A carbon dioxide (CO2) meter is probably the most underestimated device, which in my opinion should be in every apartment, because it shows how breathable the air is and with the help of it you can always see when it's time ventilate.
Such a meter is very rare in apartments, primarily because of the high price. Its first meter AZ Instruments 7798 CO2 datalogger ( https://ammo1.livejournal.com/500385.html) I bought for $ 139 and it was the cheapest model on the market. Then Dadget MT8057s appeared for 3990 rubles (https://ammo1.livejournal.com/932112.html).
Recently, CO2 meters with a large color screen appeared on Aliexpress for less than 3000 rubles. I ordered such a meter and compared it with other models.
This CO2 meter costs $ 36.89 with fast free shipping and free returns. It has no name. The white box only says the name of a certain Spanish importer. In the box there is a meter, a USB-MicroUSB cable, instructions in several languages (there is English, no Russian).
The meter has a built-in battery, but the main mode of operation is from the mains using any 5V voltage source with a USB connector, for example, charging from a smartphone. On the right is the power button and the MicroUSB connector. To turn it on and off, you need to hold the button for 2 seconds, the button has no other functions.
The screen shows the CO2 level, a circle around it that changes color depending on the CO2 value, below the temperature and humidity. The temperature is always too high, and it's not a bad sensor, but its poor location - the sensor heats up from the device itself. Under the inscription "CO2" there are some hieroglyphs (they cannot be removed). In the upper right corner there is a battery level indicator. It flashes in its entirety when charging and is on when the battery is charged.
The viewing angles of the screen are not very good. When viewed from above, almost nothing is visible.
For the initial calibration, I put four devices on the balcony (it is always 400 ppm outside, regardless of the weather and gas pollution). A day later, the picture was like this.
AZ Instruments 7798 showed 428 ppm, the first Dadget 420 ppm, the second dadget "flew" to unrealistic 312 ppm (okay, after a couple weeks will return to normal readings), and the new device showed exactly 400 PPM and this is not without reason - it simply cannot show values less than 400.
Then I installed all four devices on the table, closed the window, turned off the ventilation and began to conduct an inhuman experiment on myself. After half an hour, the room was about 600 ppm CO2.
After another 800 hour.
In two hours 1000.
The new device really measures CO2 and shows values close to other devices. And everything would be fine if not for one thing. From time to time, it suddenly starts showing 400 PPM, when in reality it is not 400 at all.
Ten minutes later, he comes to life and again begins to show correctly. But I noticed this glitch for him several times a day. Perhaps this is a marriage of my copy, or maybe they are all like that.
I will of course take advantage of the free return and send it back. I will not advise buying such a device: although it basically shows the correct values of the CO2 concentration, a glitch with a random display of 400 PPM is annoying and in order to see the screen normally you need to put the device at eye level or higher.
© 2020, Alexey Nadezhin
For ten years I have been writing every day about technology, discounts, places of interest and events. Read my blog on the site ammo1.ru, in LJ, Zen, Mirtesen.
My projects:
Lamptest.ru. I test LED lamps and help figure out which ones are good and which are not so good.
Elerus.ru. I collect information about domestic electronic devices for personal use and share it.
You can contact me in Telegram @ ammo1 and by mail [email protected].