Hi, I‘ve built a simple project, in which a mp3 file is played, when a PIR-sensor recognizes motion.
Works perfectly fine, when connected to my Mac. But when connected to a 9V battery the code to play the mp3 file is running and running. Tested with an oscillator and when connected to battery the PIR input ist always high. When connected to Mac HIGH and LOW.
Tried my MacBook with usb-c that worked. 9V fire alarm type battery didn’t work. And via usb cable plugged into phone adapter in socket also didn’t work
You don't need a 9V supply. 5V is all you need. any battery bank will work just fine. You can also get a liPo battery at 4.7V and it will work as well.