Abstract: A method for making an acoustic wave device. The method has steps of providing a substrate suitable for acoustic wave devices and processing the substrate to provide a patterned metallization thereon. The patterned metallization includes an acoustic wave filter pattern. The method also has steps of measuring a sheet resistance associated with the acoustic wave filter pattern, determining a resistance of a test pattern associated with the acoustic wave filter pattern to provide a measured resistance and computing an estimated average linewidth for the acoustic wave filter pattern from the measured resistance and the sheet resistance.

Abstract: A method and device of readily detecting deterioration of a sample at low cost, which do not require any maintenance and monitoring of the sensor properties, and accordingly can decrease a load assigned to a system side. A conductive sensor having a pair of electrodes and a conductive film which is disposed between the pair of electrodes and is composed of a conductive material formed in a continuous region so as to connect the pair of electrodes at least electrically in its initial state is placed in an atmosphere where the sample is placed. The percolation transition of the conductive material of the conductive film occurs due to the grain growth thereof, accompanied by the deterioration of the inorganic material composing the sample due to the grain growth thereof. By monitoring the variation in electric resistance of the conductive sensor due to the percolation transition of the conductive material, the deterioration of the sample can be detected.

Abstract: A method and apparatus for measuring sheet resistance and thickness of thin films and substrates. A four-point probe assembly engages the surface of a film on a substrate, and the thickness of the substrate is determined from the point of contact between the probes and film. A measuring apparatus then outputs a voltage waveform which applies a voltage to probes of the probe assembly. An inverter inverts the voltage and provides the inverted voltage on another probe of the probe assembly, thus inducing a current in these probes of the four point probe and through the surface of the film. Two other probes measure a voltage in the film created by the current. The voltages on the current probes provide a voltage close to zero at the other probes, thus allowing these other probes to measure voltages with greater precision. The current created by the voltage waveform and the voltage created across the inner probes are measured for each voltage level of the waveform.

Abstract: A protective grounding jumper cable tester basically includes a housing, a direct current power supply, a pair of jumper attachment terminals, a pair of test probe terminals, a current applying circuit connected between the direct current power supply and the pair of jumper attachment terminals for applying a direct current through a jumper cable attached between the jumper attachment terminals, and a resistance sensing circuit connected to the test probe terminals for sensing resistance to the flow of the direct current through the jumper cable by using a pair of test probes connected to the test probe terminals.

Abstract: A centralized computer system in communication with a measurement system including a multi-point probe is programmed to analyze a plurality of conductor formations on a particular substrate, store information relating to an electrical characteristic of each conductor formation analyzed, and generate a report including information as to the variance in the electrical characteristic as a function of substrate position. To step through all of the conductor formations on a particular substrate, the computer may either be programmed to move a chuck holding the substrate under test relative to the points of the probe, or the system may include switching means disposed in an electrical path between the points of the probe and the resistance measurement system, enabling the computer to step through all of the conductor formations on a particular substrate by instructing the switching means to select points associated with only a single conductor formation for connection to the resistance measurement system.

Abstract: A system and method for testing underground electric cables, while in service, for active corrosion and degree of neutral loss. The method is conducted by applying a non-harmonic selected frequency signal to the neutral(s) of the underground cable connecting a pair of structures, e.g., power transformers, from a variable frequency generator of the system. The test is conducted by a surveyor wearing foot electrodes which contact the earth as the surveyor walks along the earth over the cable in close interval steps. At each step, direct current (DC) potentials are monitored by a voltmeter between a copper-copper sulfate electrode carried by the surveyor and brought into contact with the ground at each step and the transformer ground. The potential of the gradients between the foot electrodes at the selective frequency and at the native alternating current (AC) is also measured by the voltmeter. These measurements are recorded at a stationary location on a digital data logger and/or computer.

Abstract: Portable apparatus for inducing an alternating electrical gradient into an impounded liquid media and including, directionally sensitive, sensing apparatus for monitoring gradients established in the liquid to detect leaks at a liquid impermeable membrane. A conductive electrode floated on the liquid directs an amplified square wave signal into the liquid at a 5 to 15 hertz frequency relative to a ground reference established outside the membrane. First and second recessed sensors in a portable, hollow tubular probe are manipulated within the liquid. A portable signal processor monitors a changing signal between the sensors as the probe is moved in the liquid. The sensed and source signals are snychronously sampled, integrated, subtracted in a positive correlation arrangement, and amplified to reject common mode signals within the liquid.

Abstract: A protective grounding jumper cable tester basically includes a housing, a direct current power supply, a pair of jumper attachment terminals, a pair of test probe terminals, a current applying circuit connected between the direct current power supply and the pair of jumper attachment terminals for applying a direct current through a jumper cable attached between the jumper attachment terminals, and a resistance sensing circuit connected to the test probe terminals for sensing resistance to the flow of the direct current through the jumper cable by using a pair of test probes connected to the test probe terminals.

Abstract: A method for monitoring cracks in a sample of materials by applying the theory that the phase angle increases in the sample of materials being tested where cracks have formed. The method is performed by preparing a solution capable of forming cracks in the sample, preparing an auxiliary electrode, then making the sample and the auxiliary electrode contact with the solution, preparing a frequency generator connecting the sample and the auxiliary electrode respectively, choosing a frequency, and turning on the frequency generator with an alternating current of the frequency, monitoring the phase angle measured in the sample, and determining the formation of cracks in the sample by checking whether the phase angle measured in the sample increases with time.

Abstract: A standard resistor having a known resistance value is connected to one transistor in a drive IC. The drive IC has a plurality of transistors each controlling on/off switching of a heating element. The saturation voltage of each transistor is generally the same. One of a plurality of transistors is turned on, and a discharge time required for a capacitor to discharge via a standard resistor or via each heating element and lower its voltage to a predetermined voltage is measured. The resistance value of each heating element is determined from a ratio of a discharge time via each heating element to a discharge time via the standard resistor and the resistance value of the standard resistor. A difference between the standard resistance value and a resistance value of each heating element generates a bias heat energy error during bias heating and an image heat energy error during image heating.

Abstract: Seepage of water and other impurities into hermetically sealed on plastic encapsulated modules leads to eventual device failure, as conductor material corrodes and opens, or electromigrates to establish conductive trails across a substrate, shorting the conductors. To forewarn of such failure, a sensing device defined as a separate chip is packaged in the same module with the circuit to be checked, with pinouts that can be tested with a circuit that is usually external. The sensor makes use of the moisture-induced migratory behavior that causes the problem, using a highly migratory metal or alloy to define paired electrodes spaced as closely as 2 micrometers apart. The metal of the electrodes undergoes rapid ionization and migration in the presence of trace amounts of moisture, dissolved ionic contaminants, and a small potential difference across the electrodes.

Abstract: A method and apparatus for measuring the electrical resistance of a circuit energized with AC power. The invention imposes a known DC current in the circuit under test and senses a resulting DC voltage drop that corresponds to the resistance of the circuit. The invention senses AC overvoltage conditions in the circuit under test and electrically isolates the measuring circuit from the circuit under test.

Abstract: A method for indicating electrical breakdown in a nonconductive water coog system for high power electrical equipment at an early stage so as to avoid the danger of accidental faults. The method utilizing a small resistor to generate a detectable voltage when the resistance of the water breaks down, thus degrading from a nonconductive to a conductive state. Once a voltage is detected, the electrical equipment is shut down until the cooling water is made nonconductive again. An apparatus for indicating electrical breakdown in a water cooling system for high power electrical equipment is also provided.

Abstract: Disclosed is a combined "streak-detector" and "ink-level flow detector" on opposite sides of a single printed circuit board; each detector comprising a pair of parallel printed circuit segments adapted to be "shorted" by interposition of conductive ink and coupled to register this event in an associated detect-logic stage.

Abstract: A method for detecting and locating constrictions in electrical conductors of predetermined normal cross-section. A test or reference resistance reading is made and stored pursuant to application of a test current, a stress current is applied, heating any constriction in the conductor, a resistance reading is taken immediately after the heating has taken place and the respective resistance readings are compared to determine the presence or absence of a constriction or weak spot. The disclosure also includes an exemplary circuit to implement the method. In an alternative embodiment, a second test current is applied immediately after the stress current.

Abstract: Disclosed is a combined fluid-stream misdirection detector and fluid-level flow detector on a single printed circuit board; each detector comprising a pair of parallel printed circuit segments adapted to be "shorted" by interposition of conductive liquid and coupled to register this event in an associated detect-logic stage.

Abstract: A system for testing the integrity of critical circuitry, lines and wires employs a differential amplifier having an input resistance R.sub.in and a feedback loop with a resistance R.sub.fb. The critical wires being tested must be a signal wire series connected to a resistance R.sub.S, which is in turn series connected to a return wire. A test voltage source is connected to the noninverting input of the differential amplifier. The signal wire is connected to the inverting input of the differential amplifier. The test voltage source is activated by a test control unit. When activated, the test voltage source provides two distinct outputs allowing computation of a test gain in the presence of other functional signals. The test control unit measures the output V.sub.out of the differential amplifier and computes the value of the test gain. A break in either the signal wire or the return wire will result in a test gain of 1. If the signal and return wires are shorted, the test gain will be 1+R.sub.fb /R.sub.in.

Abstract: Procedures and apparatuses for determining the integrity of a geophysical barrier are provided. In particular, an electropotential gradient is established across the barrier in an attempt to drive ionic species through the barrier. The resulting ionic transport results in a current which can be measured between the electrodes, and which can be correlated to the integrity of the barrier. The location of a leak in the barrier can be determined by the use of an electromagnetic sensor which detects an anomaly in the flux field associated with the current.

Abstract: A method and apparatus is provided for monitoring and locating the presence of fluids leaking from a containment vessel. A multiplicity of probes having conductive affinity are strategically oriented adjacent the containment vessel and periodic surveillance is made relying on conductivity of the sub-surface media within which the probes have been placed, such that disturbances in the conductivity correlate with migration of the leaking fluid. The method and apparatus may be utilized to detect migration of salinated fluids into a region where previously less salination existed. The probes can be oriented adjacent a surface and yet determine a conductivity of the sub-surface media at a plurality of different pseudo-points having varying depths. The presence, location and extent of a leak can thus be monitored.

Abstract: A method for monitoring cracks in a sample of materials by applying the theory that the phase angle increases in the sample of materials being tested where cracks have formed. The method is performed by preparing a solution capable of forming cracks in the sample, preparing an auxiliary electrode, then making the sample and the auxiliary electrode contact with the solution, preparing a frequency generator connecting the sample and the auxiliary electrode respectively, choosing a frequency, and turning on the frequency generator with an alternating current of the frequency, monitoring the phase angle measured in the sample, and determining the formation of cracks in the sample by checking whether the phase angle measured in the sample increases with time.

Abstract: A test method whereby a high current is supplied to a first pin of an integrated device to be tested, and the variation in the voltage drop between the first pin and a second pin on the device to be tested is determined; the two pins being connected to two pads in turn connected, inside the device to be tested, by a low-voltage-drop path. The variation in the voltage drop of the device to be tested is compared with the measured nominal variation of an undoubtedly sound device of the same type, to determine any excessive deviation indicative of deficiency. The supply current in fact results in power dissipation, local heating and, consequently, a variation in the resistance of the connecting wires or of the die attachment to the lead frame, the extent of which differs according to whether only one or both of the wires of a two-wire connection to be tested are present, and according to whether the die is attached properly, poorly or badly to the lead frame.

Abstract: The present invention concerns a measuring device, notably for measuring the level of glucose in blood, intended to be used with a removable sensor comprising at least one active zone. In particular, the invention concerns the electrical connection between the measuring device and the removable sensor. Each electrical contact surface of the removable sensor is connected to two electrical contact organs to enable the condition of the electrical contacts between these electrical contact organs and the corresponding contact surfaces to be checked before a measurement is carried out.

Abstract: A test fixture is provided for testing the resistance associated with contamination material on the surface of electrical contacts mounted to a printed circuit board. A probe used to engage the contacts consists of first and second conductive probe segments which form a sandwich about a layer of insulating material. A current source provides a constant alternating current which is applied across the first and second probe segments. Circuitry is provided for amplifying the alternating current voltage developed across the first and second probe segments in response to the constant current. Circuitry is provided for rectifying the amplified alternating current voltage to provide a direct current voltage which is proportional to the measured resistance of the contact engaged by the probe. Data corresponding to the bulk and contact resistance associated with the clean contact is stored in memory of a computer.

Abstract: Apparatus and method for determining the amount of oxidative and hydrolytic degradation in the surface of a highly resistive material, such as a polymer. A special probe provides an annular resistance on the surface of a sample of the material. The voltage drop across the sample determines the input to a meter circuit. A guard circuit has an applied voltage that is substantially the same as the voltage at the meter circuit input. This circuitry permits a very low voltage source to be used.

Abstract: A method and system for rapidly connecting and rapidly disconnecting a large number of point contacts onto a pipe surface for detecting defects in pipe and other structures is taught. The method and system involve independently pressing a plurality of sharply pointed pin contacts onto the pipe surface by a means, such as a spring. The system comprises a plurality of electrodes each having a plurality of pins, as illustrated seventeen (17) pins, arranged in a pattern. Each of the plurality of pins is held in a conforming opening in the electrode and is urged by springs means, such as a coil spring, against the surface of the structures. Each of the plurality of pins (sixteen (16) current pins and one voltage pin) are individually connected to a power supply and sensing apparatus. This system and method has proved operable for detecting defects in structures, such as pipe.

Abstract: An improved error detection for microprocessor-based transmitters in two-wire process control loops operating in the process control industry. In particular, techniques are shown which are useful in solving malfunctions or failures of microprocessor-based transmitters. When the transmitter is energized, the impedance of the process loop cabling is resolved and stored, displayed or transmitted as desired. The loop impedance is used to calculate potential of a power supply used to power the control loop. This information is used in testing the two-wire loop.

Abstract: Flaws in a seam of a shielded enclosure are detected by forcing a current to flow over the shielded enclosure and the seam. A small portable, hand held, compact device is placed over the seam. The device has a high impedance path which forces current to flow over the shielded enclosure and the seam. Two electrodes are resiliently pressed towards the shielded enclosure. The current flowing across the seam produces a voltage which the first and second electrodes and a detector use to detect flaws in the seam.

Abstract: A system and method of automatic, in-line electrical quality control of a carbon anode including detecting internal flaws in the carbon anode by measuring an eddy-current loss of the carbon anode and determining intrinsic resistivity of the carbon anode by measuring resistivity of the carbon anode and determining the electrical quality of the carbon anode according to the measured eddy-current loss and the measured resistivity.

Abstract: An inflatable restraint system includes a diagnostic circuit which measures the resistance of an external deployment path containing a squib. The circuit supplies a test current through the path and measures the voltage across the path which is monitored by a microprocessor. A vehicle battery supplies the power to the system and is connected to a constant current source in series with the external path to provide the test current. A current limiting device between the external circuit and ground comprises a current sink allowing a maximum safe current in the external circuit in the event of inadvertent application of battery voltage to the external circuit and, during a normal resistance test, imposes only a small voltage drop on the test current circuit.

Abstract: A network-under-test of a device is tested relative to other networks of the device by probing the network-under-test with a probe; generating a voltage which is applied across the network-under-test via the probe for developing a transient voltage between the network-under-test and the other networks of the device for stressing leakage resistance between the network-under-test and the other networks; and determining if the stressed leakage resistance is acceptable for determining integrity of the network-under-test relative to the other networks of the device.

Abstract: A method and apparatus for testing circuit boards uses a pair of probes to contact the various nodes on the circuit board. A single one of the pair of probes may be used to deposit a charge at a being tested net and checking for the presence of a charge at subsequent nets to determine whether a short condition exists. Moreover, the pair of probes is used to contact two nodes of a network being tested to measure the resistance within the network being tested; the measured resistance being compared to a nominal resistance, to determine whether an open condition exists. In addition, the pair of probes may be used to measure the resistance between networks in order to verify or determine whether a short condition exists between networks.

Abstract: A device for detecting attempts at fraud by connection of an electric feed line (13) to an apparatus for reading and writing on a chip card (3) essentially comprises a resonance unit (6) coupled to a contacting element (2) of the apparatus, and a measuring device (7). In the resonance unit (6) a generator (4) which is coupled to a resonator (1) by way of an impedance converter (5) generates a standing wave. The feed line (13) disturbs the properties of the resonator (1), that being detected by the measuring device (7) and evaluated.

Abstract: A system and method of detecting the end of useful life in a gas sensor cell having a cathode, anode, one of which is consumable, and an electrolyte, and a circuit for controlling the flow of gas to the cell and a sensing resistor and circuit connected to said cathode and said anode, the consumable electrode is provided in the form of a plurality of discrete elements which are sequentially connected in circuit with the other electrode, sensing resistor and circuit. A drop in current between respective ones of the consumable electrode is an indication of the approach of the end of the useful life of the gas sensor.

Abstract: Apparatus and method are disclosed for performing testing and fault isolation of high density passive boards (e.g. unpopulated circuit boards) and substrates. Using a small number of moving probes, simultaneous network resistance and network capacitance measurements may be performed. Thus, test time is minimized by eliminating the need for electrical switching and/or excessive probe movement during the test of a normal circuit board network. Simultaneous network capacitance and network leakage measurement are also achieved using phase-sensitive detection. Dual-frequency measurement techniques allow the measurement of both the capacitance value and resistance value of a leakage path between a network being measured and an unknown network. Any leakage resistance between a network under test and ground or power planes within the circuit board may also be determined from the measurements.

Abstract: A technique and apparatus for measurement of resistances of 0.025 ohm and ss without disconnection from the circuit. The invention is used for measurement of degradation in cable shields. The method can also be used for measurement of junction resistances in high current circuits such as auto starters. The invention allows measurements to be made with the circuits connected so that the faults are present in the measurement setup. The method includes inductive coupling of long duration repetitive current pulses onto the circuit under test, measurement and display of induced current and voltage pulses, and display of induced current and voltage pulses on an oscilloscope.

Abstract: Disclosed is a combined fluid-stream misdirection detector and fluid-level flow detector on a single printed circuit board; each detector comprising a pair of parallel printed circuit segments adapted to be "shorted" by interposition of conductive liquid and coupled to register this event in an associated detect-logic stage.

Abstract: This invention relates to a method of testing multi-channel array pulsed droplet deposition apparatus (10) comprising a multiplicity of parallel channels (12) each with pulse imparting means for expelling droplets therefrom. The apparatus is located opposite a test module (20) having detecting elements (21) with channels of the apparatus opposed and close to the respective elements. Coupling fluid (23) fills the channels (12) to be tested and the space between the apparatus and the test module. Test signals are applied to impart energy pulses to the fluid in the channels opposite the detecting elements so that signals are passed to those elements by way of the fluid which are evaluated to assess the channel performance. Various forms of the detector elements and the apparatus are disclosed.

Abstract: A method for monitoring the soundness of the protective covering on underground metal structures subjected to cathodic protection, based on the electrical resistance offered by said covering, and consisting of modulating the imposed cathodic protection current and measuring the corresponding variation in potential due to the ohmic drop, said resistance being obtained from the ratio of the variation in potential to the modulation current.

Abstract: An impending failure of an electronic circuit caused by aerosol deposition is detected by using a test circuit including a plurality of conducting paths, aerosol deposition enhancement means, controllable means to control the aerosol deposition enhancement means, conducting path isolation sensing means to measure the isolation of the conducting paths and control means to supply a control signal to the controllable means and warn of impending test circuit failure responsive to conducting path isolation. In addition, the apparatus includes deliquescence enhancement means which is controllable and responsive to the control signal from the control means.

Abstract: The monitoring circuit for a sensor connected to a low-potential and high-potential line, such as a thermal element, includes a high-resistance pulldown resistor connected between the high potential line and ground, a offset voltage source connected to the low-potential line to supply an offset voltage higher than a minimum transistor control voltage; first and second testing transistor shaving control electrodes connected to respective ones of the lines via resistor arrangements; and a third testing transistor having a control electrode connected to an output of a p-type channel FET having a control electrode connected to one of the two sensor lines. Whether the operating state of the sensor is normal, involves a short circuit to ground or the supply voltage or an interruption of the sensor lines is determined by monitoring the switching states of the first testing transistor and a series combination of the second and third testing transistor.

Abstract: A system and a method for testing the integrity of interconnection networks on a circuit board or substrate are disclosed. To test the continuity of a being tested network, two probes are used. To test the integrity of the being tested network, as it relates to other nets on the circuit board, a rectangular pulse is provided to the being tested network, and a signal in response to the stimulus pulse, provided across an external capacitor and resistor connected to the reference plane of the circuit board or substrate, is sampled by a transient analyzer. The leading edge of the thus sampled response signal provides an indication of whether the being tested net is acceptable, opened, shorted, or has a high leakage resistance to another net.

Abstract: In a non-destructive method for the detection of surface cracks in metals, an eddy current is induced in the surface region of a workpiece under test, at a frequency sufficiently high to generate an alternating magnetic field solely in the skin region of the workpiece. That alternating surface magnetic field is interrogated by means of a relatively small electro-magnetic induction sensor, having regard to the overall area of the induced magnetic field. The sensor provides a voltage output which is analysed, preferably in real time, to yield an indication sensor. Also described is a probe for performing such a method.

Abstract: A crack length sensor is fabricated in a rectangular or other geometrical form from a conductive powder impregnated polymer material. The long edges of the sensor are silver painted on both sides and the sensor is then bonded to a test specimen via an adhesive having sufficient thickness to also serve as an insulator. A lead wire is connected to each of the two outwardly facing silver painted edges. The resistance across the sensor changes continuously as a function of the crack length in the specimen and sensor.

Abstract: A method for modeling a conducting material sample or structure system, as an electrical network of resistances in which each resistance of the network is representative of a specific physical region of the system. The method encompasses measuring a resistance between two external leads and using this measurement in a series of equations describing the network to solve for the network resistances for a specified region and temperature. A calibration system is then developed using the calculated resistances at specified temperatures. This allows for the translation of the calculated resistances to a region temperature. The method can also be used to detect and quantify structural defects in the system.

Abstract: The electrolytic resistivity leak detector comprises the method of electrical resistivity to measure the gradual intrusion of aggressive chemicals into the wall of a plastic or fiber reinforced plastic vessel. This device and method includes the use of electric sensors within the wall of the vessel. The sensors provide an electrical circuit as the chemicals permeate through the wall and make contact with the sensors. A microammeter is included as an instrument to monitor and register the degree of electrical resistivity caused by the chemical intrusion.

Abstract: A method and apparatus for carrying out the checking of the state of wear of a covering fabric in a driving belt (2) mounted on a plurality of pulleys (3, 4, 5) by measuring the electric resistance variations of the belt fabric. The apparatus provides that at least two of the pulleys (3, 4, 5) should be electrically insulated with respect to each other and connected to an electric circuit (20) designed to apply an electric voltage to said pulleys in order to carry out the measuring of the electric resistance of the fabric exhibited by belt stretches (A, B) comprised between the pulleys themselves. The electric resistance thus found lends itself to be compared with predetermined resistance values corresponding to different states of wear of the belt (2) fabric. The work surface of the belt (2) is coated with an electrically conductive fabric (12) acting by contact on the pulleys (3, 4, 5) and having characteristics of tensile strength.

Abstract: A method of alternating current potential drop measurement is provided in which the flow of the current in the specimen is laterally confined by passing the applied current externally over and in the immediate proximity to the surface of the specimen. To this end, a voltage probe is provided having a longitudinally extending isolated conductor which is connected to one current contact of a pair of current contacts. In use, this is arranged to provide an external flow path for current applied to the specimen. The isolated conductor is arranged to lie adjacent to the voltage probe contacts. For convenience of mounting, the conductor may be implemented as a conductive track on a printed circuit board. The track may also be bifurcated in order to accommodate one or more short lengths of conductor which can be used to form one or more compensating inductive loops which latter may be wired to afford cancellation of picked-up induced emf.

Abstract: A method for inspecting a printed circuit board having through-holes filled with conductive paste and having a pair of current measurement lands and a pair of resistance measurement lands. The pairs of current measurement lands and resistance measurement lands are used to measure voltage and current through the through-holes using the four-probe method, thereby preventing incomplete inspection of printed circuit boards and improving the dependability of tests on the packing conditions of the conductive paste in the through-holes.

Abstract: A technique and apparatus for measurement of resistances of 0.01 ohm and s without disconnection from the circuit. The invention is used for measurement of degradation in cable shields by measuring the droop caused by circuit resistance in an induced current pulse in the undisconnected circuit. The method can also be used for measurement of junction resistances in high current circuits such as auto starters. The invention allows measurements to be made with the circuits connected so that the faults are present in the measurement setup. The method includes inductive coupling of long duration repetitive current pulses onto the circuit under test, measurement and display of induced current pulses, and display of induced current pulses on an oscilloscope.

Abstract: A strain, crack and acoustic emission conformal structural health monitoring circuit with integral preprocessor and provisions for connectorization to a central processing system includes a strain gauge (11) having crack sensing traces (21), (23), and (25) sandwiched between a bottom layer (13) and a top layer (39). Strain gauge (11) is attached to an aircraft structural surface (51) to be monitored. Successive alternating layers of interconnecting sheet layers (61) and dielectric layers (63) joined by successive layers of non-structural adhesive (65) are added sufficient to effectively attenuate any stress forces, and forces directly from the strain and cracks, from traveling upward from the aircraft structural surface (51).