Temperature Sensing Timer Help

Hi! I am looking for hardware to make a temperature probe.

My project involves measure small variances in the temperature (~0.1 C) of boiling water. For my project, I need a temperature probe that is accurate to 0.1 degrees Celsius between the ranges of 80 and 125 C. If this is not possible (or is too expensive) I should be able to use the same temperature range accurate to 0.5 degrees, but 0.1 is much preferred.

The goal of this project is to study how solutes affect the boiling point, and to boil the solution for a set amount of time. Ideally, the device would first take a user input of the boiling temperature and a second input of the amount of minutes the solution needs to boil for. Then, the temperature probe would detect when the solution hits that temperature (starts to boil) and then begin a countdown timer for the specified number of minutes. Once the specified time has elapsed, it should beep.

Originally I sought to complete this project with an Arduino Uno, however none of the probes that I have found operate within the temperature range needed. In addition, this is a laboratory study, so accuracy is paramount.

So my major questions are:

What parts do I need to complete this project?

Is it possible to complete using Arduino? If so, where can I buy a probe that fits my needs?


Check the MCP9808 out (wont be 0.1 but should do 0.5)

You should probably get some "real" calibrated laboratory equipment. At a minimum, you should have a calibrated thermometer/temperature probe to test/calibrate whatever you build.

The [u]LM35[/u] might work for you. it's rated for 10mV/degree, so if you can get 1mV resolution with your analog voltage reading, that's 0.1 degree resolution. You'll probably have to calibrate it and you might have noise/drift issues and in the real world I wouldn't expect 0.1 degree accuracy.

With the Arduino's optional 1.1V reference, the 10-bit ADC gives you ~1mV resolution, but it may not cover your full temperature range.

Are there no suitable digital temperature sensors?

Does it need to be calibrated to the real world or just give the same answer when you measure two different things that are the same temperature?

If reputability is all you need I have had pretty good luck with the DS18B20. Check out the other sensors in the same chip family some of them are more accurate but tend to cost a bit more.

I second the DS18B20 (waterproof version?). Resolution can be set to 0.5C, 0.25C, 0.125C or 0.0625C. Calibration (offset) can be done in software. Leo..