Pinout
MQ-2 gas sensor module (4-pin) pinout
Pins
- VCC (5V — the heater draws ~150mA)
- GND
- DO (digital out — the LM393 comparator pulls it LOW when AO crosses the threshold set by the trimmer; the DO LED lights at the same time)
- AO (analog out — rises with gas concentration)
Specifications
| Supply voltage | 5 V |
|---|---|
| Heater resistance | 33 Ω ±5 % |
| Heater current | ≈150 mA |
| Target gases | LPG, propane, butane, methane, hydrogen, alcohol, smoke |
| Detection range | 300–10000 ppm (combustible gases) |
| Outputs | AO analog 0–5 V + DO digital (LM393 comparator, active LOW) |
| Preheat | ≥ 24 h first use; ≈1 min per power-up |
| Output type | Relative — needs calibration for ppm |
Notes
- Needs a burn-in warm-up (24–48h first use, ~1 min per power-up) before readings settle.
- Turning the trimmer clockwise raises the threshold (less sensitive DO). AO is unaffected by the trimmer.
