I finally got the time to test the PIR with 5v of a different USB Source, which actually worked this time and even the 3.3v resulted to an output. The only problem that’s left is that I am having difficulties to find the right value for sensitivity and time (can be adjusted with a resistor). Sometimes the sensor just keeps outputting HIGH for a long time and sometimes it works as expected and turns off after not having the movement for a short time. I tried several positions and experimented with the sensor: sometimes it gets better and sometimes much worse… It seems like it makes a different how the “state of movement” or the environment is when turning on the device (power source of the sensor).
Does somebody of you know what to consider when adjusting the parameters or powering on the sensor?