A compact battery-powered door/window sensor built around the ESP32-C3-MINI-1-N4 module. The design uses a single non-rechargeable AA cell with a TPS613221A 3.3 V boost regulator, reed switch magnetic contact sensing, low-power wake/report/sleep firmware strategy, RGB status LED for setup feedback, BOOT/EN controls, programming header, and input polarity protection. It is intended for smart-home security and automation applications, supporting WiFi or Bluetooth LE hub reporting with emphasis on low idle current, reliable RF burst power delivery, and field-replaceable battery operation. #ESP32-C3 #BLE #WiFi #DoorSensor #WindowSensor #ReedSwitch #LowPower #BatteryPowered #SmartHome #IoT

9 V reed-switch alarm schematic with BC547 transistor latch/driver, LED indicator, buzzer, power input, and reed switch input.