Temperature Measurement System Design Lab
In this lab assignment, we designed a simple temperature system which outputs a DC voltage which indicates temperature. Our system will use a thermistor to indicate the temperature. We used a Wheatstone bridge circuit to convert this resistance change to a voltage change. The voltage output of the Wheatstone bridge circuit was small relative to the amount of temperature change, so we used a difference amplifier to increase the overall sensitivity of the temperature measurement system.
These two pictures are our circuit with the thermistor and potential transistor.
To make the lab work we were required to test each system individually and on the Wheatstone bridge we had to make Vab as close to zero because we wanted to know the value of Vout when we increase the thermistor temperature. On the difference amplifier we built it in the same circuit as the previous lab which was with 4 same resistor to connect the amplifier and we were supposed to get Vout=Vb-Va and with a supply power Vb with 2V and Va with 1V we got Vab=0.996V.
After we connected the two circuits together and hold the thermistor to see the Vab change by the ratio Vout=R2/R1 (Vb- Va)
This is a video showing our working circuit.
In conclusion: The ratio did not come out with Vf=10times of Vi but the voltage did increase when the thermistor was hold with our fingers.
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