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
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.
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.
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?
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.
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?
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.
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
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).
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.
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'.❤️
+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.
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.
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.
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.
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.
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, 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).
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.
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.
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.
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.
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.
Have you ever built a functioning gas leak alarm with the MQ-5? I bought one thinking I could make a gas leak detector with it, but boy is it ever finicky. For starters, it could only detect butane (from a bic lighter) when I first turned it on, it didn't see methane (natural gas) coming out of my stove until 24 hours after being turned on, the "burn in time". So now after being burned in, it can detect natural gas, but it's nowhere near as sensitive as my nose. I can smell a gas leak in the room well before the little line on the serial plotter graph starts to actually move. If you've actually built a gas leak alarm with one of these things, where did you put it? On the floor, on the ceiling? Does it work?
No, I haven't built a gas leak detector with the MQ-5. To tell you the truth, the MQ sensors are good for Arduino experiments, but they are not very reliable when it comes to serious applications. The readings are quite different almost every time and it's rather difficult to trust them. I know there are some much more serious sensors on the market, but they are also much, much more expensive.
I used one of these MQ-5 modules www.amazon.com/gp/product/B06XHKPV2Q/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 and adjusted the sensitivity way down and the digital led turns on fairly quickly when I turn on my natural gas stove. If you're using the standalone sensor as done by ElectronFun.com you might want to adjust the 20k ohm resistor to increase sensitivity.
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.
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?
What do I do once I click the MQ-5 datasheet download link? When I clicked the link it just took me to a page with download links but I don't know which one is the datasheet for MQ-5
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.
hey there i actually tried to made same using mq-6 but in monitor mode it shows all zero value can you help me with that and all the connection were correct and are of same order ?????
I'm guessing there must be something wrong with your connections. When this happens to me and I'm not able to figure out what's wrong I disconnect everything and start from the wiring diagram once more. Sometimes a faulty jumper wire may give you a headache - it happened to me twice.
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.
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.
Hi Armin, The wiring diagram for MQ-4 is the same, you need a 20k load resistor. You also need a buzzer and an Arduino GSM shield. If you have any specific questions, feel free to ask, but be aware I've never used the Arduino GSM shield yet.
According to my supplier MQ-4 is a analog no need for library. Is it true? Can you send me a diagram or schematic for this MQ-4 sensor with 20K, buzzer and GSM Shield? I really need your help on this. Thanks a lot..
Armin Lumanglas It is true, MQ-4 is an analog sensor and there is no need to use any libraries, only one of the Arduino analog input pins. The 20k load resistor is used in the wiring diagram on my project page: electronfun.com/project_2.php (that's the one described as 20-22kΩ). You can learn more about a buzzer here: www.hobbytronics.co.uk/arduino-tutorial7-piezo-beep. I've never used a GSM shield yet, but you can find out more about it here: arduino.cc/en/Main/ArduinoGSMShield.
+vijay PALASINGAM If you wanted to use a 9V battery you would want to use a voltage regulator or a buck converter. However, a 9V battery has a very low capacity and the gas sensor would drain it very quickly.
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
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.
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
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?
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 .
There are at least several GSM modules on the market. However, I tried using one of them, but couldn't make it work, because it was using only 2G, but my SIM card was not able to work properly with it. I haven't used a GSM module ever since, so I won't be able to help you with this, sorry.
I didn't manage to run my GSM module, but didn't want to waste too much time for it. If you choose a good module and use a compatible SIM card, you should be able to use the module.
+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.
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.
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
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.
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?
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?
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 RUclips videos.
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.
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.
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.
Hello, I really enjoyed your video and it was really helpful. I have a question though to ask you since I am doing a similar project with an MQ-2 gas sensor. While I am executing everything correctly, on the serial monitor I get values more than 800 (ex. 842) and when I apply gas from a lighter to the gas sensor, the values decrease dramatically reaching 40. It seems quite odd to me since I thought that the values where supposed to increase when the gas was detected. The same thing happens with an MQ-7 gas sensor applying the same gas. Any thoughts what would the problem be, if there is any? p.s. Both the gas sensors are on a board by themselves (with resistors, pins etc.) Thank you for your answer in advance!
I had a similar problem once. As far as I remember, it happens when you hook up the "B wires" through the 20k resistor to the positive rail instead of ground. I can check that when I get back home.
ElectronFun.com Well, I had it bought from ebay and the sensor seems exactly the same to this one goo.gl/N0vqqN. You can find a description (datasheet) of the sensor on the link and hopefully it is the same to my sensor.
sir i use mq2 sensor module that has 4 pins . how do i connect them to the arduino ? do i need to modify the sensor like taking out some resistors and capacitor on the module ?
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.
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.
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.
Thanks for that tutorial! Really helped me out. I have a question... Do you know if I change the resistance, say to instead 20KOhm, to something like 10KOhm, will it detect different kinds of gases? It's not clear on the datasheet but it seems to be the case. Also, your website is down... :(
+Guz Forster Hi, unfortunately it's not that easy. When you change the resistor, it won't make the sensor detect different kinds of gases. In the datasheet there is a chart called sensitivity characteristics. You can see there that different gases overlap and you can't be sure which gas your sensor picks up. Sandbox Electronics has a piece of code on their website (sandboxelectronics.com/?p=165), which will "calibrate" your sensor and show 3 types of gases. Just remember their method is based on an approximation to the original sensitivity characteristic curve, so it won't be terribly accurate.
Right, thanks! So even with this sensor, we can't actually tell which gas we are detecting, only that is detecting some sort of gas in the range of the "accepted" gases, right?
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.
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.
Its amazing and helpful for the novice guys.
Masha Mustakim I'm glad you find my video helpful :) Thank you!
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 😔😔
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.
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.
Thanks so much, I couldn't find any other info on this :)
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 for your simple and clear explanation
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.
My thumbs up for the video quiet useful since i am missing only arduino and the sensor for my detector for hydrogen.
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.
Hello, thanks for this wonderful video. Can I use any of the MQ- series to measure the quantity of gas inside the storage tank?
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.
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.
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).
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.
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'.❤️
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.
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.
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.
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.
hey nice work man. keep it up and thanks for the lesson.
Dinil Divakaran I'm glad you like the video, thanks a lot!
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.
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
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
superb tutorial. very easy to understand. thank u so much !
+Shantanu Baji Thanks a lot for your kind words :)
Great idea! Thanks for this helpful tutorial.
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).
Hi! Can I just supply the sensor with the 5V pin from the arduino?
Yes, you could do that, but you would get quite close to the Arduino's current limit. Be careful not to fry the pin or the whole Arduino.
may i ask. what type of power source do you use in making this project?.
+Azmal Jamal Sure, I used a cheap adjustable bench power supply, nothing fancy.
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.
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.
do we need to preheat the coil for getting perfect reading?..
nishank lakkakula The datasheet says you need to do it, it makes the readings more accurate.
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.
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.
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.
Have you ever built a functioning gas leak alarm with the MQ-5? I bought one thinking I could make a gas leak detector with it, but boy is it ever finicky. For starters, it could only detect butane (from a bic lighter) when I first turned it on, it didn't see methane (natural gas) coming out of my stove until 24 hours after being turned on, the "burn in time". So now after being burned in, it can detect natural gas, but it's nowhere near as sensitive as my nose. I can smell a gas leak in the room well before the little line on the serial plotter graph starts to actually move. If you've actually built a gas leak alarm with one of these things, where did you put it? On the floor, on the ceiling? Does it work?
No, I haven't built a gas leak detector with the MQ-5. To tell you the truth, the MQ sensors are good for Arduino experiments, but they are not very reliable when it comes to serious applications. The readings are quite different almost every time and it's rather difficult to trust them. I know there are some much more serious sensors on the market, but they are also much, much more expensive.
I used one of these MQ-5 modules www.amazon.com/gp/product/B06XHKPV2Q/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 and adjusted the sensitivity way down and the digital led turns on fairly quickly when I turn on my natural gas stove. If you're using the standalone sensor as done by ElectronFun.com you might want to adjust the 20k ohm resistor to increase sensitivity.
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.
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 ?
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?
What do I do once I click the MQ-5 datasheet download link? When I clicked the link it just took me to a page with download links but I don't know which one is the datasheet for MQ-5
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.
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?
hey there i actually tried to made same using mq-6 but in monitor mode it shows all zero value can you help me with that and all the connection were correct and are of same order ?????
I'm guessing there must be something wrong with your connections. When this happens to me and I'm not able to figure out what's wrong I disconnect everything and start from the wiring diagram once more. Sometimes a faulty jumper wire may give you a headache - it happened to me twice.
can you use the mq-7 sensor ? that have an accuray close to 100 % ?
I would not expect 100% accuracy when it comes to any of the MQ sensors.
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.
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.
Hi ElectroFun,
I have a thesis for Gas sensor (MQ-4) and I want to add features like alarm and SMS notification. Can you help me on this project?
Hi Armin,
The wiring diagram for MQ-4 is the same, you need a 20k load resistor. You also need a buzzer and an Arduino GSM shield. If you have any specific questions, feel free to ask, but be aware I've never used the Arduino GSM shield yet.
According to my supplier MQ-4 is a analog no need for library. Is it true? Can you send me a diagram or schematic for this MQ-4 sensor with 20K, buzzer and GSM Shield? I really need your help on this. Thanks a lot..
Armin Lumanglas It is true, MQ-4 is an analog sensor and there is no need to use any libraries, only one of the Arduino analog input pins. The 20k load resistor is used in the wiring diagram on my project page: electronfun.com/project_2.php (that's the one described as 20-22kΩ). You can learn more about a buzzer here: www.hobbytronics.co.uk/arduino-tutorial7-piezo-beep. I've never used a GSM shield yet, but you can find out more about it here: arduino.cc/en/Main/ArduinoGSMShield.
Thanks ElectroFun. More power to you..
Was Arduino the best choice for this project?
I guess Arduino is the easiest implementation.
how let say if i use 9voltage battery supply means.. is that i need to add any different resistor or not???
+vijay PALASINGAM If you wanted to use a 9V battery you would want to use a voltage regulator or a buck converter. However, a 9V battery has a very low capacity and the gas sensor would drain it very quickly.
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!!!
will everything(including codes) be used with MQ7 as well? thanks!
Yes, the wiring diagram is the same, the same code will work, but you need to adjust sensitivity (in the code and by the load resistor).
ElectronFun.com www.circuit-help.com.ph/product/co-gas-sensor-mq7/ i bought this one, will the codes be working also without the breadboard?
Einnor Lester De Villa
My code should work with your sensor. You don't really need a breadboard - it just makes prototyping easier.
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.
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
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?
may i know for testing purpose, how do i produce/get the other gases? which can be detected using MQ2 sensor
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 .
< , I want help with my project added to it GSM alarm
Can I know what codecs to install in Arduino?
Thank you very much
There are at least several GSM modules on the market. However, I tried using one of them, but couldn't make it work, because it was using only 2G, but my SIM card was not able to work properly with it. I haven't used a GSM module ever since, so I won't be able to help you with this, sorry.
So what do u think .. I can use GSM modem or not !
I didn't manage to run my GSM module, but didn't want to waste too much time for it. If you choose a good module and use a compatible SIM card, you should be able to use the module.
Hi, do you know if there are CO2 detectors available that would be able to capture a signal of human exhale?
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.
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.
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.
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.
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.
very instructive tutorial, thanks
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?
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?
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?
How to identify A and B terminals of the sensor?? What is they get reverse?? No polarity requirement for any pin ????
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 RUclips videos.
ElectronFun.com Ok sir.. Thanks :). Btw Great Video
Jason Estacio Thanks a lot :)
hello in my country i found mq-7 can i use it as this example ?
Yes, it should work with this circuit, but MQ-7 is sensitive to carbon monoxide.
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.
Hello would the kl27z card work the same as your arduino card?
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.
Is it possible to use the HS 134 in the same way ?
+Ro Ly Not really - as far as I can see it uses 4V for heating the sensor, while the MQ-2 and MQ-5 use 5V.
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.
I have an MQ5 gas sensor with 4 pins. Could you please tell me how to connect it?
+Mekki Ahmedi I guess there is one A pin, one B pin and 2 pins for the heater element. Do you have the datasheet?
www.amazon.com/gp/product/B00HG7I02A?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00
+Mekki Ahmedi : it is the one provided in the link
+Mekki Ahmedi I can see there is no documentation. Could you post a photo of the other side of the sensor - I need to see the leads.
Hello, I wanna ask, how to make stable value that displayed in serial monitor? I always get much fluctuations
hi, can it possible to print the data to lcd with this gas sensor arrangement instead of gas sensor module
Great video,can i have just readings without led?
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.
This project is great.what is the advantage of using arduino instead of other micro controller.how to add a buzzor to this circuit?
It is a very good project
hello , can i use this code to connect this sensor to TTGO WATCH MODULE GPS GSM ?
Hello,
I really enjoyed your video and it was really helpful.
I have a question though to ask you since I am doing a similar project with an MQ-2 gas sensor. While I am executing everything correctly, on the serial monitor I get values more than 800 (ex. 842) and when I apply gas from a lighter to the gas sensor, the values decrease dramatically reaching 40. It seems quite odd to me since I thought that the values where supposed to increase when the gas was detected.
The same thing happens with an MQ-7 gas sensor applying the same gas.
Any thoughts what would the problem be, if there is any?
p.s. Both the gas sensors are on a board by themselves (with resistors, pins etc.)
Thank you for your answer in advance!
I had a similar problem once. As far as I remember, it happens when you hook up the "B wires" through the 20k resistor to the positive rail instead of ground. I can check that when I get back home.
ElectronFun.com The thing is that the sensors that I have bought, they already are on a board by themselves, like this goo.gl/1HoQXg
Do you have any datasheet for this sensor?
ElectronFun.com Well, I had it bought from ebay and the sensor seems exactly the same to this one goo.gl/N0vqqN. You can find a description (datasheet) of the sensor on the link and hopefully it is the same to my sensor.
nofear7777777 What pins do you have on your sensor? Is it +5V, DOUT, AOUT and GND or something else? How did you connect it to your Arduino?
Very cool. Thanks for sharing!
Thanks for watching and your nice comment.
should we have to calibrate this sensor before using that?? thx
sir i use mq2 sensor module that has 4 pins . how do i connect them to the arduino ? do i need to modify the sensor like taking out some resistors and capacitor on the module ?
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 :)
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,
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.
Can you share what is the set up for MQ131 (O3) Ozone sensor with Arduino?
Brother
Where can I get the code for Mq135 gas sensor, so as to use it for measuring CO2 level
Thanks for that tutorial! Really helped me out. I have a question... Do you know if I change the resistance, say to instead 20KOhm, to something like 10KOhm, will it detect different kinds of gases? It's not clear on the datasheet but it seems to be the case. Also, your website is down... :(
+Guz Forster Hi, unfortunately it's not that easy. When you change the resistor, it won't make the sensor detect different kinds of gases. In the datasheet there is a chart called sensitivity characteristics. You can see there that different gases overlap and you can't be sure which gas your sensor picks up.
Sandbox Electronics has a piece of code on their website (sandboxelectronics.com/?p=165), which will "calibrate" your sensor and show 3 types of gases. Just remember their method is based on an approximation to the original sensitivity characteristic curve, so it won't be terribly accurate.
Right, thanks! So even with this sensor, we can't actually tell which gas we are detecting, only that is detecting some sort of gas in the range of the "accepted" gases, right?
+Guz Forster Pretty much yes.
Unfortunately yes.
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
What size heat shrink tubing did you use? Thanks
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.
Can we use any supply or is it necessary to have just 5 volt