Abstract: Reliability of bubble or particle detection in a flowing fluid is improved using a pulsed doppler frequency detector. When an echo signal is received, impliedly indicating the existence of a bubble or particle in the carrier fluid, then, based on the flow rate of the carrier fluid, a predetermined time interval is established following a second interrogating pulse during which the second interrogating pulse would be predicted to produce an echo if the first echo did, in fact, represent a real bubble or particle in the fluid. Detection of the second echo during this time interval confirms the existence of the bubble or particle. For fluid flows with cross section velocity profiles that are not constant, e.g. laminar flow, a plurality of different predicted time intervals are established for different points in the velocity profile spaced radially from the fluid conduit and multiple sensing cycles are employed to thereby detect bubbles or particles at different radial positions in the fluid cross section.

Abstract: A method and apparatus measures the gas bubble content of a flowing fluid on a continuous basis without extracting a sample of the fluid. A flowing fluid flows into a density sensor via a temperature and pressure sensor where the temperature, pressure and density of the fluid are determined. As the fluid exits the density sensor, a second pressure sensor determines the pressure of the exiting fluid. The outputs of the sensors are amplified and then input into a data processor. An operating panel supplies required constant data regarding the fluid and gas. The data processor calculates the gas bubble content using the above information in accordance with a predetermined formula.

Abstract: An acoustic ash depostion monitoring apparatus for a boiler arrangement having at least one soot blower. The apparatus comprises at least one tone generating apparatus for generating a tone and at least one tone receiving apparatus, located in proximity to the tone generating apparatus, for receiving the tone generated by the tone generating apparatus. Also provided are controlling apparatus for determining when the tone received by the receiving apparatus falls below a predetermined level and for enabling a soot blower in proximity to the tone generating and tone receiving apparatus when the tone received by the receiving apparatus is determined to have fallen below the predetermined level.

Abstract: A monitor and indicating circuit for use with a reverse osmosis filter for signaling the need for servicing of the filter comprises first and second conductivity cells respectively located in the water inlet and outlet pipes of the filter. An AC signal of a predetermined frequency and amplitude is used to drive an op amp whose input resistance comprises the outlet conductivity cell and whose feedback impedance comprises the inlet conductivity cell. Normally, the resistivity of the outlet conductivity cell is substantially larger than the resistivity of the inlet conductivity cell, assuming that the filter is functioning properly. As the ROF fails, the resistivity at the outlet approaches that at the inlet thereby increasing the gain of the variable gain amplifier. The output from the variable gain amplifier is then peak detected and applied to a comparator where it is compared to a predetermined reference voltage.

Abstract: This invention is directed to an apparatus or system which is used for monitoring a storm drain system in order to detect the presence of hydrocarbons or the like therein. The apparatus includes a sensor unit which is arranged to float on the surface of the storm drain effluent. A suitable alarm system is connected to the sensor unit to indicate an activation of the sensor unit. The storm drain is, typically, modified to provide a uniform sensing area adjacent to the sensor unit.

Abstract: An apparatus for detecting a liquid-vapor change of phase in a fluid substance traveling through a conduit comprises a detector housing providing a path of travel for fluid and interposed in a portion of the fluid-carrying conduit in which the change of phase is to be detected, a source of radiation disposed for directing radiation into the path of travel and a detector for detecting radiation disposed generally at an opposite side of the path of travel from the said source. The arrangement is such that radiation from the source will pass through the fluid in the path of travel prior to reaching the detector. The detector is responsive to radiation detected thereat for producing a corresponding electrical signal. A detector circuit is responsive to the electrical signal produced by said detector for producing an output signal indicative of a liquid-vapor change of phase of the fluid in the conduit.

Abstract: Devices for detecting and obtaining information about an event, for example the presence of a liquid, which comprise (1) a swellable member which swells upon occurrence of the event and (2) a restraining member which, when the swellable member swells, restricts movement of the swellable member and thus causes the impedance of the device to change. In a preferred embodiment the device comprises two elongate conductors helically wrapped around a support core, a swellable, conductive polymer member surrounding the conductors. Occurrence of an event causes the swellable material to swell and form a conductive bridge between the conductors.

Abstract: The system includes a plurality of zone valves located in a gas flow pipeline. These valves contain a fiber optic bundle that is installed in the center of the valve handle. The fiber optic light comes from a source and is read by a light detector. As long as light is detected by the light detector, the circuitry within the detector will function as a closed circuit. As soon as the detector is not sensed, the detector will function as an open circuit and will provide an alarm to a floor control panel and on to a system annunciator. The system processor is capable of performing remote shunting. The operator can determine by visual reference the location of the problem. False alarms caused by intermittent faulty loops can be identified by a built in memory circuit. The circuit is also capable of detecting loss of current flow that could be caused by a number of reasons. The loss will cause an alarm condition to occur and the operator shall be notified of the system's condition.

Abstract: Apparatus and methods are disclosed for acoustically detecting different conditions of boiling occurring within a liquid and developing useful control signals correlated to the detected boiling condition. Distinctions are made between no-boiling, sub-cooled boiling, and full or rolling boiling conditions.

Abstract: An analog ASIC (Application Specific Integrated Circuit) circuit has a power control section, a conductivity filter testing section, a light emitting diode (LED) driving section, and a bias section. The LED driving section is responsive to the conductivity filter testing section for indicating when the filter should be replaced. The power control section, conductivity filter testing section, LED driving section, and bias section are all operated in a controlled timed relation by a digital ASIC logic system to minimize power use.

Abstract: The detector includes an electrically conductive probe located within a drum drip adjacent the bottom end thereof, close to the conventional discharge gate valve. Water which accumulates in the drum drip makes contact with the probe, and a circuit is completed between the probe and the conductive wall of the drum drip. This circuit includes a local and/or remote alarm or indicating device.

Abstract: A signal responsive circuit especially adapted for use in a water treatment system for signaling the need for regeneration of an ion exchange resin bed or the replacement of a particulate filter medium. A series of three electrodes are disposed in the water treatment medium in longitudinally spaced relation along the direction of flow and an alternating current signal drives the center-most electrode. The two outer electrodes are coupled as inputs to first and second operational amplifiers having asymmetrical gain characteristics. When the effective resistance between the center electrode and the two outer electrodes are equal, which is the condition prior to the movement of the hardness front or contamination front to the location of the electrodes, a first signal output condition exists.

Abstract: A fluid detector that senses fluids, activates an alarm and preserves a sample of the fluid for laboratory or on-site testing. The fluid detector includes a first container having a sealable cap and a fluid-passing portion, a second container disposable within the first container for collecting and storing a sample of the fluid. The detector can contain a fluid-responsive material which undergoes a change upon contact with the fluid. The change in the fluid-responsive material causes the second container to be sealed. The second container can contain a fluid collector so that the fluid can be analyzed.

Abstract: A system for monitoring the operation of a water purification system of the type having an inline membrane includes a first conductivity measurement cell located upline of the membrane and a second conductivity measurement cell located downline of the membrane. The cells are electrically connected in series and across the output of a symmetrical square wave generator. A differential amplifier compares the voltage across one of the cells with a predetermined reference voltage to develop a control signal when the conductivity of downline cell relative to the upline cell rises above a predetermined threshold level. An output circuit responsive to this signal drives an appropriate one of two indicator lamps to indicate satisfactory or unsatisfactory system operation.

Abstract: A cleaning machine for carpet, upholstery, draperies, and the like is designed with a safety system to prevent the cleaning liquid from being inadvertently overheated. The system senses the electrical conductivity or the density of the liquid and then limits the heating to a temperature which has been programmed to correspond that conductivity or density.

Abstract: The invention relates to a sensor system for in-situ monitoring of lubricant oil quality. The sensor system consists of a sensing element located in-situ in contact with lubricant oil. The sensor is corrodable and upon deterioration of the oil the sensor corrodes and eventually the circuit will break. Current flow through the circuit is monitored by conventional power supply and measuring devices and upon breaking of the sensor, an indication is provided to the driver of a motor vehicle indicating that oil is to be changed.

Abstract: The invention relates to an improved sensor for use in-situ in an electrical circuit which sensor corrodes as a result of deterioration of the oil and provides a changing electrical current due to increased resistance resulting from said corrosion. The sensor preferably is a ceramic tube havign a first layer of electrolessly deposited nickel thereon with a second layer of electrolitically plated lead. Leads are attached to the ends of the tube and the sensor can then be employed in-situ in oil to, as a result of its corroding and change in resistivity, measure deteriorating oil quality.

Abstract: A water pump control system, such as for a boat, including a battery operated main motor-and-pump unit and a backup motor-and-pump unit. A pump turn-on transistor operates a relay to turn on the main motor-and-pump unit when the water level rises to a high level. A touch switch may be used to turn on the pump turn-on transistor independent of the water level. A pump turn-off transistor, which is turned on by the relay, keeps the main motor-and-pump unit on until the water level drops to a low water level. A backup motor-and-pump unit comes on if the main motor-and-pump unit has not come on after the pump turn-on transistor has been turned on.

Abstract: A plurality of probes are electrically connected to a central controller. Each of the probes is capable of providing a hydrocarbon signal, a water signal, and a dry signal to the controller upon sensing these respective environments. The controller includes an alarm transducer, relays, a keyboard, and a liquid crystal display (LCD) connected to a microprocessor and associated memories. A software program stored in memory is utilized by the microprocessor to permit users to individually select alarm conditions for each probe and relay and the latching condition for each relay which conditions are stored in memory. The probes that activate each relay may also be selected and stored. There is an RS232 port connected to the microprocessor circuit via which probe status can be requested by and communicated to a remote terminal. Upon receipt of probe signals corresponding to the selected alarm and latching conditions, the microprocessor activates the alarm and relays as programmed.

Abstract: A plurality of probes for sensing their fluid environment are electrically connected to a controller. The controller includes an alarm transducer, relays, a keyboard, and a display connected to a microprocessor and associated memories. Under keyboard control and software direction the microprocessor is operable in a monitor mode in which it monitors the probes and activates the transducer, relays, and display in response to probe signals corresponding to selected alarm conditions, and in a program mode in which the alarm conditions, relay latching conditions, and probe to relay assignments may be selected via the keyboard. A hardware timer interrupts the microprocessor periodically to clock a software timer which provides six second and six minute timers. When monitor mode is exited, the six second timer is reset and if a security code is not entered in six seconds the timer elapses and the system returns to monitor mode.

Abstract: A hollow tubular cartridge (4) is tethered on an insulated electrical lead (10) connected to a hand held box (18) containing sensing circuitry. The cartridge (4) is lowered into a fuel tank (12) for sensing water in the tank (18) by a reduced electrical resistance path between probe electrodes (6 and 8) on the cartridge (4) which is sensed by circuitry within the box (18).

Abstract: An apparatus for sensing the difference between a polar fluid and a non-polar fluid includes a control assembly, a probe assembly and a conduit electrically coupling the probe assembly to the control assembly at a remote location thereto. The probe assembly includes a float, at least one fluid sensor mounted beneath the float, a fluid sensor circuit for providing a signal indicative of the polar characteristics of the fluid, and a logic circuit having a first state when the signal indicates a polar fluid and a second state when the signal indicates a non-polar fluid. The control assembly includes cicuitry responsive to the state of the logic circuit for controlling alarms, visual indicators, and machine operations. The probe assembly may also include a detector for detecting the state of the fluid. If the fluid has a non-liquid state then the logic circuit has a third state which indicates the non-liquid state of the fluid.

Abstract: There is a plurality of probes electrically connected to a central controller. Each of the probes is capable of providing a hydrocarbon signal, a water signal and a dry signal upon sensing these respective environments. The controller includes an audible alarm transducer and a switch for activating circuitry providing either a first alarm mode which provides an alarm in response to a hydrocarbon signal or a second alarm mode which provides an alarm in response to a hydrocarbon signal and also a water signal. A continuous alarm tone is provided upon receiving a hydrocarbon signal while an intermittent alarm tone is provided upon receiving a water signal. A yellow label links a "water" sign and the transducer and a red label links an "oil" sign and the transducer.

Abstract: A C-shaped failure detector for steam traps includes a curved temperature sensitive bi-metal strip positionable against the external surface of a steam or condensate pipe, and two thermally insulative arms, one extending from each end of the strip. The contiguous surface area between the bi-metal strip and pipe varies with the pipe surface temperature, resulting in an amplified response, both in expansion and contraction. A threaded rod is pivotally mounted to one of the arms, and a sleeve threadedly engages the free end of the rod and extends freely through an opening in the other arm. The sleeve is rotated on the rod to selectively position the sleeve with respect to the second arm. The arms move angularly toward or away from each other responsive to temperature changes in the bi-metal strip.

Abstract: An apparatus and method are provided for detecting solvents, including hydrocarbons. The apparatus includes a hydrocarbon-soluble plastic rod which interconnects a mass or weight and a weighing assembly. The weighing assembly is operatively joined to an alarm indicator, which is utilized to inform the user as to whether hydrocarbons are present. In a preferred arrangement, the weighing assembly is connected to a housing, which is joined to the top of a well casing provided in the ground. The plastic rod may be of any desired length, depending upon the depth of the well casing and where it is desired to check for hydrocarbons. When hydrocarbons are detected the plastic rod dissolves or separates causing movement of the weighing assembly and the alarm indicator so that a visual indication is provided that hydrocarbons are present. The apparatus further includes a mass catch assembly for maintaining connection between the mass and the housing after the plastic rod separates due to the presence of hydrocarbons.

Abstract: A machine oil deterioration detection apparatus having a copper thin film resistor formed on an electrically insulating holding member and immersed in a machine oil. The copper thin film resistor is corroded by acid produced in accordance with deterioration of the machine oil, thus changing the resistance of the resistor. The change in resistance is detected by a detection circuit, connected to the thin film resistor, for detecting the resistance of the thin film resistor.

Abstract: A boiling sensor includes a case, which is mounted on the upper edge of a container in which liquid is to boil. A pair of electrical probes are spaced apart a small distance and mounted on the case above the liquid. Behind the probes is a collector of the material, preferably sheet nylon, which does not absorb the liquid, which is non-wettable and electrical insulative, and which has a high heat capacity. With a high heat capacity, the vapor raises the temperature of the collector slowly so that vapor continues to condense on the collector between the probes. The probes are part of an electrical circuit. The condensed water vapor allows current to flow the between the probes, and the rest of the circuit causes current to flow through a sound or visual indicator to indicate that the water is boiling. This circuit also has a voltage divider, one side of which is the electrical probe, and by adjusting the resistance on the other side of the voltage divider, the sensitivity of the circuit can be controlled.

Abstract: A fail safe circuit is provided in a salinity monitor having a salinity indicating panel for visually presenting salinity levels and a salinity cell for sensing salinity levels. The salinity cell is electrically connected to the salinity indicating panel by a plurality of salinity cell leads which supply electrical signals to the salinity indicating panel for indication of salinity levels. The fail safe circuit enables an alarm when a salinity cell lead becomes disconnected from the salinity indicating panel. Also, a back-up circuit is provided for enabling an alarm should the fail safe circuit become inoperative.

Abstract: A device for monitoring environmental exposure includes an element whose electrical properties change, in a predetermined way, in response to the environmental exposure. The element may be part of a tuned circuit or of a shield for a tuned circuit. In either case, when the tuned circuit is interrogated, preferably by an r.f. or microwave signal, it emits a signal whose intensity depends on the electrical properties of the element. Thus, an incremental environmental exposure can be measured by a change in the signal intensity. The device is particularly useful for monitoring the condition of perishable materials, because it can be located with the perishable inside a packaging material during both storage and interrogation.

Abstract: A fluid detection system capable of displaying the conditions in the environs of a large number of fluid detection probes and correlating each condition with the particular probe that detected it. There are a plurality of probes, each having a comparator preset with a unique probe identifier, such as a binary number. A counter produces digital signals representative of the binary numbers. The probe comparators are responsive to the numbers outputted by the counter and are connected to the probe power circuitry. When each comparator receives the signal corresponding to its preset number, it triggers its associated probe to produce status signals. A display circuit responds to both the number output by the counter and the probe status signals to simultaneously display the probe number and an indication of probe status.

Abstract: The degree of deterioration of lubricating oil used in an internal combustion engine is detected by measuring the lubricating oil dielectric constant with a pair of spaced sensor capacitor electrodes in the lubricating oil. The sensor capacitor is connected to a fixed capacitor to form a voltage divider connected across a constant frequency AC voltage source so that a developed voltage across the sensor capacitor corresponds to the lubricating oil dielectric constant. The frequency of the AC voltage is set at a value ranging from 50 KHz to 500 KHz.

Abstract: A boiler blowdown monitoring system wherein the conductivity of the water in the boiler blowdown line is monitored to determine if it exceeds either a preset maximum or minimum level. The system includes a blowdown sensor, a blowdown valve, a blowdown controller and an interrogation means. The water conductivity is sensed by the sensor located on the blowdown line and transmitted to the interrogation means (e.g. microprocessor) through the boiler blowdown controller. If the sensor senses a water conductivity level above a preselected maximum conductivity level or below a preselected minimum conductivity level after a predetermined time period has passed since the boiler blowdown valve was opened, then an alarm signal is sent to the boiler operator.

Abstract: Diesel fuel tends to deposit an insulating coating on surfaces it contacts. A probe, preferably in the form of a siphon tube, is coupled to a detection circuit which is responsive to either low resistance or high capacitance between the probe and ground. The probe is initially uncoated to make a resistive coupling to a fuel container when accumulated water touches the probe. When insulating deposits from the diesel fuel or other fuel oil coat the probe, capacitive coupling will occur between the probe and the accumulated water. In either case the presence of water triggers an output signal by the detection circuit.

Abstract: A sensor apparatus cooperates with an electrical system capable of delivering power to and receiving signals from the sensor. A cable housing insulated wires is connected to the sensor and disposed in proximity to a fluid possibly containing a corrosive impurity. Corrosion detecting elements are connected to the wires and are immersed in the fluid possibly containing the impurity. Further, the elements are provided with breakable regions fabricated to corrode in the presence of the corrosive impurity. To facilitate fracture, the elements are loaded in tension so the breakable regions will fracture rapidly in the presence of corrosive impurities, to thereby send an electric signal to remote electrical equipment to indicate the presence of at least one impurity.

Abstract: There is described a circuit arrangement for checking liquid food for contaminants which can be reliably operated fully automatically or at least by completely untrained staff. It comprises a conductivity measuring probe, whose output signal is processed by a transducer. From the output signal from the transducer there is substracted an amount in such a way that there is obtained a voltage which is independent of the individual nominal data of the batch. This independent constant voltage is made the reference point of a "window" of allowable deviations, the width of this window being independent of the individual batch data. The balancing of the circuit arrangement to the individual conductivity nominal value of the respective liquid food batch checked is the only change of voltages within the circuit arrangement, which takes place upon the transition from one liquid food batch to the next batch.

Abstract: A detector system for detecting air flow wherein air flow is sensed by a first detector and air flow is sensed by a second detector which is spaced a distance from the first detector, the first and the second detectors each providing output indications indicating the respective sensed air flows. The detector system includes means for receiving the output indications provided by the first and the second detectors and for providing an output indication in response to an increase in one of the first and the second detector output indications, thereby providing an output indication indicating an increase in the air flow sensed by one of the first and the second detectors relative to the air flow sensed by the other one of the first and the second detectors.

Abstract: A monitor and control system for water purification apparatus includes first and second conductivity cells located in the input water path and the purified product water path of the apparatus, respectively. The conductivity cells produce output signals exhibiting amplitudes representative of the impurity concentrations in the respective water paths. These signals are detected and modified by circuitry which imposes logarithmic characteristics upon the two signals. The two logarithmically variable signals are differentially combined to produce a signal for display which is representative of the percent of impurity rejection of the water purification apparatus. The detected signal are also individually combined with signals representative of the temperature of the water being processed. The temperature-corrected signals are then displayed to provide an indication of the impurity concentrations of the input and purified water paths in parts per million.

Abstract: An apparatus for sensing the difference between a polar fluid and a non-polar fluid includes a control assembly, a probe assembly and a conduit electrically coupling the probe assembly to the control assembly at a remote location thereto. The probe assembly includes a float, at least one fluid sensor mounted beneath the float, a fluid sensor circuit for providing a signal indicative of the polar characteristics of the fluid, and a logic circuit having a first state when the signal indicates a polar fluid and a second state when the signal indicates a non-polar fluid. The control assembly includes circuitry responsive to the state of the logic circuit for controlling alarms, visual indicators, and machine operations. The probe assembly may also include a detector for detecting the state of the fluid. If the fluid has a non-liquid state then the logic circuit has a third state which indicates the non-liquid state of the fluid.

Abstract: Oil floating on the surface of a body of water can be detected by the floating sensor of this invention which comprises a float having a central opening vertically therethrough and containing an electrical sensor, the lead wire connected to the sensor extending downwardly through the opening, forming a U-bend and extending upwardly through the opening to alarm means. A weight at the U-bend provides for automatic height adjustment of the detector as the surface of the body of water raises or lowers.

Abstract: A salinity indicatory system useful to monitor variations in the salt content of water sources provides for the simultaneous monitoring of a plurality of test stations and the operation of automatic alarm and dumping means when salinity concentrations reach or exceed predetermined set points. The alarm and dump set points are capable of being set at different levels to provide for an indication of an approaching dump condition. The system includes temperature compensating networks having thermistors and associated resistor networks mounted inside the salinity cell to function both as temperature shaping resistors and electronic scaling resistors, thereby providing the system with multi-range capability. A summary fault alarm circuit allows all alarm conditions occurring with respect to any of a plurality of perimeters to be signaled through a single, summary fault relay.

Abstract: A measure of the enroute weight of an aircraft is continuously provided by determining the zero fuel weight during takeoff, adding the weight of total fuel as measured by fuel quantity sensors, interrupting the latter measure and holding its then current value whenever the fuel quantity sensors may be in error, such as when the aircraft is not level or during aircraft accelerations, and during this time computing the rate of change of aircraft weight as a function of aerodynamic and engine parameters and subtracting the time integral of this computed value from the held fuel quantity sensor value. Upon the aircraft resuming level, unaccelerated flight, the integrator is reset and the sensed fuel quantity measure restored.

Abstract: A device is provided for recording the dispensing of a predetermined measure of a conductive fluid, e.g. water, alcoholic beverage, etc., from a container outlet. The device comprises an electrical signal generator for generating an electrical signal, e.g. a DC battery, and an electrical counting means disposed to receive this electrical signal. An electrical circuit is disposed to conduct the electrical signal from the generator to the counting means. The electrical circuit includes a switch means which is responsive to the contacting of the fluid from the outlet across a pair of electrical conductors within the outlet. When the fluid flows across the electrical conductors the electrical signal is transmitted to the counting means to record the dispensing of the predetermined measure of fluid.

Abstract: A hydrocarbon sensor float for use in detecting the presence of hydrocarbons on the surface of a liquid provides an elongated floatation member having a top end and a bottom end and also having a cavity located centrally therealong and extending completely therethrough, a sensor assembly including a sensor and at least one electrical conductor coupled to the sensor, the sensor assembly being positioned in said floatation member for locating the sensor in the cavity for allowing access of the liquid thereto and for causing the electrical conductor to extend from the top end of the floatation member, and an attachment for a variable amount of weight at the bottom end of the floatation member for providing a variable floatation level for the member with respect to the liquid surface and likewise for the sensor for allowing adjustment of the detection depth for hydrocarbons at an installation site.

Abstract: Method and apparatus for monitoring the flow of coal from a bunker through a conduit to a coal feeder. A radiation sensitive detector detects the amount of coal present at a zone of the conduit and generates a stream of pulses which is sampled at discrete sample intervals of time to determine whether the conduit zone is empty, partially filled or filled. If the conduit zone is partially filled, a partial alarm is generated, and a determination is made as to whether the conduit zone is empty. If the conduit zone is empty, an empty alarm is generated and the feeder is stopped after a predetermined amount of coal has been deposited on the feeder. If the conduit zone is partially filled and a shut-off valve between the bunker and conduit is closed, a coal build-up alarm is generated. If the conduit zone is filled and the profile of coal at the feeder is not at full profile, a coal hang-up alarm is generated.

Abstract: A temperature sensitive resistor is immersed in a bath of quench oil and is supplied with electrical power sufficient to keep the resistor at a predetermined and substantially constant temperature above the vaporization point of water. When water is present in the oil, the water is vaporized by the resistor with the vaporization acting to cool the resistor and lower its resistance value. A signal which varies as a function of the drop in the resistance value of the resistor is produced and causes an increase in the power supplied to the resistor so as to keep the resistor at its predetermined temperature. In addition, transient pulses in the signal are detected and an alarm signal is produced when there is sufficient water present in the oil bath to cause the time-average value of the pulses to exceed a predetermined threshold.

Abstract: A new circuit is added to an electrical circuit including two electrodes underwater positioned very close to an air gun gaseous exhaust wherein the exhaust from the firing air gun momentarily blows away the conductive sea water from one or both of the electrodes to produce a high voltage pulse due to the large increase in resistance in the circuit indicating the precise moment of firing of the air gun free of any uncertainty and mechanical noise which normally affects conventional transducers.This new circuit added to the above circuit is a circuit polarity reversing circuit which includes particularly a positive current generator, a negative current generator, and a sea ground for forming a third electron source when any of the two electrodes becomes defective, thus forming a fail-safe system.

Abstract: A fluid level control circuit with a safety test function for a boiler water level probe of a fail safe type is connected to a field effect transistor controlled amplifier having a well defined threshold of operation. A safety test switch means is provided to pull the amplifier's input down below the threshold point, but not to a shorted condition. By observing the output of the system it is possible to determine whether the fluid level detector is properly installed, and whether the amplifier has had any type of unsafe operating failure.

Abstract: The invention relates to a movement detector, more particularly a sensor comprising a container partially filled with a liquid into which three electrodes extend. An input alternating signal is applied to two of the electrodes and an output signal amplitude modulated in accordance with movement of the liquid in the container, is detected from another two of the electrodes by means of a sensing circuit which includes a demodulator for detecting the amplitude modulation and a circuit arrangement which provides a container movement signal in response to successive peaks in the demodulated signal which are in excess of a given threshold value being spaced apart in time from one another by a time dependent upon the peak magnitudes of the demodulated signal.

Abstract: A battery-powered toilet training device has been developed using the state-of-art electronic devices to provide improved training of toddlers in orderly habits of discharging urine and stool as well. A non-contact electronic sensor is used to detect the presence of urine and stool in the receptacle. A battery-powered toy is used to produce an audible signal and a mechanical motion to reward the toddler and to signal the trainer when the toddler's elimination begins.

Abstract: A method of obtaining data for mathematical characterization of a wave surface by transmitting a beam toward the surface so that the beam is reflected from an element of the surface in a direction determined by the instantaneous, two dimensional slope of the element. The reflected beam impinges on a screen as a spot whose time varying coordinates correspond to the time varying slope of the element. These coordinates are captured by scanning the screen with a raster scan which controls counters identifying the spot position. The instantaneous distance is measured by a capacitance probe to relate the captured coordinates to the corresponding angles of reflection by appropriate trigonometric relations.