Standard Automatic Calibrator for A-C Bridge and Amplifiers
OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT WASHINGTON DC
Pagination or Media Count:
The automatic calibration for the a-c bridge strain-gage recording equipment consist essentially of a series of relays which, by their action, display at the terminals of the unit a sequence of accurately known resistances. When connected in series with a wire strain gage and to the recording equipment, this sequence of resistances produces deflection steps on the film record. By measuring the width of the trace at each step and knowing the value of each resistance producing that step, the ratio of width of trace per unit resistance change is a simple calculation. When the strain gage factor for pressure lbs.sq.in.ohm or for thrust lb.ohm is known, the calibration in terms of pounds per square inch per unit width of trace or pounds of force per unit width of trace appearing on a film record of rocket firing may be readily determined. The automatic calibrators, therefore, provide the means of correlating the resistance-change calibration of the strain gages and the deflection obtained on a pressure-time or thrust-time film record of rocket firing.
- Test Facilities, Equipment and Methods
- Recording and Playback Devices