Hi there, I'd like to build a CO2 gas sensor using an MQ-135 gas sensor, for my environmental science class. How can I adapt this project to an MQ-135 sensor? Also, the links to your datasheets don't seem to work. Can I get access to your datasheets? How can I create a similar datasheet for an MQ-135 sensor? Any assistance is most appreciated. Cheers!
You don't have to change anything in this project, if you want to get a value between 0 and 1023. I fixed the datasheet links, thanks for letting me know they were broken.
Very good video. Simple and clear explanations. My son and I bought an MQ-4 yesterday and now I understand how to connect it to the Arduino. Thank you very much!
hi, i want to measure air quality at home and thinking of getting MQ-135 but i am not sure if sensitivity is highly enough to detect low gas level. i know that CO should be under 6 ppm in healthy air quality, will this sensor measure that? thanks in advance
+naveen mittal Hi, I don't know the exact answer to your question. To measure gas concentration in ppm you would need a calibrated sensor. I know that these MQ type sensors are not very accurate, I wouldn't trust them so much.
If you want to use this properly, you need to calibrate every startup, after warming up for 3 minutes, expose to open air, and then in your code, zero out the value. Then only measure based on the offset. This makes the readings more sane and accurate. Otherwise you will notice drift on every startup depending on the material composition of the heater and materials near it, as they will off-gas differently as they age, and should be discounted from the readings.
I did not yet get my answer? in order to preheat the sensor, do I need to use the resistor or only use straight 5v power. My datasheet said it needs to preheat for 24 hours, but it does not mention if I need to use the resistor or not, my values with out preheat are coming in like: 0 344 200 523 123 882 1023 0 50 122 The values are very unstable, but do you think it will be fixed after the pre heat?? I am a very frequent viewer of yours, I like all of your projects,A quick answer will be apreciated, thanks in advance
Excellent - thank you very much for sharing info! I'm trying to make this for my indoor garden because it's so much cheaper to make and I've just gotten into Arduino. Good luck - have fun.
Thanks for posting this video.. I found it very useful. Have you though not connecting the Audrino directly to sensor and use wifi to exchange messages?
Thanks so much, this is exactly what we need. the only problem is that would either process work for the MQ-4, as our prime mission is to measure methane. Or would it be possible to get rid of all data of all other gases for the MQ-2 and only show the methane data. We are from Moate Community School and entering a project for Cansat. Thanks so much for your help.
Yes, these are voltage values between 0-5V - there are 1024 steps. Watch my vide entitled: How to make a simple Arduino ohmmeter - you will learn how to get resistance values.
Jason Estacio Hi, I didn't want to solder and heat shrink tubing seemed to be the fastest way to connect these wires to the legs. I will consider making another gas sensor videos, but there are already a couple of videos in my schedule. I wish I had more time for UA-cam videos.
this is an interesting video. I would recommend you to explain more like how the sensor works or why to connect wires like this. I mean, now I know how the sensor works with arduino, but I can't do it if I want to add a sensor to my project. take an example, we can get some analog outputs with this diagram, but what's the meaning of this value? how to convert the number to some standard numbers? This will be really helpful because if I want to do an air monitor project with this, I don't know how to define the number. LED lights up when it's 500, but what's the real number that matters in our life? In datasheet I see a relation between sensor resistance with ppm, but maybe a starter will never figure out. anyway, this is a great video. I have subscribed and wish you have more excellent videos :)
Zelra 仙賢戀軒 Hi, thanks for your comment, subscription and advice. I'm trying to make my videos not too long. Maybe I should have explained more details about the sensor.The values are something between 0 and 1023 and they come from Arduino analog to digital converter. If you want your readings in ppm units, you would need to calibrate your sensor against a known gas concentration (maybe this part of explanation should be included in the video).
Awesome video, but can u please suggest a sensor which detects differ parameters of gas like carbon dioxide , carbon monoxide, oxygen , sulphur content in the air .I need such a sensor for measuring the air pollution .So please suggest a sensor which measure various components of air separately
Wow! There are a ton of questions/answers for this video. I tried to search throught them with some keywords, however I could not find answers I was looking for about cost and about lower detection limit and accuracy in the low range of measurements. Looking to build something similar but it would have to detect and readout values for CH4 way below the LEL at around the 10ppm range in order to be useful for my project. Sorry if this question is repetitive from those asked/answered before.
Hi, thank you very much for this very well explained video. What do you think about using the MQ2 for a consumer product ? Do you think it is sturdy and reliable enough for commercial use ? Thank you
+Amine Ben Hi, after playing with these sensors for a while I wouldn't recommend them for commercial purposes. They are good for learning and experimenting, but that's it. In my opinion they are not reliable enough for a commercial project.
When you choose serial monitor to view data in a new windor, are you be able to copy this data or not? Or a data logger shield should be used to export data needed?
Thank you for ur awesome video. But i searched a lot for this video, it could be easy and reachable if you've used the title as 'Gas leakage detection'.❤️
ElectronFun.com For aesthetic purpose. I want to design a box that can detects gas leakage and smoke. Do I just leave a small hole opening for the sensor to detect the gas? Does the airflow is adequate enough for the sensors to detect the gas? Or do I put a mini fan to circulate the air into the box chamber?
***** I haven't tested anything like that, but I guess a hole in the box might be not enough and a fan might affect your readings, but it's only my theory. It's always a good idea to try out new ideas.
Awesome video, but can you please suggest a sensor which detects different parameters of gas like carbon dioxide , carbon monoxide, oxygen , sulphur content in the air .I need such a sensor for measuring the air pollution .
Rizwan Kamleen Unfortunately you can't use it in a flame detector circuit. The MQ-2 can operate only up to 50 degrees C, see here: sandboxelectronics.com/?product=mq-2-smokelpgco-gas-sensor-module.
Hi, Liked ur video, it was informative. Wanted to knw that semiconductor gas sensor could detect methane in a range of 100ppm to 20000ppm. If yes could you suggest the sensor.
+Ismail Zabii I know MQ-4 can sense Methane, but the range is from 200 to 10000ppm. However the MQ sensors are not very accurate and reliable, so I wouldn't use it for a serious/commercial project.
Yes, these values are voltage readings. I have a 3 minute video on my channel entitled "How to make a simple Arduino ohmmeter". You'll learn how to get resistance values easily.
Hi, nice video! I'm trying to do the same as you, but with the MQ-131, ozone gas sensor. I'm trying to understand: how have you found the value of the resistance to put on your board? For the MQ-131 sensor i need to preheat the sensor for almost a day, Someone says you have to change the resistance after the preheat to have a good measure. But I have seen you can change the value of sensitivity in the sketch, so How do I have to do? In any case thank you :)
+Francesco Motterle Thanks a lot! I took my resistor's value from the datasheet. However I checked your MQ-131 datasheet and it says "load resistance: variable" - it's pretty confusing, but you can use a potentiometer and adjust sensitivity. Preheating the sensor is advised by the datasheet - yours says: "over 24 hours", so it's a good idea to do that.
Violeta Mena Hi, thanks for your comment.You can use MQ-135, the wiring diagram is the same, but to make it work with CO2 you should follow this tutorial: davidegironi.blogspot.it/2014/01/cheap-co2-meter-using-mq135-sensor-with.html#.VRBvweGfxFo There is another sensor, made specifically for CO2 - MG811, but it uses 6V and the wiring diagram is a bit different (see here): pdf1.alldatasheet.com/datasheet-pdf/view/172004/ETC2/MG811.html
There are 2 groups of 3 pins. You want to supply 5V to the middle pin in each group. This sensor is not polarized, so it doesn't matter which pin will be your GND and which one will be your 5V.
Hi, thanks! Arduino Uno is rated for 5V, so it would be better to use a 5V buzzer. If you deliver voltage to the buzzer it will turn on. If you want to change the tone, you could use Arduino "tone()" (arduino.cc/en/reference/tone).
sir good day, i have a question regarding th connection, should i rally use a separate power source of 5 volts? cant i use the same 5 volts from the arduino? can i use a normal 9 volts battery for th separated voltage input for the gas sensor? thank you sir, this will be a help
also sir i have tried to view the serial monitor and wait for atleast 5 minutes to trim down the output sensed value by the mq5, but still output value ranges from 600 above till 1023
Hi, according to the MQ-2/MQ-5 datasheets the sensors consume up to 800mW, which is about 160mA at 5V. Here: playground.arduino.cc/Main/ArduinoPinCurrentLimitations you can find Arduino pin current limitations: the 5V rail can deliver 200mA maximum. The sensor's heater alone would consume 160mA out of 200mA. If you connect anything more than the sensor, you may fry your Arduino board. Yes, theoretically you can use a 9V battery for the gas sensor, but you would have to use a 5V voltage regulator. However, I would not recommend using a 9V battery, because it will not last for long. A typical 9V batteries have about 300-580mAh capacity. Your gas sensor would probably work for less than 2 hours (if you're lucky). The MQ-2 and MQ-5 need a 24h preheating (burn-in). You should hook up your sensor to the circuit and leave it in on for 24 hours (make sure everything is connected properly to prevent from overheating and eliminate the risk of fire). You can do this only once. It is meant to make the readings more consistent. It should help in your case.
good eve sir... can this project last for continuous use??? lets say a week or more without turning the power off?? will the sensor overheat or burn?? thanks alot sir
Hi, the sensor should be able to work constantly without problems. You can even find in the datasheet that the sensor should be powered constantly for over 24 hours before first use (it's called preheat time). If you don't exceed the maximum voltage 5.1-5.2V the sensor will not overheat.
Thanks! Yes, it is possible to present the readings on an LCD display. Would you like to see the values from the Arduino (0-1023) or convert them to ppm units? If you want to get the readings in ppm units you would need to calibrate the sensor against a reference sensor.
Very nice video. I wanted to ask you, if I want to use the gas sensor with Arduino on a flying drone, do you think this technique can work? Or I should proceed with another way? Thank you for your time...
+Georges Tufenkji Thank you for your comment and watching. Your idea is very cool! I believe it should work, however these sensors are not super accurate - bear that in mind.
Hello ElectroFun, Very great job! When searching some MQ sensors to buy, I found out that some of then already come with a board on themselves, and has four pins for connecting, like somoene said on a comment bellow. The DataSheet of this device is identical to that one you've linked above, and the circuits I've found just say to connect de VCC pin to de Arduino's 5V, the GND pin to Arduino's GND and the AOUT pin to Arduino's A0, without any resistor or mentioning the heaters. I just wanna know how three things about this kind of device: - How does the heating system works? How do I preheat the sensor? - Why in this case it's ok to connect the whole sensor and board in the Arduino's 5V pin? Won't this damage my Arduino, or only if I connect some other devices to it, like LED or Buzzer? - And the load resistor, why isn't it necessary any more? How can I adjust the sensitivity of my sensor whitout it? Thanks! (sry for my english)
Hi Lucas, Thanks a lot for your comment! That's true, there are some sensors mounted on a piece of breadboard with pretty much all needed circuitry. The load resistor is there, both A pins are connected to each other and both B pins are connected to each other as well. There are some boards like this with only 3 pins: VCC, GND and AOUT (sense line). You can even buy sensors, which are already calibrated and show PPM readings, but they are usually much more expensive. To your questions: 1. The sensor is most accurate in a certain temperature range and needs a heater, which is a simple coil. In the datasheet you can usually find information how long you should preheat the sensor - it means you should leave your sensor connected and running continuously for this period of time (for example 24h). 2. The sensor won't kill your Arduino by itself. It usually draws up to 800mW at 5V, which makes 160mA. Arduino 5V-GND pins can deliver up to 200mA at 5V. You have just 40mA left and it's not the best idea to draw maximum current all the time from your Arduino. 3. The load resistor is usually mounted on the sensor PCB. You will usually find a potentiometer on such boards that you can use to adjust the sensor's sensitivity.
Hello, I really liked the video and i want to ask you few things on this, can we have sensor, alarm speaker and simple power supply which makes compatible and sense the gas. can you pls describe.
Thank you! Yes, it is possible to have a gas sensor with a power supply or some kind of battery and a speaker, which would alarm you, if it sensed certain gas concentration. The easiest way to make something like this would be to replace the LED with a small speaker. I want to build a simple gas leakage detector in one of my next videos and use a speaker, or an LED bar graph or an LCD to show the results. I'm not able to tell you exactly when, because I have a "regular" job, which prevents me from making videos quicker and more frequently. I can see many people are interested in gas sensors, so this video will get higher priority.
Hello, Thank you for the video. It's helpful !! I would like to know if the use of the resistors is necessary or not ? and what are the effects if i don't use them? thanks.
Nada Hi, thanks for your comment! The resistor is necessary according to the datasheet. I guess the readings would be completely inaccurate without the resistor.
Hi. We read the datasheet of Mq-135 sensor, which sense for multiple gases in arduino. However we have a problem because our laptop only read one column, as you shown in this video. We do not know what kind of gas we are reading (how we do that?), and furthermore, we want read all gases in several columns. is possible to do this? thank so much in advance.
+Sinhué Haro Corzo You might want to use Sandbox Electronics piece of code to "calibrate" the sensor and get a separate reading for each gas: forum.arduino.cc/index.php?topic=181780.0. I haven't put too much time into it yet, but I know some people get pretty decent results.
Hey great project. I am doing something similar but I am confused are the sensor value same as the concentration value of the gas, I want to measure the consentration of LPG in a room.
+alnada alkubaisi Thanks :) Unfortunately it's not that easy. The readings are just analog values taken from the sensitive element and converted by Arduino to digital values between 0 and 1023. To get values in some well known units like ppm, you need to calibrate the sensor. Normally you would need special equipment to do it, but if you want to use an MQ-2 sensor, there is a piece of code made by Sandbox Electronics, which simplifies the calibration process, but the readings will be less accurate. You can read more about it, here: sandboxelectronics.com/?p=165. By the way - I'm starting my new video about the MQ-2 calibration with the Sandbox Electronics piece of code.
sir this is really cool.im a newbie wih arduino and i wanted to know if it is possible to use this on a biodigester to create a system that will moniitor the gas flow and amount of slurry. if its ok i would like to ask u some more questions.
Hi, you have a very interesting project. You can ask and I will answer if I know the answers :) I have a question too - what type of gas does this biodigester produce?
it produces methane. its a portable small scale biogas. it uses anaerobic way of producing the methane.. i wanted to build a monitoring system for this and should be low cost. that is why i am choosing arduino. thanks for the help sir.
ElectronFun.com i would like to ask what sensors will i be needing and what model of arduino. when i tried searching, i read about seeduino stalker had been used for gathering data from a portable biogas. can i ask for some idea on how can i start with this project. thanks. and is it ok that im asking here?
alpaxthegreat You may use MQ-4 gas sensor, which is sensitive for Methane and CNG Gas. When it comes to Arduino board - it depends on what you want to do with your data. Do you want to make a standalone device for monitoring and gathering data on e.g. SD card, or do you want to have it hooked up to a computer, which would store your data? Seeeduino Stalker is a nice board with a slot for SD cards and a backup battery holder, but there's no USB connector. To use USB, you need to buy some additional connector (at least that's what I read on the wiki page). Sure, you can ask questions here. I thought about opening a forum, I would like to have a place where all people from this community could help each other, but I don't know if it's not too early. By the way - what do you think about that?
Yes, you can use MQ-135 in exactly the same way and with my Arduino code. Just experiment with the load resistor value and "sensorValue" in the Arduino code.
+animefatboy676 Sure you can use multiple sensors with one microcontroller. Just remember not to power these sensors from your microcontroller board, use a separate power supply.
Thilo 012 Hi, it depends. If you want to have your readings in ppm units for example, you would want to calibrate the sensor against a calibrated sensor so you could know the exact gas concentration. Another thing is consistency of readings - if you're getting inconsistent data you probably need to preheat you sensor by leaving it on for 24 hours (see the datasheet).
Thilo 012 A few days ago I would tell you that you need to calibrate your sensor by comparing it with another already calibrated sensor or adjust it by exposing it to a precise gas concentration and it is true. These methods seem to be the most accurate, but there is another way (I hope) based on sensitivity characteristic curves from the datasheet. I'm going to experiment with this stuff and if I succeed, I may prepare a video about it.
These sensors output an analog value, which has not much to do with PPM. To convert it to PPM units, you want to calibrate the sensor and use it in the code.
Hi, that's a great video, could you please tell me how you can make another one for detecting multi gases in the same time or if it's possible can you make another video , thanks in advance for you reply.
The A and B pins are used to sense the gas concentration, but I wasn't getting into details about their exact operation, so I won't be able to explain much about this topic, sorry.
Can I convert the readings to percentage and regulate the logging time interval. Also added like three more sensor and find their percentage composition in the biogas.I want to use it to log biogas composition from my digester.
You can easily adjust the logging time interval and add more sensors - each one should use a separate Arduino analog pin. The most difficult part would be the conversion of the readings into percentage.
can we get more than 1 ppm valuesof several gasses at once???? I want build a gadget for detect all percentage of gasses that emitt from a vehicle silencer at once. I wanna to display all the ppm values on a display....
Unfortunately no. These sensors can't detect which gas they are exposed to. Each of them is able to detect several different gases, but it won't be able to differentiate between them.
I'm glad you like the video, thanks for the comment and good luck with your experiments. If you have any questions while experimenting, feel free to ask :)
ElectronFun.com yes kind off.... I was trying to use it at my home after making it... is computer connection necessary each time?? and can bread board be replaced by something? Regards
Hi love your videos, I'm in the middle of a project building a gasification unit to run a generator on woodgas, would you be able to do a video on how to use an Arduino with a car 02 sensor to control a rc servo adjusting the gas to air ratio?
hi.. may I know which sensor can be use to detect n2. nitrogen.. I mean building a N2 supply inside a isolate small compartment. , would like to add in a sensor to detect leakage. Thank you
You can use MQ-3 alcohol sensor in exactly the same way as presented in this video, because it has identical pinout and voltages. When it comes to the eye blink sensor - do you mean some kind of system with glasses which would detect if you blink or not?
that a really good work,its nice and please can i get a manual or instruction on how i can calibrate both MQ7 and MQ8 on Arduino uno board for detecting CO and H2
Hi there, Your videos are really great and I need to make one of your gas sensor alarm using Arduino. Can you PLEASE tell me where I can find the download link for the Arduino software for this project. I cannot see it anywhere.
Robin Davidson Thanks a lot! You can download the code from the project page on my website, here: electronfun.com/project_2.php The link is also in the description of the video.
Hey man. Awesome project! If I am trying to make a reliable diy smoke alarm which sensors will I need? The MQ-7 for CO and MQ-2 for everything else? Thanks!
Thanks a lot Jim! You could use the MQ-2 alone as a smoke detector. However, I wouldn't use these sensors in my home smoke detectors. They are nice when you want to learn how to use Arduino with them, but their reliability isn't very good.
+Aiza Marie Sambo You would need to connect each sensor to a separate Arduino's analog input. Each sensor should have it's own resistor connected to ground. The rest of the connections would remain untouched. The code should be updated to read from 3 different analog inputs. When it comes to the power supply - for 3 sensors you would need at least 500mA at 5V.
That is really cool. Maybe you can help me with my thesis project. I have a very small amount of flow of CO2 and it's really a pain to detect it with anything actually. I was thinking of a hot wire anemometer. I found that it's possible with arduino but not sure where to begin. Will appreciate your opinion on this.
Thank you :) To tell you the truth - I wouldn't use these MQ sensors for anything serious. They are quite inaccurate without proper calibration. When it comes to the hot wire anemometer - I haven't played with this at all, but you could start reading here: playground.arduino.cc/Main/ThermalAnemometer. Sorry I couldn't help you more.
You're better off getting the complete modules, they come with a calibration pot and other components to make it more stable. They are very cheap on Aliexpress too.
Hi i have a quick question, well two really. Can you connect multiple different MQ series sensors in parallel ? to each other ? also is it possible to add an LCD display to display the levels ?
Hi, MQ sensors are purely analog and it's not really possible to stack them (use one analog pin to read values from different sensors). You would need one analog pin for every single sensor. It is possible to add an LCD to the sensor. I'm working on a new tutorial on using an LCD with Arduino Uno.
Frank Lopez It's not only for the heater coil, but for the whole sensor. These sensors are symmetrical and you don't know which pair is A and which is B. You can rotate it by 180 degrees and it looks the same. It doesn't matter which pair is A and which is B for you. Just remember that the sense wire, which is connected to A0 has to be hooked up to the grounded pair. If you connected the A0 to the positive pair your highest reading would be 0 and the lowest would show 1023.
Great video. However, you are just showing the analog input of the sensor which is useless when detecting any particles. The data sheet shows you how to calibrate the sensor and show the value in ppm.
hey i have mq-2 module...is there any need of giving connections to A ,B and H pins?or directly to Vcc pin?also is there any need of connecting Rl? bcz module have built in potentiometer?
It's better to use an external power supply, because the MQ-2 consumes up to 160mA, while Arduino Uno can deliver 200mA maximum. If you connect something more than just the sensor, you can burn out your Arduino.
Hello man... I need put the sensor in a tube to detect the the H2S Through the tube area... Do You know if it's possible? I can measure the gas volume pass by the tube?
There is no easy way of interpreting this data. You should calibrate your sensor to get the readings in ppm units for example. I have another video about software calibration of an MQ-2. It's quite short, but I explained a bit about sensor calibration there.
Mavrick Lomerio Hi, it is normal that the sensor is getting hot - it needs certain temperature to work properly. Is 0 your highest reading when you apply gas and goes up when you stop?
+Praveen Vijapur Good question, but I haven't found such information in the datasheet. From my experiments I would say these sensors are not very sensitive.
Thank you for the video. Sir, How do we calibrate the gas sensor to sense a specific compound? I read the datasheet it said we have to connect a resistor or potentiometer to measure a specific compound. How do I do that, sir?
Ali Altaey Thank you. Yes, the code will work with MQ-138. When it comes to calibration - you should calibrate it against an already calibrated sensor. There is also another method that you can try at home - just in the code, based on sensitivity characteristics, but I wasn't very successful with this, at least yet.
Well done- very nice video. Would you mind describing how you could modify this project such that the Arduino reads two or more sensors simultaneously, such as an MQ135 and MQ138? I would like to use the Arduino with 2 or more sensors to trigger a relay that would turn on/off an energy recover ventilator. I live in the city, so air quality varies where I live. Thanks! John
Thanks a lot! You can read 2 or more sensors easily. In this video I connected the sensor to the breadboard and put a wire between the 'B' pins and A0 analog pin on the Arduino. Hook up another sensor in exactly the same way, but the wire from the 'B' pins should be connected to another free analog pin (e.g. A1) on the Arduino. You also need to update the Arduino code by adding A1 definition and read from this pin in 'void loop()'. If you have any problems with the code or schematic, please let me know and I'll try to help you.
why not connect it to arduino 5v power supply and why after 2 - 3 minutes the readings go low? is the sensor only supposed to work for 2-3 min and then shutdown or the other way around to heat up?
It might be possible, but to tell you the truth I haven't heard about it before. I googled something like zinc oxide nanorod sensing element, but have no idea how it works and if it's possible to use it with Arduino.
Hi there, I'd like to build a CO2 gas sensor using an MQ-135 gas sensor, for my environmental science class. How can I adapt this project to an MQ-135 sensor? Also, the links to your datasheets don't seem to work. Can I get access to your datasheets? How can I create a similar datasheet for an MQ-135 sensor? Any assistance is most appreciated. Cheers!
You don't have to change anything in this project, if you want to get a value between 0 and 1023. I fixed the datasheet links, thanks for letting me know they were broken.
Very good video. Simple and clear explanations. My son and I bought an MQ-4 yesterday and now I understand how to connect it to the Arduino. Thank you very much!
+Saul Arias Thanks a lot! Have fun with your project :)
hi,
i want to measure air quality at home and thinking of getting MQ-135 but i am not sure if sensitivity is highly enough to detect low gas level. i know that CO should be under 6 ppm in healthy air quality, will this sensor measure that?
thanks in advance
+naveen mittal Hi, I don't know the exact answer to your question. To measure gas concentration in ppm you would need a calibrated sensor. I know that these MQ type sensors are not very accurate, I wouldn't trust them so much.
If you want to use this properly, you need to calibrate every startup, after warming up for 3 minutes, expose to open air, and then in your code, zero out the value. Then only measure based on the offset. This makes the readings more sane and accurate. Otherwise you will notice drift on every startup depending on the material composition of the heater and materials near it, as they will off-gas differently as they age, and should be discounted from the readings.
Thanks so much, I couldn't find any other info on this :)
I did not yet get my answer? in order to preheat the sensor, do I need to use the resistor or only use straight 5v power. My datasheet said it needs to preheat for 24 hours, but it does not mention if I need to use the resistor or not, my values with out preheat are coming in like:
0
344
200
523
123
882
1023
0
50
122
The values are very unstable, but do you think it will be fixed after the pre heat??
I am a very frequent viewer of yours, I like all of your projects,A quick answer will be apreciated, thanks in advance
Syed Ayman Waiting for your reply
three years no reply 😔😔
Excellent - thank you very much for sharing info! I'm trying to make this for my indoor garden because it's so much cheaper to make and I've just gotten into Arduino. Good luck - have fun.
I'm glad you like the video. Thank you for watching and commenting! Good luck with your project :)
ElectronFun.com Ty - keep up the good work - peace.
Thanks for posting this video.. I found it very useful. Have you though not connecting the Audrino directly to sensor and use wifi to exchange messages?
You need something to read the analog values from the sensor before transmitting them over wifi anyway
Thanks so much, this is exactly what we need. the only problem is that would either process work for the MQ-4, as our prime mission is to measure methane. Or would it be possible to get rid of all data of all other gases for the MQ-2 and only show the methane data. We are from Moate Community School and entering a project for Cansat. Thanks so much for your help.
Thank you for your comment. These sensors can detect a range of gases, but they are not able to differentiate between them.
The values in serial monitor are voltage values.Am i correct?I want resistance values too.Is it possible?
Yes, these are voltage values between 0-5V - there are 1024 steps. Watch my vide entitled: How to make a simple Arduino ohmmeter - you will learn how to get resistance values.
The best tutorial sir !! But can you explain the working of the circuit or provide a source to understand the working.
+Aryaveer Garg Thanks :) What would you like to know?
Thanks for your simple and clear explanation
My thumbs up for the video quiet useful since i am missing only arduino and the sensor for my detector for hydrogen.
Is preheating a one time thing during calibration or should I preheat for 24 hours every time I want to use the sensor ?
Fortunately preheating is a one time thing. Preheating your sensor for 24 hour before every single use would be very inconvenient, to say the least :)
Preheating is done by vcc right ?
Hi, what is the use of heat shrink tube? and can you make another video with gas sensor including an alarm for security purpose? using arduino.
Jason Estacio Hi, I didn't want to solder and heat shrink tubing seemed to be the fastest way to connect these wires to the legs.
I will consider making another gas sensor videos, but there are already a couple of videos in my schedule. I wish I had more time for UA-cam videos.
ElectronFun.com Ok sir.. Thanks :). Btw Great Video
Jason Estacio Thanks a lot :)
this is an interesting video. I would recommend you to explain more like how the sensor works or why to connect wires like this. I mean, now I know how the sensor works with arduino, but I can't do it if I want to add a sensor to my project.
take an example, we can get some analog outputs with this diagram, but what's the meaning of this value? how to convert the number to some standard numbers? This will be really helpful because if I want to do an air monitor project with this, I don't know how to define the number. LED lights up when it's 500, but what's the real number that matters in our life? In datasheet I see a relation between sensor resistance with ppm, but maybe a starter will never figure out.
anyway, this is a great video. I have subscribed and wish you have more excellent videos :)
Zelra 仙賢戀軒 Hi, thanks for your comment, subscription and advice. I'm trying to make my videos not too long. Maybe I should have explained more details about the sensor.The values are something between 0 and 1023 and they come from Arduino analog to digital converter. If you want your readings in ppm units, you would need to calibrate your sensor against a known gas concentration (maybe this part of explanation should be included in the video).
Awesome video, but can u please suggest a sensor which detects differ parameters of gas like carbon dioxide , carbon monoxide, oxygen , sulphur content in the air .I need such a sensor for measuring the air pollution .So please suggest a sensor which measure various components of air separately
Wow! There are a ton of questions/answers for this video. I tried to search throught them with some keywords, however I could not find answers I was looking for about cost and about lower detection limit and accuracy in the low range of measurements. Looking to build something similar but it would have to detect and readout values for CH4 way below the LEL at around the 10ppm range in order to be useful for my project. Sorry if this question is repetitive from those asked/answered before.
Hi, thank you very much for this very well explained video. What do you think about using the MQ2 for a consumer product ? Do you think it is sturdy and reliable enough for commercial use ? Thank you
+Amine Ben Hi, after playing with these sensors for a while I wouldn't recommend them for commercial purposes. They are good for learning and experimenting, but that's it. In my opinion they are not reliable enough for a commercial project.
Thank you for your answer. Would you recommend any gas/smoke sensor for commercial purposes ?
+Amine Ben Sorry, I don't have any commercial experience.
When you choose serial monitor to view data in a new windor, are you be able to copy this data or not?
Or a data logger shield should be used to export data needed?
Yes, you can select, copy and paste the text from the Serial Monitor window.
Thanks for a great idea for my college project , what is the principle behind this model???
Thanks for the comment. What would you like to know exactly?
Its amazing and helpful for the novice guys.
Masha Mustakim I'm glad you find my video helpful :) Thank you!
Thank you for ur awesome video. But i searched a lot for this video, it could be easy and reachable if you've used the title as 'Gas leakage detection'.❤️
Hello. Do you need a fan to direct the ambient gas if this sensor sits inside an enclosure box?
***** Why do you want to install the sensor in a box?
ElectronFun.com For aesthetic purpose. I want to design a box that can detects gas leakage and smoke. Do I just leave a small hole opening for the sensor to detect the gas? Does the airflow is adequate enough for the sensors to detect the gas? Or do I put a mini fan to circulate the air into the box chamber?
***** I haven't tested anything like that, but I guess a hole in the box might be not enough and a fan might affect your readings, but it's only my theory. It's always a good idea to try out new ideas.
Awesome video, but can you please suggest a sensor which detects different parameters of gas like carbon dioxide , carbon monoxide, oxygen , sulphur content in the air .I need such a sensor for measuring the air pollution .
Can i use it in flame detector circuit? Until which temperature it can easily work? If i use it near to fire will it works?
Rizwan Kamleen Unfortunately you can't use it in a flame detector circuit. The MQ-2 can operate only up to 50 degrees C, see here: sandboxelectronics.com/?product=mq-2-smokelpgco-gas-sensor-module.
Hi,
Liked ur video, it was informative.
Wanted to knw that semiconductor gas sensor could detect methane in a range of 100ppm to 20000ppm. If yes could you suggest the sensor.
+Ismail Zabii I know MQ-4 can sense Methane, but the range is from 200 to 10000ppm. However the MQ sensors are not very accurate and reliable, so I wouldn't use it for a serious/commercial project.
+ElectronFun.com Could u suggest me a sensor which is very accurate and also can measure below 100ppm. thank you
+Ismail Zabii Sorry, I don't know any good sensors that would be able to measure below 100ppm.
Great idea! Thanks for this helpful tutorial.
The values in serial monitor are voltage values ,right? can I also know how to view the resistance values also?
Yes, these values are voltage readings. I have a 3 minute video on my channel entitled "How to make a simple Arduino ohmmeter". You'll learn how to get resistance values easily.
Hi, nice video!
I'm trying to do the same as you, but with the MQ-131, ozone gas sensor.
I'm trying to understand: how have you found the value of the resistance to put on your board?
For the MQ-131 sensor i need to preheat the sensor for almost a day, Someone says you have to change the resistance after the preheat to have a good measure.
But I have seen you can change the value of sensitivity in the sketch, so How do I have to do?
In any case thank you :)
+Francesco Motterle Thanks a lot! I took my resistor's value from the datasheet. However I checked your MQ-131 datasheet and it says "load resistance: variable" - it's pretty confusing, but you can use a potentiometer and adjust sensitivity.
Preheating the sensor is advised by the datasheet - yours says: "over 24 hours", so it's a good idea to do that.
Hi, excellent video. Does the ensamble and code work for other Arduino sensors?. I`m interested in CO2. Thanks.
Violeta Mena Hi, thanks for your comment.You can use MQ-135, the wiring diagram is the same, but to make it work with CO2 you should follow this tutorial: davidegironi.blogspot.it/2014/01/cheap-co2-meter-using-mq135-sensor-with.html#.VRBvweGfxFo There is another sensor, made specifically for CO2 - MG811, but it uses 6V and the wiring diagram is a bit different (see here): pdf1.alldatasheet.com/datasheet-pdf/view/172004/ETC2/MG811.html
ElectronFun.com Thanks!!!
hey nice work man. keep it up and thanks for the lesson.
Dinil Divakaran I'm glad you like the video, thanks a lot!
Hello Sir. Can you tell me which pins are the Vcc pins since, they are all identical?? Thank you
There are 2 groups of 3 pins. You want to supply 5V to the middle pin in each group. This sensor is not polarized, so it doesn't matter which pin will be your GND and which one will be your 5V.
Sir, then will the analog output pin not change?
The pins I'm talking about are just heater coil pins used for heating the sensor. The A and B pins should be connected like in the video.
ElectronFun.com Sir, but how do we identify the A and B pins since they are all identical?
Daniel Ravichandran
It doesn't matter which pair is A or B for you.
Hi, great video, I want to add in a 6v buzzer, what the best way to do so? I have never used this code before, thanks!
Hi, thanks! Arduino Uno is rated for 5V, so it would be better to use a 5V buzzer. If you deliver voltage to the buzzer it will turn on. If you want to change the tone, you could use Arduino "tone()" (arduino.cc/en/reference/tone).
sir good day, i have a question regarding th connection, should i rally use a separate power source of 5 volts? cant i use the same 5 volts from the arduino? can i use a normal 9 volts battery for th separated voltage input for the gas sensor? thank you sir, this will be a help
also sir i have tried to view the serial monitor and wait for atleast 5 minutes to trim down the output sensed value by the mq5, but still output value ranges from 600 above till 1023
Hi, according to the MQ-2/MQ-5 datasheets the sensors consume up to 800mW, which is about 160mA at 5V. Here: playground.arduino.cc/Main/ArduinoPinCurrentLimitations you can find Arduino pin current limitations: the 5V rail can deliver 200mA maximum. The sensor's heater alone would consume 160mA out of 200mA. If you connect anything more than the sensor, you may fry your Arduino board.
Yes, theoretically you can use a 9V battery for the gas sensor, but you would have to use a 5V voltage regulator. However, I would not recommend using a 9V battery, because it will not last for long. A typical 9V batteries have about 300-580mAh capacity. Your gas sensor would probably work for less than 2 hours (if you're lucky).
The MQ-2 and MQ-5 need a 24h preheating (burn-in). You should hook up your sensor to the circuit and leave it in on for 24 hours (make sure everything is connected properly to prevent from overheating and eliminate the risk of fire). You can do this only once. It is meant to make the readings more consistent. It should help in your case.
good eve sir... can this project last for continuous use??? lets say a week or more without turning the power off?? will the sensor overheat or burn?? thanks alot sir
Hi, the sensor should be able to work constantly without problems. You can even find in the datasheet that the sensor should be powered constantly for over 24 hours before first use (it's called preheat time). If you don't exceed the maximum voltage 5.1-5.2V the sensor will not overheat.
Really interesting video. can we show amount of gas (gas thickness) using lcd display? pls
Thanks! Yes, it is possible to present the readings on an LCD display. Would you like to see the values from the Arduino (0-1023) or convert them to ppm units? If you want to get the readings in ppm units you would need to calibrate the sensor against a reference sensor.
Very nice video. I wanted to ask you, if I want to use the gas sensor with Arduino on a flying drone, do you think this technique can work? Or I should proceed with another way? Thank you for your time...
+Georges Tufenkji Thank you for your comment and watching. Your idea is very cool! I believe it should work, however these sensors are not super accurate - bear that in mind.
Okay, I will keep you posted with the implementation of the project :)
Great, I would like to know how it turns out.
Hello ElectroFun,
Very great job!
When searching some MQ sensors to buy, I found out that some of then already come with a board on themselves, and has four pins for connecting, like somoene said on a comment bellow.
The DataSheet of this device is identical to that one you've linked above, and the circuits I've found just say to connect de VCC pin to de Arduino's 5V, the GND pin to Arduino's GND and the AOUT pin to Arduino's A0, without any resistor or mentioning the heaters.
I just wanna know how three things about this kind of device:
- How does the heating system works? How do I preheat the sensor?
- Why in this case it's ok to connect the whole sensor and board in the Arduino's 5V pin? Won't this damage my Arduino, or only if I connect some other devices to it, like LED or Buzzer?
- And the load resistor, why isn't it necessary any more? How can I adjust the sensitivity of my sensor whitout it?
Thanks! (sry for my english)
Hi Lucas,
Thanks a lot for your comment!
That's true, there are some sensors mounted on a piece of breadboard with pretty much all needed circuitry. The load resistor is there, both A pins are connected to each other and both B pins are connected to each other as well. There are some boards like this with only 3 pins: VCC, GND and AOUT (sense line). You can even buy sensors, which are already calibrated and show PPM readings, but they are usually much more expensive.
To your questions:
1. The sensor is most accurate in a certain temperature range and needs a heater, which is a simple coil. In the datasheet you can usually find information how long you should preheat the sensor - it means you should leave your sensor connected and running continuously for this period of time (for example 24h).
2. The sensor won't kill your Arduino by itself. It usually draws up to 800mW at 5V, which makes 160mA. Arduino 5V-GND pins can deliver up to 200mA at 5V. You have just 40mA left and it's not the best idea to draw maximum current all the time from your Arduino.
3. The load resistor is usually mounted on the sensor PCB. You will usually find a potentiometer on such boards that you can use to adjust the sensor's sensitivity.
ElectronFun.com , Thanks for helping.
Do you know were can I find these sensor that already come calibrated in PPM? Or, at least, their avarage price?
Sorry, I can't find these calibrated sensors anymore. I don't remember prices, but it depended on the type of the sensor.
ElectronFun.com Ok, thank you for helping.
Hello, thanks for this wonderful video. Can I use any of the MQ- series to measure the quantity of gas inside the storage tank?
Is it possible to add a LCD display that shows the gas concentration in ppm to this
Yes, it is possible, but you would have to calibrate the sensor against a reference and then convert units from Arduino's 0-1023 to PPM.
ElectronFun.com do u have a code with LCD? thanks
Hi . thank you sir . please help me .
Which parts did you use in this circuit
What are the materials used in this circuit
Hi, all parts and materials are enlisted in the video at 0:30 - 1:00.
Okay sir . thank you :)
Uğur Karaca
No problem, thanks for subscribing :)
Hello,
I really liked the video and i want to ask you few things on this, can we have sensor, alarm speaker and simple power supply which makes compatible and sense the gas. can you pls describe.
Thank you! Yes, it is possible to have a gas sensor with a power supply or some kind of battery and a speaker, which would alarm you, if it sensed certain gas concentration. The easiest way to make something like this would be to replace the LED with a small speaker.
I want to build a simple gas leakage detector in one of my next videos and use a speaker, or an LED bar graph or an LCD to show the results. I'm not able to tell you exactly when, because I have a "regular" job, which prevents me from making videos quicker and more frequently. I can see many people are interested in gas sensors, so this video will get higher priority.
Hello, Thank you for the video. It's helpful !!
I would like to know if the use of the resistors is necessary or not ? and what are the effects if i don't use them?
thanks.
Nada Hi, thanks for your comment! The resistor is necessary according to the datasheet. I guess the readings would be completely inaccurate without the resistor.
Hi. We read the datasheet of Mq-135 sensor, which sense for multiple gases in arduino. However we have a problem because our laptop only read one column, as you shown in this video. We do not know what kind of gas we are reading (how we do that?), and furthermore, we want read all gases in several columns. is possible to do this? thank so much in advance.
+Sinhué Haro Corzo You might want to use Sandbox Electronics piece of code to "calibrate" the sensor and get a separate reading for each gas: forum.arduino.cc/index.php?topic=181780.0. I haven't put too much time into it yet, but I know some people get pretty decent results.
Hey great project.
I am doing something similar but I am confused are the sensor value same as the concentration value of the gas, I want to measure the consentration of LPG in a room.
+alnada alkubaisi Thanks :)
Unfortunately it's not that easy. The readings are just analog values taken from the sensitive element and converted by Arduino to digital values between 0 and 1023.
To get values in some well known units like ppm, you need to calibrate the sensor. Normally you would need special equipment to do it, but if you want to use an MQ-2 sensor, there is a piece of code made by Sandbox Electronics, which simplifies the calibration process, but the readings will be less accurate. You can read more about it, here: sandboxelectronics.com/?p=165.
By the way - I'm starting my new video about the MQ-2 calibration with the Sandbox Electronics piece of code.
+ElectronFun.com Hi, thanks for the replay it was very helpful.
+alnada alkubaisi Thanks :)
This was an amazing tutorial. Just wanted to know what is the alternative to heat shrink tube as I can't find any
i'm a little late so i dont think its helpful, but you can just wrap some tape around your exposed wires and it'll be fine
sir this is really cool.im a newbie wih arduino and i wanted to know if it is possible to use this on a biodigester to create a system that will moniitor the gas flow and amount of slurry. if its ok i would like to ask u some more questions.
Hi, you have a very interesting project. You can ask and I will answer if I know the answers :) I have a question too - what type of gas does this biodigester produce?
it produces methane. its a portable small scale biogas. it uses anaerobic way of producing the methane.. i wanted to build a monitoring system for this and should be low cost. that is why i am choosing arduino. thanks for the help sir.
alpaxthegreat
Thanks for your answer. If you have any questions feel free to ask.
ElectronFun.com
i would like to ask what sensors will i be needing and what model of arduino. when i tried searching, i read about seeduino stalker had been used for gathering data from a portable biogas. can i ask for some idea on how can i start with this project. thanks. and is it ok that im asking here?
alpaxthegreat
You may use MQ-4 gas sensor, which is sensitive for Methane and CNG Gas. When it comes to Arduino board - it depends on what you want to do with your data. Do you want to make a standalone device for monitoring and gathering data on e.g. SD card, or do you want to have it hooked up to a computer, which would store your data?
Seeeduino Stalker is a nice board with a slot for SD cards and a backup battery holder, but there's no USB connector. To use USB, you need to buy some additional connector (at least that's what I read on the wiki page).
Sure, you can ask questions here. I thought about opening a forum, I would like to have a place where all people from this community could help each other, but I don't know if it's not too early. By the way - what do you think about that?
This project is great.what is the advantage of using arduino instead of other micro controller.how to add a buzzor to this circuit?
Sir, can we use gas sensor MQ-135 in the same way as shown in the video?
with same connections and same code?
Yes, you can use MQ-135 in exactly the same way and with my Arduino code. Just experiment with the load resistor value and "sensorValue" in the Arduino code.
ElectronFun.com Thank you very much
Renil Sebastian
No problem :)
superb tutorial. very easy to understand. thank u so much !
+Shantanu Baji Thanks a lot for your kind words :)
Do you know if you can use a MQ2 and MQ5(or any other sensor" in one set up?
+animefatboy676 What do you mean by "one set up" - one Arduino board?
+ElectronFun.com just off one arduino or microprocessor
+animefatboy676 Sure you can use multiple sensors with one microcontroller. Just remember not to power these sensors from your microcontroller board, use a separate power supply.
Hello, do you have to calibrate the sensors ?
I start a little project with a MQ4 but I am not sure if the datas are correct.
Thilo 012 Hi, it depends. If you want to have your readings in ppm units for example, you would want to calibrate the sensor against a calibrated sensor so you could know the exact gas concentration. Another thing is consistency of readings - if you're getting inconsistent data you probably need to preheat you sensor by leaving it on for 24 hours (see the datasheet).
ElectronFun.com yeah i want ppm readings. but how can i calibrate it ?
Thilo 012 A few days ago I would tell you that you need to calibrate your sensor by comparing it with another already calibrated sensor or adjust it by exposing it to a precise gas concentration and it is true. These methods seem to be the most accurate, but there is another way (I hope) based on sensitivity characteristic curves from the datasheet. I'm going to experiment with this stuff and if I succeed, I may prepare a video about it.
Was Arduino the best choice for this project?
I guess Arduino is the easiest implementation.
I want to use two sensor mq4 and mq7.Is it possible to take ppm value from this sensor using arduino?? Send the code and block diagram plz
These sensors output an analog value, which has not much to do with PPM. To convert it to PPM units, you want to calibrate the sensor and use it in the code.
Hi, that's a great video, could you please tell me how you can make another one for detecting multi gases in the same time or if it's possible can you make another video , thanks in advance for you reply.
Do we use any Microcontroller or arduino.?
I am bit confuse in both of them
Arduino is a microcontroller. I'm showing how to use the sensor with Arduino Uno, but you can use any microcontroller with analog pins.
are we restricted to any arduino or we use any arduino for gas sensors
I'm sorry, but I don't understand your question.
if i put a 100 ohm resistor instead of a 120 ohm resistor for the led, will it work?
Yes, it will work :)
What exactly is the function of the A and B pins?
The A and B pins are used to sense the gas concentration, but I wasn't getting into details about their exact operation, so I won't be able to explain much about this topic, sorry.
Can I convert the readings to percentage and regulate the logging time interval. Also added like three more sensor and find their percentage composition in the biogas.I want to use it to log biogas composition from my digester.
You can easily adjust the logging time interval and add more sensors - each one should use a separate Arduino analog pin. The most difficult part would be the conversion of the readings into percentage.
can we get more than 1 ppm valuesof several gasses at once???? I want build a gadget for detect all percentage of gasses that emitt from a vehicle silencer at once. I wanna to display all the ppm values on a display....
Unfortunately no. These sensors can't detect which gas they are exposed to. Each of them is able to detect several different gases, but it won't be able to differentiate between them.
Superb video ...I am a new comer to innovation and gonna start my first experiment with this.
Thanks for so detail and simple explaination :)
I'm glad you like the video, thanks for the comment and good luck with your experiments. If you have any questions while experimenting, feel free to ask :)
ElectronFun.com Thnks! Pal...
Will do the same definitely :)
Dear pal ,
CAn we also assemble it into a single device?
How to do so?
Regards
Akhilesh Sharma
What do you mean by single device? Do you want to build a simple Arduino using only necessary parts and use it with the sensor?
ElectronFun.com yes kind off....
I was trying to use it at my home after making it...
is computer connection necessary each time??
and can bread board be replaced by something?
Regards
Hi love your videos, I'm in the middle of a project building a gasification unit to run a generator on woodgas, would you be able to do a video on how to use an Arduino with a car 02 sensor to control a rc servo adjusting the gas to air ratio?
hi.. may I know which sensor can be use to detect n2. nitrogen.. I mean building a N2 supply inside a isolate small compartment. , would like to add in a sensor to detect leakage. Thank you
I'm not aware of a sensor from the MQ series, which could be used to detect nitrogen, sorry.
Dear sir , this can be used to detect chlorine .
Hi, do you know if there are CO2 detectors available that would be able to capture a signal of human exhale?
How to identify A and B terminals of the sensor?? What is they get reverse?? No polarity requirement for any pin ????
Thanks for the great video! The resistor leads are a little hard to see, does it go from the ground rail to the same row as the B pins?
pls make a vedio on alchol sensor and eye blink sensor to prevent accidents
You can use MQ-3 alcohol sensor in exactly the same way as presented in this video, because it has identical pinout and voltages. When it comes to the eye blink sensor - do you mean some kind of system with glasses which would detect if you blink or not?
hello sir, Is it possible to take both the CO and smoke values at a time ? and how to show the demo for the CO?
I have a video about calibrating an MQ-2. You can get CO, LPG and smoke values at the same time. See my last video.
that a really good work,its nice and please can i get a manual or instruction on how i can calibrate both MQ7 and MQ8 on Arduino uno board for detecting CO and H2
Thanks a lot :)
Unfortunately the software calibration I showed in the video entitled "How to use gas sensors with Arduino" works only with the MQ-2.
Hi there, Your videos are really great and I need to make one of your gas sensor alarm using Arduino. Can you PLEASE tell me where I can find the download link for the Arduino software for this project. I cannot see it anywhere.
Robin Davidson Thanks a lot! You can download the code from the project page on my website, here: electronfun.com/project_2.php
The link is also in the description of the video.
Can we use any supply or is it necessary to have just 5 volt
Hey man. Awesome project! If I am trying to make a reliable diy smoke alarm which sensors will I need? The MQ-7 for CO and MQ-2 for everything else? Thanks!
Thanks a lot Jim! You could use the MQ-2 alone as a smoke detector. However, I wouldn't use these sensors in my home smoke detectors. They are nice when you want to learn how to use Arduino with them, but their reliability isn't very good.
Sir may i ask, for instance i am going to use 3 MQ-2 gas sensor. What will be the connections? and how about the power source?
+Aiza Marie Sambo You would need to connect each sensor to a separate Arduino's analog input. Each sensor should have it's own resistor connected to ground. The rest of the connections would remain untouched. The code should be updated to read from 3 different analog inputs. When it comes to the power supply - for 3 sensors you would need at least 500mA at 5V.
That is really cool. Maybe you can help me with my thesis project. I have a very small amount of flow of CO2 and it's really a pain to detect it with anything actually. I was thinking of a hot wire anemometer. I found that it's possible with arduino but not sure where to begin. Will appreciate your opinion on this.
Thank you :)
To tell you the truth - I wouldn't use these MQ sensors for anything serious. They are quite inaccurate without proper calibration.
When it comes to the hot wire anemometer - I haven't played with this at all, but you could start reading here: playground.arduino.cc/Main/ThermalAnemometer.
Sorry I couldn't help you more.
You're better off getting the complete modules, they come with a calibration pot and other components to make it more stable. They are very cheap on Aliexpress too.
I agree. The sensor looks like an octopus.
Why did you choose those resistor values specifically?
Thanks, the tutorial was great!
Thank you very much :)
thank you for this video but i need to know what is the unit of this values (500 what?) that we get it from the sensor pleas ?
+saadoudi abdel madjid Have you seen my latest video? I explained these values quite a bit.
not yet but i need just to know what is the unit of MQ2 values output like 300 OR 400 what unit and thank you
+saadoudi abdel madjid You can't easily convert this value to anything standard like ppm units. Watch the second video, where I talked about it.
Sorry for replying so late. See my short video about MQ-2 calibration here: ua-cam.com/video/QYSDSKn2Vf8/v-deo.html - you will get your answer there.
Hi i have a quick question, well two really. Can you connect multiple different MQ series sensors in parallel ? to each other ? also is it possible to add an LCD display to display the levels ?
Hi, MQ sensors are purely analog and it's not really possible to stack them (use one analog pin to read values from different sensors). You would need one analog pin for every single sensor.
It is possible to add an LCD to the sensor. I'm working on a new tutorial on using an LCD with Arduino Uno.
ah alright thats fine thanks makes sense to use a different analog pin
i know you said polarity dont matter but is this for the heater coils? or everything ? how do i know which is A or B?
Frank Lopez It's not only for the heater coil, but for the whole sensor. These sensors are symmetrical and you don't know which pair is A and which is B. You can rotate it by 180 degrees and it looks the same. It doesn't matter which pair is A and which is B for you. Just remember that the sense wire, which is connected to A0 has to be hooked up to the grounded pair. If you connected the A0 to the positive pair your highest reading would be 0 and the lowest would show 1023.
Great video. However, you are just showing the analog input of the sensor which is useless when detecting any particles. The data sheet shows you how to calibrate the sensor and show the value in ppm.
hey i have mq-2 module...is there any need of giving connections to A ,B and H pins?or directly to Vcc pin?also is there any need of connecting Rl? bcz module have built in potentiometer?
I'm not sure if you are talking about the same module I have. On mine there are A, B pins and the heater element, nothing else.
I m talking about Mq-2 gas sensor module...u have only sensor..here,s the details. wiki.sainsmart.com/index.php/SainSmart_MQ2_Gas_Sensor_Module
I have not used these. Try to find the datasheet.
should we have to calibrate this sensor before using that?? thx
do you know the sensor to measure the Oxygen (O2) gas?? btw this video really helpful for my experiment project. thank you
Sorry for replying so late. Unfortunately I couldn't find an O2 sensor. At least from the MQ series.
How to calibrate the sensor board, how to find out/select exact RL, RS values? Any info or links?
+Mohd Jahangir If you want to know as much as possible about MQ-2 calibration or conversion to ppm, go here: sandboxelectronics.com/?p=165.
thank you for vedio..
is the wiring of MG811 is the same ???
Unfortunately in case of MG811 the wiring is a bit different.
Can I use male female wires instead of solder pls reply sir?
When hook up MQ-2 with 5V onboard pin, the voltage drop to 4.86V
Is it better to use the external very smooth 5V regulator ?
It's better to use an external power supply, because the MQ-2 consumes up to 160mA, while Arduino Uno can deliver 200mA maximum. If you connect something more than just the sensor, you can burn out your Arduino.
Can the code be used for a MQ9 gas sensor?
Really good video, good job!
Thanks a lot! Yes you can use the same code for an MQ-9.
Hello man... I need put the sensor in a tube to detect the the H2S Through the tube area... Do You know if it's possible? I can measure the gas volume pass by the tube?
Hi sir how do you interpret the data gathered in the serial monitor? What is the unit of measurement of the data showing in the serial monitor?
There is no easy way of interpreting this data. You should calibrate your sensor to get the readings in ppm units for example. I have another video about software calibration of an MQ-2. It's quite short, but I explained a bit about sensor calibration there.
fantastic!this is helping me out. will it be able to do on Smoke detector?
Thanks! :) MQ-2 gas sensor is sensitive to smoke and can be used in gas or smoke detecting devices.
Hi, another question
It is normal if the gas sensor is hot and the readings start at 0 at serial monitor? thank you :)
Mavrick Lomerio Hi, it is normal that the sensor is getting hot - it needs certain temperature to work properly. Is 0 your highest reading when you apply gas and goes up when you stop?
ElectronFun.com around 150+ :)
Mavrick Lomerio The readings never drop anywhere near 0.
ElectronFun.com noted.... :) thank you so much
Mavrick Lomerio No problem :)
sir , sensors which u r usinng in how much area they can have sensitivity ,i mean in how much area they can sense presence of gas...........
+Praveen Vijapur Good question, but I haven't found such information in the datasheet. From my experiments I would say these sensors are not very sensitive.
+Praveen Vijapur +ElectronFun.com
well, you both haven't read the datasheets.
+Eike Epunkt sir u know any answer?
+Eike Epunkt I guess you have, so could you kindly help a little bit if you know the answer?
+Eike Epunkt I guess you have, so could you kindly help a little bit if you know the answer?
Great video,can i have just readings without led?
Thank you for the video. Sir, How do we calibrate the gas sensor to sense a specific compound? I read the datasheet it said we have to connect a resistor or potentiometer to measure a specific compound. How do I do that, sir?
Hello,
you did fantastic job! well done. How can you calibrate your sensor? is this code valid for other gas sensor such as MQ 138 ?
Cheers
Ali Altaey Thank you. Yes, the code will work with MQ-138. When it comes to calibration - you should calibrate it against an already calibrated sensor. There is also another method that you can try at home - just in the code, based on sensitivity characteristics, but I wasn't very successful with this, at least yet.
Well done- very nice video. Would you mind describing how you could modify this project such that the Arduino reads two or more sensors simultaneously, such as an MQ135 and MQ138? I would like to use the Arduino with 2 or more sensors to trigger a relay that would turn on/off an energy recover ventilator. I live in the city, so air quality varies where I live. Thanks!
John
Thanks a lot! You can read 2 or more sensors easily. In this video I connected the sensor to the breadboard and put a wire between the 'B' pins and A0 analog pin on the Arduino. Hook up another sensor in exactly the same way, but the wire from the 'B' pins should be connected to another free analog pin (e.g. A1) on the Arduino. You also need to update the Arduino code by adding A1 definition and read from this pin in 'void loop()'. If you have any problems with the code or schematic, please let me know and I'll try to help you.
ElectronFun.com Thanks so much! I'll get a build going and get back to you.
John
why not connect it to arduino 5v power supply
and why after 2 - 3 minutes the readings go low? is the sensor only supposed to work for 2-3 min and then shutdown or the other way around to heat up?
hello...can we use the gas sensor to determine tea aroma?
It might be possible, but to tell you the truth I haven't heard about it before. I googled something like
zinc oxide nanorod sensing element, but have no idea how it works and if it's possible to use it with Arduino.