MQ-136 Hydrogen Sulfide Gas Sensor Documentation

Dimensions

16mm (diameter) x 8mm (height)

Weight

2g

Operating Temperature

-20C to 50C

Operating Humidity

20% to 90% RH

Applications

Industrial process monitoring

Environmental monitoring

Personal safety devices

Air quality monitoring

Waste management

Oil and gas exploration

Technical Specifications

Detection Range

1-100 ppm H2S

Sensitivity

1-10 k/ppm

Output Signal

Analog voltage (0-5V)

Power Supply

5V DC

Current Consumption

150mW (typical)

By providing accurate and reliable H2S detection, the MQ-136 Hydrogen Sulfide Gas Sensor is an essential component in various applications where safety and environmental monitoring are critical.

Pin Configuration

MQ-136 Hydrogen Sulfide Gas Sensor Documentation
Pin Description and Connection Guide
The MQ-136 Hydrogen Sulfide Gas Sensor is a highly sensitive and selective sensor module designed to detect Hydrogen Sulfide (H2S) gas concentrations in the air. The sensor module has 6 pins, which are described below:
Pin 1: VCC (Power Supply)
Function: Power supply pin for the sensor module
Voltage: 5V (typical), 4.5V to 5.5V (operating range)
Connection: Connect to a 5V power supply, such as a breadboard power rail or a microcontroller's 5V output.
Pin 2: GND (Ground)
Function: Ground pin for the sensor module
Connection: Connect to a common ground point, such as a breadboard ground rail or a microcontroller's GND pin.
Pin 3: DO (Digital Output)
Function: Digital output pin that provides a logic level output based on the detected gas concentration
Logic Level: High (H) when the gas concentration exceeds the set point, Low (L) when the gas concentration is below the set point
Connection: Connect to a digital input pin of a microcontroller or a logic-level device.
Pin 4: AO (Analog Output)
Function: Analog output pin that provides a voltage output proportional to the detected gas concentration
Output Range: 0V to 5V
Connection: Connect to an analog-to-digital converter (ADC) input pin of a microcontroller or an analog input device.
Pin 5: HEATER (Heating Element)
Function: Heating element pin to heat the sensor element
Voltage: 5V (typical), 4.5V to 5.5V (operating range)
Connection: Connect to a 5V power supply, such as a breadboard power rail or a microcontroller's 5V output. Note: The heating element should be connected to a power supply with a current limiting resistor (typically 1k) to prevent overheating.
Pin 6: NC (No Connection)
Function: No internal connection, reserved for future use
Connection: Leave unconnected.
Connection Structure:
To connect the MQ-136 Hydrogen Sulfide Gas Sensor to a microcontroller or a development board, follow this structure:
VCC (Pin 1) -> 5V Power Supply
GND (Pin 2) -> Ground
DO (Pin 3) -> Digital Input Pin (e.g., Arduino Digital Pin)
AO (Pin 4) -> Analog Input Pin (e.g., Arduino Analog Pin)
HEATER (Pin 5) -> 5V Power Supply with 1k current limiting resistor
NC (Pin 6) -> Leave unconnected
Remember to follow proper soldering and wiring techniques to ensure reliable connections and prevent damage to the sensor module.

Code Examples

MQ-136 Hydrogen Sulfide Gas Sensor Documentation

Overview

The MQ-136 Hydrogen Sulfide Gas Sensor is a highly sensitive and accurate gas sensor used to detect the presence of hydrogen sulfide (H2S) in the air. This sensor is widely used in industrial, environmental, and safety applications, such as gas leak detection, air quality monitoring, and industrial process control.

Technical Specifications

Detection Range: 1-100 ppm
 Sensitivity: 1-5 mA/ppm
 Output Signal: Analog voltage (0-5V)
 Power Supply: 5V DC
 Operating Temperature: -20C to 50C
 Response Time: <10 seconds

Interface and Pinout

The MQ-136 sensor has a 6-pin interface, with the following pinout:

VCC: Power supply (5V DC)
 GND: Ground
 OUT: Analog output signal
 HEAT: Heater voltage (optional, for temperature control)
 NC: Not connected
 NC: Not connected

Code Examples

### Example 1: Basic Analog Read with Arduino

This example demonstrates how to read the analog output signal from the MQ-136 sensor using an Arduino board.
```c
const int sensorPin = A0; // Analog input pin for the sensor
const int ledPin = 13;   // LED pin for indicating H2S presence

void setup() {
  pinMode(sensorPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  int sensorValue = analogRead(sensorPin);
  float voltage = sensorValue  (5.0 / 1023.0);
  float ppm = voltage  (100.0 / 5.0); // Assuming 1-100 ppm detection range

if (ppm > 10) {
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }

Serial.print("H2S Concentration: ");
  Serial.print(ppm);
  Serial.println(" ppm");

delay(1000);
}
```
### Example 2: I2C Interface with Raspberry Pi (using ADS1115 ADC)

This example demonstrates how to read the analog output signal from the MQ-136 sensor using a Raspberry Pi and an ADS1115 ADC chip.
```python
import time
import board
import busio
import adafruit_ads1x15.ads1115 as ADS

# Initialize I2C bus and ADS1115 ADC
i2c = busio.I2C(board.SCL, board.SDA)
ads = ADS.ADS1115(i2c)

# Configure ADC channel and gain
channel = ADS.P0
gain = ADS.PGA_1_1

while True:
    # Read analog voltage from ADS1115
    voltage = ads.read_adc(channel, gain)
    ppm = voltage  (100.0 / 5.0)  # Assuming 1-100 ppm detection range

if ppm > 10:
        print("H2S detected! Concentration: {:.2f} ppm".format(ppm))
    else:
        print("No H2S detected.")

time.sleep(1)
```
Note: These examples are for illustrative purposes only and may require modifications to suit specific application requirements. Additionally, proper calibration and testing are recommended for accurate gas detection and safety precautions should be taken when working with hazardous gases like hydrogen sulfide.