My DIY battery-powered wireless driveway visitor detector, take 3! A much harder problem than I anticipated. Attempt 1 was using a cheap and low power PIR sensor. Too many false alerts. Attempt 2 was a radar presence detector. Doesn't work outdoors, way too many false alerts. This one uses a commercial outdoor PIR sensor, which seems to work quite well so far. On the down side, it uses quite a bit of power (20mA continuous), so I've had to add a lithium battery with solar charger. Nice thing about a LiFePO4 battery is that I don't need a fancy solar charge controller, I just use a buck converter set to about 14V. The grey box houses a microcontroller with a LoRa transmitter, mounted on an aluminium bracket that I can hang on my driveway pre-cast wall, so that the PIR sensor looks across the driveway. I put the battery and charger into an ice cream container and placed a roof tile over it to protect against rain and sun. The receiver side is an ESP32 connected to a LoRa receiver and buzzer that plays a ding-dong chime and also sends an MQTT message for futher automation. #diy #lora #pir #motion #sensor