The MQ-8 is a hydrogen (H₂) gas sensor designed for detecting hydrogen leaks. It uses a sensitive tin dioxide (SnO₂) layer that changes resistance based on hydrogen concentration. The sensor offers high sensitivity, fast response, and stability. Operating on 5V, it outputs analog and digital signals, making it compatible with microcontrollers like Arduino.
| Detection Range: | 100ppm to 10000ppm |
|---|---|
| Operating Voltage: | 5V DC |
| Heater Voltage: | 5V ± 0.2V |
| Heater Power Consumption: | ~800 mW |
| Preheat Time: | 24h to 48h (initial), ~2 minutes (typical) |
| Response Time: | ≤10 seconds |
| Recovery Time: | ≤30 seconds |
| Operating Temperature: | -20°C to 50°C |
| Humidity Range: | ≤95% RH |
| Dimensions (L×W×H): | 32mm × 20mm × 22mm |
Please keep the following notes in mind before using/connecting the MQ-8:
| Pin name | Description |
|---|---|
| VCC | Power supply (5V) |
| GND | Ground connection |
| AO | Analog output |
| DO | Digital output |
Using the potentiometer on the back of the board, you can set the threshold at which the DO output switches from HIGH to LOW. The DO pin can be connected directly to a microcontroller or a development kit.
The sensor also has an AO analog output, which should be connected to the A/D converter (e.g.: analog input on Arduino). This allows for more accurate determination of the alcohol content by measuring the proportional voltage signal.
Due to the similarities in the module's structure and connections, all circuit diagrams and codes can be found under MQ-3.
Avoid flames, sparks, or heat sources during testing — hydrogen is explosive at low concentrations!
Charging Nickel-Metal Hydride (NiMH) batteries releases small amounts of hydrogen gas, so you can place it nearby the sensor to detect hydrogen.
Apply a 5-12V DC power source over two separated electrodes (e.g., stainless steel wires, graphite from pencil leads) in a glass of water with some dissolved salt (NaCl) in it. (see also: Electrolysis of water)