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  • 27/02/2017

    Hi All, It can be hooked up to a simple usb/serial converter (only 4 wires required). Make sure the data lines (Tx and Rx) use 3V signalling. Running a simple powershell script the data is displayed. Script: [Byte[]] $request = 0xff, 1, 0x86, 0, 0, 0, 0, 0, 0x79 [Byte[]] $res = 0, 0, 0, 0, 0, 0, 0, 0, 0 $port = new-Object System.IO.Ports.SerialPort COM57,9600,None,8,one $port.Open() $port.Write($request, 0, 9) Start-Sleep -Milliseconds 50 For ( $i = 0; $i -lt 9; $i++ ) { $res[$i] = $port.ReadByte() } Write-Host "CO2: $($res[2] * 256 + $res[3]) ppm, Temp: $($res[4]-40) C" $port.Close() Display: CO2: 876 ppm, Temp: 24 C If you try it, please set the port parameter (COM57 in my case) according to your system. Bleph

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  • 22/12/2018

    Is it a fiber fabry perot interferometer that exploits the absorption of the infrared ray of CO2 ? Is it necessary to remove the protective film on both sides of the sensor before use?

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  • 23/01/2018

    This is a MH-Z19B 0 - 2000ppm Not a 0 - 5000 ppm Confirmed with an oscilloscope. Seems accurate I am very pleased. Just remember to calculate for 2000 ppm.

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  • 08/07/2017

    Seems to do what it says on the box. Inside with a gas heater (with flue) on I got (with the script above, cheers) an uncomfortably high reading >1200ppm so I took it outside and got 385ppm after a few minutes, which seems right. So I have a window open now :-)

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  • 16/12/2020

    datasheet in some aspects misleading. Finally I got it working. It now shows reasonable results. Quality looks good.

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  • 28/02/2018

    it arrived in 2 weeks, in a good packaging. It works well. good deal.

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  • 17/01/2017

    Works as specified, worm up phase is longer than 3 minutes, but under 5 min. Supplycurrent is quit high with peaks, but on average also as specified.

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  • 19/09/2018

    Я иногда задавался вопросом, почему в зимюю пору утром бывает тяжелая голова. Прошлой зимой даже купил увлажнитель воздуха, думал это из-за сухого воздуха. Купив этот датчик и собрав прибор я понял что голова тяжелая из-за высокой концентрации СО2. В квартире с пластиковыми окнами за ночь конценрация СО2 поднимается до 1500-1800 ppm. Если окно оставлено на проветривание то концентрация СО2 на превышает 600-700 ppm. Рекомендую отключить автокалибровку и делать калибровку вручную раз в пару недель.

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  • 18/10/2017

    Eventually I got this working with my Raspberry Pi-0w, we can use this for teaching respiration etc. in schools, the quick response to perturbation is helpful. CO2 concentration as expected, but I didn't yet check quantitative accuracy. Need to solder pins but connects straight to pi serial uart, no extra interface needed, although pi serial config is tricky. You can find sample python codes on internet (but check carefully for characters lost on copy-paste). Seems robust, working non-stop for days.

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  • 16/02/2021

    Everything was ok with the shipping. The soldering of the pins was a little difficult. It works ok together with a TTGO ESP32. Measurements are between 400 and 1000 ppm in a room were I work. Only drawback when working on battery the measurements go to maximum, current consumption is around 150-180 mA so maybe battery is weak.

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