Does someone knows how to wire this breakout (MQ-7 High Sensitivity CO Carbon Monoxide Detector Sensor - Black - Free shipping - DealExtreme) ?
I know that the MQ7 needs to have some burning time, how do I do that ? Thanks !
This is a basic guide for MQ gas sensors, Arduino Playground - MQGasSensors
Connect the sensor as:
- Vcc to 5V. The 5V output pin of the Arduino might not supply enough current, so you might need an extra power supply of 5V.
- GND to GND
- AOUT to an analog input of the Arduino
- DOUT, you can connect it to an digital pin, but you don't need it.
The sensor board has a comparator and a digital output. That is kind of nonsense, the Arduino can detect the analog level.
The heater for the MQ-7 needs 5V and sometimes 1.4V. You can create the 1.4V with a PWM signal and a mosfet to switch the heater.
If you want something with full description, look at the websites of Sparkfun and Adafruit.
If you want something cheap, search for it on Ebay.
Thanks for the reply Erdin, I'll try to check how it works with a mosfet. I think that the comparator is to check the threshold of the adjustable potentiometer and then turn on the digital out pin.
You need a 'logic level' mosfet, that turns on with the 5V signal of the Arduino.
For protection you could add a resistor of 1k from the Arduino output to the gate.
Try without the mosfet and without the 1.4V first. If you use it with 5V and apply a gas to the sensor, the output should change a lot. Once you have that, you can go on.
Normally, the potentiometer is the load resistor.