# Window Open Reminder Sensor

A window position monitor with HVAC integration. Magnetic sensor detects open/closed state, sends alert if window left open while heating/cooling running. The 50x30x15mm case mounts on window frame. Battery powered 12+ months. Prevents energy waste and high utility bills. This window sensor project is perfect for makers, DIY enthusiasts, and electronics hobbyists. Search volume: 1600/month.

All parts, CAD, wiring, and firmware generated by Modo AI Hardware Builder with human direction.

--- Validated fit

--- Electrical OK

--- Assembly ready

## Parts

### ESP32-S3 Wireless MCU
Espressif Systems  
`ESP32-S3`compute  
Why: Main microcontroller for data processing, monthly logging, and EPA risk level calculations. Built-in ADC for sensor interfacing.

### BME280 Environmental Sensor
Bosch Sensortec  
`BME280`sensing  
Why: Provides temperature and humidity measurements to complement radon monitoring for comprehensive environmental assessment.

### OLED Display Module
Orient Display  
`AOM12864A0-0.96WW`user\_input  
Why: Visual display for EPA risk levels with color-coded status indication and radon concentration readings.

### RGB Status LED
XINGLIGHT  
`XL-5050RGBC-WS2812B`user\_input  
Why: Color-coded visual indicators for EPA radon risk levels (green=low, yellow=moderate, red=high).

### 3.3V LDO Regulator
Shenzhen Slkormicro Semicon Co., Ltd.  
`AMS1117-3.3 SOT-223`power\_regulation  
Why: Voltage regulation for stable 3.3V supply to all system components from battery power.

### 18650 Battery Holder
MPD (Memory Protection Devices)  
`BK-18650-PC4`power\_regulation  
Why: Battery power source for portable, long-term radon monitoring operation.

### Power Switch
C&K  
`OS102011MS2QN1`power\_regulation  
Why: On/off control for battery powered operation and power management.

### Battery Charger IC
Microchip Technology  
`MCP73831T-2ACI/OT`power\_regulation  
Why: Enables convenient recharging of 18650 battery for continuous long-term monitoring.

| Part | Why | MPN | Qty |
| --- | --- | --- | --- |
|  | Main microcontroller for data processing, monthly logging, and EPA risk level calculations. Built-in ADC for sensor interfacing. | `ESP32-S3` | 1 |
|  | Provides temperature and humidity measurements to complement radon monitoring for comprehensive environmental assessment. | `BME280` | 1 |
|  | Visual display for EPA risk levels with color-coded status indication and radon concentration readings. | `AOM12864A0-0.96WW` | 1 |
|  | Color-coded visual indicators for EPA radon risk levels (green=low, yellow=moderate, red=high). | `XL-5050RGBC-WS2812B` | 3 |
|  | Voltage regulation for stable 3.3V supply to all system components from battery power. | `AMS1117-3.3 SOT-223` | 1 |
|  | Battery power source for portable, long-term radon monitoring operation. | `BK-18650-PC4` | 1 |
|  | On/off control for battery powered operation and power management. | `OS102011MS2QN1` | 1 |
|  | Enables convenient recharging of 18650 battery for continuous long-term monitoring. | `MCP73831T-2ACI/OT` | 1 |

8 unique parts, 10 total components.