Thermistor issue

[nisha01]

Hello, I am currently working with the TI LM 19 as my sensor. I waterproofed it with a hard plastic straw, saran wrap, and tape. However, when I did my voltage versus temperature graph, the reading was not close to being linear, and the best line of fit did not seem like a good option to get the right temperature since it was very broad. Also, when I calculated my temperature with my negative slope and a y-intercept in the 200s, I noticed the temperature is extremely off.

Would you recommend switching thermistors, or what are the other errors that could be made? Please let me know, my competition is in very few days.

[jinhusong]

Switch to thermistor is a safe way to go.

As long as your sensor is repeatable, you can calibrate with like 1 degree steps, then with interpolation between data points, you should be able to get good results.

The repeatability is the key. If it is not stable, just switch.