Improving thermistor resolution

Hey guys,

I've got a thermistor with a range of 0-100 C and its current resolution is only about 0.1 C when using the analog pin on the Arduino. I am looking for a resolution closer to 0.01 C, and I think an easy way to do this would simply be to make the measurement range smaller (about 10 C). I have seen some methods which involve using op amps and Wheatstone bridges, but I was wondering if anyone knew of a way to modify this range using a sketch.

Thanks!

Over what range do you need 0.01°C resolution? The A/D converter has 1024 states so your maximum range will be 10.24°C. What is the low end of the range? What is the resistance of the thermistor at the low end and the high end?

One problem you will have is that using the thermistor as part of a voltage divider you will be unable to get your voltage range to start at 0V. That means that some portion of the A/D range will be lost. That leaves you with a less than 10°C range, possible much less.

Perhaps and external A/D with 15 or 16 bit accuracy would give you the resolution you want.

I've got a thermistor with a range of 0-100 C and its current resolution is only about 0.1 C when using the analog pin on the Arduino. I am looking for a resolution closer to 0.01 C

You should be shopping for new hardware.

A range of 20-30 C would be sufficient for my needs. I'm not sure what the resistance is at those values, though. Would I have the same problem with the hole in the A/D range if I used external hardware to limit the range of the thermistor?

you might check the mcp3551 adc - sorry no link ...

mooch444: Would I have the same problem with the hole in the A/D range if I used external hardware to limit the range of the thermistor?

If you can offset the voltage to read 0 at the low end an +5V at the high end you would be able to separate the range into 1024 steps. Unfortunately the steps are probably not going to be linear so they would not all be 0.01°C steps.

you might check the mcp3551 adc - sorry no link ...