Controlling ventilation with the MT8057 carbon dioxide detector

Many users of the popular carbon dioxide (CO2) detector MT8057 ask us questions about how to implement the control of inlet or exhaust ventilation with the help of this detector. After reviewing our range, we found the device with which we want to offer a solution to this problem.



The appearance of the detector can be seen in Fig. one.





Fig. one

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The MP515 module was selected as the power control element for the fan. The appearance of the module can be seen in Fig. 2





Fig. 2



The MT8057 is a precision instrument for measuring CO2 concentrations in air. The device is equipped with a liquid crystal display for accurate control and three indicators for operational control of the concentration of carbon dioxide. As a nice addition, the device shows the state of the temperature at its installation site. If necessary, using the control buttons you can change the on-line indication of the operational control.



The MP515 is a power relay with an electronic key. The module is designed to control power devices up to 2000 W from the low-current outputs of various sensors and control devices, providing galvanic isolation from the electric device. To control the module, you need a voltage from 1V to 5V, which can be obtained from the head unit. The module provides a place to install a 433 MHz MK324 wireless receiver. The module can be powered either from a + 5V voltage source, for example, PW0512 , or from a USB port of a PC or a smartphone or phone charging adapter.



To connect the power relay, we need to disassemble the MT8057. For this, it is necessary with the help of a small screwdriver to bend the latches in the slots of the sensor housing of fig. 3





Fig. 3



Then loosen the three screws and disconnect the air intake tube fig. four.





Fig. four



Now remove the card and position it on the display itself. Then it will be necessary to solder one of the three wires to the extreme resistor RledR, limiting the current of the red LED with the inscription LedR, Fig. five.





Fig. five



The second wire is soldered to the output of the ModeKey button connected to the common bus of the board. The third conclusion is soldered to the middle contact of the THRO element, fig. 6





Fig. 6



On this conclusion comes the supply voltage + 5V. We need this voltage to power the MP515 power module. As a matter of fact, such a connection will allow us to power the entire circuit both from the microUSB input of the sensor itself, and from the miniUSB input of the power module. This will be useful when installing this scheme.



Wiring diagram of the fan to the power relay can be seen in Fig. 7





Fig. 7



If necessary, manual control of the inlet ventilation, together with the power module, you can apply the wireless control kit MK324, fig. eight.



MK324 is a set of four channel transmitter and receiver, 433 MHz band. The console is powered by a 12V battery, Series 23A. Working time from one element at least 1 year. The receiver is designed for 5V supply voltage. The range of the kit is 30m. It is quite enough for application in the conditions of the private house or apartment. Since only one control channel will be used in the wireless module, the free ones can be used to control lighting or other electrical appliances.





Fig. eight



This kit is effortlessly installed on a regular place, provided in the MP515 power relay. After such a simple modification, it will be possible to forcibly turn on the ventilation with the yellow CO2 sensor indication.

The installation of the fan, ventilation, can be seen in Fig. 9.





Fig. 9



Video of the system assembly can be seen here:







Fresh air to you!