Exhaust gases multi-band air quality sensor on arduino - part 1

For my graduation project I need to develop a model of exhaust gases distribution between city buildings.
The model will made with help of PyQGIS and about this i will write later.
For source data collecting i `m  going to use the self made multiband exhaust gas detector (air quality monitor) based on arduino-like board (dccduino - with love from China) and set of specialized gas sensors.

What I'm going to use:

Components for future exhaust gas sensor 

From left to right:

1. MQ-138 with module. This sensor will be used for detecting of organic components of air. The description of this module says that it is sensitive to aldehydes, alcohols, ketones, and aromatic compounds :
   • 1 to 100ppm benzene
   • Toluene 10 to 100ppm
   • Methanol 5 to 100ppm
   • Alcohol 30 to 300ppm
   • Acetone 10 to 300ppm
• Formaldehyde 1 to 10ppm 
2. MQ-131with module. This sensor will used for ozone detection. In description is written that it is able to detect concentration range 10ppb-2ppm.
3. NAP-505 (top, grey with white round) - electrolytic CO (Carbon Monoxide) gas sensor with high selectivity and sensitivity. The only sensor from set that not depends from humidity and need own circuit with expensive operative amplifiers.
4. TGS-2201 (Figaro - 5N2201) (little black, bottom) - exhaust gases sensor. This sensor is interesting because this is dual sensor. Under one pack we have 2 sensors for diesel and petrol exhaust gases. About this one i had not found a lot of info, official website of FIGARO have not contains the datasheets, but i had found the one. As like as NAP-505 this sensor deeds own circuit but luckily this circuit needs only resistors. 
5. DHT21 (AM2301) (right, top) - digital temperature and humidity sensor - 2 in one. This is  simple digital module that needs to make correlation between humidity-temperature and data from sensors. The practice shows that this sensor is very passive for data stabilization when it is needs to be used as a mobile monitoring device. I think that this passivity is effected by big plastic casing. In future I will check this.
6. DCcduino UNO - full copy of Arduino Uno with price of 7$ (cost includes USB cable + pin dapters).

MQ modules and DHT has been connected with arduino without any problems. In MQ I had used only analog outputs because now i need only make a test.

NAP-505 i will connect later, where i will have operative amplifiers from it`s circuit.

The datasheet of NAP-505

TGS-2201 connecting process

The datasheet for this exhaust gas sensor i had found only on this page.

You can download this datasheet.

TGS-2201 circuit is not difficult

As we can see in datasheet - the R1 and R2 range can be between 10k to 200k and depends on weather and measurement environment (i think).

The pins of sensor

Resistor circuit

I had used both resistors with resistance near 15k and that was a bad idea because one channel of this exhaust gas sensor (petrol channel) shows a much big values, so it needs to be calibrated. (see screenshot of serial monitor)

The first compilation of air quality exhaust gases sensor 

This is arduino with connected air quality sensors (except carbon monoxide and humidity\temperature).  100% chaos :)

This is a beta for outdoor measurement.

This is an attempt to make it not so ugly. Unsuccessful.

In future i will make for this one the normal casing and LCD display from cellphone.

sudo screen /dev/ttyUSB0

As you see on this screenshot - values are not adequate and need to be calibrated, about which i will write later. (overall is a pseudo-overall because it considers gases "importance rate")

To be continued..