Hi, I would like to record a voltage on a ardruino pin A0 using the 3.3V from the arduino. I connect the 3.3V to one part and the A0 to another part. I want to know when there's contact between the two parts (resulting in 3.3V on pin A0) and when there's no contact (resulting in 0V on pin A0). I'm unsure about how to create this circuit. When there's no contact I still meaure 1.5V (noice), and when I move the parts the voltage is going up and down a lot (lots of noice). Also, when there's contact on between the two parts I can't measure a 3.3V, its varying from 3.0V to 3.3V. When I remove the V the voltage that i'm recording is also going down pretty slowly. Can anyone help me out in this matter. What resistor should I possibly use and most importantly: How? Thanks in advance.