Final Project

For our EECEE2210 final project, my team designed a temperature-sensitive cooling system. The main component is a temperature-to-voltage converter circuit (see left) which utilizes an LM741 op-amp, 10 kΩ NTC thermistor, 50 kΩ potentiometer, 100 nF capacitor, and a collection of resistors to ensure a temperature change yields a reliable change in output voltage. See the final report and presentation for detailed information about the final design.

Full Circuit Diagram

Testing Results

To evaluate the performance of the temperature-to-voltage converter, two experiments were conducted. A hairdryer was used to increase the temperature of the thermistor, and a cold soda can was used to simulate a cooling effect. In both situations, the voltage changed linearly with the change in temperature. These results make sense given the use of an NTC thermistor which experiences a decrease in resistance with an increase in temperature (resulting in a larger output voltage). The cooling circuit consists of a 5 V fan and an 8 Ω, 0.2 W speaker connected to an Arduino Uno that reads the output voltage. Once the output voltage reaches 4 V, the fan switches on and the speaker plays a 1 kHz tone for 1/10th of a second, twice per second.