Abstract: Frequency stabilization of an oscillator by compensating for slow frequency variations due to ambient temperature variations is achieved by diverting a fraction of the oscillator output to a waveguide line section having a coefficient of thermal expansion/.degree. C which is greater than the coefficient of relative frequency drift/.degree. C of the oscillator comprising, in sequence, a variable attenuator and a movable short. The variable attenuator is used to primarily adjust the amplitude of the diverted signal by one-half the desired amount preferably without varying the phase of the diverted signal. The movable short is primarily used for signal phase adjustment while simultaneously reflecting the attenuated signal back through the attenuator and towards the oscillator output.

Abstract: A plurality of window comparators and voltage controlled oscillators are arranged to receive analog input signals which are converted to output frequencies that are linearly proportional to the analog signals over a substantially infinite amplitude range.

Abstract: Spot welds are evaluated using stress-wave emission techniques by measuring the stress-wave energy emitted from the weld area during n time intervals of the weld cycle, where n.gtoreq.4. Each of the time intervals corresponds to a different aspect of the weld cycle such as, for example, the initiation of heating, the separate solid-to-liquid phase transformation in each of the articles being welded, material combination within the weld nugget, cooling stresses occurring during resolidification, and post-weld cracking. The energy values obtained for each of the time interval can be compared with predetermined acceptable energy value ranges for corresponding ones of the intervals and/or compared with predetermined ratio values between two or more of the obtained interval values to determine the quality of a weld.

Abstract: The strength of an adhesion bond can be determined using stress-wave emission techniques. One method measures the stress-wave emitted from the bonding area during the compression phase of the formation of the bond and compares this measurement with a predetermined substantially linear relationship between the emitted stress-wave energy and the strength of the adhesion bond. For more accuracy, a second method measures the stress-wave energy during both the compression phase and a pressure-relief interval, determines the difference between the two measurements, and compares the difference value with the substantially linear relationship. An alternative to the second method subtracts a predetermined threshold value from the pressure-relief interval measurement, reduces the compression phase measurement by the excess determined by said subtraction step, and compares the reduced compression phase measurement with the predetermined substantially linear relationship to determine the strengh of the bond.

Abstract: A windable resistance-capacitance (R-C) network having at least three terminals and formed of adjacent first and second alternating layers of dielectric and electrically conductive low-resistance material is disclosed, in which discrete resistance and capacitance network elements of predetermined value are interconnected and formed by removing portions of the layers of conductive material along appropriately positioned lines. The present network can be economically mass produced and the formed resistance and capacitance elements exhibit a minimal distributive effect.

Abstract: Continuous welds are monitored by detecting and processing stress-wave signals emitted from the moving weld area to provide an indication of both the weld energy supplied to the weld area by the welding apparatus, and the development of microcracks in the cooling weld area. According to the present invention, the detected stress-wave signals emitted from the weld area are amplified and filtered to provide excellent signal-to-noise ratios and then applied to either one, or both, of (a) an RMS voltmeter, and (b) a spectrum analyzer to provide an indication of the weld energy supplied to the weld area and the development of cracks in the cooling weld area.

Abstract: Apparatus is disclosed for detecting and measuring peak-to-peak values in an electrical input signal, the signal comprising at least one positive-going and one negative-going peak and can include waveforms characterized by short duration and fast rise time pulses. In operation, one of the at least one input signal peaks is referenced to a predetermined d.c. voltage level, such as, for example, 0 volts d.c., and an electrical output signal is generated which is representative of the magnitude of the input signal with respect to the predetermined d.c. voltage level. The output signal is generated by electrical circuitry capable of accurately tracking fast rise time pulses and then stretching the other unreferenced at least one peaks to prevent decay thereof.

Abstract: Spot welds are evaluated using stress-wave emission techniques by detecting and measuring the stress waves emitted from a weld area during a first solid-to-liquid phase transformation period and a second liquid-to-solid phase transformation period of the weld. The stress waves emitted during the first transformation period provide an indication of the weld nugget size, while the stress waves emitted during the second transformation period provides an indication of the amount of post-weld cracking in the weld area. By subtracting the stress-wave energy measured during the second transformation period from the stress-wave energy measured during the first transformation period, an indication of the strength of the weld is obtained.

Abstract: Apparatus for measuring deviation from straightness, or wall curvature or axial curvature, of an elongated member by ultrasonic pulse-echo techniques comprises at least three ultrasonic transducer means and an associated processing system.In operation, each of the transducer means transmits ultrasonic search signals towards the elongated member and detects signals reflected from diametrically opposed points on a reference surface of the member. From the transmitted search and the received echo signals, a signal is generated in the associated processing system indicating the distance between the face of each transducer means and the associated reference points on the wall surface of the elongated member. The generated distance signals can then be processed to generate signals indicating wall curvature and axial curvature in the plane formed by the diametrically opposed points.

Abstract: Method and apparatus are disclosed for concurrently thermocompression bonding a plurality of lead frames to a plurality of planar articles. In operation, a plurality of lead frames are referenced to a plurality of unheated bonding tips and to the associated metallized bonding sites on a first side of a plurality of planar articles. The bonding tips are then simultaneously activated to independently move the referenced lead frames and articles in a first direction to engage the second side of each article with a heated thermode, and apply a sufficient compressive force to bond the leads of each lead frame to the associated bonding sites on the referenced article. The bonding tips are then returned to their initial or starting position.