Mq7 Circuit Diagram. V h vc heating voltage 5v high 60s heating voltage 14v low 90s. More by the author.
In order to make the sensor with better performance suitable rl value is needed. The mq7 is a simple to use carbon monoxide co sensor suitable for sensing co concentrations in the air. Mq 2 gas sensor arduino.
This schematic diagram is the same as with the mq 3 alcohol sensor and mq 6 lpg sensor.
One is heating circuit having time control function the high voltage and the low voltage work circularly. One is through the dout pin which gives a high when the concentration threshold is reached and low otherwise. The purpose of the variable resistor is to adjust the output voltage and to maintain. It looks like building up a layer of gasproducts during the measurement phase.