Last modified April 9, 2021
- 1 ❔ Is it possible to reduce the possibility of contracting Covid with a CO₂ meter of less than 20 Euros?
- 2 👁️🗨️ Homemade CO₂ meter structure
- 3 ✔️ Build the homemade CO₂ meter
- 4 NodeMCU boards with VU pin
- 5 📺 Video with the complete CO2 Meter tutorial
- 6 🔵 Using the CO₂ meter
- 7 Benefits of this CO₂ meter project
- 8 🌀 Home CO₂ Meter Options and Extensions
- 8.1 Add an OLED screen
- 8.2 Add a custom box
- 8.3 Adding temperature, humidity and atmospheric pressure data
- 8.4 Add notices and audible alarms
- 8.5 Creation of CO₂ evolution graph
- 8.6 Using the meter as portable / portable
- 8.7 Equip the battery meter (portable CO2 meter)
- 9 🛒 What if I want to buy a ready-made CO2 meter?
- 10 📢 Do you have problems? CO2 meter faq
- 11 📜 History of the eMariete CO2 meter
- 11.1 PeluCO₂: A CO₂ meter on your wrist (wearable)
- 11.2 Battery powered CO₂ meter (well done)
- 11.3 Color touch screen for CO medidor meter Wow!
- 11.4 Are home CO₂ meters as reliable, accurate and precise as commercial ones?
- 11.5 Gallery: User CO₂ Meters
- 11.6 Connect a BME280 sensor to ESP Easy
- 11.7 CO2 on a giant screen for bars, restaurants, classrooms and the like
- 11.8 CO2 meter with ESP8266 (NodeMCU) and Senseair S8 sensor
- 11.9 Power from NodeMCU, Wemos Mini D1 and Arduino
- 11.10 MH-Z19B FALSE CO2 Sensors
- 11.11 3D printed box for CO2 meter
- 11.12 Connect and control WS2812B LEDs to ESP8266 with ESPEasy
- 11.13 Using a buzzer with ESPEasy
- 11.14 The MH-Z19B CO2 Sensor Bible
- 11.15 Connect an SSD1306 OLED screen to ESPEasy
- 11.16 Comparison of CO2 sensors MH-Z19B vs Senseair S8
- 11.17 A homemade CO2 meter with Wifi against the coronavirus
- 11.18 What does CO₂ have to do with Covid?
Virtually all scientists have agreed in recent months: The virus is transmitted and contagious through the air, and one of the most effective ways to reduce the possibility of contracting Covid is adequately ventilating spaces.
The best way to ensure that a space is properly ventilated is to measure the CO2 present in the air.
If you are still not convinced of this, and want to know more, I suggest you read the following article:
❔ Is it possible to reduce the possibility of contracting Covid with a CO₂ meter of less than 20 Euros?
In the article that I just showed you, I have told you why the answer is a resounding YES!, Y In this article I am going to tell you how you can build your own homemade CO₂ meter easily and cheaply.
What I propose is a CO₂ (carbon dioxide) meter with home wifi, what you can build for less than 20 Euros, and that I guarantee that the result will be an instrument as accurate and with many more functionalities than many commercial CO₂ meters of several hundred euros.
This meter uses a CO2 sensor with NDIR technology Y It has nothing to do with the € 60 or € 80 meters that are sold online in terms of reliability, precision and functionalities.
Don't be scared by the length of this article. Yes, it is long, but it has nothing to do with the difficulty. This article is long because I have decided to explain everything step by step, in great detail and with captures, photographs and even videos of each step. Really I could have written a much shorter article explaining how to build this CO2 meter, but it would not have been so complete.
The idea is that anyone can build this CO2 meter, no need for prior knowledge or special equipment (Except for the welder, which, as we will see later, we can even do without).
In addition, it is a montage fully modular, so you can easily expand it, turning it into a CO₂ meter with all kinds of accessories, visual and audible alarms And till touch screen.
However, if you don't want to build your own CO meter, because you do not have time, you do not like the gadget, or any other reason, You can access a buying guide with the best offers in commercial CO₂ meters by clicking hereYou can buy it at a good price and have it at home in 24 hours.
👁️🗨️ Homemade CO₂ meter structure
The CO₂ meter that I am going to describe it has nothing to envy to commercial units of several hundred euros, being superior in many cases, both for precision and functionalities.
It has the following characteristics, advantages and functionalities:
Economic. Less than 20 Euros at the time of writing (it has risen somewhat due to the increase in price of the CO2 sensor due to high demand, but I hope it will go down again)
- High accuracy (50ppm +/- 3% of reading)
- Connection Wifi
- Smart (can perform many tasks based on the data)
- Web server internal
- Integration with home automation system
- Publication of data on the internet
- Support of MQTT and HTTP
- LCD display Y touch screen optional
The CO₂ meter with Wifi is composed of only two components, Low cost:
- Module NodeMCU, or similar, with microcontroller ESP8266 with integrated Wifi
- Sensor CO₂ MH-Z19B or Senseair S8 (there are other sensors available and supported by this project)
Its construction, commissioning and use is very easy, I estimate that you can do this project in one or two hours. You just have to follow the steps in this tutorial to build our CO₂ meter with Wifi:
- Download the firmware from this website
- Record ESP8266 Microcontroller Module
- Connect CO₂ sensor MH-Z19B using only four wires
I have chosen low cost components to build the carbon dioxide meter, in order to keep the price very low.
Buying the components in the links that I propose in AliExpress, with shipping from China, the costs would be:
|MH-Z19B|| Some 18 Euros for the CO₂ sensor MH-Z19B on AliExpress. |
I recommend that you order the one with a range of 5000 ppm.* See below my recommendation to use the Senseair S8 sensor.
Be careful not to buy the MH-Z19C version without looking at its downsides (below).
Many vendors advertise the MH-Z19B but they actually ship the MH-Z19C.
|NodeMCU|| Some 2 Euros from the plate NodeMCU with ESP8266 microcontroller in this AliExpress link. It also has many positive reviews and if you choose AliExpress Standard Shipping, which costs less than € 2, you should receive it in a couple of weeks. |
You will see that there are several models. I recommend that you ask for the one that says «CP2102«
Use the sensor Senseair S8 LP.
There is a real avalanche of fake MH-Z19B sensors, both on AliExpress and Amazon. These sensors give fluctuating and far from reality measurements, in the best case.
I spend a lot of time checking purchase links that I put and trying to make sure, as much as possible, that they are original, but sometimes there are surprises.
If you want to play it safe, and you don't mind spending a little more, I suggest you use the sensor instead of the MH-Z19B Senseair S8 LP. Besides being less likely to get a fake one, it's a sensor, from a European company, of better quality and more precision than the MH-Z19B.
I leave you here the link in which I bought: Senseair S8 LP. It's original and it came to me very fast (one week):
You can find more information about fake sensors by clicking on: MH-Z19B FALSE CO2 Sensors
If you don't want to wait that long, you have the option of buying these components on Amazon, with fast shipping. It is more expensive, but if you want it quickly, you will have it at home in 24 hours, in many cases.
An important advantage of Amazon is that, now that there are so many fake MH-Z19B sensors, at Amazon you know that it is easy to return it, if you are not satisfied.
- This MH - Z19 C02 gas sensor has high sensitivity, high resolution.
- Provides a variety of forms output modes, such as UART and PWM wave.
- Anti water vapor interference, no poisoning.
- Temperature compensated, excellent linear output.
- ✔️ Powerful Microcontroller: The AZ-Delivery Module is a powerful ESP8266 (ESP-12F) microcontroller with 802.11 b / g / n WLAN and integrated antenna.
- ✔️ Rapid Prototyping: It is simple to use, allowing you to easily create prototypes through simple programming through Lua code or Arduino code. Plus, with a motherboard-compatible design (27.5mm pin spacing).
- ✔️ Dimensions (L x W x H): 58mm x 31mm x 13mm.
- ✔️ Large storage and processing space: AZ-Delivery ESP8266 with Wi-Fi has large storage and processing space on board that allows it to integrate with application-specific sensors and devices and support minimal load during runtime. Boost your development in the fastest way combining with NodeMcu Firmware!
- ✔️ This product includes an E-Book that provides helpful information on how to get started on your project, helps with quick setup, and saves time in the setup process. We provide a number of application examples, complete installation guides, and Arduino libraries.
- ESP8266 CP2102 NodeMCU LUA ESP-12E WIFI serial wireless module.
- Efficient Microcontroller ESP8266 (ESP-12E) with WLAN 802.11 b / g / n and integrated 25dBm antenna.
- Built-in micro-USB, with flash and reset switches, easy to program.
- Convenient prototyping through simple programming by Lua-Script or Ar duino-Code and compatible Breadboard construction.
- Full I / O port and Wireless 802.11 compatible download, no reboot required.
Other purchase options:
Right now, when there are so many fake MH-Z19B sensors, the most advisable thing would be to buy it in the official store of the sensor manufacturer (Winsen), in this way you will have the security of receiving the original sensor.
The problem is that the manufacturer does not sell the MH-Z19B one at a time, it has to be in pairs. So if you want to build two, or have someone who wants another, this may be a good option:
|MH-Z19B||2 CO₂ sensors MH-Z19B for about 38 Euros in the official manufacturer store on AliExpress. |
Here you will have the sure to receive the original sensor, and not a copy.
I recommend that you order the one with a range of 5000 ppm.
Just missing a box.
As a box I propose four options:
- Leave it «in the air«. If it is going to be hidden, it is an inaccessible place, there should be no major problem.
- Put it somewhere ornamental element, any adornment or accessory that is in the room and that allows to hide and protect it.
- Buy one plastic box. I use one that I am buying 10 by 10 in several similar assemblies. Simple and cheap. You can find it here, although there are many similar ones. You can also use one of the gray boxes that are usually used in outdoor electrical installations, drilling it properly.
- A 3d printed box. It is the solution that I used. You can find the design and tutorial in this blog, as well as others boxes designed by other users and have been made available to readers selflessly.
You have to consider two important things: You have to try that the CO₂ sensor is heated as little as possible because its measurements are sensitive to temperature and you have to install it so that it receives the air from the room without problems (Do not put it in a closed box or with little ventilation).
CO₂ sensor MH-Z19B
The MH-Z19B carbon dioxide gas sensor is a general-purpose, small-size smart sensor that uses the principle of non-scattered infrared (NDIR) to detect the presence of CO₂ in the air. It has good selectivity, long service life, and other characteristics, such as built-in temperature compensation.
It has simultaneous serial, analog and PWM output and is easy to use. It is a high-performance sensor that combines reliable infrared absorption gas detection technology with good design and an attractive price.
MH-Z19B sensor parameters
|Gas detected||Carbon dioxide|
|Operating voltage||4.5 ~ 5.5 V DC|
|Average current||<60m A (@ 5V supply)|
|Peak current||150 mA (supply @ 5V)|
|Interface level||3.3 V (compatible with 5V)|
|Measuring range||0 ～ 2000 ppm
0 ～ 5000 ppm
|exit sign||Serial (UART) - TTL level 3.3 V - PWM analog output|
|Preheating time||3 minutes|
|Operating temperature||0 ~ 50 ° C|
|Operating humidity||0 to 90% RH (non-condensing)|
|Dimensions||33mm × 20mm × 9mm (Length * Width * Height)|
|Lifetime||> 5 years|
|Gold-plated gas chamber, waterproof and corrosion resistant|
|High sensitivity, low power consumption|
|Temperature compensation, excellent linear output|
MH-Z19B Sensor Applications
|HVAC Refrigeration Equipment|
|Surveillance and air quality equipment|
|Fresh air systems|
|Air purification equipment|
|Schools and educational centers|
You can see here his datasheet.
The ESP8266 module
The ESP8266 module is a complete microcontroller on a small chip that includes Wifi and TCP / IP stack and is also very cheap.
|ESP8266 usually used mounted on a moduleas it does not include flash memory or USB and needs some external components to work.|
For this montage I have chosen the NodeMCU module why:
I could have chosen any other module, such as the very large and small ESP12E, but it would have complicated the assembly a lot, due to the additional components that would have been necessary and also its programming, as it does not have a USB port.
With the NodeMCU everything is much easier.
That said, there are other versions of the NodeMCU module, like the little Wemos D1 Mini, which you can choose. The assembly will be very similar, although you will not be able to use the instructions and photos on this page directly.
I have a Wemon D1 Mini around here, so if there are many requests, I will consider making a prototype with it to document it on the blog and take pictures.
✔️ Build the homemade CO₂ meter
Enough of introduction, explanations, data and verbiage and Let's go to the mess! To construction!
You have, below, a video with the entire detailed process, to make it easier for you.
The construction of the CO₂ meter, commissioning and use is very easy, I estimate that you can do this project in one or two hours. We just have to follow these steps to build our CO₂ meter with Wifi:
- Download the firmware from this website
- Record ESP8266 Microcontroller Module
- Connect the CO sensor sensor using just four wires
I find it a useful and quick project for the experienced hobbyist and a excellent first project for the newcomer to electronic gadget. (Only four welds! Who gives more for less?)
Download the CO meter firmware
The first thing you have to do is download the program to your computer what then we will load in the NodeMCU and that it will control the operation of our CO₂ meter.
This program is based on the fantastic project ESPEasy, that I have been using for several years with very good results.
To simplify the task as much as possible, and that you do not have to search and download the different necessary programs and files (and find which are the correct ones to use, because there are many), you can download it from here with one click Y in one package that I have prepared and that it contains just what is necessary.
Below you can find the video with detailed instructions for the ESPEasy recording in the NodeMCU.
IF you have a board other than NodeMCU (4MB memory) you may have to download the complete package from the ESPEasy releases page on GitHub. This is necessary, for example, with the Wemos D1 Mini Lite board (not necessary with the normal version, "not Lite").
Connect CO₂ sensor MH-Z19B
The connection of the MH-Z19B or Senseair S8 sensors (they connect exactly the same) to the NodeMCU is very easy, it only requires four connections.
If you prefer to use the plate Wemos D1 Mini, you can be guided by the following diagram.
You will need to a soldering iron, tin and a pay a little attention, but it shouldn't take you more than 5 or 10 minutes, even if you have little experience in these matters, or be your first electronics project.
For connection of the MH-Z19B sensor to the NodeMCU, we can use the cable that comes with the MH-Z19B, cutting the connector on the end.
If your sensor is not the version that comes with a connector, nothing happens, you will need some cables to connect it.
Once we have cut the connector, we strip the cables and make the following connections (please note that this pin number does not match the manufacturer's):
|Pin MH-Z19B||Colour||Function||NodeMCU connection|
|1||Brown||Analog output||Without connection|
|3||Black||Negative power supply (GND)||Pin GND|
|4||Red||Positive feeding (Vin)||Pin Vin|
|5||blue||Data input (RXD)||Pin TX|
|6||Green||Data output (TXD)||RX pin|
The manufacturer recommends that, when welding with a soldering iron, it be done at a temperature of (350 ± 5) ° C, and that the soldering time is 3 seconds maximum. This translates into: sweat it fast, don't linger.
Also bear in mind that it is a delicate component and sensitive to static electricity. Do not handle it a lot and, above all, avoid touching the contacts as much as possible. I do not know a single case of the users who have built the meter following this tutorial, that the sensor has been damaged, but it never hurts.
In the following images you can see the assembly process, including its connections, in detail:
Cut the CO2 sensor connector
In my case, I ordered the MH-Z19B sensor version with connector.
The first thing I do is, since the cable has a connector on both sides, cut the connector on one side.
Optional: Remove unnecessary cables
The connector comes with all seven wires attached.
As we only have to connect four (Black, Red, Blue and Green), I remove the other three cables so that they do not get in the way and that the assembly is cleaner.
Stripping the wires
We strip the end of the four cables.
It is enough to peel one or two millimeters. The shorter the more "clean" they will be when soldered.
We carefully weld the sensor supply to the NodeMCU
- Red wire (positive) to terminal marked Vin
- Black wire (negative) to terminal marked GND
Remember: If you use the Senseair S8 sensor, it connects exactly the same.
Solder the data cables
We solder the sensor data input and output cables to the NodeMCU
- Blue wire (RXD, data input) to terminal marked TX (data output)
- Green wire (TXD, data out) to terminal marked RX (data in)
Remember: If you use the Senseair S8 sensor, it connects exactly the same.
This is how the wiring will be, once we have soldered the four cables.
The finished CO2 meter
Now it only remains to connect the sensor to the NodeMCU, being careful not to put the connector backwards.
This will be how our CO2 meter will look, once the four cables are soldered and the sensor connected.
We only need to place it in the box or in a place where it is protected (even if it is on air).
NodeMCU boards with VU pin
There are many different NodeMCU boards with slight variations between them. There are some NodeMCU boards that have a pin marked VU.
This pin, VU, is a direct connection to the positive of the USB. You can take advantage of it to connect the sensor to this pin if it suits you (and I recommend it).
📺 Video with the complete CO2 Meter tutorial
In this video you can see everything you need to build the CO₂ meter, including electronic part, NodeMCU recording and configuration.
The video has been recorded using an MH-Z19B sensor and a NodeMCU board. Remember that, if you use the Senseair S8 sensor (recommended) its connection is exactly the same (in this case see also this article I've written with the differences when using the Senseair S8).
If you have any questions or problems, do not stop consulting this section.
You also have at your disposal the Telegram group, where you will find all the help you need.
🔵 Using the CO₂ meter
At this point, your CO₂ meter with Wifi is already finished. You only have to configure it, place it in the room you want to control and read the CO₂ data from time to time.
I recommend that you see the configuration in the video, where it is explained in detail. However, below you have additional information.
CO₂ meter setup with Wifi
The meter needs a basic configuration to function, which basically consists of: Setting up the Wifi to connect it to the network of your home, office, school, etc. and tell ESP Easy which sensors you have connected (in this case only the CO2 sensor) and what to do with them.
ESP8266 Wifi Configuration
As soon as you record the ESP8266, and to facilitate the configuration of the Wifi, you will see that it creates an access point called ESP-Easy.
All you have to do is connect from your computer, tablet or phone to that access point and configure the meter, in a very simple way, through a web page, thanks to the fact that the program that we have recorded in the ESP8266 includes a web server with the necessary pages for easy setup.
Configuration of the ESP8266 inputs and outputs
Through the same web page that you used to configure the Wi-Fi connection, you can now configure the inputs and outputs of the ESP8266 to tell you what's connected.
In our case, the only thing our ESP8266 has connected is the CO2 sensor and you are going to configure it so that it knows how to read the values that this generates and what to do with them.
As you will discover, it is very easy to expand the project to include other sensors and actuators as sensors temperature and humidity, LCD screens, etc. (you have links to detailed tutorials below).
Reading the CO₂ data from our meter
Your CO₂ meter with Wifi is already working, reading the CO₂ data of the air in the room where you have placed it and processing that data.
To read and process this data you have many possibilities that will allow you to read the CO₂ value directly and do many other things, such as store them, create graphics, create alarms of various types when certain values are reached, send them to the internet, integrate them with your home automation system and much more.
The most basic use is see the CO₂ present in the room in real time. For that you only have to connect to the meter web page, with your web browser computer, tablet or mobile phone and access the "Devices" tab, where you will see the existing value at that moment. The most recommended is save this page to your favorites, for access it easily and directly whenever you want.
CO2 meter calibration
Both MH-Z19B and Senseair S8 LP sensors they are already factory calibrated. That does not mean that you can ignore them forever (as in any CO2 meter, commercial or not).
Over time it is usually necessary recalibrate sensor zero point, but don't worry it's very easy.
You can find the instructions to calibrate the sensor here: Zero Point Calibration
Benefits of this CO₂ meter project
There are several projects similar to this on the internet. From small basic prototypes with the basic functionalities to obtain local CO2 measurements to complete systems that include all kinds of functionalities, own software platform for capture and visualization, etc.
I am going to present you here what I think are the main advantages and benefits and the advantages From this project of CO2 meter.
Reliability of measurements
What a CO₂ meter has to do, as obvious as it may seem, is to measure and CO₂, and do it with a certain precision (that you know how much CO₂, there is with enough precision), reliability (that the meter works correctly at all times) and repeatability (always measure the same thing under the same conditions).
There are many projects that promise to measure CO2 but actually use electrochemical sensors of general use for the detection of organic volatiles that do not measure only CO2, but all those gases together, so you really don't know what you are measuring.
There are, for example, many 'CO2 meters' using sensors such as the MQ-135 or CCS811, but these sensors they are not used to measure CO2. These sensors measure all organic gases together (Ammonia, Nitrogen Dioxide, Alcohol, Benzene, Carbon Dioxide and Monoxide, smoke, etc.), so if there is someone who is throwing hydroalcoholic gel or someone smoking or there is a source of combustion, such as a fireplace, the measurements will trigger without the possibility of knowing what is causing them to shoot.
In case I have not made it clear: DO NOT MOUNT A METER BASED ON THE MQ-135 or CCS811 SENSORS IF YOU WANT TO MEASURE CO₂!
The project that I present here, uses an NDIR sensor that only measures CO₂. The same sensor used in commercial meters for hundreds of euros. When you get a measure you will know that that measure it is from CO₂ and not from other gases, which surely does not interest you.
Many commercial meters that call themselves "CO₂ meters"Up to € 200 in price, they use the MQ-135 and CCS811 sensors. Run away from them if you want to measure CO₂!
In case it is not clear, the only parameter that you could obtain with sensors like the MQ-135 or the CCS811 would be: «Value in unknown units of something unknown in the air, which is not known what it is or in what quantity it is«. As you can see, something very little useful.
Ease of construction
In many projects that are online, we see that they are relatively complex to build, with many components and welds. Sometimes it is necessary to have measuring instruments to make adjustments.
This project has been designed to be extraordinarily easy to build and is within reach of anyone with no knowledge of electronics. You only have to make four connections and it does not require measuring instruments or adjustments of any kind.
I know there are teachers who are building this meter with children, as an activity in class. See if it's simple!
Ease of programming
Many of the projects that we find on the internet are complicated to program. It is even necessary to have programming tools, such as compilers, IDEs, or specific editors.
Also in many projects we have to edit configuration files by hand, which makes it difficult for the non-expert user.
In this project, no need to program anything. It's all pre-programmed and all you have to do is save the supplied program, which you can download from this page, in the NodeMCU with a very simple process, following the video I have prepared.
Easy to set up
Many projects have very complicated configuration processes, for non-experts, in which it is necessary to modify multiple parameters, often modifying parameter files by hand or even the source code of the program before compiling and loading it into the meter.
In this project, all the configuration is done very easily, through a web page. No need to edit files by hand or modify code.
Easy to calibrate
Many projects, especially those based on sensors like the MQ-135 and the like, need tedious and very complicated calibration processes, which sometimes has to be repeated daily or every time it is going to be measured.
This project does not require any type of calibration. The sensor comes already factory calibrated and then I know autocalibrate him alone periodically.
Expandable modular design
Most existing designs on the internet have certain functionalities and these they are what they are. It is not possible to reduce or expand the design without making changes to the electronics and, above all, programming.
This project is completely modular and expandable without the need for changes in programming nor in the basic circuit. You can start with a basic CO₂ meter and later expand it, in a very simple way, with different types of screens, LEDs, additional sensors (such as temperature and humidity), etc.
Communications and integration
That the CO2 meter can communicate with the outside and send its data (and even receive it) is very useful on many occasions. In most of the projects available on the internet, either the meter you have no possibility of communication, or your possibilities are very limited.
This project, on the contrary, has some huge communication possibilities that allows you to send data to virtually any device or system, without making any changes to your programming, supporting most of the possibilities like MQTT, HTTP, Telnet, UDP, P2P, etc.
Don't you know what all that I've put on you is? Don't worry! You don't have to know anything about it, they are just options that are there for whoever wants to use them.
In most projects the possibilities to consult the data are very limited. Being necessary to do major changes in your design or programming to be able to add new display options.
In this project, you can visualize the data, both in real time and historical, very easily in multiple ways: integrated web page, screens of various types, multi-color LEDs, mobile app, historical graphics on cloud platforms such as Thinkspeak, etc..
On many occasions it is interesting to know the CO2 concentration or historical remotely.
With most of the devices that we find on the internet this would be impossible or would require important changes in your programming.
With this project this is very simple, being able to consult from the mobile, at any time and from anywhere in the world, current and historical measurements.
Most projects offer real-time measurements, but do not have any data persistence system, to be able to store measurements for later analysis or integration into other systems.
This project allows, in addition to the easy use of cloud services (as Thingspeak, IFTTT and the like), databases like InfluxDB (both local and remote), etc.
Portability and mobility
Sometimes it is interesting to be able use the CO2 meter portable or on the move. Most of the existing projects on the internet do not contemplate this possibility.
This project contemplates the configuration, permanently, of two Wi-Fi networks, so that if the first is not available, the meter connects to the second automatically.
Not only that, but if we turn on the meter in a place where there is no Wi-Fi network that it has configured, It will automatically enable us a web page to which we can connect from the mobile to configure any other Wi-Fi network in a few seconds.
We can also configure the second wifi network so that use the internet connection that our mobile provides automatically.
In addition, being fed by a standard micro USB port, we can use a normal powerbank to run the meter on battery (based on my tests we can expect a autonomy of up to 48 hours depending on the powerbank we use).
I will also shortly publish a extension to equip our meter with internal lithium-ion battery (also called Li-Ion) with built-in charger (vote for her in the comments, the more people ask for her I will give it more priority).
🌀 Home CO₂ Meter Options and Extensions
The ESP8266 controller and the firmware it is based on are very powerful and you allows you to add endless possibilities.
Then you will see some of the possibilities, simpler, that this carbon dioxide meter allows you.
These extensions they are explained in detail in this blog and in my YouTube videos (Some have been contributions that users like you have made to the blog), but you can easily make many more extensions yourself.
Add an OLED screen
In the following article you can see the step-by-step tutorial to add an OLED screen to the meter, in case you prefer to see the values easily, without using your mobile or computer. It is also interesting to be able use meter without Wifi connection.
Add a custom box
A custom box is the perfect complement to your meter. It will give a more professional finish and will protect the assembly from bumps and snags.
You can use a electrical junction box, adapting it very easily.
In the following article you will find custom boxes for 3D print, both the one designed by Mariete, and others, selflessly contributed by users who have built this CO₂ meter.
Adding temperature, humidity and atmospheric pressure data
Easily add a thermometer, hygrometer and barometer to your CO₂ meter for just a few euros. Y all without reprogramming and with only four cables!
Add notices and audible alarms
You can easily add a buzzer and set alarms and warnings when certain levels of CO2 are reached.
In this article you have a complete explanation with everything you have to do prepared to copy and paste.
Creation of CO₂ evolution graph
You can create, in a very easy way, a graph with the evolution of CO₂, using the free cloud service from ThingSpeak. Like this:
The ThingSpeak service allows you to store the data from your sensors in the cloud for free and consult them from your mobile, tablet or computer.
Thanks to user ManeKoYou can see quick instructions in the comments below to automatically send your CO2 meter data to ThingSpeak (press here if you want to go directly to the comment where it is explained).
Using the meter as portable / portable
Sometimes it may be convenient to use the meter in portable (in a different place than you normally have it).
This use, so convenient, is very simple and for this you have several possibilities:
Setting up a second Wi-Fi network
You can configure a second wifi network with its SSID and password, to which the CO2 meter will connect automatically if you can't find the main wifi network.
For it you only have to include the data of the second wifi (SSID and password) in the configuration tab («Config«) And you won't have to do anything else.
A very interesting use of this possibility is to use, when you are away from home, the access point you can create your cellphone. In this way it easily becomes a connected portable meter. Perfect for IoT solutions.
Connection to any Wi-Fi network, when neither of the two configured is available
When neither the main Wi-Fi network nor the secondary network is available, the CO₂ meter will automatically create a Wifi access point to which you can connect from any mobile, tablet or computer. You just have to find the access point and connect to it to be able to configure a new Wi-Fi network.
Equip the battery meter (portable CO2 meter)
In the following article I explain, step by step and with video, how you can equip the meter with a rechargeable battery and thus convert it into a portable CO₂ meter with sufficient autonomy to use it throughout the day.
🛒 What if I want to buy a ready-made CO2 meter?
If, for whatever reason, you don't want to build your own homemade CO2 meter, you have the option of buying a commercial one. Plug and play.
There are many models on the market, but, I must warn you that many of them are worth absolutely nothing, in order to measure the concentration of CO2, because they have a type of sensor that is affected by all types of gases and the meter is not capable of distinguishing CO2 from any other gas (and there are many gases in the air that go and they come, so you'll never know if it's measuring CO2 or something else).
Whichever meter you buy, I recommend that you buy one that has an NDIR sensor (And keep in mind that, if it doesn't wear it, it probably won't wear it).
If you want a commercial meter that is not very expensive and that works well, I would propose one of these two options:
- Date, time, CO2, humidity, temperature (℃ / ℉ switchable) full color, 3.2-inch screen, and other data clearly.
- The application field of the carbon dioxide detector is public site, agriculture, animal husbandry, industry and more. With professional-grade detection technology, this CO2 meter has stable performance and high precision.
- You can store up to 999 groups of data and have a historical data trend table for you to review.
- Real-time CO2 monitoring by the high precision sensor, and it will alarm you once the CO2 exceeds the setting value.
- Compact size with portable storage, easy to operate and carry. The rechargeable lithium battery is included or can be powered via a 5V USB cable.
- Level of air quality, humidity, temperature and noise
- Tips on creating a healthier environment
- 3 profiles in the app: baby, person with asthma, general
- Real-time notifications (ios 9 or higher for iphone, ipad, ipod, android 4.2 or higher)
- Connect multiple healthy home coaches to your smartphone to control multiple rooms
I have this one down here that is very similar, but with some additional things that make it a weather station:
- Control your indoor and outdoor environment in real time: indoor and outdoor temperature, humidity and air quality, indoor noise level, barometric pressure
- Receive alerts in real time: with our weather station, configure indoor and outdoor alerts and receive notifications on your smartphone; you will know when to ventilate with the ventilation alert
- Access your data remotely and with your voice: access your weather measurements with ease and at any time from your smartphone, tablet or computer, or by using your voice to interact with alexa on amazon echo or with siri thanks to the compatibility with apple homekit
- Analyze the past: access the history of your data to observe what happens when you are not there or analyze the graphs to understand the weather trends
- Foresee the future: check the 7-day weather forecast to adapt your clothing and your outdoor activities
If you want to see more models available at a good price, the best sellers, the best offers, etc. you have the option to visit this CO2 meter buying guide.
📢 Do you have problems? CO2 meter faq
Although the project is really simple, there is always the possibility that you may have a question or that some kind of problem will appear.
In the list that you will see below, it is not that there are many things because of many problems (most are simple doubts and the problems are almost always the same, and they almost always have to do with the charger or the USB cable), but because it they have built hundreds of people and any little doubt that has arisen I have documented it.
Here I leave you the Frequently asked questions made by users who have been encouraged to build the CO2 meter.
📜 History of the eMariete CO2 meter
Here you can check the articles that I have published over the years (since 2017 when I published the first prototype) related to the CO₂ meter.
In these articles you can find a lot of information to expand the meter with new functionalities, learn more, etc.