YJJ CJMCU-6814 MiCS-6814 Triple Gas Sensor Module for CO NO2 NH3 IAQ Monitoring

Product Description:

YJJ CJMCU-6814 MiCS-6814 Triple Gas Sensor Module for CO NO2 NH3 IAQ Monitoring

Features:

MEMS metal oxide semiconductor (MOS) gas sensor module with pure analog output and no I2C interface. It has three independent heating sensing units, suitable for qualitative / relative detection of air quality. It cannot be directly used as a high-precision measurement-level instrument. Calibration is required.

Electrical parameters

- Power Supply: **DC 5V (4.9~5.1V)**
- Output: **3 analog voltage signals (CO / NH3 / NO2)**
- Pin definitions (from left to right): `CO`, `NH3`, `NO2`, `GND`, `+5V`
- Preheating time: Recommended **24-hour aging preheating**; stable reading after initial power-on is approximately 30 minutes
- Operating temperature and humidity: **-30℃ ~ +85℃, 5%~95% RH (no condensation)**
- Module size: **17 × 14 × 3.2 mm**, with 2 M3 mounting holes
- Weight: ≈2g

Gas detection & range

Table

| Gas | Measuring Range |
| --- | --- |
| CO Carbon Monoxide | 1 - 1000 ppm |
| NH3 Ammonia | 1 - 500 ppm |
| NO2 Nitrogen Dioxide | 0.05 - 10 ppm |
| C2H5OH Ethanol | 10 - 500 ppm |
| H2 Hydrogen | 1 - 1000 ppm |
| CH4 Methane | > 1000 ppm |
| C3H8 Propane | > 1000 ppm |
| C4H10 Isobutane | > 1000 ppm |

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Note: The three analog input pins of this module correspond **respectively to CO, NH3, and NO2**; other gases are cross-sensitive and cannot be precisely distinguished individually. They exhibit cross-interference characteristics.

Key features and precautions

1. Principle: The resistance of the gas sensor changes. The higher the gas concentration, the greater the change in the corresponding channel resistance, and the ADC reads the voltage change. **It is only suitable for relative change monitoring. The manufacturer does not guarantee the direct ppm absolute accuracy**, and zero-point calibration and load resistance matching must be performed.
2. Cross-sensitivity: Ethanol, hydrogen, and other gases will simultaneously affect multiple outputs. It is not suitable for precise differentiation in complex mixed gas environments.
3. Load resistance: The conventional scheme requires an external voltage divider resistor (the resistance values of different channels vary greatly. CO, NH3, and NO2 recommend different voltage divider resistors).
4. Application scenarios: Simple indoor air quality monitoring, rough exhaust detection, IoT environment collection; **Not suitable for safety explosion prevention, legal metrology, or toxic gas alarm

Specifications: