K8055 & thermistor reading scale

I’m beginner with electronique and meet some problemes to have my K8055 card working. I would like to have a fan working when the temperature is above xx°C.

so I tried to get analog input throught a thermistor.
I get some usable results with Light sensor, humidity sensor but get poor result with temperature sensor.
In fact I can not have an accurate reading of temperature :
when the temperature is 5°C changing the analogue get only 1 step changing.

how could I amplified this change and have a accurate temperature reading ?

thank you in advance for your help and indulgence for my english and poor electronique skill…


We’d suggest you get a K8067 temperature sensor, it has been designed to work with the K8055.

thanks you for your reply I will look a this card…

In fact I will have to put an other thermistance in water for other needs…
I was looking on the internet and if I understood well I bought
a PT100 sensor and I should have bought a PT1000 sensor Instead in order to have
a more large change …
could you confirme me that it’s could be a solution …

thank you for your help and quick answer



Maybe you found this thread:
There you’ll find some links to other discussions concerning this topic.

The problem with the PT100 and PT1000 is the low resistance change vs. temperature change.
You’ll get very small change in the reading and bad resolution.

Thank you,
I read all the thread and if I understand well the only solution is to
amplify the output of the thermistor…?

Which one of the following solution is suitable :

-changing resitance R8 and R9 of the Kit
-use a LN335 instead of a PT100 sensor
-add and Amplification to the PT100 output



In the K8067 there is LM335 used. The output can be set to fulfill the 0V…5V input range for the K8055. No need to do any modifications to the K8055.
If you do not use the K8067 then all the alternative solutions you listed to increase the gain are usable.

In k8067 datasheet is specified a formula for working to °C grades.
°C = (101 * AD-value / 256) - 23 //for 8 bits ADC convertor
I have some questions related to this formula.101 and -23 values are meaning what?I’ve also looked in lm335 datasheet but i can’t discover how u calculate.:question:

These are fixed values and relate to the range and accuracy of the calculation.