Hey guys, I am currently working on an Arduino project where I need to use a PIR(pyroelectric infrared sensor). I am building my own circuit for it from scratch. I am using the circuit example from the datasheet of the sensor I am using (IRA-E700, datasheet: http://www.farnell.com/datasheets/2199772.pdf). I have changed some values, however, to filter out 50Hz signals since i was getting a lot of noise with that frequency. I have almost understood the circuit completely, but there are a couple of things I still haven't understood:
What is the purpose of the capacitor C3? I am guessing it's used for some sort of filtering of the noise you get with a PIR. I'm just not sure how such a filter would work?
What is the purpose of capacitor C6? I know it has to do with getting the voltage up to 2.5V since the op-amp has 2.5V on its non-inverting input. I'm guessing the capacitor interacts with the op-amp somehow, but I just don't know exactly how.
Thank you in advance for the help guys! I apologize if I left any information out.