Thanks a lot for the detailed description for temperature sensing modules in the “Learn” Section! I’d like to build one of the modules for PT1000 sensors and have a question: the LM324 (operational amp to amplify the sensor signal) has a V+ and a V- pin. Do I need an negativ -5V input additional to the +5V from the arduino or can I simply connect the negtive port to GND? How can I set that negative voltage up?
I know that the question was already ask in RTD Temperature sensor module, but the answer doesn’t help me much - I look in the datasheet and there a negativ source is required but I don’t know which voltage and how I can provide it.
If you look at the data sheet, Pin 11 is labelled as VEE/GND, and on the Maximum Ratings page it gives 32 V or ±16 V. And on page 6 it shows both single and split supply arrangements. So you can do both.
But here is how to see which you need in the “Learn” diagram: Look at the input to the + input of the “voltage follower” amplifier. It has a d.c. bias with two resistors. That is also done at the input of the multiplexer, and it tells me that the whole circuit works between 0 V and +5 V.
So no, a negative source is not required, but you can use one if your application needs it. This does not need it.
You would need a split supply if your input went negative at some time, or if you needed the output to go negative. Here the output must remain positive, in the range 0 - 5 V, to interface to the Arduino.