BW August 2015

8/3-8/4

Using the data from the calibration tests, I calculated ratios of the temperature measured by the free thermistor to the temperature measured by the fixed thermistors. It was surprising that at certain times during the tests the ratios changed rapidly. The reason for the sudden changes was that the heating curves rise steeply from room temperature, and as the temperature rises their slope decreases. Where the slopes are steep, the ratio can change quickly when one curve rises faster than another. Another reason for sudden changes was the behavior of the heating curves once the temperature reached its target range. As the temperature rose and fell across that range, some of the heating curves fluctuated more than others, and the ratios changed quickly in some cases.

8/10-8/11

I wrote the temperature formula for the thermistors on the marker board in Dr. Jones' office. He told me to put the variables in a spreadsheet and calculate the temperature measured by the fixed thermistors using the voltage measurements and the formula. I should graph the temperature measured by the fixed thermistors and the temperature measured by the free thermistor, and then I should adjust the variables until the fixed thermistor's temperature curve matched the free thermistor's temperature curve. He advised first adjusting Tref so that the initial temperature of the fixed thermistor equaled the initial temperature of the free thermistor. Once the initial temperatures were equal, I would have a good chance of aligning the heating curves by adjusting B.

When I followed these instructions, three of the fixed thermistor curves matched the free thermistor curve well. The Front Left End curve was not as close to the free thermistor curve.