I'm trying to use a PIR sensor following the below blog
The problem is that is detecting always a movement. I have tried to attach a multimeter between the ground and the Output (which is the one that is wired to the Arduino input pin for reading) but the voltage goes up and down (1.15 - 4.29) all the time.
Is something wrong with this sensor?
What is the best (not too expensive) PIR sensor for Arduino ?