Battery powered motion sensor using Blynk to send notifications to your phone.
Having setup Home Assistant a while back I needed a movement sensor that could run on battery. The NodeMCU Multisensor remixed from Bruh Automation led me to create a simple motion sensor that can be run on an 18650 battery for months if not years. Using a Nodemcu v1.0 and making use of its deep sleep capability minimizes power usage only triggering notifications after motion.
Nodemcu Development board
2N222 NPN Transistor
Arduino code on github here complete with wiring diagram.