(Day 4): Temperature Measurement System- Thermistors in a Circuit

Thermistors are circuit elements that vary in resistance as temperature increases or decreases. Resistance and temperature are inversely proportional to each other in a thermistor.

The purpose of this lab was to design a circuit with a voltage output that varies by at least 0.5 V as the temperature of the thermistor increased from room temp to body temp (25 C and 37 C). Our first step was to theoretically solve for resistance values that would allow us to achieve the desired change in Voltage. Those calculations are shown below.

The next step was to create a circuit like the one drawn in the top left corner of the theoretical solutions. The next picture shows the voltage source, thermistor, resistor, and voltmeter successfully connected in a circuit.

Below is the successful trial of changing the voltage by a minimum of .5 V when the temperature of the thermistor is changed from room to body temperature.T

While we weren't successful on the first 2 trials, we finally found the resistor R = 5.6 kilo-Ohms from our supply of D12 resistors that would allow us to achieve the desired results. The process was slow and steady, but fulfilling nonetheless.

Summary of our trials and error calculations.