Abstract: Pressure sensing diaphragms comprise a cylindrical or spherical crystalline member in which an internal cylindrical or spherical chamber is provided. In the internally loaded embodiments, a fluid is introduced into the chamber and the pressure exerted by the fluid causes generally tensile stress in the region of the diaphragm generally about the chamber. In the externally loaded embodiments, the diaphragm is immersed within the fluid and the pressure exerted by the fluid causes generally compressive stress in the region of the diaphragm generally about the chamber. For each of the embodiments, the stresses arising cause certain mechanical and electrical properties of the crystalline material to change. The change in these properties is detected by observing the frequency behavior of one or more oscillators whose frequencies of operation are controlled by respective surface acoustic wave devices provided in the regions of elastic deformation.

Abstract: Provided is a pressure sensor of semiconductor type, having a semiconductor diaphragm, wherein the diaphragm comprises at least one of thin wall parts and at least one of thick wall parts, and defines therein recesses formed in the lower surface of the diaphragm below the thin wall parts, piezoresistance elements are laid on the upper surface of the diaphragm near the thin wall parts, and a supporting member is sealingly jointed to the thick wall parts at the lower surface of the diaphragm, so that the recesses are sealed and confined so as to prevent high pressure fluid from blowing off when the thin wall part is broken.

Abstract: A pressure sensor having a semiconductor body is disclosed. The sensor comprises a substrate of a compound semiconductor and an epitaxial layer of a mixed crystal, in which different conduction band minima with different effective masses are closely adjacent energywise, particularly from the mixed crystal series gallium-aluminum-arsenic with the composition Ga.sub.1-x Al.sub.x As, in which the aluminum concentration is 0.19.ltoreq.x.ltoreq.0.43. The sensor described has a simplified design and predetermined pressure ranges can be set by varying the concentration of the crystal constituents.

Abstract: A broad bandwidth electro-mechanical transducer is shaped into a wedge of varying thickness, with a plurality of PZT elements or sheets embedded in an inactive polymer. The transducer is driven at frequencies corresponding to resonance of the thickness dimensions. The piezoelectric elements with different thicknesses are decoupled mechanically from one another using an inactive polymer of low Q so as to prevent interference.

Abstract: A semiconductor device comprising a semiconductor substrate having at least two resistor elements, wherein said resistor elements have a specific resistance ratio relative to each other, an insulation layer formed on a major surface of said semiconductor substrate, a circuit wiring layer formed on said insulation layer covering a portion of said insulation layer which corresponds to at least one of said resistor elements, and a dummy wiring layer made of the same material as that of the circuit wiring layer and formed on the insulation layer covering that portion of said insulation layer which corresponds to the resistor element or elements not covered by said circuit wiring layer, and where the ratio of an overlapping area of one resistor element in said circuit wiring layer and an overlapping area of the other resistor element and said dummy wiring layer is equal to a resistance ratio of said resistor elements.

Abstract: A fuel injector has a lift sensor in the form of a cylindrical piezoelectric ceramic member having metal film electrodes on each side thereof and which is sandwiched between an insulated terminal element having a flat surface abutting one side of the piezoelectric element and a flat ground plate formed with projections which projections engage the wall of a bore in which the piezoelectric element is disposed so as to both hold the element in place and establish an electrical connection between the housing in which the bore is formed and the second side of the piezoelectric element. A spacing shim having a flat surface abutting the ground plate engages one end of a spring which biases the valve element of the fuel injector toward a closed position.

Abstract: A pressure transducer employing a semiconductor diaphragm having a convoluted central section surrounded by a rigid peripheral section. The convolutions are a series of concentric grooves formed as squares producing a square nonplanar diaphragm in the preferred embodiment. The convolutions are formed on the semiconductor wafer by an anisotropic etch. Piezoresistive devices are diffused into the diaphragm in the peripheral region to form a bridge array. The transducer structure thus formed is capable of producing a linear and large magnitude voltage signal in response to a relatively small applied pressure or force.

Abstract: In an apparatus for testing lubricating or material properties, two clamping assemblies are pressed together. Each clamping assembly has a clamping surface facing the clamping surface on the other assembly. The first clamping surface has two annular roller paths with the axes of the paths spaced apart. The second clamping surface has one annular roller path intersecting the roller paths on the first clamping surface. Four balls roll in the roller path of the second clamping surface with two of the balls rolling in one of the roller paths of the first clamping surface and the other two balls rolling in the other roller path of the first clamping surface. The clamping assembly with the second clamping surface oscillates back and forth relative to the clamping assembly with the first clamping surface. The pulling force developed by the movement of the balls is measured as an indication of the properties of a lubricant filled into the roller paths or of the materials of the balls and the roller paths.

Abstract: A knock detecting apparatus for detecting the occurrence of knocking in an internal combustion engine by detecting variations in the pressure of engine cooling water. A sealed double diaphragm structure is formed by a first diaphragm which is directly responsive to variations in the cooling water pressure and not resonant at the knock frequencies and a second diaphragm which is resonant at the knock frequencies. A noncompressible fluid is contained in the sealed double diaphragm structure between the two diaphragms. Pulsations of the second diaphragm, resonant at the knock frequencies, are detected by a magnetic device or a piezoelectric device operative to output an ac signal.

Abstract: A transducer operating on the strain gauge principle having integral temperature compensation and calibration resistors is disclosed. In the presently preferred embodiment, a silicon dioxide layer is disposed on a silicon substrate. Platinum alloy strain gauge resistors are disposed on the silicon dioxide layer and form a Wheatstone bridge circuit configuration. Laser trimable chromium nitride, platinum alloy and gold temperature compensation and calibration resistors are formed on the silicon dioxide layer from the same films used to form the strain gauge, adhesion layers, conductors and bonding pads, to permit the transducer to be calibrated such that its electrical characteristics are in conformance to specified tolerances when the transducer is subjected to temperature variations.

Abstract: A vehicle equipped with a spring and shock absorber suspension has a piezoelectric wafer interposed between the spring and a part of the vehicle in such manner as to cause the wafer to be subjected to a compressive or decompressive force in response to relative vertical movement of the vehicle part and the suspension. The application of such force to such wafer results in the generation of an electrical current pulse which is transmitted to an indicator mounted within the vehicle in a position to enable the driver to monitor the condition of the shock absorber.

Abstract: A vortex flow metering apparatus comprising a sensor unit having first and second piezoelectric sensors selectively arranged in the concavity or a vortex generator having a measured fluid produce a Karman's vortex according to its velocity, a first conversion amplifier to which a signal from the first piezoelectric sensor is applied, a second conversion amplifier to which a signal from the second piezoelectric sensor is applied, an operator circuit to which outputs from the first and second conversion amplifiers are applied and which through addition or subtraction and other operations, removes noise components due to disturbance vibrations. The first and second piezoelectric sensors are selectively arranged at two points whereat stress distribution of the noise component due to disturbance vibration and stress distribution of a signal component due to vortex dynamic lift are different from each other.

Abstract: To provide a high output signal, a strain bolt (12, 12a) is screwed (13, 13a) into a tapped bore extending through the housing wall (10), the bolt having a bore (14) extending therethrough, and a region or zone (18) of reduced outer diameter to form a comparatively thin-walled tubular or sleeve-like region which, upon application of fluid, typically liquid fuel pressure within the housing, tends to elongate the portion of the bolt of reduced wall thickness; a piezo-ceramic transducer assembly, preferably formed of two oppositely polarized disks (23, 24) is clamped between an integral head (FIG. 1: 19) or a separate clamping nut (FIG. 2: 31) and the outer wall of the housing, or an abutment surface formed by the upper surface of an intermediately positioned tightening nut (FIG.

Abstract: This process involves detecting piezo-electric potentials which are characteristic of a mechanical strain exerted on a long rigid member made of organic material. For this purpose, the potentials at two points spaced apart on this member are measured by means of two operational amplifiers CI.sub.1 and CI.sub.2 in order to obtain a signal which is characteristic of the stress rather than of its derivative and these signals are processed by means of analog operators OA.sub.1, OA.sub.2, OA.sub.3 in order to identify the bending .DELTA. F and torsional T stresses which are then compared with reference values RT, RF in order, for example, to trigger a signal. This process can be used for opening a safety ski binding.

Abstract: A semiconductor pressure sensor has an encased sensor unit, and a metal casing having a pressure introduction pipe and housing therein the sensor unit. The metal casing has therein synthetic resin poured by potting to fix the sensor unit securely in the metal casing. Through-type capacitors are affixed to the metal casing. The sensor unit produces an electrical signal transmitted out through the through-type capacitors and over lead wires connected to the through-type capacitors. With this arrangement, the semiconductor pressure sensor is protected against electromagnetic interference (EMI), and moisture is prevented from entering the metal casing.

Abstract: An apparatus for sensing the condition of a pressurized fluid including a semiconductor chip having a diaphragm portion adapted for exposure to the pressurized fluid and an adjacent terminal portion adapted for connection to external circuitry for providing a measurement of the condition of the fluid. The semiconductor chip has sensing elements formed within the diaphragm portion and conductor elements in electrical contact with the sensing elements formed within and extending from the diaphragm portion to the terminal portion. A fluid barrier is provided for isolating the diaphragm portion from the terminal portion to prevent the terminal portion from being exposed to the pressurized fluid, while permitting pressurized fluid to contact the diaphragm portion so that the condition of the pressurized fluid can be sensed.

Abstract: In a flow meter of the traveling wave type having a flexible undulating membrane, velocity detecting means is utilized to determine the velocity of propagation of the traveling wave associated with the undulating flexible membrane between at least two known locations on the flexible membrane. The velocity of propagation is proportional to the volumetric flow rate of fluid through the flow meter.

Abstract: This specification discloses an apparatus and method for providing electrically distinguishable signals occurring as a function of the position of a moving element. The electrical signals are generated by a piezoelectric apparatus and can be used to determine a variable such as revolutions per minute of the movable element. Particular ones of the electrically distinguishable signals can be used for initiating a function such as the firing of the spark plugs.

Abstract: A transducer device for measuring mechanical values on hollow bodies, such as the internal pressure in pipes, by detecting deformation in the outer surface thereof, comprises a housing for removably enclosing the hollow body whose outer surface deformation is to be measured and at least one elastic sensor element which is capable of being elastically and at least indirectly pressed against the outer surface of the hollow body by an elastic endorsing element and capable of stretching due to the deformation of the hollow body due to frictional contact therewith. The endorsing element is combined with the sensor element and/or at least a part of the housing into one piece, whereby manufacture and adjustment of the transducer device are simplified.

Abstract: For the purpose of converting the mechanical energy of surface waves on bodies of water, a power generating piezoelectric structure (10) is provided comprising piezoelectric material members, preferably in the form of one or a laminate of sheets (14) of such material, each sheet having an electrode (24) on opposite surfaces thereof. Each pair of electrodes and the piezoelectric material therebetween define a power generating element, each of which is preferably dimensioned, relative to the wave lengths of selected waves on the body of water in which the generator is to be used, for increasing the efficiency of power conversion. A support means (12) is provided for maintaining the structure in a preselected position within and below the surface of the water. Preferably, the piezoelectric generating elements are flexible and are supported in such manner to allow flexure thereof in response to movement of the surrounding water.

Abstract: An acceleration pickup or detector which is provided with a cable outlet located at right angles to a direction of the main vibrations to be detected, especially for detecting knocking signals in internal combustion engines. Connecting elements linking leads of the connecting cable with the acceleration pickup are disposed on a side of the acceleration pickup opposite to the axis of symmetry with respect to the cable outlet. An additional mass is provided on the side of the connecting elements, which mass forms a common counter mass with the connecting elements for the connecting cable.

Abstract: A stress sensitive semiconductor die and housing means therefore comprising a ceramic base member having a recessed portion and a shoulder portion around the periphery. A washer-like support member is positioned within the recess, one face of which is bonded to the base member, said support member having a central aperture. A stress sensitive semiconductor die is bonded to the other face of the support member with the center of the die being in substantial register with the aperture in the support member. Finally, cover means are attached to the shoulder portion.

Abstract: A transducer device for measuring mechanical values on hollow bodies, which comprises a housing and at least one elastic sensor element mounted in the housing. The element is so formed as to be connected with at least two points of the housing and has a free length between these connecting points so as to be stretched over the surface of the hollow body when the transducer device is attached.

Abstract: The invention relates to elastic surface wave pressure gauges.The gauge comprises a plate on which are located the electronic components of the gauge and a pressure sensor grouping the electromechanical elements on a header having connecting pins. The header is provided with a pressure inlet which traverses the plate.The invention is also applicable to the measurement of the pressures of fluids in order to optimize the supply to internal combustion engines. The pressure inlet is made of a rigid metal header and separately grounded for shielding of the surface acoustic wave electrodes to prevent "pull-in" where the oscillators inadvertantly lock on the same frequency.

Abstract: A vibratory, force transducer includes a pair of elongate, generally parallel bars coupled together at their ends in a type of double-ended tuning fork arrangement. The bars each have a thickness of t, a width of w and a length between fixed ends of L. The distance separating the points where the bars are coupled together is m. Apparatus is provided to cause the bars to vibrate in a transverse direction and in substantially 180.degree. phase opposition. Apparatus is also provided for determining the frequency of vibration of the bars so that when the bars are subjected to either compressive or tensile forces along the longitudinal axis of the bars, the magnitude of such forces can be readily determined by simply determining the magnitude of the frequency change. The values of w and t are selected so that 0.

Abstract: Disclosed is a method and means to increase or decrease, on demand, the drag exerted by a fluid on a boundary. The boundary comprises a surface portion of a structure enclosing a moving fluid or may comprise a portion of the outer surface of an object moving through the fluid. Drag is varied by means of a set of piezoelectric sensors and an accompanying set of piezoelectric driver elements arranged in close proximity to one another at the boundary and electrically interconnected so that the pressure exerted by the moving fluid is sensed by one or more sensors and converted to an electrical signal which is then transformed into an electrical drive signal which is applied to one or more driver elements to cause a flexing of the driver element(s) in a predetermined direction so that drag is either reduced by moving the driver(s) away from the fluid or increased by moving the driver(s) towards the fluid.

Abstract: A rotation angle detecting device with a pair of variable capacitors which are formed with a rotating object, i.e. a movable electrode, and two stationary electrodes disposed around the rotating object, so that the capacitors operate in a differential mode. Alternatively, the central electrode can be stationary while the two outer electrodes move with the rotating object. The capacitors are combined with oscillators, so that a signal varying with the rotation of the rotating object is provided by obtaining the difference between the output frequencies of the oscillators.

Abstract: A stress sensitive semiconductor unit comprising means for supporting a very long elongated cylindrical support member having a stress sensitive semiconductor die bonded to one end thereof, a plurality of metal elongated terminal pins held in rigid hermetically sealed insulative relationship with said header, first and second insulative spacers having central bores sized larger than the outer diameter of the glass tubular member and positioned in axial proximity to one another with the first spacer being abutted against the header and with the second spacer being sized so that the outer axial end thereof is substantially in planer register with the active face of the semiconductor die, the ends of the terminal pins being mechanically and electrically connected to conductive areas or portions on the face of the second spacer.

Abstract: A flowmeter incorporating a pressure differential member creating a differential pressure between an upstream flow path and a downstream flow path of a pipe. The flowmeter has pressure connecting lines located on either side of the pressure differential member and constituted by conduits issuing on the surface of the device. The pressures in the upstream and downstream flow paths are transferred to a differential pressure sensor constituted by two elastic surface wave oscillators supplying signals, whose frequency is proportional to the pressures. The signals are then transmitted to a mixer, whose output supplies a beat signal, whose frequency is equal to the difference of the frequencies of the signal supplied by the oscillators. This frequency difference is directly proportional to the differential pressure.

Abstract: A sensor for sensing a property, such as vibration, of a body, which includes an outer hollow tubular sensor casing, having open and closed ends and provided on its outside side with a protuberance adapted for connection to said body, such as by screwing; a base mounting plate mounted across the inner space in the tubular casing; a sensor element for producing an electrical output signal, mounted on the side of the base mounting plate remote from the open end of the tubular casing; an end closing member which closes the open end of the tubular casing; and an electrically conducting sensor lead structure, connected at its one end to the sensor element for receiving a sensor output electrical signal therefrom, and passing, in order therefrom, through an aperture in the base mounting plate, and through an aperture in the end closing member, to the outside of the sensor.

Abstract: A piezoelectric, acoustic vibration detecting element is positioned in a fluid flow to be measured so as to be moved according to the intensity of the fluid flow away from a source of acoustic vibration. As the distance between the acoustic vibration source and the element increases with increasing fluid flow intensity, reducing the acoustic pressure on the element, the magnitude of an electrical output signal produced by the element decreases providing a detectable measurement of the change in the fluid flow intensity.

Abstract: A semiconductor pressure sensor employing the piezoresistive effect of single crystal silicon resistors to measure the flexure of a semiconductor diaphragm. In the preferred embodiment, a Wheatstone bridge composed of a first pair of resistors disposed on the center of the diaphragm and a second pair of resistors disposed on the periphery of the diaphragm is employed. Due to the nature of the diaphragm flexure, the first and second pairs of resistors exhibit piezoresistivity in opposite directions enabling pressure measurement with greater sensitivity. The diaphragm is mounted on and supported by a silicon clamp ring. The diaphragm and the clamp ring together form a unitary semiconductor structure.

Abstract: The present invention relates to a pressure gauge of the type comprising a piezoelectric substrate one face of which is polished and carried two delay lines using interdigital combs forming part of two oscillators whose output signals are mixed. The gauge comprises a two-part case communicating with a pressure gauge inlet, a piezoelectric wafer fixed by its edges to a support, the whole forming a sealed dividing wall with respect to the fluid contained in the inlet, this latter exerting its pressure on the non-polished face of the wafer. A printed circuit carrying the required electronic circuits is connected to the delay lines and inserted between the two parts of the case. A protection device may be provided for avoiding contact between the polished face and polluted air, while maintaining constant pressure on this face.

Abstract: A listening device for pinpointing water leakages, which includes a manually operated rod having a handle at one end for manually positioning of the listening device. An acoustic pick-up apparatus is mounted on the other end of the rod, and it comprises a ceramic audio tone transducer which is operatively connected to an amplifier-receiver which has a level meter on which visual leak signals may be seen. The acoustic pick-up apparatus is also connected to a head phone set to allow hearing of the leaks. The transducer includes a brass diaphragm directly attached to a threaded stud for mounting in the rod.

Abstract: The invention discloses an elastic wave accelerometer for measuring acceleration at least in one direction.The device comprises a solid support, a seismic mass and a piezoelectric wafer embedded in the seismic mass and in the solid support. An acceleration in one direction in the plane of the wafer produces an extension in one portion of the wafer and a compression in the other. Elastic waves are excited in the two portions of the wafer. Two oscillators are obtained by means of amplifiers and the frequency difference between the two oscillators is proportional to the acceleration.The invention applies to accelerometers for inertial navigation.

Abstract: An altitude difference measuring apparatus for measuring the difference between the altitudes at a first and second points on the basis of the barometric difference between the points, having an air pressure holding section with an electromagnetic valve for hermetrically containing an amount of air. At the first place an amount of the ambient air is held hermetrically in the air pressure holding section, and at the second place the barometric difference between the air pressure in the air pressure holding section and the ambient air pressure is converted into an electric signal, and in accordance with the electric signal the difference between the altitudes at the first and second points is indicated.

Abstract: A pressure-measuring device which operates in digital representation comprises:a first chamber subjected to the pressure to be measured;a second chamber subjected to a reference pressure and connected to the first chamber through at least one opening fitted with a valve;a device for measuring the difference both in magnitude and in sign between the pressures prevailing respectively within the first and second chambers, said device being intended to deliver an electrical signal which is a function of said difference;a circuit for detecting the instants at which said difference attains a predetermined increment +.DELTA.P or a predetermined decrement -.DELTA.P and for detecting instants at which said difference becomes zero;an element connected to said circuit for initiating the opening of the valve or valves when the difference attains the values .+-..DELTA.

Abstract: A novel process and system for computing and adjusting the optimum ignition advance in an internal combustion engine wherein knocking is detected by means of an accelerometer rigidly fastened to the cylinder head of the engine. An output from the accelerometer is integrated, converted into digital form, and processed by processing circuits to derive an average value C proportional to n preceding knocks and two comparison thresholds S.sub.1 and S.sub.2, each a linear function of the preceding average value C. The accelerometer output integrated and converted into digital form is compared with each of these thresholds and the existence of a preknocking or audible knocking value is deduced and then used to act on the programmed electronic ignition advance.

Abstract: A transducer device for measuring the internal pressure in pipes, comprises two housing parts which are articulately connected with one another by a connecting element and adapted to be fixedly mounted on the pipe by means of a clamping device. Each housing part contains at least one measuring element with a bipolar take-off of the test signals. At least one pole of each take-off is electrically conductingly connected with a part of the connecting element which is electrically insulated relative to the other pole and the connecting element comprises connection terminals for the further conduction or transmission of the test signals. The other pole is potentially in direct connection with the pipe.

Abstract: Positive feedback is utilized with a flexible piezoelectric strip that is stretched in tension to cause the strip to oscillate at a frequency which is determined by the magnitude of the force stretching the flexible strip. Since the oscillation frequency can readily be measured, the strip is utilized as a device for measuring tension.

Abstract: A vortex-shedding flowmeter in which a liquid or gas to be metered is conducted through a flow tube having a shedding body transversely supported thereon. Torsionally-supported at a downstream position behind the shedder on a shaft which projects outside of the flow tube to provide a shaft extension is a sensor, the pivot axis of the shaft being normal to the longitudinal axis of the tube. In operation, as the incoming fluid stream is divided by and flows past the shedder, vortices are successively detached therefrom and appear alternately on either side of the sensor, thereby developing a torque about the pivot axis. The torques are developed alternately in the clockwise and counterclockwise directions, causing the torsionally-supported sensor to oscillate at a rate proportional to the flow rate of the fluid. These oscillations are converted by a transducer operatively coupled to the sensor into a corresponding electrical signal.

Abstract: A force detector for detecting a force directly as a stress is disclosed which includes a piezoelectric unit for detecting a stress, a vessel for housing the piezoelectric unit, and a seal member for sealing the piezoelectric unit firmly and integrally in the vessel.

Abstract: The present invention is directed to a torque wrench wherein a head comprises an engaging member capable of being coupled, antirotationally, with a screw or the like. A handle lever is movable within limits relative to the engaging member and a load sensor is provided between the engaging member and the handle lever and controls an indicating means. The load sensor according to the present invention is a piezoelectric member fitted with electrodes connected with the input of an electric amplifier which is fed by a battery housed in the handle lever. The electric amplifier controls an electronic indicator which indicates the torque applied to a screw or the like.

Abstract: A self-powered monitor unit with a tuned mechanical resonator power unit and a radio transmitter is mounted on every piece of rotating equipment being monitored, such as machinery with ball bearings. Bearing vibrations are sensed and the generation of a defect signal triggers the transmission of a radio signal modulated to identify the source. A central station receives and demodulates an emitted radio signal and displays the location with a fault condition. Large numbers of equipment can be monitored conveniently by unattended units.

Abstract: A minute change detecting system comprises sensor means which changes its electrical constant according to a physical change of an object under measurement to affect the oscillation frequency of at least one of two high-frequency oscillators, and mixer means for producing a beat frequency signal from the output oscillation frequencies of the two oscillators, thereby to detect the physical change.

Abstract: The invention relates to a piezoelectric quartz force transducer having the shape of a double-ended tuning fork.

Abstract: An integrated spark plug-combustion pressure sensor capable of extended use in normal operation of an automobile. Thermally conductive gas sealing means are provided between the plug insulator and shell. A piezo-electric pressure sensor element is positioned to sense combustion pressure through changes in the stress of plug shell and is enclosed as an integral part of the plug for protection against the harsh engine environment.

Abstract: A semiconductor transducer comprises a semiconductor strain gauge composed of a mono-crystalline semiconducting material and a strain sensing region formed in a first main surface of the mono-crystalline semiconducting material, and a strain measuring member coupled to the semiconductor strain gauge through an alloy material. An electrical insulating layer is attached to a second main surface of the mono-crystalline semiconducting material which is coupled to the strain measuring member through the alloy material. The insulating layer is extended to a side surface of the mono-crystalline semiconducting material thereby to cover the same side.

Abstract: The invention is a single crystal force transducer in which the crystal is simultaneously resonated in two different modes having substantially the same frequency-temperature characteristics and different frequency-force characteristics. The difference in the change between the two resonant frequencies with a force applied to the crystal is therefore a temperature compensated signal indicative of the applied force. In the preferred embodiment the two resonant modes are anharmonic modes having a plurality of antinodes angularly disposed to each other.

Abstract: A sensor developing a digital output in response to force induced deflection in which the deflection is of a beam formed to have, under stress, a surface undulate in both compression and tension. The signal is developed from piezoelectric transducers connected in a pair of oscillator circuits utilizing surface acoustic wave paths through, respectively, the tension and the compression portions of the beam surface. The frequencies of the oscillators are compared and the frequency difference resulting from beam deflection is sent as a signal to a counter to give a digital read out of the force causing the deflection. The beam is formed of steel and the piezoelectric surface for the surface waves and the interdigitated conductors forming the transducers are deposited by thin film techniques on the beam.