Strain-gauge bridge + in-amp
8 parts
A Wheatstone bridge turns a 0.4 % gauge resistance change — 351.4 Ω among 350 Ω arms — into a 9.98 mV differential riding on top of 5 V, and the differential probe wired across the bridge reads exactly that, while either node alone barely moves. The instrumentation amp converts it to a ground-referenced 0.996 V. At t = 10 ms a timed switch shunts 175 kΩ across the gauge — shunt calibration — trimming 0.70 Ω off it and stepping the output to 4.97 mV / 0.496 V. The INA is a labelled behavioural macromodel (fixed differential gain of 100 with a ±12 V output clamp; no CMRR, offset drift or noise), and the strain gauge is honestly just a resistor at a slightly different value — which is what a strain gauge is.
- V1 10V
- TDSW1 10ms
- R1 175kΩ
- R2 351Ω
- R3 350Ω
- R4 350Ω
- R5 350Ω
- INA1 ×100
