An Improved Strain-Gage Signal Conditioner for Dynamic Stress Measurement
SVERDRUP TECHNOLOGY INC ARNOLD AFS TN
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A new signal conditioning circuit has been developed for single-active-arm strain gages typically used for dynamic stress measurement on turbine engine rotor blades. This new circuit uses constant-voltage excitation and corrects for lead wire resistance changes by automatically controlling resistances in series with the lead s to the gage. This technique provides a balanced configuration which offers better high-frequency common-mode rejection and has less broadband noise than with constant-current excitation but still is insensitive to lead wire resistance changes. Also included is a unique Delta R calibration circuit that provides a more accurate simulation of actual gage resistance change. The circuits described may be useful in any AC-coupled strain-gage system.
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