SaM ~ Resistive Bridge Example • Strain Gauge

Remeber:

• Example of a ”$\frac{1}{4}$ balanced resistive bridge” using a single strain gauge sensor, we will refer to the “design of a resistive bridge lecture”.
• (1.) Find $x_{\max }$:
  $x_{\max }=G\cdot {\epsilon }_{\max }=4\cdot 50000\mu \epsilon$
  ⇒ $x_{\max }=0.2$
• (3.) Check accuracy or maximum error:
  $\Delta \epsilon =10\mu \epsilon$ ⇒ $\Delta x=4\cdot 10^{-5}$
  Then:${\Delta V_{TH}|}_{x=0}=\frac{V}{4}\Delta x$And for $V=10\text{V}$ we obatain: $\Delta V_{TH}=100\mu \text{V}$

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• Remember $\Delta x$ : required accuracy, or better in this case accuracy of the sensor.

⇒ Point 3. Check accuracy

• $\Delta V_{TH}$ is the accuracy of the bridge
  ⇒ The “output accuracy” of $V_{TH}$ will be $100\text{micro}V$, we then need to assert that this accuracy is larger than the noise, to have a proper sensor.