Smart phones have many sensor but not enough for me. So I attached a bunch of sensors to an arduino mega. Specifically the MQ2 through 9 set plus BME680, DHT22 and CCS811. Those are all gas and weather sensors. Specifically temperature, humidity, pressure, several combinations of TVOC, eCO2.
MQ-2 Methane, Butane, LPG, smoke 5V
MQ-3 Alcohol, Ethanol, smoke 5V
MQ-4 Methane, CNG Gas 5V
MQ-5 Natural gas, LPG 5V
MQ-6 LPG, butane gas 5V
MQ-7 Carbon Monoxide Alternating 5V and 1.4V
MQ-8 Hydrogen Gas 5V
MQ-9 Carbon Monoxide, flammable gasses. Alternating 5V and 1.4V
MQ135 Air Quality (Benzene, Alcohol, smoke) 5V.
The MQ set is just 15 usd. That is why I bought it. The MEGA easily handles computation and the SD card takes days to fill but the entire system is a big energy hog. Some of these sensors are redundant and unnecessary. Which sensors should I remove and which should I add? For example how about a Geiger counter? I am asking now for design and month long shipping from china.
20 MEGA 10 sdcard&read 5 RTC 20 BME680 20 CCS811 15 MQ 5 DHT22 15 Kmashi55Wh battery. Total: 100USD.