1、 Size: 32mm X22mm X27mm length X width X height

2、 Main chips: LM393, ZYMQ-136 gas sensors

3、 Working voltage: DC 5V

4、 Features:

1. Has signal output indication.

2. Dual signal output (analog output and TTL level output)

3. TTL outputs a valid signal at a low level. (When the signal light is on when the output is low, it can be directly connected to the microcontroller)

4. The analog output voltage is 0-5V, and the higher the concentration, the higher the voltage.

5. Has good sensitivity to hydrogen sulfide, liquefied gas, natural gas, urban gas, and smoke.

6. Has long-term service life and reliable stability

7. Fast response and recovery characteristics

5、 Application:

A gas leakage monitoring device suitable for households or factories, suitable for monitoring devices such as liquefied gas, butane, propane, methane, alcohol, hydrogen, smoke, etc.

Explanation: This module is an MQ-136 hydrogen sulfide sensor. Please preheat for about 20 seconds before use:

Step 1: Supply the module with 5V DC power (be careful not to connect the positive and negative poles in reverse, otherwise it may burn the chip).

Step 2: If the DOUT and TTL high and low levels are selected, the output signal can be directly connected to the microcontroller IO port or an NPN type transistor to drive the relay. The potentiometer RP is used here to adjust the threshold value of the output level jump. As shown in the schematic diagram below, when the sensor detects the gas being measured, the voltage value at pin 2 of the comparator LM393 is directly proportional to the gas concentration detected by the sensor. When the concentration value exceeds the threshold set by the potentiometer RP, the point on pin 2 of the comparator is higher than the point on pin 3. At this time, the comparator 1 outputs a low level, the LED light is on, and R3 is the current limiting resistor of the LED light. C1 is the filtering capacitor. The sensor outputs a low level. Conversely, when there is no signal, the sensor outputs a high level, which is equal to the power supply voltage.

Step 3: If AOUT is selected for analog output, there is no need to worry about the potentiometer. Simply connect the AOUT pin to the input terminal of AD conversion or a microcontroller with AD function. Based on our experience: in a normal environment, that is, an environment without the measured gas, the sensor output voltage value is set as the reference voltage. At this time, the voltage at the AOUT end is about 1V. When the sensor detects the measured gas, for every 0.1V increase in voltage, the actual concentration of the measured gas increases by 200ppm (in simple terms, 1ppm=1mg/kg=1mg/L=1 × 10-6 is commonly used to represent gas concentration or solution concentration). Based on this parameter, the measured analog voltage value can be converted into concentration value i