Abstract: A body fluid excretion volume measurement apparatus for medical application. The apparatus stores body fluid excreted from patients in a body fluid storage tank and measures the resistance value with a resistance sensor. The resistance value depends on the shape of the body fluid storage tank, and if the tank is columnar, the resistance value is monotonically increasing with respect to the depth of body fluid. The output of the resistance sensor is processed by a measurement part and electric measurement of the body fluid volume stored in the body fluid storage tank is performed automatically.

Abstract: An apparatus and method employing a liquid level detection conductance probe mounted in a container to sense resistive differences between the probe and container depending upon the presence or absence of liquid therebetween. A sensing circuit senses probe signal variations and stores a probe signal. A comparator compares the stored probe signal to current probe signals and switches means connected to the comparator depending upon the presence or absence of liquid between the probe and container. The sensing circuit has sufficient sensitivity to differentiate between liquid between the probe and container and foam or scale deposits therebetween.

Abstract: A liquid level measuring and indicating system using a positive temperature coefficient wire as a sensor, a microprocessor based operating circuit, and an electronically controlled display device. With energy to operate the system being supplied by a battery, circuit includes energy conservation provisions.

Abstract: An aircraft fuel gauging system has three or more optical pressure sensors 1 and 3 mounted in a tank 10. One sensor 1 is mounted on the floor 14 of the tank, the other sensors 2 and 3 being displaced from the first sensors and from each other in the x, y and z directions. The output of each sensor 1 to 3 is representative of the mass of fuel above the sensor and is supplied to a processor 20. The processor 20 is also connected to an three-axis accelerometer system 21, a pressure sensor 24 above the liquid and a density sensor 25. Utilizing these inputs the processor 20 computes the location of the fuel surface and, from information in the store 22 of tank shape, calculates the mass of fuel.

Abstract: An extended resistance temperature sensor formed of a plurality of lengths of pre-insulated resistance temperature detector (RTD) wire. The RTD wire is either unheated, self heated or is heated by means of strands of heater wire integrated with or placed closely adjacent to the RTD wire. The RTD wire itself, or together with the heater wire, is bonded together in one embodiment. Alternatively the RTD wire, or with the heater wire, may be encased in insulated shrink tubing, thin wall metal tubing or both. Connectors are provided to supply electrical current for heating purposes or to connect the RTD wire to detection circuitry, or both. Protective sheaths are provided over the connectors.

Abstract: An electrode is lowered toward the surface of a liquid column until electrical contact is made between the electrode and a liquid column to establish current flow between the electrode and the liquid column. The electrode is raised from the liquid column. An additional quantity of liquid is added to the liquid column to cause the column to rise. The electrode is lowered toward the surface of the liquid column until electrical contact is again effected. The distance of travel of the electrode is measured as a determination of the rise in height of the liquid column and of the additional volume of liquid added to the column.

Abstract: A device for monitoring pressure variations for mercury manometers including; a manometer tube with a column of mercury; at least two taps in the tube with one tap in the mercury column and the other above the column; a power supply interconnected between the taps; a resistance element extending between the taps in the mercury; and means for sensing the output voltage across the taps representative of the variations in the shunting effect on the resistance element of the mercury column as it rises and falls with pressure.

Abstract: This invention relates to a pressure equalizing vessel for a hemodialysis concentrate. To ensure the supply of concentrate at a constant pressure to the concentrate pump for preparing dialysis fluid, even in cases where a central concentrate supply system is used, the present invention suggests that a cylindrical upright vessel 1 whose lower portion is provided with a concentrate inlet and whose upper portion has arranged thereon a venting means 4 should have inserted thereinto a concentrate suction tube 7 which is equipped with at least one level sensor (FIG. 1).

Abstract: The detecting device according to the present invention is provided with a case, a first and second detecting pads which juts from the case and which can be closely attached to the outer wall of the receptacle, supports which are connected to the first and second detecting pads in a thermal-conducting manner, a first thermistor and heater embedded in the support of the first detecting pad, a second thermistor embedded in the support of the second detecting pad, and a detector circuit which measures the quantity of heat transmitted from the first detecting pad into the receptacle in accordance with a change in the output of the first thermistor when the first detecting pad and the support thereof are heated by the heater to a preset temperature which is above the reference temperature of the second detecting pad and the support thereof, thus detecting the level of a liquid in the receptacle from the measured quantity of heat transmitted.

Abstract: A liquid level sensor system for a tank includes a stillwell having a transducer assembly positioned in the bottom of the stillwell. A guide conduit surrounds a flexible plastic coated wire bus which extends through a sidewall of the tank and which connects the transducer assembly to an indicator assembly located outside the tank. The conduit includes an end cap which secures the wire bus within the conduit. Installation and removal of the transducer assembly and wire bus is accomplished at a location outside the tank by removing the end cap and pulling or pushing the transducer assembly through the conduit by means of the wire bus.

Abstract: The present invention provides a level detector to sense whether the level of a liquid having a nonambient temperature such as a cryogenic liquid has reached a predetermined point. A stainless steel type T thermocouple probe is provided for generating a temperature signal referrable to absolute temperature. A high thermal conductivity the type T thermocouple probe is adapted to be mounted so that it submerges in the liquid when the level of the liquid has reached the predetermined point tube is, at one end, in good thermal contact with a thermocouple contained within distal end of the thermocouple probe and, at the other end, is exposed to ambient conditions. The high thermal conductivity tube acts to conduct heat between the ambient and the thermocouple.

Abstract: An RTD (resistance temperature sensor or detector) sensing device which is a long, thin, unitary device adapted to be distributed across an extended field for the continuous, uninterrupted sensing or interrogation of such field, avoiding the inaccuracy, unreliability, and excessive expense of conventional "point" RTD and thermocouple sensors currently employed for this purpose. According to the invention, a very long, thin, ductile protective metal outer sheath houses a coextensive body of insulation material, which in turn supports and electrically insulates one or more coextensive RTD filaments and in most forms of the invention one or more heater filaments. Distributed RTDs of the invention may, along their lengths, have continuous linear function sensitivity, continuous variable function sensitivity, or step function sensitivity.

Abstract: An ink jet recording apparatus comprises an ink jet head having an ink path communicating with a discharge opening for discharging ink; electrodes arranged in said ink path; a residual ink quantity detection means for detecting residual ink quantity in said ink path in accordance with a resistance value, current value or voltage value from said electrodes; and a correction means for correcting said resistance value, current value or voltage value in accordance with the difference in a resistance of the ink. This enables the correction means to compensate for different ink resistances and thus provide accurate residual ink detection even when different inks are used or ink resistance changes because of a change in ambient conditions.

Abstract: A water level sensing probe having a probe body (24), a protective sleeve (28), and an external housing (26) is disclosed. The body contains a detector board (40) that partially protrudes from its bottom and a logic board (42) that partially protrudes from its top. The detector board senses the level of electrically conductive fluid and transmits an indication of that level to the logic board that controls the operation and partially processes the data in response to commands received through a cable (28). The detector board is protected by the protective sleeve (28) while the logic board is enclosed in the external housing (26). The probe is used by positioning on the bottom of a fluid containing tank or other vessel. Water at the bottom of the tank forms a bridging contact between a ground plane and a number of traces on the detector board proportional to the level of the water.

Abstract: A liquid level sensor for detecting a level of an electrolyte where: a pair of resistance films are formed on an insulating substrate: a plurality of electrodes are intermittently mounted on the resistance films in the longitudinal direction; the resistance films are soaked in the electrolyte in the vertical direction along the longitudinal direction; the liquid surface is detected from the variation of the resistance value of the resistance films caused by the short-circuiting of pairs of the electrodes in the electrolyte. The exposed surface of the resistance film is covered by a moisture-resistance film. The result is that undesirable change of resistance value of the resistance film caused by being moistened can be reliably prevented.

Abstract: A two wire and a three wire resistive fluid level sensor for measuring fluid levels within a container are disclosed. The sensor includes a plurality of resistors connected in series. The sensor produces an output signal by providing a short circuit to the circuit nodes between the resistors so that a stair-step output signal is created as the float moves in conjunction with the liquid level in a container. The value of the resistances can be varied in order to accommodate various cross-sectional tank contours and thus produce a usable, readily and easily configurable sensor. The structure of the sensors enables measurement of depth variances far in excess of prior art sensors.

Abstract: A liquid level responsive sending unit is positionable in a vehicle fuel tank to deliver a signal to a fuel gage on the vehicle dashboard. An electrical damping circuit is provided on a circuit board carried on the sending unit, such that momentary fluctuations in a fuel level sensor float are smoothed out. The signal transmitted to the gage is a signal representing a time-averaged condition of the sensor. The damping circuit location in the fuel tank is advantageous as regards signal accuracy calibration, manufacturing quality control, ease of assembly, and access for component replacement purposes.

Abstract: An electronic manometer for measuring pressure differentials between first and second outlets of a U tube supporting a column of mercury. The U tube includes for each arm a coaxial feedline which is terminated by the column of mercury. The coaxial feedlines are connected to first and second oscillators where they serve as the frequency determining circuit element of the oscillators. The wavelength of each oscillator frequency of oscillation is directly proportional to the height of the mercury column. A frequency counter and computer are connected to measure this wavelength, and apply any necessary corrective factors to the measurement.

Abstract: A liquid level sensor for sensing liquid levels within a container is disclosed. The sensor includes a conductive plastic resistor and conductive plastic conductors deposited onto a thin polymer insulator. The conductive plastic resistor is a potentiometric resistive track which is electrically contacted at points along the length of the resistor by a contact assembly attached to a float. The polymer insulator is attached to a conductive support member or conductive strip disposed substantially vertically in the liquid. The float is disposed about the conductive strip. The contacts provide a short circuit between the resistive strip and conductive strip and thereby provide a resistive circuit connection analogous to the wiper of a potentiometer.

Abstract: An alarm system for use in a salt-brine tank of a water softener has a sensor including a stem member having a lower end received in the bed of salt within the salt-brine tank and an upper end projecting above the bed of salt. An spaced pair of electrodes are supported at the stem member upper end and are responsive to direct contact with a brine solution inside the tank for generating the signal indicative of an abnormal condition. An electronic circuit is coupled to the sensor for generating an alarm which includes two counters coupled to a clock circuit such that any alarm indicative of the abnormal condition is delayed for a predetermined period of time after the sensor signals the abnormal condition, and the alarm is generated as spaced, short bursts of sound, the spacing between the bursts of sound being greater than the duration of the bursts.

Abstract: Electrical contact is made between an electrode and a liquid column to establish current flow between the electrode and the liquid column. The electrode is raised up the liquid column until electrical contact is broken. An additional quantity of liquid is added to the liquid column to cause the column to rise and make electrical contact with the electrode. The electrode is raised up the liquid column until electrical contact is again broken. The distance of travel of the electrode is measured as a determination of the rise in height of the liquid column and of the additional volume of liquid added to the column.

Abstract: A cryogenic level sensor assembly. A sensor assembly includes a continuous length of high temperature ceramic superconductor material, an exterior housing for holding the length of ceramic superconductor material, a support material disposed between the ceramic superconductor material and the exterior housing, and a resilient retention material disposed opposite the ceramic superconductor material for holding the superconductor material while allowing expansion and contraction thereof during thermal cycling.

Abstract: A current mode chopper amplifier is used to convert low dc current flowing in a resistive element into ac for signal processing to eliminate drift and noise. The ac signal is then converted back to dc as output. The input circuit for the chopper is an operational amplifier driving a pass transistor and serving also as a voltage follower, which drives the resistive element. A polarizing voltage is applied to the input of the operational amplifier, and followed by the resistive element. The current in the resistive element flows through the pass transistor to the chopper, but not through the polarizing voltage source.

Abstract: A circuit for detecting hydrocarbons comprises an input circuit receptive of an input signal representative of the electron movement in an unknown sample to be detected for producing a first amplified signal and a signal processing circuit receptive of the first amplified signal from the input circuit for producing a first output signal when the input signal represents the presence of hydrocarbons. The input circuit comprises four transistors connected as common base amplifiers with the base of a first of the four transistors receptive of the input signal, the base of a second of the four transistors connected to the emitter of the first transistor, the base of a third of the four transistors connected to the emitter of the second transistor, the base of a fourth of the four transistors connected to the emitter of the third transistor to produce the first amplified signal at the collector of the fourth transistor and wherein for the first transistor 70<hfe.ltoreq.120, for the second transistor 150.ltoreq.

Abstract: An electrode for level detection includes a detection electrode including conductor portions and resistor portions arranged and formed one after the other in a level change direction. An insulating coating layer is formed on either each conductor portion or each resistor portion. The insulating coating layer may be of a film having a property to repel a liquid to be measured.

Abstract: A leak alarm system monitors the wetness of a floor. The alarm system comprises a housing having a flat bottom surface and support feet for supporting the housing off the floor such that each one of the support feet is in contact with the floor. Each support foot comprises an electrode of the alarm system. A low resistance condition between two electrodes of opposite polarity, such as occurs in the presence of a water leak, activates the alarm.

Abstract: A sensor for sensing the level of adhesive medium in a dispensing device, which sensor comprises; (a) a coil which is adapted to surround a dispensing device for dispensing adhesive medium at an adhesive dispensing station; (b) means for connecting the coil to the input of an oscillator; (c) detector means for detecting the frequency of the output of the coil; (d) conversion means to perform a frequency to voltage conversion on the varying frequency detected at the detector means (c); (e) analogue to digital conversion means to convert the signal from the frequency to voltage conversion means (d) into a form which can be compared with a calibration scale obtained by measuring the signals generated at the output of the coil, when the coil is surrounding a dispensing device containing at least two different known quantities of adhesive medium; and (f) display means for displaying the result of this comparison.

Abstract: In an ink near-end detecting device, a pair of electrodes are arranged in the porous material in the ink tank and in the ink pool provided below the ink tank, respectively, so that the time instant the ink in the porous material has been nearly used up is detected from the variation of the electrical resistance between the electrodes with the consumption of the ink in the porous material.

Abstract: A leak and liquid level detector includes a transistor as its main operating element with a pair of normally open base contacts connected to the transistor base. The transistor emitter is connected to ground and the transistor collector is connected to a suitable audio alarm, or alarm light or to a programmable logic controller. When a liquid leak bridges over the base contacts, a power circuit is closed across the contacts biasing the transistor and causing an electrical signal to flow from the collector to actuate the alarm, light or controller. The base contacts are linearly adjustable to sense various leak heights. The detector in one mode of use can be positioned horizontally to detect leaks and in a second mode of use is positioned vertically to detect a change in a liquid level in a tank, pipe column or the like.

Abstract: An oil level sensor has a cylindrical hollow sensor body and an elongated inner electrode provided in the sensor body at a distance from the inner wall of the sensor body. The sensor body is made of conductive resin including carbon particles.The sensor body is electrically connected to the elongated inner electrode and to a control unit for indicating a shortage of the fluid. The control unit is a shielded wire comprising a lead wire connected with the elongated inner electrode and a wire shield connected with the cylindrical hollow sensor body. The elongated inner electrode has a flange at a base portion thereof so as to be firmly secured in the inner electrode guide and an insulator sleeve plugged into the cylindrical hollow sensor body, whereby the flange is held between the inner electrode guide and the insulator sleeve.

Abstract: The present invention is a liquid sensing device used for in determining the presence or absence of liquid in a container by the presence or absence of electrical current flow between two conductive probes. Moreover, the present invention prevents the false indication of liquid as can result from the presence of foam, or from bridging of the probes at the proximal ends thereof. A main body portion is formed of an electrically conductive material and has a probe channel extending therethrough. A non-conductive plug is inserted into the proximal end of the probe channel and provides for the retaining of a conductive probe that extends along the central axis of the probe channel. An end cap is secured to the distal end of the main body and covers the distal end of the probe channel for preventing foam access into the probe channel.

Abstract: A device for injecting a fixed quantity of sample liquid is provided with a unit for aspirating and injecting sample liquid. The sample aspirating and injection unit has a nozzle connecting portion. The liquid injection device is provided with an injection nozzle attached to and detachable from the nozzle connecting portion of the sample aspirating and injecting unit and electrodes are attached to the injection nozzle. Conductive members which are electrically connected to the electrodes of the injection nozzle are attached to the nozzle connecting portion of the sample aspirating and injecting unit, and a detecting unit which cooperates with the electrodes to detect the surface level of sample liquid is connected to the conductive members.

Abstract: The specific density of the liquid/air mixture is measured at successive levels within the reception vessel for the liquid using a reference measurement (Io) representing the specific density of the degasified liquid within a reference measuring path. The ratio of each obtained density value measurement and the reference value is calculated for each measuring level and multiplied with the specific density of the liquid to allow an accurate measurment of the overall liquid volume or flow-rate. Preferably the reception vessel (1) has a respective measuring electrode (El . . . En) at each measuring level with a common counter electrode (Eo) coupled to an oscillator (4) via a constant voltage circuit (5) and a coupling capacitor (6). Each measuring electrode (El-En) is coupled via a multiplexer (7) and an active rectifier (9) to an A/D converter (10) coupled to a microprocessor (11) controlling a read-out display (12).

Abstract: A device for measuring displacement comprises a pair of sensor elements of which output voltage changes stepwise in dependency upon displacement of a measurement object, a differentiating circuit for detecting time points at which the output voltage of the pair of sensor elements suddenly changes, and a counter for counting the sudden change time points of the output voltage detected by the differentiating curcuit.

Abstract: One electrode of the probe is its tubular outer sleeve (3), and the other is its central rod (4). The insulators (9,16) separating the two are attached rigidly to the central rod, whereby the outer sleeve may slide off the probe for cleaning and servicing purposes. The outer sleeve is held in place simply by friction from the O-ring seals (12,30). When the sleeve is removed, the central rod, insulators, etc., remain as a structurally complete sub-assembly. Electrical contact with the outer sleeve is made through an expandable canted coil spring (20), mounted on an insulator. The central rod is formed with a massive center section (7), for weighting the probe. The probe is supported on a graduated tape (36), in which are embedded the electrical leads (38) to the probe. The leads are securely attached and sealed in place by means of heat-shrinkable material (50), which is wrapped around the leads, heat-shrunk, and compressed into a pocket (27).

Abstract: Changes in underwater sediment level in a marine environment are monitored electronically using a probe embedded in the sediment. The probe includes an electrical current source to generate an electric field extending across the sediment interface. Voltage measurements are taken at at least three sensors on the probe whose positions are known relative to the current source. The height of the sediment interface relative to the current source can then be calculated, and logged, and changes in sediment level can be monitored. The conductivities of the sediment and seawater can also be calculated by taking additional voltage measurements.

Abstract: A fluid detection system includes a central monitor, an overfill probe for detecting the approach of the overfill condition of a tank of liquid, and n other probes, where n is an integer greater than or equal to 1. The probes are connected to the monitor via electronic cables. The monitor communicates with the probes by producing probe identifier signals comprising integers starting with zero up to the number n. Each probe includes a signal receiving and sending means which compares the identifier signal sent by the monitor to a preset identifier number for that probe and sends a status signal indicative of the fluid status at that probe when it receives the identifier signal that is the same as the preset number. The overfill probe is set with the identifier zero. The monitor includes a timing circuit which determines a six second probe check cycle.

Abstract: A heat radiating type liquid level sensor comprises a liquid level measuring resistor having a first temperature coefficient and an inverting amplifier gain of which is dependent on the change in resistance of an input resistor thereof. The input resistor has a second temperature coefficient. The liquid level measuring resistor and the input resistor are placed side by side so that the input resistor can experience the same ambient temperature as the liquid level measuring resistor.

Abstract: A level detecting resistor (Rd) is inserted into a liquid (5) and has a length immersed in the liquid. The level detecting resistor (Rd) is supplied a constant current (Id) from a constant current source (1). The voltage drop (Vd) developed across the level detecting resistor (Rd) is supplied to a non-inverting input terminal of a differential input amplifier (OP1, R1-R4). The output (Vo) of the differential input amplifier is then divided by a series-circuit of a temperature compensating resistor (Rc) and a resistor (R5). The divided voltage (Va) across the resistor (R5) is fed back via a voltage follower (OP2) to the non-inverting input terminal of the differential input amplifier.

Abstract: A fuel or fluid level measurement arrangement for a spacecraft includes one or more electromagnetic transmission lines extending into the reservoir. The presence of fuel adjacent the transmission line changes the dielectric constant or loss characteristics of the transmission line(s) in a measurable manner. In one embodiment, strip transmission lines extend parallel to the fluid surface at various degrees of ullage, and the fuel level can be established to within the spacing between the transmission lines.

Abstract: A liquid level indicating system particularly applicable to monitoring the fuel level in a motor vehicle includes an anti-slosh feature incorporated into a system amplifier to substantially eliminate fluctuations in the fuel level indicated by a fuel gauge driven by the amplifier. The anti-slosh feature is provided by limiting the slew rate of the amplifier during normal operation of the system. The slew rate is limited by using a limited current source to provide dc bias current within the amplifier such that the output can change only at the limited slew rate. To make the system respond rapidly upon start up of a vehicle including the system, the normally limited current source is supplemented by a secondary current source which provides substantially higher dc bias current within the amplifier and accordingly a substantially higher slew rate for the amplifier.

Abstract: A fluid level detector comprises a thermoresistive probe and a controlling circuit. The probe replaces the conventional dip stick on internal combustion engines and other machinery having an oil sump and a dip stick tube. The probe comprises an elongated wand of insulative material to which is threaded a length of thermoresistive wire, the resistance of which varies with the amount of immersion thereof into the oil. The circuitry operates various light emitting diodes for alerting operating personnel of the oil level. The probe wire is connected to the circuitry via conductive strips bonded to the wand and conductive elements in contact with the strips and leading to the circuit. An insulative sheath surrounds the wand and strips. A rubber grommet attached to the upper end of the probe seals the machine dip stick tube.

Abstract: The use of a probe for the control of foam build up in a fermenter, which probe comprises a guard electrode (13), first and second insulators (14 and 15) separated by the guard electrode, a detecting electrode (12) separated from the guard electrode by the first insulator, and a plug (18) and socket (17) for connecting the probe to a power source, the second insulator being provided with fermenter mounting means in the form of a flange (16), a sensor comprising the aforementioned probe for use with an antifoam supply regulator, a foam control system and a method of controlling the build up of foam in a fermentation vessel.

Abstract: An electronic interface controller is disclosed. The controller is particularly suited for use in controlling dehydration processes of light, heavy and extra heavy crude oils on the basis of the interface between the oil and water. The controller includes sensor elements which generate a signal representative of current flow between the sensors to indicate the conductivity of liquids between the sensors. A first device, responsive to a current flow signal from the sensors, generates a control signal according to the conductivity of liquid in contact with the sensors. A timer is provided for delaying a control signal generated by the first device for a delay period between 0 and 180 seconds.

Abstract: A distillation type of water purification system has a raw water inlet valve for admitting raw water continuously to a boiling tank at a rate greater than the rate at which raw water is converted to treated water. A drain valve located at the bottom of the boiling tank is energized by a raw water level sensing means whenever the raw water level reaches a predetermined level, to discharge water from the boiling tank. Treated water is stored in a storage tank having a pump for discharging treated water to the user upon demand. A single conductivity sensor in the storage tank controls the pump to allow it to operate only if the sensed conductivity is above a first predetermined value but not at or above a second predetermined value greater than the first value. An improved condenser has two sets of tubes, each set is arranged in a pair of planes oriented transverse the flow of cooling air with the tubes parallel. The internal cross-sectional area of one set is about twice that of the other.

Abstract: Electrodes for measuring the level of milk flowmeters and positioned together in a holder of a non-conductive material that extends tight through the bottom of the flowmeter with their active surfaces vertically separated. The electrodes are adjacent pins with their cylindrical surfaces inside the milk flowmeter completely surrounded by the holder to the extent that only the faces of the electrodes are active.

Abstract: In an apparatus for measuring the level of filling of a fuel tank of a motor vehicle in which a transmitter gives off a transmitter signal which is dependent on the level of filling of an electronic signal-processing unit, there is provided in an electronic signal-processing unit, in addition to a program for the evaluation of the transmitter signal and the control of an indicating device, also a further program. Upon an initial placing in operation of the electronic signal-processing unit connected with the transmitter, the further program forms, at a known level of filling, preferably with empty tank, a correction value from the relationship between the transmitter signal and a stored desired value signal, and stores the correction value in a nonvolatile memory.

Abstract: An emergency battery monitor is adapted for use with at least one storage battery. The battery has first and second output terminals across which an output voltage is produced, the battery, when in normal operation, exhibiting an output voltage falling within a nominal value range having predetermined maximum and minimum values. The battery has at least one cell which contains a liquid electrolyte. The electrolyte, when the battery is in normal operation, has a predetermined minimum level in the cell. The monitor includes a member associated with the cell, which is electrically conductive when the level of the electrolyte is at least equal to the minimum level and is electrically non-conductive when the level of the electrolyte falls below the minimum level. Integrated circuits coupled to the output terminals and the member produce a first signal designating normal battery operation when the member is conductive and the value of the output voltage falls within the nominal value range.

Abstract: A washer fluid monitor comprising a pair of electrically conducting probes projecting downward into a washer fluid reservoir and incorporated into part of the positive feedback loop of a Wien bridge oscillator. One of the probes is grounded; and the Wien bridge oscillator is modified with an additional capacitor isolating the other probe from the DC supply and intermediate voltages so that it is essentially grounded at the oscillator frequency to greatly reduce or eliminate ionic currents in the washer fluid and resulting probe degradation without the need for an isolating transformer.

Abstract: A fluid detecting alarm system includes a source of electric current, an alarm electrically connected to the source, a normally open switch electrically connected to the alarm for de-energizing the alarm when the switch is open and energizing the alarm when the switch is in current-conducting condition, and a medium, responsive to the presence of the fluid, for causing the switch to conduct current. In particular, a self-contained liquid water detecting system has a well with a mouth opening through a lower wall of a case. The switch takes the form of two electrodes, spaced apart, and bridged by a dry pulverulent salt, substantially nonconductive when dry and conductive when wet. The open mouth of the well is closed by an adhesive coated foraminous sheet, to retain the salt but to permit liquid water to pass through to wet the salt to cause it to conduct sufficiently to energize the alarm.