A double d.c. bridge circuit for precision measurements with load cells
T S Parramore · Journal of Scientific Instruments · 1958
By arranging the strain gauges on a load cell as a closed bridge which is wired in parallel with a similar reference bridge in the measuring instrument, a very sensitive and accurate manually balanced null deflexion method of measuring the output of a load cell can be achieved at low cost. This method is also suggested as an alternative to the present d.c. methods used for load cell measurement in the calibration of testing machines. The prototype bridge has a discrimination of one part in 10 000. A practical difficulty when used with load cells greater than 50 tons capacity is to calibrate against a standard of sufficiently high accuracy.