Abstract: A fault detection circuit in a boiler-water level system includes a dual-frequency signal generator which develops two AC components with no associated DC component. The two frequencies are mixed and sent through an impedance matching circuit to match the impedance of the signal generating portion of the system with the impedance of the boiler water under measurement. The impedance-matched signal is then directed to two legs, one leg directed through one of a plurality of electrode probes and then to a first filter circuit, and the other leg is directed a second set of filters. In combination, the filters pass either the higher or the lower of the two frequencies to determine an open or short condition in the level sensing circuitry, as well as a steam vs. water condition.

Abstract: A fault detection circuit in a boiler-water level system includes a dual-frequency signal generator which develops two AC components with no associated DC component. The two frequencies are mixed and sent through an impedance matching circuit to match the impedance of the signal generating portion of the system with the impedance of the boiler water under measurement. The impedance-matched signal is then directed to two legs, one leg directed through one of a plurality of electrode probes and then to a first filter circuit, and the other leg is directed a second set of filters. In combination, the filters pass either the higher or the lower of the two frequencies to determine an open or short condition in the level sensing circuitry, as well as a steam vs. water condition.

Abstract: A sight flow indicator having a viewing window for monitoring liquid flowing therethrough is disclosed. The flow indicator is configured to disentrain gas and particulate from a portion of the fluid. The flow indicator is also configured to reduce the velocity of fluid flowing therethrough. The portion of the fluid from which gas and particulate has been disentrained is diverted from the main flow stream, past the viewing window. The relatively clean liquid sample flowing past the viewing window lends itself to relatively accurate optical analysis using, compared to the bulk fluid flowing through the flow indicator. The flow indicator is well-suited for use with a spectrometer or other optical analyzer.

Abstract: A gasket (20) is provided for sealing a member with a rough micro-surface to a member with a smooth micro-surface. The gasket (20) has a layer (24) of graphite material and a layer (32) of an elastomeric or fibrous gasket material. An inner surface (28) of the graphite layer (24) is laminated to an inner surface (30) of the elastomeric or fibrous layer (32). When used for sealing, the graphite layer (24) is placed adjacent the member with the smooth micro-surface and the elastomeric or fibrous layer (32) is placed adjacent the rougher member. Alternatively, in addition to having a layer (32) bound to an inner surface of the graphite layer (24), a layer (38) of elastomeric or fibrous gasket material may be bound to the outer surface (26) of the graphite layer.

Abstract: A highly accurate system to measure the level of material in a vessel. A probe is provided in the vessel. The vessel and the probe are at different potentials so as to create a capacitance therebetween. The air and materials in the vessel act as dielectrics. As the material level varies, so does the capacitance. This capacitance is subjected to a charge-discharge-charge cycle yielding integrated net neutral charge. The duration of the cycle is compared to a reference time to determine capacitance, which is proportional to the level of material in the vessel.

Abstract: A low intrinsic capacitance probe system for measuring capacitance to detect the liquid fill level of a pressure vessel that incorporates a high pressure center rod retention system and an explosionproof flame path seal into its mounting gland. The system reduces or eliminates the cold flow of PTFE within the probe and eliminates the need for periodic retorquing.

Abstract: A system for controlling a bipolar constant current when the current is being supplied to an active or reactive element. Tracking is extended to either sink or source modes. A switchable driven ground state is also provided. An operational amplifier buffer senses the voltage amplitude at the junction of the system output and active or reactive load element. This relatively low impedance output is summed or offset with a regulated voltage. This level is again buffered to present a low output impedance and series connected with a current limiting resistor.

Abstract: A highly accurate system to measure the value of a capacitor using proportionality against a time base reference. The capacitor under test is linearly sequentially charged in three discrete steps yielding integrated net neutral charge as well as a delay for discharging dielectric absorption during each measurement cycle.

Abstract: A semiconductor transducer with a diaphragm is constructed utilizing a substrate wherein a first portion of that first face is etched to a planar level to achieve a second portion as a physical stop on this substrate, the physical stop having a planar stop face, a sloping sided cavity is etched into a semiconductor wafer from a first face thereof to form a deformable diaphragm in this semiconductor wafer. The semiconductor wafer is anodically bonded to the substrate planar level, with the physical stop located in the cavity and with the stop face acting to prohibit excess movement of the diaphragm. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

Abstract: Responses of a human subject may be by voice, hand or foot movement, or bodily secretions, as examples. A hiatus of such responses may be termed a lapse in the continuity of the response, including a hesitation pause in the voice, hesitation in the movement of writing, a movement of hand or foot on a monitored control of a motor vehicle or vehicle simulator, or pulsatile bodily secretions on a monitored control of an implantable insulin pump. In a voice response, the hesitation pause may be more than about one second in the voice of a subject during a dialogue or monologue. The hiatus rate of such responses is indicated by the present apparatus, as in the average hiatus duration for two or more hiatus rates. The dominant hiatus rate is also determined and indicated. A microprocessor is utilized in such determination.

Abstract: A full-wave bridge rectifier has its input connected directly across a 115 volt RMS alternating current line operating at 60 Hz wherein the output of the bridge provides 120 Hz pulsating direct current at 161 peak volts. A pair of transistors, switching on and off in alternating fashion, continuously apply to a low power requirement load only a leading edge portion and a trailing edge portion of each of the 120 Hz direct current pulses. The resultant direct current voltage, e.g. 11.3 peak volts, across the load is thus substantially reduced to a desirable level as compared to the voltage, 161 peak volts, of the pulsating direct current provided at the line driven bridge output. In another embodiment, the function of the transistors is provided by a pair of operational amplifiers which control the switching of a field-effect transistor in series with the load.

Abstract: A mechanical dial indicating gauge or meter that, without mechanical loading, optoelectronically detects and encodes the pointer position as a digital signal by use of a technique of distributed point position latching. Counter means drives a circuit which cylically sequentially lights LED's along a scale and the count is latched that corresponds to current counter position when a detector on the scale pointer is activated during the sequential lighting. This latched count provides the digital signal of pointer position. This digital signal may then by transmitted to remote indicators, controllers, computers, and/or may be compared to preset values yielding set point outputs. An electrical lead for the detector includes a spiral loosely surrounding the pointer stem.

Abstract: A highly accurate and miniaturized pressure transducer is disclosed which includes first and second capacitors as a part of the integrated circuit, which also includes an Eccles-Jordan astable multivibrator. The miniaturization of both the capacitors and the entire multivibrator circuit in an integrated circuit establishes all components so that they are very closely matched on the two halves of the multivibrator, and so that whatever environmental disturbances, e.g., electrical, thermal, noise, etc., are encountered, are shared by both halves, and hence negated, so far as output drift is concerned. The multivibrator has a rectangular wave output and the duty cycle thereof is proportional to the force or pressure applied. This duty cycle is changed upon applied pressure, which changes one of the capacitors, and measurement of the duty cycle is a measurement of the applied force or pressure.

Abstract: Responses of a human subject may be by voice, hand or foot movement, or bodily secretions, as examples. A hiatus of such responses may be termed a lapse in the continuity of the response, including a hesitation pause in the voice, a movement of hand or foot on a monitored control of a motor vehicle or vehicle simulator, or pulsatile bodily secretions on a monitored control of an implantable insulin pump. In a voice response, the hesitation pause may be more than about one second in the voice of a subject during a dialogue or monologue. The hiatus rate of such responses is indicated by the present apparatus, as is the average hiatus duration for two or more hiatus rates. The dominant hiatus rate is also determined and indicated. A microprocessor is utilized in such determination. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

Abstract: Current provided to a generally constant impedance load is monitored to detect a predetermined load current decrease not resulting from normal load voltage fluctuations, such decrease indicating an abnormal increase in load impedance. A latching alarm is actuated when the predetermined load current decrease is detected. The degree of load current decrease tolerable without activating the alarm is determined by a user-adjustable percentage-of-change sensitivity control. A logic gate blocks alarm functions when the load current decreases to an abnormally low level. The disclosed device can be used to monitor the status of a line voltage energized heat trace cable constituted by a plurality of parallel-connected resistance wire heating elements. Multiple monitoring devices can be used in conjunction with a master alarm which can be reset without resetting the particular monitoring device alarm that triggered the master alarm.