> For the complete documentation index, see [llms.txt](https://docs.acrome.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.acrome.net/smd-applications/boardoza-sensors/mq-4-methane-gas-sensor.md).

# MQ-4 Methane Gas Sensor

### Overview

The Boardoza MQ-4 is a specialized electrochemical sensing module engineered for the reliable detection of Methane (CH₄) and Compressed Natural Gas (CNG) in ambient environments. Built around a robust metal-oxide semiconductor (MOS) chemiresistor, this sensor exhibits high sensitivity to methane concentrations ranging from 200 to 10000 ppm, making it a critical component for gas leak detection, industrial safety monitoring, and domestic air quality systems.

The module simplifies the integration of the raw MQ-4 sensor by providing onboard signal conditioning circuitry, offering both analog and digital output interfaces for seamless connectivity with modern microcontrollers.

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|                                                                       Front Side                                                                       |                                                                       Back Side                                                                      |
| :----------------------------------------------------------------------------------------------------------------------------------------------------: | :--------------------------------------------------------------------------------------------------------------------------------------------------: |
| ![Boardoza\_MQ4\_GAS\_MKPV2\_Front\_View](https://github.com/Boardoza/Boardoza_MQ4_Methane_Gas_Sensor_Breakout_Board/raw/main/assets/MQ-4%20Front.png) | ![Boardoza\_MQ4\_GAS\_MKPV2\_Back\_View](https://github.com/Boardoza/Boardoza_MQ4_Methane_Gas_Sensor_Breakout_Board/raw/main/assets/MQ-4%20Back.png) |

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<div align="left"><figure><img src="/files/a4w5ZBu3spZQCgmeQeVU" alt="" width="375"><figcaption></figcaption></figure></div>

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### Core Technical Specifications

The module is defined by the following operational parameters:

* Target Gas: Optimized for Methane (CH₄) and Natural Gas (CNG) detection.
* Detection Range: Capable of sensing concentrations between 300 ppm and 10000 ppm.
* Sensing Architecture: Metal-Oxide Semiconductor (SnO₂) chemiresistor, where conductivity increases in the presence of target combustible gases.
* Operating Voltage: designed for standard 5V DC supply rails to power the internal heating element.
* Heater Consumption: approximately 150mA, required to maintain the sensing element at optimal catalytic temperature.
* Response Time: Fast response (< 10s) suitable for real-time safety alerts.
* Sensitivity Adjustment: Features an onboard precision potentiometer for calibrating the digital trigger threshold.

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### Key Engineering Features

#### Dual-Signal Output Architecture

To maximize versatility, the breakout board provides two distinct output modes:

1. Analog Output (A0): Delivers a continuous voltage signal proportional to the gas concentration. This allows for precise ppm estimation when coupled with an MCU's Analog-to-Digital Converter (ADC).
2. Digital Output (D0): Provides a simple TTL logic signal (High/Low) based on a pre-set threshold. This is ideal for standalone alarm systems where a microcontroller might be overkill or for triggering interrupt-based safety shutdowns.

#### Integrated Comparator Circuitry

The digital output stage is driven by an onboard LM393 comparator. This integrated circuit compares the analog sensor voltage against a reference set by the onboard potentiometer, providing a clean, hysteresis-free digital signal for robust alarm triggering without software debouncing.

#### Industrial-Grade Stability

The MQ-4 sensor element is known for its long-term stability and resistance to alcohol and smoke interference, ensuring a low false-positive rate in specific methane detection applications compared to general-purpose combustible gas sensors.

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### Hardware Interface and Signal Mapping

The module interfaces via a standard 4-pin header, clearly labeled for rapid prototyping:

Power Terminals

* VCC: Positive supply input. Must be connected to a stable 5V source to ensure consistent heater performance.
* GND: Common system ground.

Signal Outputs

* A0 (Analog Out): The primary measurement pin. Output voltage increases as gas concentration rises.
* D0 (Digital Out): The threshold trigger pin. Logic Low (0V) typically indicates gas presence exceeding the calibrated limit (adjustable via potentiometer).

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### Applications

* Domestic Safety: Leak detectors for residential natural gas pipelines and stoves.
* Industrial Monitoring: Methane concentration logging in coal mines or waste management facilities.
* Portable Gas Analyzers: Handheld sniffers for locating pipe fractures.
* Smart HVAC: Ventilation control based on indoor air quality metrics.

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### Board Dimensions:

![MQ4 Methane Gas Sensor](https://github.com/Boardoza/Boardoza_MQ4_Methane_Gas_Sensor_Breakout_Board/raw/main/assets/MQ-4%20Dimension.png)

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{% hint style="info" %}
Ready to integrate? You can purchase the **MQ-4 Methane Gas Sensor** directly from our [Online Store](https://www.robotshop.com/products/acrome-mq4-methane-gas-sensor-breakout-board?qd=2fbb3af2cc1b35765a78c5669574db21). Worldwide shipping is available for engineering samples and production batches.
{% endhint %}

{% embed url="<https://www.youtube.com/watch?v=TtW3a_jSY8o>" %}