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MQ-7 Gas Sensor For Carbon Monoxide Detector Module

MQ-7 Gas Sensor For Carbon Monoxide Detector Module

β‚Ή121.00Price

πŸ” What this sensor is

The MQ-7 Gas Sensor Module is a low-cost carbon monoxide (CO) detector commonly used in Arduino and IoT projects.

πŸ‘‰ It detects:

  • 🫁 Carbon Monoxide (CO) β€” a dangerous, odorless gas

🧠 Core Concept (VERY IMPORTANT)

πŸ‘‰ This is a heating-type gas sensor (MQ series)

It works using a cyclic heating process:

  • πŸ”₯ High temperature β†’ cleans sensor

  • 🌑️ Low temperature β†’ detects CO

➑️ This makes it more selective to CO compared to other MQ sensors

βš™οΈ Key Specifications

  • Target Gas: Carbon Monoxide (CO)

  • Detection Range: ~20 – 2000 ppm

  • Operating Voltage: 5V

  • Output:

    • Analog (A0)

    • Digital (D0 with comparator)

  • Preheat Time: β‰₯ 24–48 hours (important!)

  • Heater Current: ~150 mA

⚑ Working Principle

  • Uses SnOβ‚‚ (tin dioxide) sensing layer

  • CO gas reduces sensor resistance

  • Module converts it into voltage

πŸ‘‰ More CO β†’ higher output signal

πŸ”„ Unique Feature (IMPORTANT)

πŸ‘‰ Unlike MQ-2 / MQ-135:

MQ-7 uses two-phase heating cycle:

  • 5V heating (60s) β†’ cleaning phase

  • 1.4V heating (90s) β†’ sensing phase

➑️ Accurate readings only in low-temp phase

⚠️ Most modules don’t control this automatically
πŸ‘‰ You must handle it in code (advanced use)

πŸ”Œ Pinout

  • VCC β†’ 5V

  • GND β†’ Ground

  • A0 β†’ Analog output

  • D0 β†’ Digital output (threshold adjustable)

🧠 Output Behavior

CO LevelOutput
LowLow voltage
MediumMedium voltage
HighHigh voltage

πŸ‘‰ Analog output is non-linear

πŸ’‘ Applications

  • 🏠 Home CO alarm systems

  • πŸ”₯ Fire detection

  • πŸš— Car exhaust monitoring

  • 🏭 Industrial safety

  • πŸ€– Air quality projects

⚠️ Important Notes (VERY IMPORTANT)

❗ 1. Requires long preheating

  • Needs 24–48 hours initially
    πŸ‘‰ Otherwise readings are unstable

❗ 2. Not highly accurate

  • Gives approximate ppm, not precise

  • Needs calibration

❗ 3. High power consumption

  • Heater uses significant current
    πŸ‘‰ Not good for battery projects

❗ 4. Cross sensitivity

  • Also reacts to:

    • Hydrogen

    • Methane
      πŸ‘‰ Not 100% CO selective

❗ 5. Temperature cycle control (advanced)

πŸ‘‰ For accurate CO detection:

  • Must control heater voltage cycle
    ➑️ Otherwise readings are less reliable

πŸ†š MQ-7 vs Other Sensors

SensorGasAccuracyUse
MQ-2Smoke/LPGLowGeneral
MQ-135Air qualityLowBasic AQ
MQ-7COMediumCO detection
SCD40CO₂⭐ HighPrecise COβ‚‚

πŸ‘ When to use this

Use MQ-7 if you want:

  • Low-cost CO detection

  • Basic safety systems

  • Arduino beginner projects

πŸ‘Ž When NOT to use

Avoid if:

  • You need precise ppm measurement

  • Battery-powered device

  • Professional safety system

🧠 Final Understanding

πŸ‘‰ This sensor = β€œlow-cost carbon monoxide detector”
πŸ‘‰ Good for learning & basic projects, not industrial accuracy

πŸš€ Pro Tip

πŸ‘‰ Better setup for air safety:

  • MQ-7 β†’ CO detection

  • ENS160 β†’ VOC + AQI

  • SHT41 β†’ temperature + humidity

➑️ Combined = complete air monitoring system πŸ”₯

Quantity
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