A brief description
I. Size:32mmX20mmX23mm long X width X high
main chips:LM393 , MQ-135 The gas sensor
Third, the working voltage: DC5 V
1, A signal output indication.
2Dual signal output?And analog output TTL Level output?
3, TTL Output valid signal is low.?When the output low signal light can be directly connected microcontroller?
4Analog output 0 ~ 5V Voltage, the higher the concentration the higher the voltage.
5Of carbon monoxide with high sensitivity and good selectivity.
6The stability of long-term service life and reliable
For carbon monoxide detection device family, the environment. Suitable for the detection of carbon monoxide gas and the like.
Applicable occasion: SCM learning, electronic competition, duct development, graduation design. . .
Explanation: This module MQ-135 air sensor, Please use the warm-up before about 20S:
The first step: to the module for 5V DC?Note that the positive and negative do not reversed, otherwise easy to burn chip?.
Step Two: If you choose DOUT, TTL high and low ends of the output signal can be directly connected to the microcontroller IO port or a connected NPN type transistor to drive the relay, Potentiometer RP is used here to adjust the output level transition threshold, By the schematic diagram can be analyzed when the sensor detects the gas being measured, LM393 comparator pins 2:00 voltage value detected with the sensor is portional to the gas concentration, when the concentration exceeds a threshold set by the potentiometer RP the comparator 2 feet 3 feet above the point of the point, this time, the comparator 1 pin output low, LED lights, R3 limiting resistor for the LED lights, C1 is the filter capacitor. Sensor output low, on the contrary, when there is no signal when the sensor output high, equal to the supply voltage.
Step Three: If you choose AOUT, analog output, so you do not have control potentiometer, the AOUT pin connected directly to the input of the AD converter or a microcontroller with AD function on it. According to our experience: in a normal environment, that is: no measured gas environment, setting the sensor output voltage value of the reference voltage, then the voltage AOUT end around 1V, when the sensor detects the gas to be measured, Voltage is increased by 0.1V, the actual measured gas concentration increases 20ppm ? Simply put: 1ppm = 1mg / kg = 1mg / L = 110-6 used to indicate the gas concentration, or concentration. ?According to this parameter can be converted to an analog voltage value of the measured concentration values in the microcontroller inside. Note: If you are used to do precision instruments, please purchase on market standards to calibrate the instrument, or there is an error, because the concentration and the ratio of the output voltage relationship is not linear, but tends to be linear.
reminder: After the sensor is powered, need to warm about 20S, measured data becomes stable, heat sensor is a normal phenomenon, because the internal heating wire, hot if not normal.
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