MQ7 Carbon Monoxide (CO) Coal Gas Sensor
MQ7 overview
The MQ7 gas sensor belongs to the MQ gas sensor family series. The gas-sensitive layer of the MQ7 sensor determines the performance of the gas sensor and its capacity to detect harmful gases (CO gas in particular) effectively and provides adequate warnings proactively. Whenever CO gas comes into contact with the sensing element, the resistivity of the element changes. The change is then measured to get the concentration of the gases present. The MQ7 sensor comes in a package similar to the MQ3 alcohol sensor and can be used with its corresponding breakout board.
The core sensing material in an MQ7 gas sensor is SNO₂ for which the conductivity is lower in clean environments and higher when smoke or a harmful gas (main carbon monoxide) is present. A simple circuit makes measuring this change in conductivity and turning it into data reasonable without difficulty, but it does require some calibration.
Key specifications
Datasheet
MQ7 features
- The analog output voltage, the higher the concentration the higher the voltage.
- The carbon monoxide detection with better sensitivity.
- There are four screw holes for easy positioning;
- Product Dimensions: 32 x 20 x 22 mm (LxWxH)
- With a long service life and reliable stability
- Simple drive circuit
- Extremely quick response time.
- Rapid response and recovery characteristics
- Preheat duration 20 seconds
MQ7 pinout
| Pin | Name | Description |
|---|---|---|
| 4 | VCC | This pin powers the module, typically the operating voltage is +5V |
| 3 | GND | Used to connect the module to the system ground |
| 2 | DO | You can also use this sensor to get digital output from this pin, by setting a threshold value using the potentiometer |
| 1 | AO | This pin outputs 0-5V analog voltage based on the intensity of the gas. |
MQ7 specifications
| Operating voltage | DC 5 V. |
|---|---|
| IC driver | LM 393. |
| Size | 11 x 33 x 20 mm. |
| Range | 10 to 1000 ppm. |
| Characteristic gas | 100 ppm CO. |
| Sensitive resistance | 2 to 20 10kohm 10 Kilo ohm at 100ppm CO. |
| Sensitivity | ≥ 3%. |
| Return time | ≤ 30 s. |
| Heating resistance | ± 31ohm 3ohm. |
| Heating current | ≤ 180 mA. |
| Reaction time | ≤ 1 s. |
| Heating voltage | 5.0V ± 2V / 1.5 ± 1V. |
| Heating power | approx. 350 mW. |
| Ambient temperature | -20 ° C to + 50 ° C. |
| Humidity | ≤ 95% RH. |
| Oxygen content | 21%. |
MQ7 applications
- Carbon monoxide detectors and alarm systems for homes and industries.
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