I have a CN-0338 (NDIR Thermopile-Based Gas Sensing Circuit) gas sensor board. i make the second board (upper board) from the "CN0338-DesignSupport" files. now i have some questions and i will become thankful if you help me.
1- in " EVAL-CN0338-ARDZ-Shield-SCH-RevA" file the amount of R1 and R2 are not mentioned. is it necessary to use these resistances? if not how i can find the real amount of them?
2- when i use this board with out connecting the detector , the amount of reference differential voltage is zero but the action differential voltage is not zero, is it true? our these data are an electerical noise ?
3- when i use this board for a certain gas concentration, the measured concentration have a lot of fluctuations, are these data true? if not how i can fix it? i attach one of my outputs.
I become so thankful for your help.