Probably, now even any student knows that such a dangerous gas as methane is odorless, and it is simply not possible to detect it in the air without special devices. Methane is the main component of natural gas. Methane, the same gas that flows through the pipes and in your home, with the slight change that smelling additives are specially added to it so that it can be detected by smelling.
But if you can smell it, then why make a sensor, you ask? The fact is that a person can smell already dangerous concentration of gas. The sensor has a higher sensitivity. And if there is a small gas leak in the room within a few hours, this concentration may not have a smell, but there will be a 100% risk of explosion. To avoid this and detect beginners small concentrations of gas in the air and use gas sensors.
This, of course, is most likely a test project that shows the basic principle of working with a gas sensor, but no one in the future will prevent you from improving and making it a serious project.
I will give a list of parts and materials that are needed to build our sensor. (Link to the store)
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2. 9V battery and plug.
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6. (any n-p-n structure will do).
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11. Other materials such as soldering iron, solder, flux and wires.
So let's get started setting up this project!
The scheme is pretty simple. Her heart is the MQ-02 gas sensor, but you can also use the MQ-05, MQ-04 sensors.
MQ-02 - reacts propane, methane, alcohol vapor, hydrogen, smoke. The MQ-02 gas sensor is a complete module. He has an amplifier and a variable resistor on his board, with which you can adjust the sensitivity.
My circuit consists of a multivibrator assembled on a 555 timer chip.
The work is simple: When a certain level is exceeded on the timer, a multivibrator is launched at the output of which an LED and a buzzer with an integrated generator are connected. An intermittent signal sounds and the LED flashes. The device is powered by a 9 volt battery, through the stabilizer it drops to 5 volts.
