Abstract: A method for measuring the level or volume of a fluid within a fluid storage vessel which comprises: providing a multi-capacitor fluid level sensor formed of a pair of capacitors of fixed and substantially like capacitive value and two capacitors having like open dielectric spaces for receiving varying levels of the fluid within the vessel and with the fluid in the spaces consisting of a pair of capacitors of variable capacitive value; connecting the four capacitors of the sensor together to form the four capacitive sides of a Wheatstone bridge circuit; applying a source of alternating current of constant voltage and set frequency across the bridge circuit to a first set of bridge terminals at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor; interrogating the bridge circuit through a detection circuit connected across the bridge to a second set of bridge terminals independent of said first set of terminals and at opposite corners

Abstract: A system for measuring the level or volume of a fluid within a fluid storage vessel which comprises: a multi-capacitor fluid level sensor formed of a pair of capacitors of fixed and substantially like capacitive value and a pair of capacitors having like open dielectric spaces for receiving varying levels of the fluid within the vessel. The four capacitors of the sensor are connected together to form the four capacitive sides of a Wheatstone bridge circuit. A source of alternating current of constant voltage and set frequency is applied across the bridge circuit to a first set of bridge terminals at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor. A detection circuit is connected across the bridge to a second set of bridge terminals (independent of said first set of terminals) and at opposite corners of the bridge, each of such terminals located between a fixed capacitor and a variable capacitor of the sensor.

Abstract: A multi-cylinder stencil duplicator includes ink-applying means in the form of a coating member offering a fixed nip between the coating member and a cylinder of the duplicator, ink being applied to one side of that nip and being held back as a wedge at the nip during rotation of the duplicator cylinder. The dispensing of ink to the wedge is controlled in response to variations in the capacitance between the coating member and the cylinder, so that when the ink wedge drops below a given threshold value further ink is dispensed.

Abstract: An electronic liquid level gauge for measuring the level of a liquid contained in a vessel by employing an electrode pair immersed in the liquid. The electrode pair is associated with an oscillator which generates pulses of a repetition period directly proportional to the electrostatic capacity of the electrode pair. A counter is provided which is reset by an oscillator pulse and starts counting reference pulses of a predetermined repetition rate with a predetermined time delay relative to the occurrence of the oscillator pulse.

Abstract: An apparatus for measuring the quantity of a liquid such as a fuel in a tank, which comprises liquid level measuring electrodes, comparing electrodes dipped always in the liquid to detect the capacitance inherent to the liquid, an LC oscillator for converting each capacitive value measured by the electrodes into a corresponding frequency signal, reference electrodes constituting a level feeder together with the oscillator to compensate for capacitive variation of the latter, and a microcomputer for calculating a liquid quantity in the tank based on the frequency signals and for displaying the calculated quantity.

Abstract: An inlet tube, connected to a source of liquid, such as milk, supplies liquid to the top of a container. An orifice at the bottom of the container permits drainage from the container into an outlet tube. The level of liquid in the container is related to the instantaneous flow rate, in a known manner, as long as the pressure in the container, above the liquid surface, equals the pressure in the outlet tube after the orifice. A conduit connects the upper portion of the container, at a point above the liquid therein, and the outlet tube, below the orifice, to equalize the pressure therebetween, as well as to act as an overflow bypass. Various types of sensors may be used to determine the level of liquid in the container. A signal, representative of the sensed liquid level, is developed and processed to represent the flow rate.

Abstract: A failure sensing accumulator device and to a system embodying the same. The accumulator and system are characterized in that various failure situations are sensed by a capacitive sensor apparatus which is capable of detecting failures at an early stage and localizing the damage resulting from such failure to the failed accumulator.

Abstract: An electric liquid level detector for detecting the remaining quantity of liquid stored within a liquid container, comprising a pair of helically coiled electrodes extending vertically in the container and being fixed at their one ends to the upper portion of the container and at their other ends to the bottom of the container, the electrodes being submerged into the liquid stored within the container; and an oscillator circuit of the resistance capacity type including a variable condenser which consists of the electrodes, the oscillator circuit being arranged to oscillate at a frequency in dependence upon variation of the electrostatic capacitance between the electrodes so as to indicate the level of the stored liquid.

Abstract: A probe for the measurement of the level of conductive materials within a conductive vessel is disclosed which is particularly suitable for the measurement of the level of conductive granular materials such as coal or other minerals or plastics or vegetable matter which are conductive. In a preferred embodiment the probe comprises a conductive steel core covered with a layer of insulating plastic and covered further with a layer of a semi-conductive material which preferably comprises a plastic which has been partially filled with a conductive material such as carbon black. Other embodiments wherein the probe may comprise a conductive plate covered by insulation further covered by a similar semi-conductive layer are also disclosed. Reference is made to prior art disclosures of circuitry and theory which enable the use of the probe of the invention.

Abstract: A method and apparatus are provided for monitoring the length of a liquid column such as the filling level of a beverage bottle. A predetermined high frequency signal is applied to a parallel circuit wherein, in one branch, a liquid column is connected by means of electrodes coupled to the ends of the column such that the column, i.e., a filled bottle, will produce more or less resonance in the first branch. The increase or decrease of resistance at resonance in the first branch will be reflected in a corresponding change in the power or current detected in the second branch. In instances where preset limit values are exceeded, an error is indicated and the improperly filled bottle is removed. When monitoring the filling level of beverage bottles, the latter are successively guided past the electrodes, with the upper electrode being coupled to the necks of the bottles through an air gap.

Abstract: A standardized, modular, fuel quantity gaging system suitable for use with aircraft having a plurality of fuel tanks. The system utilizes a standard electronic module, preferably located on the front spar of the center wing box, to house a redundant, centralized, microprocessor-based electronic assembly. This assembly processes the tank-generated fuel quantity signals and produces a digital data stream which is distributed to display units in the cockpit and at the refueling control panel. The digital signals are transmitted over two 2-wire data busses from the standard electronic module to the cockpit and to the refueling panel. One of these buses is active, the other being held in standby, for use as needed. The two busses are part of separate data processing channels extending between the fuel quantity signal multiplexers in the standard electronic module and the indicators in the cockpit and at the refueling panel.

Abstract: A liquid level measuring device has an outer capacitance tube, an imperforate glass tube coaxially within the outer tube defining a capacitor annulus between them, and an inner capacitor sleeve coaxially within the glass tube and having separate longitudinally extending sleeve sections. The separate sleeve sections cooperate with the outer capacitance tube to form a plurality of capacitor sections each having a separately measurable value which varies between dry minimum and submerged maximum.

Abstract: A device for the capacitive measurement of a level of filling having a measurement capacitor which dips into the fluids to be measured in accordance with the filling level thereof, and a unit for forming an electric value corresponding to the filling level and a unit for compensating for different dielectric constants of fluids which comprise a compensation capacitor dipping into the fluid. A circuit forms an electric value corresponding to the filling level and compensates the different dielectric constants of the fluid such that only the imaginary part of the complex conductance of the measurement capacitor and of the compensation capacitor enters into the electric value, but not the real part thereof in each case.

Abstract: A tubular shaped fluid level or fluid volume sensor for mounting in a fluid storage vessel for sensing the level or volume of the fluid within the vessel which comprises: a first pair of like electrically conductive capacitor elements each formed to present two electrically connected capacitive plate areas, the capacitor elements being spaced from one another and shaped and arranged to generally define together the outer periphery of the tubular sensor; and a second pair of like electrically conductive capacitor elements each formed to present two electrically connected capacitive plate areas, the second pair of capacitor elements being positioned within and spaced from the first pair of capacitor elements and being spaced from one another and shaped and arranged to generally define together the inner periphery of the tubular sensor.

Abstract: A fluid level or fluid volume sensor or probe for mounting in a fluid storage vessel for sensing the level or volume of the fluid within the vessel which is comprised of four like electrically conductive capacitor elements each formed to present two electrically connected capacitive plates disposed in angular relation to each other. Electrical insulating material constitutes centrally located means for mounting the capacitor elements in fixed spaced relationship from one another around such mounting means and for positioning the elements so that each capacitive plate thereof defines with a capacitive plate of the next adjacent capacitor element a dielectric space therebetween whereby the mounted capacitor elements together form four like dielectric spaces. Material of known constant dielectric value fills two of the dielectric spaces thereby forming with their respective space defining capacitive plates two capacitors of known fixed and substantially like capacitive value.

Abstract: A residual ink detection mechanism for detecting the amount of residual ink within an ink container of an ink jet printer is disclosed wherein the ink container comprises a flexible bag, and electrodes are provided at least at opposite positions of this bag to constitute a capacitor, so that the amount of residual ink within the ink container may be detected by detecting the electrostatic capacity between these paired electrodes.

Abstract: An arrangement for determining the level in a container includes a capacitive probe disposed in the container, a measuring transducer arranged in the vicinity of the container, and a remote evaluation apparatus. The measuring transducer produces a signal corresponding to the capacitance between the probe and the container. This signal, which is indicative of the level in the container, is transmitted from the transducer to the evaluation apparatus via a two-wire line, which also transmits the current supply DC voltage from the evaluation apparatus to the transducer. The transducer includes a switch for periodically switching from the probe capacitance to a test capacitance. The evaluation apparatus comprises a time control circuit which periodically varies or interrupts the DC voltage on the two-wire line, and the transducer includes a control circuit which responds to the voltage changes to actuate the switch.

Abstract: An electrode assembly for use in a capacitance type probe for measuring volume or height of an electrically conductive liquid. The probe includes an inner conductor which an electrical conductive wire is connected at one end. The inner conductor is surrounded by a thick-wall TEFLON tube which functions as an insulator. A thin-wall TEFLON sleeve is heat shrunk onto the thick-wall TEFLON tube and the ends of the thin-wall sleeve are heated and sealed about the thick-wall tube to prevent any leakage of fluid to the inner conductor. The assembly is also provided with a polyurethane foam to provide rigidity and to prevent moisture from forming within the assembly.

Abstract: An electrostatic type fuel measuring device comprises a pair of oppositely arranged electrodes separated by insulating spacers immersed in liquid fuel in a tank so that a variation of the electrostatic capacity between the electrodes due to a variation in the liquid fuel level is detected electrically and the fuel amount is measured and indicated.

Abstract: Capacitance measuring apparatus comprises a variable capacitor VC and a reference capacitor FC. Circuits D, ID, are provided for generating a periodic waveform for application directly to the variable capacitor, and in inverted form to the reference capacitor. Switches means SM are operated by control logic CL to connect the two capacitors in sequence to the input of an integrating amplifier IA, the output of which is applied to a comparator CM to which is also applied a reference level. The output of the comparator controls the control logic. Output of the control logic is converted to an indication of the capacitance of the variable capacitor relative to that of the reference capacitor.

Abstract: A capacitance probe sensor device is disclosed which has a probe formed of KYNAR insulated wire spaced from an uninsulated metallic ground electrode. An oscillator and associated capacitance-resistance network connected to the probe serve to provide a linear output voltage proportional to the change of capacitance between the insulated wire and the ground electrode. The capacitance probe sensor device can be used in a number of applications. They include the measurement of water level, the determination of a liquid's flow rate, and the moisture content of soil.

Abstract: Apparatus for determining the fuel level in a fuel tank and for detecting the presence of water in the fuel tank. The fuel level in the tank is determined by detecting the change in capacitance between a pair of electrodes positioned with a generally vertical orientation so that as the fuel rises in the tank, an increasing area of the plates is adjacent to the fuel. Since the presence of water in fuel is very undesirable, the apparatus also includes means for detecting this water before it can effect engine performance and before it can effect the accuracy of the fuel level indicating circuitry.

Abstract: The present invention is part of a liquid gaging system and comprises an apparatus for measuring and storing a value related to an unwetted capacitance of a capacitive sensor, the stored value being available for use in liquid measurements. Included is a capacitive sensor for mounting in a tank, the sensor having an unwetted capacitance variable in dependence on manufacturing tolerances. The sensor capacitance is also related to stray capacitance in the system. The invention further includes apparatus for measuring the sensor unwetted capacitance including the sensor capacitance contributed by the stray capacitance in the system. The apparatus for measuring is connected to the sensor. The invention also comprises apparatus for storing a value related to the sensor unwetted capacitance measured by the apparatus for measuring, the apparatus for storing being connected to the apparatus for measuring.

Abstract: An improved level measuring system based upon capacitance to current conversion is provided with equipment for compensating for variations in dielectric constant in a measured liquid. A reference probe is located entirely within the liquid to be measured, but is sensitive to changes in dielectric constant. The measurement probe responds both to changes in dielectric constant and variations in liquid level. A differential output from the reference probe and the measurement probe effectuates compensation for variations in the dielectric constant in the material measured. A control unit at the output provides means for automatic calibration through a microprocessor.

Abstract: The circuit of a primary element capacitor is energized and arranged to produce a proximity signal not substantially affected by the conductivity of fluid-like material accumulated on the capacitor structure. The energization, circuit components, and capacitor insulation minimize the electrical characteristics of the material accumulation on the capacitor.

Abstract: A liquid gaging system comprising a sensor for providing a liquid measurement signal related to a liquid depth at a particular location in a tank. The system further comprises storage apparatus for storing data including characterization parameters, each parameter being based on tank shape and volume and on sensor location, each parameter defining a relationship between a liquid depth and a value related to a liquid quantity. The system also includes determining apparatus for determining a value related to a liquid quantity in the tank based on the liquid measurement signal and the data, the determining apparatus being connected to the sensor and to the storage apparatus.

Abstract: A device for measuring the fill level of a liquid medium in a container by easuring the capacitance between electrodes contained in the medium is disclosed. A pair of electrodes in which one of the electrode is divided over its height into two partial surfaces (F1, F2) which are insulated from one another. Each surface forms a partial capacitor (C1, C2) with the other electrode. The divided electrode is characterized in that at least one of the surfaces (F1) or (F2) has a width which increases or decreases over the height of the electrode. By the appropriate combination of the partial capacitances, the level of the medium can be determined as well as a separate determination of the fluid's susceptibility (K).

Abstract: The present invention is part of a liquid gaging system and comprises an apparatus for monitoring a quadrature signal from a capacitor sensor. Included is a capacitive sensor for providing a liquid measurement signal related to a liquid in a tank, the liquid measurement signal comprising a capacitive signal and a quadrature signal. The invention also includes apparatus for monitoring the quadrature signal through null detection of the capacitive signal, the null detection being implemented through a rebalance approximation sequence. The apparatus for monitoring is connected to the sensor.

Abstract: In a liquid level sensing apparatus having a stillwell in a liquid-holding tank disposed around the sensing device, a bubble shield is provided to interdict the upward flow of bubbles to the stillwell to protect the sensor from contact with bubbles or foreign matter which could result in a false reading.

Abstract: A characterized liquid gaging system sensor comprising sensor apparatus for determining a depth of liquid in a tank at a particular location in the tank. The sensor also includes storage apparatus for storing characterization parameters, each parameter being based on tank shape and volume and on the location of the sensor apparatus, each parameter defining a relationship between a liquid depth and a value related to a liquid quantity. The sensor apparatus and the storage apparatus are connected.

Abstract: A capacitance sensing device for detecting the amount of material flowing through a passage includes layers of disk-shaped insulating substrates having electrode films formed on surfaces thereof facing each other, and the insulating substrates are supported by an insulating support member as a unit and spaced from each other. The electrode films are alternately connected by a pair of conductors to form a capacitor. Electric circuit elements, forming a detection circuit which is connected to the pair of conductors and which detects a change in capacitance of the capacitor depending on the amount of material flowing through the spaces between the electrode films, are formed on the outer surface of an outermost one of the substrates in a form of a monolithic circuit or a hybrid circuit.

Abstract: The present invention is part of a liquid gaging system and comprises an apparatus for reducing error introduced by an incapacitated sensor. Included are a plurality of sensors, each sensor providing a liquid measurement signal relating to a liquid depth at a particular location in a tank. The invention also comprises apparatus for selectively monitoring the liquid measurement signal of each individual sensor, the apparatus for selectively monitoring being connected to the sensors. Also included is apparatus for identifying at least one sister sensor corresponding to each sensor. The invention further comprises apparatus for determining an estimated liquid depth corresponding to an incapacitated sensor by using the liquid measurement signal of at least one sister sensor corresponding to the incapacitated sensor. The apparatus for determining is connected to the apparatus for selectively measuring and the apparatus for identifying.

Abstract: Circuitry for nulling a signal from a capacitive sensor apparatus with a signal from a reference. The invention includes capacitive sensor apparatus for providing a liquid measurement signal. Also included is reference apparatus for selectively providing a series of reference signals having predetermined amplitudes, the reference apparatus having terminal apparatus for receiving rebalance approximation sequence control signals for selectively controlling the signal amplitudes. The invention further includes null detecting apparatus for detecting the presence of a null, the null detecting apparatus being connected to the capacitive sensor apparatus and the reference apparatus.

Abstract: A multiple segment three-terminal type capacitance probe with segment selection, capacitance detection and compensation circuitry and read-out control for level/density measurements in a fluidized-bed vessel is provided. The probe is driven at a high excitation frequency of up to 50 kHz to sense quadrature (capacitive) current related to probe/vessel capacitance while being relatively insensitive to the resistance current component. Compensation circuitry is provided for generating a negative current of equal magnitude to cancel out only the resistive component current. Clock-operated control circuitry separately selects the probe segments in a predetermined order for detecting and storing this capacitance measurement. The selected segment acts as a guarded electrode and is connected to the read-out circuitry while all unselected segments are connected to the probe body, which together form the probe guard electrode.

Abstract: A liquid level measuring system for the underground fuel storage tanks of a fuel dispensing station having a multiple segment capacitance probe in each storage tank and a microcomputer for periodically measuring the capacitance of each segment of each probe and calculating the level and volume of fuel in each tank using capacitance and volume calibration constants automatically updated by the microcomputer from the measured capacitance data and from fuel delivery data automatically fed to the microcomputer.

Abstract: A capacitance sensing circuit utilizes an operational amplifier connected in a comparator configuration. The capacitance to be measured is connected to one input of the operational amplifier and is also connected to the output of the operational amplifier through a resistor to form a free-running multivibrator. The period of the multivibrator output depends upon the value of capacitance being measured. A switching transistor is connected to the output of the operational amplifier to cause a changing current output signal. The output signal is obtained as a change of current in a current sensor connected to the collector of the transistor.

Abstract: A capacitive system for sensing the level of material includes a conductive member electrically connected to ground potential, a probe including a sensing element arranged to establish a capacitance between the sensing element and conductive member which is determined by the level of the material and a shielding element interposed between the conductive member and the sensing element to form an electrically neutral zone therebetween to thereby reduce the effect of a conductive buildup of the material on the probe on the capacitance between the conductive member and the sensing element, and a first circuit electrically connected to the sensing and shielding elements for applying generally the same electrical potential to both the sensing and shielding elements, the first circuit having an output which varies in response to a change in the capacitance between the conductive member and the sensing element.

Abstract: The present invention is part of a liquid gaging system and comprises an apparatus for self testing the system. Included is an excitation signal generator apparatus for providing an excitation signal and a precision reference component for providing a precise electrical load. The invention also comprises apparatus for monitoring the precision reference component. Also included is apparatus for connecting the precision reference component to the excitation signal generator apparatus and to the apparatus for monitoring.

Abstract: An RF probe and method for making same including laminating sheets of thermoplastic insulation to both sides of a layer of wire screen which is evacuated and pressure thereafter applied by fluid pressure acting on a diaphragm pressing member.

Abstract: A generated signal is passed through an elongated signal conveying element positioned preferably perpendicular to the surface of a fluid the level of which is to be measured. The signal is directed from the signal conveying element to a detector element which senses the signal output from the signal conveying element. The signal output detected varies linearly with the depth of immersion of the signal conveying element into the fluid. In one embodiment, the signal conveying element is a capacitive probe comprising two plates or wires, one of which is grounded to the fluid into which the two plates or wires are immersed. Proper selection of accompanying circuitry results in detected signal changes which vary linearly with immersion changes. A second embodiment employs an electromagnetic wave, e.g. light, signal which passes through a light pipe signal conveying element. By nearly matching the light pipe index of refraction with that of the fluid, a predetermined percentage of the wave is lost into the fluid.

Abstract: There is disclosed a capacitance probe for determining the level of high electrical resistance material in a vessel. The probe comprises at least two parallel, large surface area blades which are supported from a mounting plate and spaced apart to define a capacitance path. One blade is attached to an insulator body which is attached to the mounting plate while the other blade is directly attached to the mounting plate in electrical continuity therewith. The insulator body is a ceramic sleeve having a length sufficient to prevent shunting of the capacitance path. The probe is particularly intended for detection of level of fly ash and the like in a receiver vessel.

Abstract: A capillary tube viscometer is provided in which the viscosity of a fluid can be measured at a temperature above the normal boiling point of at least one component in the fluid. The fluid is heated to the desired temperature in a sealed viscometer which is constructed so as to withstand high pressure. The fluid is then allowed to flow through a capillary tube and the time required for the fluid to flow through the capillary tube is measured. The viscosity of the fluid is then calculated based on the Hagen-Poiseuille law.

Abstract: A probe for the measurement of the level of conductive materials within a conductive vessel is disclosed which is particularly suitable for the measurement of the level of conductive granular materials such as coal or other minerals or plastics or vegetable matter which are conductive. In a preferred embodiment the probe comprises a conductive steel core covered with a layer of insulating plastic and covered further with a layer of a semi-conductive material which preferably comprises a plastic which has been partially filled with a conductive material such as carbon black. Other embodiments wherein the probe may comprise a conductive plate covered by insulation further covered by a similar semi-conductive layer are also disclosed. Reference is made to prior art disclosures of circuitry and theory which enable the use of the probe of the invention.

Abstract: An apparatus for measuring the level of fluid in a container by the use of measuring electrodes forming a measuring condenser, and compensation electrodes forming a compensation condenser by which the effect of various dielectric constants of the medium upon the measuring result can be compensated in an evaluation circuit, wherein the measuring electrodes and compensation electrodes are arranged on an oblong common line in such a manner that the compensation electrodes are located near at least one suction channel for the medium and the measuring electrodes are near the medium to be measured.

Abstract: A drilling fluid monitoring system and method includes a pump stroke counter providing an electrical signal representing the volume of drilling fluid pumped into a well, a flow sensing device providing an electrical signal representing the volume of drilling fluid flowing out of the well, fluid level an electrical measuring device providing an electrical signal representing the fluid level changes within a tank, and a device receiving the electrical signals emitted by the pump stroke counter, flow sensor and measuring device to indicate changes in the circulation of the well drilling fluid.

Abstract: A non-intrusive fuel measuring system particularly adapted for use in fuel tanks of diesel engines. The fuel measuring device may be utilized for measuring fuel level, fuel consumed, fuel flow rate, mass flow rate and other parameters. The fuel device comprises a capacitive probe, digital interface circuit means and data processing means. The capacitive probe is mounted within a conventional fuel gauge port of the fuel tank and does not interfere with normal flows of the recirculating diesel fuel.

Abstract: A plurality of conductive strips are situated on a receptacle for receiving a liquid which at least partially comprises dielectric material. A first electrode is commonly situated in spaced relation to each of the conductive strips and provides an electrical signal which is capacitively transmitted between the electrode and each of the conductive strips. A second electrode is commonly situated in spaced relation to each of the conductive strips and the electrical signal is capacitively transmitted between each conductive strip and the second electrode. The electrical signal being capacitively transmitted is modified as the liquid comes in proximity to each conductive strip whereby the level of the liquid is detected.

Abstract: A capacitance type fuel quantity gauge for a fuel tank which includes a probe capacitor in the fuel tank having a capacitance which varies in accordance with the fuel level and connected by one conductor to the output of a Lo-Z oscillator, two oppositely polled diodes connected together and to the capacitor, the positive diodes connected by another conductor to a signal conditioner and the negative diode connected to the one conductor by an inductance, the one conductor connected to the oscillator output and to the signal conditioner by a capacitor and inductance, respectively, so that the one conductor carries both the Lo-Z signal and the DC negative signal.

Abstract: A capacitance type fuel quantity gauge for an aircraft fuel tank including a probe capacitor whose capacitance varies in accordance with the level of fuel in the tank with a Lo-Z oscillator connected to the probe capacitor together with a pair of diodes for producing a DC output signal which is fed to signal processing circuitry, the diodes being disposed in a metal enclosure for isolation from interfering signals and the interconnecting leads to the diodes passing through feedthrough capacitors to block the entry of such interfering signals into the metal enclosure.

Abstract: A detection circuit for detecting discrete states of multiple capacitive sensing devices in a continuum provides an output which is linearly variable with respect to changes in the states of the sensing devices. The circuit uses either a time interval measurement or voltage measurement which has a magnitude which linearly corresponds to changes in the states of the sensing devices. By continuously monitoring these outputs, a continuous indication of discrete changes in the states of the sensing devices is detectable. In accordance with the present invention, a single drive electrode and a single sense electrode in combination with a plurality of sensing devices capacitively transmit electrical pulses in accordance with the various states of the sensing devices whereby the detection circuit detects discrete changes in a state of the sensing devices in a continuum.