Discusses modifications that could be made to circuitex brid

Discusses modifications that could be made to circuit(ex: bridge circuit) to account for changes in ambient temperature?

Solution

To analyze the effect of the ambient temperature, the gauge in arm RQ has been placed inside a controlled temperature oven. The ratio arm PQ has fixed value metal film resistance. The resistance of the arm PQ has been set to be as the resistance of the gauge in arm RQ. . It shows that the output voltage rises with increase in ambient temperature and the variation is almost linear. Further experiment was performed by replacing the arm RQ with another strain gauge and putting both the gauges inside the oven. Temperature of the oven was varied over the same range and the output voltage of the detection circuit was noted. Results indicate that the output change due to ambient temperature is significantly reduced. Small variation in the output can be attributed due to mismatch of the gauges. Thus if the input excitation voltage of the bridge circuit is assumed to be constant then, the output of the signal processing circuit depends only on the change in resistance of the gauges which in-turn depends on the strain. However, the output also depends on the excitation voltage.