Abstract: A sensor apparatus, which is threadably engaged into the auxiliary drain orifice in the drain pan. The sensor includes a pair of water contact points on a first end, which is on the threaded end of the sensor, so that should fluid or water make contact with the points, it effects a bridge across the points for creating a circuit there across. Upon this occurring, the electrical components contained within the sensor would relay a message through the thermostat wire, to the air conditioning system which would automatically shut the system down. Likewise, there is on the second end of the sensor a fluid high level indicator light, which would glow when this eventuality occurs. Therefore, when the owner would attempt to restart the system, the system would not reactivate. Therefore, upon inspection of the coils, etc.

Abstract: An infrared sensor is particularly well suited for the detection of heat sources, specifically from fires. It comprises an infrared detector receiving infrared radiation from a focused refractive optical unit. An optical chopper and electronic amplifier enable the sensor to operate without drift and with immunity to temperature changes in the sensor itself. The infrared radiation from the optical unit is appropriately filtered so as to optimize reception in a frequency band between 2.6 and 2.8 microns. In this band, there exists negligible energy from the sun due to absorption by gas molecules in the earth's atmosphere. Consequently, the sensor can be used in full sunlight without becoming saturated by the large magnitude infrared radiation of the sun. The sensor contains circuitry providing an audible output signal whose pitch is proportional to the intensity of the infrared radiation received from nearby heat sources. The device does not require any visual attention from a firefighter.

Abstract: Apparatus for monitoring particles in fluid systems in which a detector has electrical contacts that are bridged by particles captured from suspension in the fluid. Upon detection of a particle, a control microprocessor stores a predetermined quantity of electrical energy on a capacitor, which is then discharged through an inductor to burn off the particle at the detector. The burn-off charge and return lines from the charge storage capacitor are un-grounded, and are connected by respective electronic switches through relay contacts to the conductors connected to the chip detector. The relay contacts are also connected to the inputs of a differential amplifier for detecting presence of a chip bridging the detector contacts and monitoring continuity of the conductors to and from the detector. The relay is powered by system voltage, and in the event of system power failure connects the chip detectors directly to warning lamps on an operator panel.

Abstract: A toilet (6) has a solenoidal valve (1) in working relationship to a water-level probe (23), an overflow probe (25) and a floor-water probe (21) to prevent leaks reliably. A signal alarm (31) also is provided to warn of any problems and where they are in order to be able to repair them without the services of a professional plumber in many instances.

Abstract: A ground water alert device includes an elongated water proof cable member which has a predetermined length and is inserted into a water level monitoring pipe of a well for a predetermined depth above a water table, a cable housing for delivering and collecting the cable member, a water sensor such as a probe which is electrically connected to a free end of the cable member for lowering into the monitoring pipe to the predetermined depth above the water table, a DC power source, a control circuitry electrically connected between the DC power source and the cable member for generating alert signals when the water sensor detects water, a depth indicator having a plurality of length scales uniformly provided along the cable member to indicate the length of the cable member from the water sensor, and a cable supporter for securing the cable member in place at a top end of the monitoring pipe so as to ensure the predetermined length of the cable member retaining in the monitoring pipe.

Abstract: An apparatus and method for providing liquid and gas proof sealing between a metal rod and a plastic housing molded there around. The rod includes a plurality of annular intrusions or protrusions along a length thereof. The plastic material is formed around the rod and the annular intrusions or protrusions. After the plastic material has cooled the rod is translated linearly with respect thereto whereby the annular intrusions or protrusions cause a cold flow movement or disruption of the plastic material. This movement results in a liquid and gas tight sealing between the rod and the plastic housing. The invention herein has particular application for liquid level sensing probes located within gas pressurized vessels. In such examples the rod or rods are used for sensing liquid level by means of electrical conductivity with the sensed liquid.

Abstract: An orientation sensor especially suitable for use in an underground device is disclosed herein. This orientation sensor includes a sensor housing defining a closed internal chamber, an arrangement of electrically conductive members in a predetermined positional relationship to one another within the chamber and a flowable material contained within the housing chamber and through which electrical connections between the electrically conductive members are made such that a comparison between an electrical property, specifically voltage, of a first combination of conductive members to the corresponding electrical property of a second combination of conductive members can be used to determine a particular orientation parameter, specifically pitch or roll of the sensor.

Abstract: A liquid level detecting system for detecting a conducting liquid level in a non conductive container which utilizes a grounding rod mounted in a lower portion of the container and a conductive sensing rod mounted at a position above the grounding rod. An oscillator is provided having a frequency in the range of about 600 hertz to about 100 kilohertz. The output of the oscillator is applied to the sensing rod through a high impedance circuit and a high pass filter. In another embodiment, the high pass filter may have the higher end frequencies attenuated to produce a band pass filter which selectively passes the frequency of the oscillator. The voltage drop across the circuit which includes the conductive sensing rod to ground is detected by a voltage peak detector and a threshold detector to produce an output which detects the drops in voltage when the conductive fluid level in the tank rises so that both the sensing rod and the grounding rod are covered, completing the circuit.

Abstract: The device for determining and/or monitoring a predetermined level of contents in a container comprises a sensor, which is so mounted on the container at the level of contents to be monitored that it comes into contact with the contents of the container when the same reach the predetermined level. The sensor is excited to mechanical vibrations at its natural resonant frequency by an exciting arrangement. An evaluating circuit serves for causing indicating and/or switching operations in a manner dependent on whether the frequency of the mechanical vibrations of the sensor is higher or lower than a switching frequency. Associated with the sensor is an electrical circuit element which has a characteristic parameter, whose value bears an unambiguous relationship to the natural resonant frequency of the sensor. In the evaluating circuit the switching frequency is set in accordance with the value of the characteristic parameter of the electrical circuit element.

Abstract: The electronics enclosure comprises, surrounded by a metal shroud, an open end closed off by a plug of insulating material fitted in the metal shroud, in which contact members are provided for connecting the electronics assembly accommodated in the electronics enclosure to outer connecting leads. One of the contact members is a grounding contact member including a ring on which radially protruding spring claws of elastic material are provided. The plug is provided with a peripheral groove, and the ring of the grounding contact member is applied level with the peripheral groove in the plug such that the spring claws protrude into the peripheral groove. The length of the spring claws is dimensioned so that on insertion of the plug in the metal shroud they are flexed in the metal shroud and come into spring contact with the inside surface of the metal shroud.

Abstract: A fluid level detection system (50) for ink in a printing press (10) having a vessel (58) having walls (60) defining a chamber (62), an elongated rotatable shaft (64) in the chamber (62), a motor (66) for rotating the shaft (64), an elongated flexible blade (68) affixed to the shaft 64 such that the motor (66) rotates the blade (68), and a proximity sensor (72) adjacent the walls (60) of the vessel (58) to detect the rotating blade (68) in the absence of ink at the level of the blade (68), with the blade (68) flexing in the presence of ink such that the sensor (72) does not detect the blade (68).

Abstract: A connector for a fuel gauge in a fuel cell which has an inner tube (12) and a spaced-apart concentric outer tube (14). A housing assembly (16) is mountable to outer tube (14) and includes a contact (19) electrically connected to the outer tube. A sleeve assembly (25) is slidably mounted in a bore (24) in the housing assembly and extends through an opening (29) through the outer tube, and a first end (32) of a contact assembly (26) within sleeve assembly (25) extends through an opening (35) in the inner tube and self-secures thereto. The contact assembly of the sleeve assembly makes electrical contact with the inner tube (12) at opening (35) and is connected at second end (33) by an electrical lead to the fuel gauge. An electrical lead also connects contact (19) connected to outer tube (14), to the fuel gauge so that an electrical potential between the inner tube and the outer tube may be measured.

Abstract: A water purifier includes filters and a storage tank for storing water purified by the filters. A water detector disposed below the tank detects water leaked from the tank and supplies a corresponding signal to a control mechanism which shuts off the water flow through the purifier, displays a visual indication of leakage, and sounds an audible alarm.

Abstract: An automatic photographic developing apparatus for photosensitive materials includes a number of processing baths which are filled with processing solutions of different types for processing silver halide coated photosensitive materials. A same number of solution tanks communicated with the respective processing baths are provided for supplying the processing solutions, produced by dissolving solid agents, to the respective processing baths. A level sensor is installed in each of the solution tanks which monitors the level of the processing solution in the respective solution tanks. A plurality of shield members are provided, each shield member surrounding and protecting a respective one of the level sensors, and each shield member being detachably mounted to its respective level sensor. Each of the shield members includes a plurality of split members which are separable from each other and which are connectable to each other to surround the respective level sensor.

Abstract: An apparatus for sensing the level of fluid, including a two electrode device being disposed in the fluid and a microprocessor. The microprocessor being connected to the two electrode device and delivering alternating current thereto. The microprocessor reads the voltage across the device, compares the voltage to a predetermined voltage level, and produces a warning signal in response to the fluid level being below a predetermined fluid level.

Abstract: An elongate, flexible sensor for sensing an electrically conductive liquid, such as water, has two flexible electrodes extending along the sensor and two flexible sleeves extending therealong and being attached adhesively to each other along the sensor. Each electrode is a ribbon made from a carbon-filled, silicone rubber material. Each sleeve extends around an associated one of the electrodes and is braided from a filamentary, polyester material so as to define multiple apertures enabling such a liquid reaching the sensor to pass through the sleeves so as to cause a short circuit between the electrodes.

Abstract: A sensor system is operable for detecting the presence of water in an oil emulsion inside the lower gear unit of a marine engine, and for providing an alarm signal when the presence of water is detected within the gear unit. The sensor system includes a ring oscillator circuit and a symmetrical array of passive input probes which are disposed in the oil/water emulsion inside the oil chamber. Each of the passive input probes is electrically connected to the ring oscillator circuit wherein the probes function as fixed capacitors for measuring the electrical characteristics of the emulsion. When a voltage is applied to the oscillator circuit, the oscillator circuit generates an oscillating signal that circulates at a frequency which varies according to the dielectric-properties of the liquid emulsion. When water is introduced into the chamber, the water is emulsified with the oil thereby changing the electrical characteristics of the oil.

Abstract: The determination and/or monitoring of a predetermined material level in a container is effected with the help of a material level sensor which contains a mechanical oscillatory structure, an electromechanical excitation transducer and two electromechanical reception transducers. The mechanical oscillatory structure is secured at the height of the predetermined material level in such a way that it comes into contact with the material when said material reaches the predetermined material level. Each reception transducer is connected to the input of an assigned circuit channel, which contains an amplifier circuit, the output of which is connected to the excitation transducer and which is so constructed that the mechanical oscillatory structure is excited to produce oscillations with its natural resonance frequency. The two circuit channels are activated alternately by means of a control circuit.

Abstract: An automated liquid level sensing system for use in an automated, continuous, and random access analytical system is disclosed. A pipette probe is positioned above, and lowered into, a liquid sample container which contains the liquid to be detected. The probe is energized by a near radio-frequency (RF) signal source. A receiving antenna is positioned below the sample container, and is oriented so that very little signal is detected from the probe while the probe is in air. When the probe contacts liquid in the sample container, the electromagnetic field of the RF signal is increased and reoriented toward the receiving antenna. An autozero circuit maintains a near-zero output from the receiving antenna when slow changes in signal level occur due to changes in probe position or other environmental factors. The autozero circuit allows the sudden increase in signal amplitude, due to liquid contact, to pass to a receiver.

Abstract: In devices for determining and/or monitoring a predetermined level with a sensor that is excited to perform mechanical oscillations at its self-resonant frequency by means of an electronic excitation circuit which is excited via a piezoelectric excitation and a reception transducer and an evaluation circuit for triggering display and/or switching processes, there exists the difficulty that the natural frequencies of the sensors are different due to the manufacturing conditions, and that the operating frequency must be adjusted individually for each sensor. This disadvantage makes repair and maintenance procedures quite difficult.

Abstract: A fire safety apparatus particularly useful in association with Christmas trees comprising a smoke detector, circuitry for processing a signal generated by the smoke detector, an audible alarm, a moisture level sensor and circuitry for interruption of the flow of electricity to a receptacle. In the event of a Christmas tree fire, the smoke detector activates the circuitry which cause the audible alarm to be sounded. The audible alarm is sensed by a receiver which contains the circuitry for interruption of the flow of electricity and is in the form of one or more switches. Any appliances, such as Christmas tree lighting which are plugged into the receptacle, are deactivated by the interruption of electrical flow at the receptacle. Additionally, moisture sensing probes are provided which activate circuitry which cause the alarm to be sounded when the moisture level contained in a Christmas tree base falls below a certain level.

Abstract: A probe for measuring the moisture content of wood in the center of a stack of wood has a moisture content sensor near a first or forward end thereof. The forward end of the probe is bendable and in one form is articulated. An extendable member also is mounted at the forward end of the probe. The extendable member is pivoted by a slide handle at an opposite end of the probe between reclined and extended positions. The forward end of the probe is inserted into a stack of wood between layers of the stack. The extendable member is extended to press the sensor against wood in the center of the stack. A meter connected to the sensor then registers the moisture content of the wood.

Abstract: A fuel gauging system for use in determining the level of fuel in a tank. The system incorporates a resonant circuit for measuring the resonant frequency of at least one probe immersed in the fuel located in the tank. From measurements of variations of the frequency of resonance, the level of liquid in the tank is determined, and the fuel quantity is then calculated and displayed.

Abstract: A transistor and integrated circuit-free remotely indicating status device for holding tanks for recreational vehicles and pleasure boats contains no moving parts, is resistant to corrosion, and is inexpensively and simply manufactured and installed. In one embodiment, common LED indicating devices may be alternatively toggled between water tank and waste tank sensor circuits.

Abstract: An optical tank-level gauge includes an elongated gauge rod magnetically coupled at its lower end to a float for rising and falling with the liquid level. The outer surface of the rod is provided along most of its length with alternating reflecting and non-reflecting circumferential stripes of equal height, the rod having non-reflecting zones at its opposite ends. An optical read head is fixed on the tank and includes LEDs for illuminating the rod and four optical sensors spaced apart longitudinally along the rod and arranged into quadrature pairs relative to the stripes, so that each pair reads a longitudinal extent of the rod substantially equal to the height of one stripe. Each of the non-reflecting end zones has a height such that, in either the full or empty condition, the fields of view of all four optical sensors will be completely within one or the other of the end zones.

Abstract: A volume sensing device for determining the volume of liquid present in a standard plastic disposable pipette during a pipetting operation, which operation can be an aspiration or dispensing of liquid. The device comprises a cylinder made of hard synthetic material into which a disposable pipette is lowered at a predetermined velocity. The pipette which is being lowered into the cylinder holds an amount of liquid the volume of which the volume sensing device approximately determines. A pair of metal rings are coaxially mounted near the top end of the plastic cylinder. The pair of metal rings are preferably mounted in mating machined recesses of the plastic cylinder. This pair of metal rings is separated from each other by a small gap which forms the dielectric material of a capacitative circuit when the upper ring is connected to one portion of this circuit and the lower ring is connected to an other portion of the capacitative circuit.

Abstract: A piezoelectric liquid level switch is provided which can be made immune to standing wave effects and provides an unequivocal response to liquid contact.

Abstract: The level of ink present in an ink-supply cartridge of an ink-jet type printer is detected by a sensor that moves with the reciprocating pen carriage of the printer. A flag is connected to the collapsible supply cartridge so that the flag position changes relative to the path of the carriage movement as ink is depleted from the cartridge. The sensor detects the presence of the flag and the position change of the flag is precisely measured by the carriage motion control system. An indicition of the cartridge level derived from the flag position is provided.

Abstract: A fluid level sensing system, particularly for sensing the water level in a steam generating boiler, comprises a vessel connected to the boiler so as to contain water and steam at substantially the same level as in the boiler, a number of vertically spaced electrodes projecting into the vessel, and circuitry for measuring the electrical impedance sensed by each electrode. The circuitry, which can be multiplexed to each electrode in turn, includes a first comparator for producing an output when the sensed impedance lies between the normal maximum impedance of the water and the normal minimum impedance of the steam above the water, this output being demultiplexed to drive a vertical display to show the level of the steam/water interface. The circuitry additionally includes a second comparator for producing a further output when the sensed impedance lies below the normal minimum impedance of the water, which further output is indicative of a variety of different fault conditions and drives a fault indicator.

Abstract: A boiler water level system comprises a plurality of electrodes arranged to sense the resistivity of the fluid at each of a plurality of different levels in a pressure vessel. The pressure vessel is coupled to one end of the boiler such that the level of the water in the pressure vessel is substantially the same as the level in the boiler, and each electrode senses the resistivity of the fluid (ie water or steam) between the tip of the electrode and the wall of the pressure vessel. Such a system on its own inherently produces a digital output of relatively low resolution, so to improve resolution, and to provide an analogue output if desired, additional circuitry is provided to sense the progressive change in the impedance sensed by each electrode as the water rises to progressively immerse that electrode and then carries on rising towards the next electrode.

Abstract: There is disclosed a two wire AC power supply for proximity switch integrated circuits. A problem has existed with previous power supplies in that such have been implemented using discrete devices, which take up valuable room on any printed wiring assembly. This invention therefore provides a two wire AC power supply for a proximity switch integrated circuit, wherein at least some circuitry associated with the power supply is provided within the integrated circuit. The power supply preferably comprises a bridge rectifier (BR1), a voltage regulator (Z1, R1, M1), a thyristor (SCR), a diode (D1), a storage capacitor (CVS), a comparator, and an AND gate, wherein at least the comparator and the AND gate are provided within the integrated circuit.

Abstract: A continuous liquid level measuring system having a guarded capacitance probe and related drive circuit for providing accurate level measurements, even when measuring the level of ionic and highly viscous fluids. The capacitance probe has two parallel electrodes, each constructed of a half-tube section, that are separated from each other by an insulated guard wire. The probe is excited by a 1 MHz excitation signal applied across the electrodes. The current through the electrodes is a function of the capacitance between the electrodes, which is affected by the relative permitivity of the surrounding liquid. The effects of highly viscous ionic liquids that adhere to the probe are reduced by exciting the guard wire with a guard signal that is 180.degree. out of phase from the probe's excitation signal. The guard signal changes the electric field existing in the space adjacent the junctions of the two electrodes to reduce any liquid coating effects on the level measurement.

Abstract: A drain tube that can be used, for example, in an air cooling system, includes an inlet end for attachment to the drain pan of the air handler, and an outlet end for transporting liquid out of the drain pan. A liquid sensor probe is located at least partially in the drain tube, and includes a probe end that extends from the drain tube inlet end into the drain pan when attached to the drain pan. The liquid sensor probe detects the undesired accumulation of liquid in the drain pan caused by a blockage in the drain pan, in the drain tube, or in any other portion of the drainage tubing. A control circuit generates an output signal when excess liquid is present at the probe end of the liquid sensor so as to sound an alarm and/or turn off the air cooling device. The outlet end of the drain tube can be attached to a first leg of a cross-shaped fitting. The cross-shaped fitting includes a second leg opposite to the first leg through which a cleaning device can access the first leg, the drain tube, and the drain pan.

Abstract: A device is disclosed for sensing any of a wide range of liquid hydrocarbons. A ribbon-like sensor is employed, which has an inner, silicone rubber layer and an outer, silicone rubber layer and which has two broad faces and two narrow edges. The silicone rubber layers are capable of absorbing and swelling in the presence of a liquid hydrocarbon. The inner layer but not the outer layer is filled with electrically conductive particles, preferably carbon black particles, so as to be capable of switching from having an electrical impedance which is relatively low to having an electrical impedance which is relatively high when swollen in the presence of a liquid hydrocarbon. As made from an open cell, polyethylene foam, a porous body is attached to the sensor. The porous body is capable of floating with the sensor on water or on a liquid hydrocarbon and of conducting a liquid hydrocarbon through the porous body to the sensor.

Abstract: A method and apparatus for a liquid level sensor control circuit of a bioassay apparatus for controlling a position of a sampling probe with respect to a surface of a liquid in a container. The apparatus includes a sampling probe, an oscillator circuit coupled to the sampling probe for producing a first output signal having a constant frequency, a comparator coupled to the oscillator circuit for comparing the amplitude of the first output signal to a first reference amplitude and for producing a change signal when the amplitude of the first output signal changes with respect to the reference amplitude, and a controller responsive to the change signal for controlling the position of the sampling probe with respect to the surface of the liquid.

Abstract: A Christmas tree ornament uses a water sensor that provides on demand an indication by light and/or sound if the tree needs water. A portion of the ornament contains a funnel side which allows water to be added to the tree. The other portion of the ornament contains the circuitry for the sensor. A sensor, in the form of a pair of electrodes or terminals, connected to the circuitry, is contained in the water of the Christmas tree stand. The circuitry further includes a battery, an on/off switch, a resistor, a green LED, and a red LED mounted on a display panel. In operation, when the switch is turned on, the green light is energized indicating that the battery is good (a safety feature). If the red light is not on, it is an indication the tree needs water. Water can be added through a funnel side of the ornament. When the electrodes are immersed in the water, a circuit is completed and the red light turns on to indicate sufficient water for the tree.

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 water level detector and indicator system includes a water level detector and a water level display controlled by the water level detector to give a respective output signal when the level of water changes from one position to another. The water level detector can be a mechanical type which uses a float to control a multi-step switch causing a series of indicator lamps to give light respectively. The water level detector can be an electronic type which uses metal probes to detect the change of water level, and a controller driven by the metal probes to control buzzers and indicator lamps to work.

Abstract: A test circuit for testing operation of a liquid level detector. The liquid level detector includes a probe that is placed at a test site. A control circuit monitors changes in capacitance of the probe due to changes in the liquid level at the test site. A test switch grounds an input to the probe which and causes the control circuit to sense an alarm condition. If the detector does not activate an alarm when the test switch is actuated, the detector is not properly functioning and repair or replacement of the level detector is needed.

Abstract: The present invention provides a locator/monitor capable of locating a boring tool and monitoring the progress of the tool for control purposes. The locator/monitor may be used in expedited locating methodology and straightforward calibration techniques of the present invention. A durable and cost effective pitch sensor is also provided by the present invention. In addition, the present invention provides a slotted transmitter housing formed of an electrically conductive material, where the magnetic field generated by the transmitter is capable of penetrating to the surface.

Abstract: A fail safe output stage for a tank fluid level detection circuit having power supply/output leads periodically places a shunt across the leads to periodically generate a LOW signal which alternates with a HIGH signal to indicate an underfilled condition. In a filled condition, a steady signal appears across the leads. The output stage of the detection circuit consists of a parallel connection of switching devices where the "on" impedance of any single switching device is insufficient to place the detection circuit output lead in a LOW logic state. Therefore, in a condition where one of the switching devices fails, the detection circuit output may continue to alternate, but the alternating output is not recognized as such by a disable circuit which does not detect a LOW logic condition on the output lead. Accordingly, the failed output is interpreted as an filled condition, resulting in a shutdown of the system.

Abstract: An improved water sensor unit wherein a plurality of water-related appliances or equipment can be simultaneously monitored and, in the event of sensing water with respect to any one of the several items being monitored, appropriate action is taken, such as shutting off the power to the unit and simultaneously shutting off the water supply to that particular unit. The sensor unit comprises a plurality of electronic circuits which include thermal circuit breakers acting as a "fault memory." When a fault occurs, the circuit breakers are tripped. Thus, the fault condition will be "remembered" indefinitely until human intervention.

Abstract: A liquid level detecting device having an overflow reservoir, a flow restriction means and a level detecting means. The reservoir defines a cavity for collecting an electrically-conductive liquid overflowing from a container. This reservoir, which has a low level position associated therewith, includes inlet means through which the overflowing liquid enters, outlet means through which the collected liquid exits, and vent means through which built-up gases escape.Flow restriction means controls the rate at which the collected liquid exits through the reservoir's outlet means. Flow restriction means is calibrated such that the rate at which liquid exits the reservoir does not exceed the rate at which liquid overflows therein.In one embodiment, level detecting means includes a capacitive sensor switch which is fixedly secured to the reservoir to detect whether the liquid level is below the reservoir's low level position.

Abstract: A battery-operated fluid level monitor has a novel circuit and sensor for providing signals, both audible and visible, for indicating low fluid level, low battery voltage, and proper fluid level. The monitor is useful as a device that can inform when a Christmas tree needs water. The monitor can also be economically fabricated, and this is important for mass production applications, such as a Christmas tree monitor.

Abstract: A computerized diagnostic system includes a microprocessor-based electronic controller which controls a portable machine. Electronic sensors provide raw, operating parameters to a RAM type memory of the controller. A locator locates predetermined RAM addresses of raw machine operating parameters which are known to be useful in the monitoring and diagnosis of the portable machine. A remote, microprocessor-based computer diagnoses and monitors the electronically controlled machine. A display means displays the user friendly symbols in function-specific groupings which reveal patterns of machine operation, and which identifies the process which the machine is performing.

Abstract: A fuel heater formed form an elongated structure which defines a fuel channel passing through the length thereof and which defines in the bottom thereof a fuel intake. The unitary structure also defines a heating fluid inlet and outlet on one side of the fuel channel which communicate with one another on that one side of the fuel channel and fuel measurement means. The fuel measurement means is fit to a conduit formed in the elongated structure. The fuel measurement means can be a capacitive-type level sensor.

Abstract: The device comprises at least two oscillation rods that are mounted at a distance from each other on a membrane, the edge of which are connected with a screw insert. A clamping screw is connected with the membrane on the side opposing the oscillation rods in such a rigid manner that the clamping screw and the membrane assume a position to each other in which their symmetry axes coincide. The clamping screw is surrounded by a stack of annular piezoelectric elements, electrode rings as well as insulating rings. This stack forms the excitation and reception transformer of the device. The stack-shaped excitation and reception transformer is clamped and mounted between the membrane and a hexagonal nut. The stack braces itself on a shoulder that encompasses the membrane within a distance by the metal ring that closes the stack. The clamping force is chosen such that the membrane is simultaneously prestressed in a concave manner.

Abstract: A two-level detector for an electrically conductive liquid having a common electrode serving as a potential reference and situated at a low level, a high electrode situated at a high level, and a low electrode situated at the low level, the electrodes being connected by conductors to electronic apparatus for detecting the liquid at said two levels by means of currents flowing through the liquid. The high and low electrodes are made of metals that have different electrode potentials. A first conductor and a second conductor interconnect the electrodes to constitute an electrical primary cell that is short-circuited when both electrodes are simultaneously in contact with the liquid. The second conductor is extended to connect the electrode assembly to a signal terminal of the electronic apparatus. The common electrode is made of a metal whose electrode potential is different by about 0.

Abstract: A water supply control apparatus for a household plumbing system having a main water supply line includes a shut-off valve disposed in the main water supply line, electric motor means for actuating the shut-off valve and being operable to move between open and closed positions, at least one temperature sensor adapted to be located in a position of exposure to cold temperatures, at least one moisture sensor adapted to be located in a position of exposure to water leaking from household appliances, control means, connected to the electric motor means, the at least one temperature sensor and the at least one moisture sensor, for actuating the shut-off valve to the closed position when either a freeze condition is detected by the at least one temperature sensor or a water leak is detected by the at least one moisture sensor.

Abstract: A warning device is disclosed for an evaporative cooler or swamp cooler. The alarm comprises a pair of closely spaced electrodes mounted at a desired position above the floor of a water reservoir in the evaporative cooler. During normal operation of the evaporative cooler, the electrodes are not submerged in the pater. Upon malfunction of the float valve in the water supply to the reservoir, uncontrolled amounts of water are added to the reservoir, and the water level rises. When the water level attains a specified depth, the electrodes become submerged in the water. An electrical circuit is associated with the electrodes, and when the electrodes become submerged in the water, the electrical circuit is closed. The closing of the circuit activates an audible alarm which can be heard by inhabitants in the building being served by the evaporative cooler. Preventive maintenance can then be undertaken before extensive damage is done by water overflowing from the water reservoir of the evaporative cooler.