, or an obstruction in a cuvette (42). The output of the infrared detector (50) provides a high and low voltage signal to be applied to a feedback control loop (12) and to an output circuit (14).
The feedback control loop (12) includes a peak detector (22), a contamination detector (24), a pulse-width modulator (26) and a low pass filter (28), the latter providing a DC bias on the infrared lamp (44). The peak detector (22) is connected to the pulse-width modulator (26) to maintain the lamp voltage constant and is connected to comparators (56,62) to compare both outputs of the peak and contamination detectors (22,24). The contamination detector (24) will respond to blockage in the cuvette (42).
The output control circuit (14) includes a sample-and-hold circuit (30) and a subtractor (32) connected to the output of said infrared detector to receive the high and low voltage signal from the infrared detector, the outputs of which produce an output signal without the DC bias which is then inverted to provide a high quality waveform.
Apparatus And Method For Measuring Heart Condition
Bruce E. Mount - Diamond Bar CA James R. Barela - Duarte CA
City of Hope-A National Medical Center - Los Angeles CA
G06G 760 A61B 502
Apparatus and method for continuous measurement and display of the endocardial viability ratio of a patient to provide an indication of the condition of the heart muscle. A system using signals representative of the systemic arterial pressure and the left atrial pressure as inputs to generate a tension time index and a diastolic pressure time index by separation of the systemic arterial pressure wave form into two parts and selective integration of the inputs, followed by division to obtain the desired ratio.