As the pandemic on going and we stay indoor more often, monitor carbon dioxide and other harmful TVOC particle in our living space since to be a good idea.
But such sensor are usually price above 150-200 USD each, do we have a more affordable version?
When I browse the internet, I stumble upon this :
ZN-2CO1 Air Quality Detector
And it claim it can detect :
- CO2 (400-6000PPM)
- TVOC (0-2.0mg/m3)
- HCHO (0-0.6mg/m3)
and Temperature and Humidity as well.
Cost well below 30 USD, which is way to cheap, knowing how much a normal CO2 sensor will cost like.
I did a teardown, found out that
It only have 2 sensor:
DHT11 clone - Temperature and Humidity sensor, most probably clone
TPM-300A-V2.2 TVOC Air Quality sensor - using TP-401 sensor
Documentation below:
http://www.szdovelet.com/product/html/?167.htmlhttps://solarbotics.com/wp-content/uploads/tp-401a_indoor_air_quality_gas_sensor.pdfThere is no CO2 Sensor or any precision sensor inside the product.
The MCU of the display is STM32F0 china clone GD32, a lipo charging circuit, a switching regulator for 3.3V, a 2.4" IPS LCD display.
The TPM-300A-V2.2 module actually output a data stream:
2C E4 00 5D 00 1B 01 BB 44
- 2C E4 is the module address
- 00 5D TVOC high low bit
- 00 1B CHOH high low bit
- 01 BB CO2 high low bit
- 44 Parity bit
Conclusion:
Don't buy this. the product is fake. The data read out is not the actual reading and just make out.