Abstract: A testing device which measures minute changes in battery electrode thickness due to repeated charge/discharge cycles. The testing device uses a moving wall to detect changes in electrode dimensions, typically thickness. The moving wall is adjacent a surface of the electrode, and is connected a sensor that measures wall displacement induced by electrode dimensional changes. Also included in the testing device is a thermocouple that senses the temperature of the device, allowing the data sampling and processing means to correct for thermal expansion/contraction during operation. The testing device can be used during the battery cycling as it does not interfere with the charge/discharge/recharge process. The testing device can be used to measure either a single electrode, or a plurality of electrodes assembled into an electrode stack and incorporated either into a test cell or into a working battery.

Abstract: A line card circuit to prevent false off-hook signals resulting from the permanent loss of battery voltage at a line card. In the battery present condition, the 5V operating voltage is connected to the collector lead of an NPN transistor, which also supplies the output signal of the system. The emitter lead of the transistor is connected to ground. The -48V battery voltage is connected to the transistor base lead and biases the base negative with respect to the emitter, maintaining the 5V logic "1" output signal on the collector lead. There is a resistor and capacitor in series, forming an RC circuit, across the 5V collector lead and the -48V base lead. In the battery present condition, there is a significant charge across the capacitor. In the battery absent condition, the -48V battery voltage is lost and the voltage on the base lead rises to a positive voltage in a time interval governed by the discharge time of the RC circuit, thus causing the system output signal to drop to logic "0".

Abstract: A method and a device to assess the adequacy of a cathodically protected underground pipeline with consideration of AC corrosion. A steel probe and a CSE are installed near the pipeline at a depth. The steel probe is electrically connected to a pipeline. The measurements of AC probe currents flowing between a steel probe (2) and the pipeline (1) are per-formed simultaneously with those of on-and off-potentials, and DC probe currents.

Abstract: A system and method for comprehensive analysis of a multi-cell battery, such as of the nickel-cadmium type, on an individual cell level basis and overall battery basis. For an unsealed battery, which affords access to the individual battery cells, (FIG. 2) tests are carried out to determine the presence of any shorted or reversed cells, and these can be repaired or replaced ((6)-(11)). The individual cells are then tested for sufficient electrolyte on the basis of comparing the cell internal resistance to a maximum internal resistance for the cell and electrolyte added as needed ((12)-(15)). A sealed battery, to which there is no access to the individual cells, is first tested for shorted or reversed cells on a battery level basis ((16)-(19)).

Abstract: Method and apparatus for detecting or analyzing chemical reactions, such as an enzyme reaction, and other events in which electron translation is accompanied by photon emission utilizing a magnetometer probe to detect a change in electromagnetic field strength as a characterization of the event. The event may be of unknown cause and a recorded time course of the change in electromagnetic field strength may be compared with known events to determine the cause of the unknown cause event.

Abstract: Each voltage sensor is provided one to one for a plurality of batteries, for detecting a terminal voltage of each battery. A current sensor detects a current flowing from the plurality of batteries to a load. A reading section reads for each battery a voltage value detected by a corresponding voltage sensor and a current value detected by the current sensor at every predetermined period of time, and collects a predetermined number of detected voltage values and corresponding detected current values. A remaining capacity calculator calculates a battery remaining capacity for each battery based on the plurality of detected voltage values and the plurality of corresponding detected current values, selects a battery remaining capacity having a minimum value from out of a plurality of calculated battery remaining capacities, and calculates a remaining capacity of the whole of the plurality of batteries based on the selected battery remaining capacity.

Abstract: Particulates are trapped by laser beam and brought into contact with electrodes to electrochemically and spectroscopically measure the reaction process thereof.Precise measurement of the process of chemical reactions such as electrochemical and photochemical ones of a single particulate is made possible.

Abstract: A defibrillator and electrode system that gives the user a visible and/or audible indication of the condition of the electrodes and other parts of the defibrillator system prior to deployment of the electrodes and use of the defibrillator. In a preferred embodiment of the method of this invention, a patient simulation and analyze circuit within the defibrillator periodically tests the condition of the system and provides the user with a visual indication of the system's condition.

Abstract: A marine pipeline comprising (a) pipe, (b) a coating that electrically insulates the pipe from sea water, and (c) an alternating current heating circuit comprising the pipe in series with ambient sea water, wherein the heat generated by alternating current flowing in the pipe is for improving flow of fluids through the pipeline. A marine pipeline comprising: a) pipe, b) a coating that electrically insulates the pipe from ambient sea water, and c) an alternating current heating circuit that is grounded to the ambient sea water and comprises the pipe in series with a return conductor, wherein the heat generated by the alternating current flow in the pipe is for improving flow of fluids through the pipeline.

Abstract: A cathodic protection monitoring system for buried metal objects comprising a transponder hard-wire connected to a sacrificial anode and a reference electrode, each of the transponder, the sacrificial anode and the reference electrode being buried underground in close proximity to the buried metal object to be protected, thereby forming a first principal circuit between the sacrificial anode and the buried metal object and forming a second principal circuit between the reference electrode and the buried metal object. The system further comprises a portable transceiver disposed above ground tuned to a frequency of the transponder. Power for operation of the transponder is drawn from the cathodic protection circuit, thereby obviating the need for connections to above ground power supplies.

Abstract: A high sensitivity multiple waveform voltammetric method and instrument are provided for use in electrochemical and other applications. The method consists of applying one or several variable potential excitation signals between electrodes of an electrochemical cell to produce an electrochemical reaction in the solution. The excitation signals include a DC bias potential increasing cyclically by a potential step to form a potential staircase signal sweeping across a potential domain, and a number of pulse trains either of opposite polarity or shifted in potential per potential step. An electric current derived from a diffusion flux of ions through the solution is measured as a result of the applied excitation signal.

Abstract: A ground loop detector circuit and method for an instrument that is used with either a pH sensor or a conductivity sensor. In the instrument used with a pH sensor, an AC diagnostic signal is provided to the sensor. A high input impedance diagnostic signal monitor monitors the voltage at a node adjacent the output of the diagnostic signal source. The occurrence of a ground loop causes the voltage at the node to drop. The instrument used with the conductivity sensor, not only monitors current returning to the diagnostic circuitry from the sensor but also uses a high input impedance monitor to monitor the current leaving the diagnostic circuit to the sensor. The relationship between the current from the sensor and the current to the sensor can be used to determine if a ground loop has occurred as such a loop will cause the current from the sensor to be less than the current to the sensor.

Abstract: An electrolyte level monitor used in combination with a battery having multiple cells. The monitor includes a circuit having an indicator which operates when the electrolyte level is at or above the minimum acceptable electrolyte level. The circuit is connected across cells of the battery to provide a potential to operate the monitor.

Abstract: This relates to a device consisting of a first plurality of light sources that light only when the voltage of a storage battery in a storage battery-generator system is below a predetermined voltage value, which is between the nominal voltage value of the storage battery and the charging voltage value of the storage battery-generator system, indicating that the battery is not receiving charge. A second plurality of light sources that light only when the voltage of a storage battery in a storage battery-generator system is above a predetermined voltage value, which is between the nominal voltage value of the storage battery and the charging voltage value of the storage battery-generator system, indicating that the battery is receiving charge.

Abstract: An mixing assembly which transfers a number of nutritional fluids from individual source containers into a collection container while noninvasively sensing the type of fluid being transferred is provided. The mixing assembly utilizes a transfer set to establish fluid communication between the source containers and the collection container. A sensing assembly is configured to noninvasively sense a number of the types of fluid flowing through the transfer set to help to prevent improper mixing. For other fluids for which the sensing assembly alone may not be able to distinguish with the desired accuracy, the mixing device utilizes a method to approximate the flow rate of that fluid with the flow rate also providing an indication of that type of fluid. By combining the output of the sensing assembly with the flow rate determination, additional fluids can be identified.

Abstract: The present invention provides a rapid coulometric analysis for the quantitative determination of a sample substance with high reproducibility without any application of voltage etc. from the outside, as well as a galvanic cell and a device for use in said coulometric analysis. According to the present invention, a wide variety of components can be analyzed by selection of electroactive substance introduced into the galvanic cell. The present invention enables a simple and easy analysis for food components such as glutamic acid, ascorbic acid, etc., water quality such as COD, etc.

Abstract: A conductivity cell for use in determining ionic concentrations in the gap between two semiconductor substrates or wafers. The wafer gap conductivity cell is composed of two flat electrodes separated by a fixed gap. The electrodes are fabricated from wafers of the same type and dimensions used as semiconductor device substrates. All or a portion of the surfaces of the wafer electrodes are coated with a conductive material. The wafer gap conductivity cell is placed in a wafer cassette or other suitable wafer holder, whose other slots are filled with wafers which are to be cleaned or subjected to another fabrication process. The cell can be used to characterize the processes used during the fabrication of semiconductor devices and assist in investigating the effect on the processes of different process vessel designs.

Abstract: A method for producing a battery tester label is disclosed. The method includes forming an inserted tester device and a base layer, which are combined together to form the battery tester label. The resulting tester label can be applied to a battery. Also disclosed are methods for producing a plurality of battery tester labels disposed on a common releasable liner. The resulting array can be stored for subsequent application to batteries, cut into relatively long strips for rolling and storage, or immediately applied to batteries.

Abstract: A test station for measuring the effectiveness of cathodic protection including a cylindrical plastic reference tube extending downwardly through the soil to near the protected structure, such as a pipe. Two plastic coupon tubes extend within the chamber of the reference tube attaching to opposite sides of its interior sidewalls. First and second circular cylindrical rod-shaped coupons attach to, and sealingly engage, the bottom ends of the coupon tubes. Insulated conductors extend from attachment to each coupon upwardly through the coupon tubes. A first coupon is electrically connected to the pipe, and the second coupon is used to measure a free-corrosion (native) potential.

Abstract: Fluid transmission pipelines and similar structures which are cathodically protected from electrolytic corrosion and are disposed in urban areas under pavements and other structures which prevent access to the soil for verifying pipe-to-soil potentials are subjected to pipe-to-soil potential measurements using a reference electrode disposed in a container which has a permeable bottom and which is capable of saturating a pavement layer with a brine electrolyte to provide electrical conductivity between the reference electrode and the soil. Validation of electrical conductivity is made by a second reference electrode of a dissimilar metal which is also disposed in a container having a permeable bottom and an electrolyte which permeates the pavement layer and establishes electrical conductivity between the soil and the second reference electrode. Potential measurements between the first and second electrodes validate ion transport between the soil and the first reference electrode.

Abstract: The present invention provides a rapid coulometric analysis for the quantitative determination of a sample substance wherein the coulometric analysis has high reproducibility without any application of voltage, etc., from an outside source, as well as a galvanic cell and a device for use in said coulometric analysis. According to the present invention, a wide variety of components can be analyzed by selection of electroactive substance introduced into the galvanic cell. The present invention enables a simple and easy analysis for food components such as glutamic acid, ascorbic acid, etc., water quality such as COD, etc.

Abstract: A combination and unitary corrosion monitor and reference cell for cathodic protection systems includes an elongated tubular metal element of the same material as the structure to be protected and a reference cell on one end of the tubular element, adapted to be buried or submerged in an electrolyte. The tubular element includes resistance connections along its length and a reference resistance element sealed inside. Ratiometric resistance measurements enable the extent of corrosion and corrosion rates to be determined with automatic compensation for temperature changes. Both the resistance measurements and the potential measurements from the cell may be taken from the same test station or location.

Abstract: Fluid transmission pipelines and similar structures which are cathodically protected from electrolytic corrosion and are disposed in urban areas under pavements and other structures which prevent access to the soil for verifying pipe-to-soil potentials are subjected to pipe-to-soil potential measurements using a reference electrode disposed in a container which has a permeable bottom and which is capable of saturating a pavement layer with a brine electrolyte to provide electrical conductivity between the reference electrode and the soil. Validation of electrical conductivity is made by a second reference electrode of a dissimilar metal which is also disposed in a container having a permeable bottom and an electrolyte which permeates the pavement layer and establishes electrical conductivity between the soil and the second reference electrode. Potential measurements between the first and second electrodes validate ion transport between the soil and the first reference electrode.

Abstract: A corrosion degree measuring method capable of field measurement for intergranular corrosion, particularly the sensitization degree, of the plant's structural materials in a narrow space. The metal electrode made of a material being measured and the counter electrode to the metal electrode are immersed in an electrolytic solution. A voltage is applied to the metal electrode in the anodic direction so as to raise the potential of the metal electrode up to the passive state potential and to keep the metal electrode at the passive state potential. The passive state potential is used as a reference potential, and a pulse-like potential signal is applied to the metal electrode in the cathodic direction. At the time of the application of the pulse potential signal, a current between the metal electrode and the counter electrode is measured, and the corrosion degree of the material being measured is determined from the intensity of the current.

Abstract: A system for testing electrochemical energy conversion and storage devices includes means for sensing the current from the storage device and varying the load across the storage device in response to the current sensed. The system is equally adaptable to batteries and fuel cells. Means is also provided to sense system parameters from a plurality of locations within the system. Certain parameters are then stored in digital form for archive purposes and certain other parameters are used to develop control signals in a host processor.

Abstract: Water quality sensor apparatus comprising a substrate on which a plurality of sensors are supported in spaced apart relationship, each sensor being responsive to a different water characteristic and each sensor comprising a sensor region which, in use, is arranged to be contiguous with water the characteristics of which are to be sensed, which sensor regions are electrically connected to connector means via conductors supported on the substrate, the conductors and the connector means being arranged to be non-contiguous with the water in use of the apparatus.

Abstract: An device for monitoring workplace air comprises a monitor cell comprising a base and a removable assembly. The removable assembly comprises (1) a flat, electrically insulating substrate having a first surface, (2) an electrolyte cell having an anode and a cathode disposed on the first surface, the anode and cathode spaced apart to define a controlled volume for holding a quantity of an electrolyte, and (3) means for applying a controlled electrical potential to the cathode. The base comprises (1) an air inlet portion for sampling air, (2) an air outlet portion connected to an air sampling pump, (3) a channel connecting the air inlet and the air outlet and adapted to introduce air to the electrolyte in the electrolyte cell, (4) a reservoir for storing the electrolyte for the electrolyte cell, and (5) a wick for supplying electrolyte from the reservoir to the electrolyte cell.

Abstract: A method and an apparatus are provided for detecting a current residual capacity of a battery employed in an electric vehicle, such as an electric car. During a charging process, a value of the charge current of the battery is measured and an estimated discharge voltage corresponding to a current battery accumulated power is determined. A power of the battery as a product of the value of the charge current of the battery and the estimated discharge voltage is thereafter computed and the computed power is added to the current battery accumulated power to provide a new current battery accumulated power for display. During a discharging process, values of the discharge voltage and the discharge current are measured. The amount of consumed power is thereafter computed as a product of the values of the discharge voltage and the discharge current. The computed amount of consumed power is subtracted from a current battery residual capacity to produce a new current battery residual capacity for display.

Abstract: A method and apparatus are disclosed for measuring a resistance of a sensor. The apparatus injects a first test current into the sensor and then measures a substantially stable first voltage level across the sensor when the first test current is present. The apparatus then injects a second test current into the sensor, the second test current being substantially equal to but opposite in polarity to the first test current. A substantially stable second voltage level across the sensor is measured when the second test signal is present. Using the first measured voltage level and the second measured voltage level, the apparatus calculates the resistance of the sensor.

Abstract: A cathodic protection measurement apparatus including a coupon made of similar material as a buried metal pipeline to form an artificial holiday, where the coupon is buried near and electrically connected to the pipeline to receive the same level of cathodic protection current as the pipeline. A test wire is connected to the pipeline and routed to a normally-closed contact switch located at an access point of a test station. The switch is also connected to a coupon wire, which is routed and connected to the coupon to complete the electrical connection. A reference electrode having a measuring surface contacting the soil close to the buried coupon includes an electrode wire provided to the access point. A voltmeter is connected between the switch and the reference electrode wire, and the switch is then opened to electrically isolate the coupon from the pipeline.

Abstract: A method for monitoring the state of, and for locating any detachment of, the protective covering of immersed or buried pipelines or other metal structures subjected to cathodic protection with constant current, on the basis of the overall electrical resistance offered by the pipeline/covering/ground system, consisting of applying local sinusoidal wave excitation currents of different frequencies to the pipeline and measuring the corresponding voltage responses, then comparing the measured responses of the system to determine, on the basis of response differences or coincidences at the various frequencies, whether within the portion under consideration there is detachment with corrosion underway or whether there is simple covering decay.

Abstract: A battery encased with a label containing an integral test circuit device that is thermally insulated from the battery by an expanded material and is activated by depressing a selected area of the label whereupon a thermally sensitive material associated with the test circuit displays whether the battery has capacity. A method for producing the test circuit device is also disclosed.

Abstract: A simple, expedient method for measuring the effectiveness of a corrosion inhibitor provided to a metallic surface by a surface layer, wherein the layer is formed by use of the corrosion inhibitor is a corrosive fluid. The method employs the measuring of a high frequency phase angle as an indicator of inhibitor effectiveness.

Abstract: The measurement of electrokinetic potential is of importance in paper-making. A measuring cell (12) for a specific potential known as streaming potential of the kind disclosed in EP B1 0 079 726 is now provided with measuring electrodes (40, 42) of a metal which forms a reversible electrochemical reaction with pure water to oxidize the metal. The electrodes (40, 42) used in the measurement mode in the cell have a film comprising an oxide of the metal electrochemically formed thereover. Such electrodes are found to give more stable and consistent measurement than the stainless steel electrodes used previously. Silver, lead, copper and alloys such as lead and silver are preferred. The measuring electrodes (40, 42) are regenerated within the cell (12) through electrochemical reduction to bare metal, followed by oxidation to re-form the film. This is performed with the aid of auxiliary electrodes (60, 62) in the cell. A control system (50) for the measurement and regeneration mode is described.

Abstract: A corrosion sensor (1), apparatus for detecting corrosion of a surface incorporating the sensor, a structural assembly (1,21) incorporating the sensor and method for detecting corrosion of a surface employing the sensor are provided. The sensor comprises a thin flexible non-conducting substrate (18) for attachment to a surface subject to corrosive influence and an array of at least two thin flexible metallic electrodes (2,3,4) carried on the substrate wherein the electrodes are disposed closely adjacent one another so as to permit the generation of electric current by electrochemical action therebetween upon corrosion of the electrodes.

Abstract: The build-up of the deposits on surfaces immersed in water in monitored by passing the water through a galvanic cell comprising a pair of dissimilar metal electrodes (5, 6) mounted on opposite sides of a passage (4) for the water in a housing (1,7), and detecting and interpreting galvanic current developed between the electrodes (5, 6).

Abstract: An electroless plating deposition speed measuring apparatus is provided with a sensor having an electrode couple whose pair of electrodes are opposed to each other and a sensor drive circuit that cyclically applies voltage to the electrode couple to measure a polarization resistance between the pair of electrodes of the electrode couple. Measuring data from the sensor drive circuit are supplied to a processing circuit. The processing circuit computes and processes the measuring data to find the plating deposition speed. Data of the plating deposition speed from the processing circuit are supplied to a display circuit to display the data of the plating deposition speed. In a preferred embodiment, each of the pair of electrodes of the electrode couple has a conductor and a non-conductor, wherein the surfaces of the conductors and the non-conductors of the respective electrodes are arranged in facing and opposite relation to each other.

Abstract: A test unit for a monitoring device includes reference and measuring electrodes coupled to a preamplifier and a temperature compensating resistor for the preamplifier. The test unit has components corresponding to those of the monitoring device as well as a power supply and a voltmeter coupled to the output of its preamplifier. Cables are provided for substituting either or both electrodes of the monitoring device for the electrodes of the test device, and a switch is provided for substituting a temperature compensation resistor of the monitoring device for the temperature compensation resistor of the test device. A cable is adapted for connection to either preamplifier for supplying it with operating potentials derived from the power supply and for coupling the output of either preamplifier to the voltmeter.

Abstract: A sensor for use during the construction of a concrete structure to enable an assessment to be made of whether or not a pour of fresh concrete has settled uniformly throughout the placement area. One of two main electrodes is fitted with an auxiliary electrode in parallel such that the polarity of the electrodes is reversed when they are immersed in water and when they are immersed in fresh concrete. By monitoring this function, it is possible to detect the presence or absence of fresh concrete in accordance with the polarity. In the case of a sensor without an auxiliary electrode, it is still possible to monitor changes in the voltage level when the electrodes are immersed in water and in fresh concrete, thereby providing access to a similar mode of assessment.

Abstract: A dynamic precious metal assay which includes the steps of introducing a controlled amount of liquid electrolyte onto a sample of precious metal alloys, placing an inert electrode in contact with the sample in the presence of the electrolyte to create a wet junction, driving a first pulse of electric current through the electrolyte in the wet junction to cause an oxidation/reduction reaction of the alloying materials present in the alloyed sample to form an electrolytic-based paste, terminating the electric current and allowing the current in the paste to decay to an asymptotic level, driving a second pulse of electric current through the electrolytic paste in the junction at an amplitude above the asymptotic level, driving a third pulse of electric current, at a higher amplitude than the second pulse, through the electrolytic paste in the junction, instantaneously measuring the electrolytic conductance of the electrolytic paste, comparing the conductance with an empirical table of electrolytic paste conducta

Abstract: A cathodic protection monitoring system which provides IR drop free cathodic protection potential measurements which are indicative of the effectiveness of the cathodic protection system. The system measures the polarized potential between a reference electrode and a coupon subsequent to decoupling the coupon from the protected structure. The present invention controls the time or times at which the potential is measured in order to ensure that the potential is measured only after the polarized potential has achieved a relatively steady state value. More particularly, the cathodic protection monitoring system controllably measures the polarized potential after the potential has stabilized to the extent that there are no inductive or capacitive voltage spikes present, and before the coupon potential decays significantly due to depolarization.

Abstract: A circuit is described which tests whether an amperometric electrochemical gas sensor monitoring the concentration of toxic gases in an atmosphere is working properly. The sensor has a sensing electrode, a reference electrode, and a counter electrode and in normal operation the potential between the reference electrodes is fixed by means of an operational amplifier. When there is gas in the atmosphere, the gas reacts electrochemically at the sensing electrode, causing the amplifier to supply electrical current to the counter electrode which results in an electrical potential to the sensor that is proportional to the amount of toxic gas in the atmosphere. The sensor is periodically tested to determine whether it is working properly by applying a pulse potential between the sensing and reference electrodes. If a current flow results then a signal is sent to an alarm device.

Abstract: A sensor cable for detecting the presence of electrically conductive liquids, e.g. water. The cable has decreased sensitivity to contamination and condensation than conventional cables which are covered by braids. First and second elongate conductors are positioned in first and second channels which partially surround the conductor and are part of first and second insulating support members; each channel has at least one shoulder which extends outwardly from the channel beyond the conductor. The channels are positioned so that when the cable is placed on a flat substrate in any position, neither the first nor the second conductor contacts the flat surface and at least one first shoulder and at least one second shoulder make intermittent contact with the flat surface. In a preferred embodiment, the first and second conductors follow a generally spiral path down the length of the cable.

Abstract: A method and apparatus for compensating for charging current at a working electrode of an electrochemical cell. And a method for measuring faradaic current at the working electrode. Includes measuring the current at the working electrode while a time-varying potential difference is applied between the working electrode and a reference electrode. And while the applied potential difference is held constant for a short time and the working electrode current is again measured, where this current is the faradaic current. The faradaic current is then filtered from the total current to determine the charging current thereby compensating for double layer charging current in the cell.

Abstract: An apparatus for measuring cathodic protection voltage levels on a concealed conductive structure, includes a probe having a standard half cell reference electrode, a working electrode and an auxiliary electrode mounted in a fixed spacial relationship to each other, wherein the reference electrode, working electrode and auxiliary electrode are each in contact with an electrolytic solution. A voltage measuring device is provided for receiving a voltage from said reference electrode. The voltage measuring device provides an indication of the voltage difference between the reference electrode and a common reference point. A switch is included for connecting and disconnecting the working electrode with the common reference point. A voltage detecting circuit detects voltage between the concealed conductive structure, which is subject to a cathodic protection voltage, and the common reference point.

Abstract: Apparatus for measuring electrolyte concentrations in fluid samples. The apparatus includes an ion selective electrode capable of generating a voltage differential having a magnitude related to the concentration of the corresponding electrolyte in the sample. A voltage to optical transducer circuit is provided to convert the voltage differentials to a digital code and then to an optical signal which is related to the concentration of the electrolytes. The optical signals are suitable for detection by conventional optical detector apparatus of assay instruments. A passive duplex transfer is utilized to simultaneously read one optical signal while transferring the next bit of the digital code. The duplex transfer configuration also makes novel use of the photodetection properties of an LED.

Abstract: In an amperimetric measurement apparatus comprising an amperimetric cell having a pair of electrodes arranged for contact with a solution, a potential difference is established between the electrodes, and a corresponding electric current is conducted in a forward direction through a current path which includes the electrodes and the solution. An output corresponding to the current indicates the concentration of a solute in the solution. The electrical charge passing through said cell in response to said potential difference is monitored by an integrator. The forward current is interrupted repeatedly and a reverse electric current is imposed on the cell during the interruptions of forward current. The magnitude and duration of the reverse current are regulated in response to the electrical charge flow corresponding to the forward current, so that the net flow of charge through the cell over a time period including an equal number of intervals of forward and reverse current intervals is substantially zero.

Abstract: Apparatus for measuring electrolyute concentrations in fluid samples. The apparatus includes an ion selective electrode having a plurality of ion selective detection sites. Each site has an affinity for a preselected electrolyte of interest and generates a potential having a magnitude related to the concentration of the corresponding electrolyte in the sample. A voltage to optical transducer circuit is provided to convert the voltage differentials to optical signals having intensity related to the concentration of the electrolytes in a first embodiment, a digital code related to the concentration of the electrolytes in a second embodiment, and an optical absorption or density value related to the concentration of the electrolytes in a third embodiment. The optical signals are suitable for detection by conventional optical detector apparatus of assay instruments and may be processed using conventional two point linear interpolation techniques to determine the concentrations of the preselected electrolytes.

Abstract: Apparatus for controlling the use of consumable accessory units with machines where a memory device associated with each accessory unit holds information concerning the accessory unit, and circuitry in the machine acts in response to the information.

Abstract: A system for measuring parameters in an environment having a metallic body positioned in an electrolytic medium includes a current density sensing device positioned adjacent the metallic body in a non-invasive manner. The device is sufficiently sensitive to measure current density in the milliamp per square centimeter range. A housing is provided for enclosing at least a portion of the current density sensing device in an electrically and thermally non-conductive manner. A computer is used for processing the data from the current density sensing device and wiring is provided for electrically interconnecting the two. The current density sensing device, which can be used separately from the apparatus, includes a toroidal transformer and a square wave magnetically coupled oscillator which drives the transformer. A pair of multi-section low pass filters are provided for monitoring the transformer. A fixed gain differential instrumentation amplifier is utilized for processing an output of the transformer.