I'm currently undertaking a project that uses a thermistor and a voltage divider circuit to calculate the temperature. I'm reading the voltage into my Arduino Uno. I've set up a room temperature test and my circuit gives credible results against a reference thermometer and I'm satisfied with its performance in that range. However, once I place my thermistor probe into a water basin that is kept at a constant temperature by using a hot plate, my thermistor gives a reading that is 3-6 degrees more than my reference thermometer. Does any one have any ideas why there is such a degradation in performance and how can I rectify this?
+Vref---[Thermistor]---+--[1.8K]---GND | ADC @ thermPin
I'm using a lookup table which contains expected values through my required range of temperature.
Any help is appreciated. Thanks.