water-leak-sms-alarm

A small battery-powered device that detects water leakage and sends an SMS alert.
 

Features

• Completely off until water (or anything conductive) closes the circuit between two of its legs,
  thereby latching on the "soft latching power circuit".
  Which can later be turned off again by the microcontroller.

• Latches on by either water detection or by pressing the test button.

• Sends an SMS alert if water is detected.

• Sends SMS diagnostics if the test button is pressed.

• Built with an ESP32 and PlatformIO, in C++.

 

Schematic and PCB

KiCad files can be found here: 📂 _kicad/
More images in: 📂 _images/

Parts used

• ESP32 D1 Mini NodeMCU
• SIM800L with external antenna
• 3.3V LDO: MCP1700-3302E (250mA)
• LED: WS2812B
• P-channel mos: NTR4101PT1G
• N-channel mos: PMV16XNR
• Cap 470uF: Electrolytic
• Cap 1uF: Ceramic
• Cap 100nF: Ceramic
• SW1: Momentary DPST switch
• Conductive legs in copper/brass

Schematic

PCB

Uses mostly through-hole components for easier soldering.
ESP32 is mounted on the bottom side of the PCB.

 

SMS Example