Linearizing a Thermistor


Thread Starter

Steve Tomporowski

When you use a resistor in parallel with a 91k thermistor, you get fairly large linear region and then at low temps and high temps the curve levels off. In these areas you can't get enough counts per degree for any kind of accuracy. I know that adding a couple of amps and diodes can stretch these areas out, but before I 'reinvent the wheel', has anyone done this before? Basically I'm looking not for total linearity, but enough counts per degree (10 bit A/D) to do 0 to 450 F. I should be able to get at least 2 counts/degree....

You are trying to scratch the right ear with the left hand, is it ?
I know your answer: that you have to live with the thermistor because of this and that.
Get the curve from the supplier and check with that supplier for an eventual linearising equation, to suit your need.
Also, look in the Omega catalog.
In the worst case make your own look up table.