DIY - Arduino - CO2 - METER ( Monitor INDOOR Air Quality )

Disclaimer :Without pretending to be the ultimate truth, don't try to reinvented the wheel ...and replicate all good ideias and projects as soon as Possible for all at your account and risk !!!

The Arduino CO2 Monitor is a great way to ensure you're living in a healthy environment .With easy setup and simple to understand data.

The Unit will be able to measure and maintain the reads levels recorded for pre-set time at your choice : 90 secs ...until 3 days .

Auto Shutt off ( just to Display Oled ) if any changes Occur in 5 minutes to save Energy

ABC MODE ( Auto Base Calibration ) Built into Software - with manual mode Option too

Temperature compensation ( Built in )

Long Life Span acc Datasheet ( 5 years )

Code pre Complled ( .hex code included )

THIS GADGET DON'T INTEND TO REPLACE THE COMMERCIALS ONES

... Let's go !!!

Supplies

Parts

Arduino ( Uno - Nano - Mini - Pro - Mega ) - Take care Pinouts ... any supplier
Wall Clock ( 10 " ) ..single AA battery operated ... any Supplier -
Usbasp + Connector any supplier ( Optional ) ..can be used the Arduino IDE + AVRDUDESS .
MH-Z19 ( B-.or-.C) ... any supplier ...i used ( Winson - Brand )...it came pre-tested...calibrated ...with a folder with parameters checked ...Ask for the 400 - 5000 ppm option at moment tp buy.

winsen-sensor.com/d/files/MH-Z19B.pdf ( Datasheet of The Magic Part )

Display Oled - I2C - 0.96
Salad Box ( Daiso ) Daiso has stores around the Globe & Net Suppliers
Wires & Switches any supplier
Led Bi-colour (Red & Green) any supplier
Power Supply ( 5,0 v - 300 ma .) any supplier Wall Unit or Power Bank .
Acrylic or Wood base for Fixing the Meter ...i use Acrylic

Tools

Srewdrivers ( tiny ones )

Pliers

twezzers

Hot Glue

Soldering Iron

Solder

Step 1: Retrofit the Wall Clock

This step is delicate however not hard to do .

Take out 4 little screws ( kindly touch ...no much power... ) on the back side .
Take care with thin glass ( ...very thin ) on the front .take away fro safe place .
Then pull the pointers out carefully ( the three ones ...hours ...minutes and seconds ) we just use the minutesone after all.
Take out the little nuts on the central .
Pull out the Plastic cover of the " Electronic PCB " moving away the pins with tiny screwdriver ...carefully its easy to broke or bend ..and if you do ...lets go buy another one !
As soon you open, mark the gears ...or take a pic ...to remember the order ... use a twezzers to do this.
In the PCB , take out the 32.768 hz( The Crystal watch ) ... make a little cut in any trail to isolate the " bubbleChip " ...we only use coil , which have two wires thinnest than a hair wire !!! ...use a 30 w. Iron do take out the Crystal, and a sttlleto to make the cut on PCB and isotale the Buble Chip .
Solder two Thin Wires ( 10 cms long ) on the tabs of the Coil in the Pcb .
Reassemble the Gears ( Inverted order from the start when we retired the gears)
Close the Plastic Cover ...gently .. very gently ...due the axes of the gears don't allows extreme power on it ..and it can be bent or broken ...so another Watch must be bought .
Put a drop of hot glue into the hole of the two wires leaving the Box...protection against incidents...
THAT"S ALL ...for the Analog Display ...the Cool Vision of this Meter !!! The Job outweighing the Results ...You have a Analog Giant Display which runs Forward & Backwards ( DIY ) to display the CO2 Measures .

You can jump this Step (The number One )however ...for me is the Charming Look of the Meter ...and just use the Oled Display which have a lot of information included ( see in next step ).However you must take a closer view on it , on the contrary of the Lager one ( can be viewed away ) together a Led which indicates ( Increasing Values...Red Led Blinks ) and ( Deceasing values Green Led Blinks ) ..far away too. in this mode the Meter can be seen away .

Step 2: Designing the Plate of the Meter

I use The Inkscape to do this Job, but you can use Microsoft Designer, Word ...even designer ~this by hand ...there's a lot of tips in the Net for do this.

Inkscape 1.3 - Windows : 64-bit : msi | Inkscape

Analog Clock Vector Design in Inkscape - YouTube

Step 3: Oled Display

The Unit without the Analog Display ( Step number 1 ) , had all information on this screen :

Actual Value measured (CO2 ) is show in ppm .
The Two last measures Showed within pre-set at your choice : 90 secs, 3 Mts , 6 mts , 15 mts , 30 mits , 1 hr , 3 hrs , 6 hrs , 12 hrs, 24 hrs , 48 hrs and 3 days .
Show if the auto-zero is on / off ( Auto zero is the Mode ABC built in the Software ..acc Datasheet ) or Manual mode setting by Grounding Digital pin of the Arduino ( D2 ) and HD of the Sensor HD-Z19B ...for (7 seconds ) soon after Wake Up time of the Unit . The mode is show at top right up corner of the Display .
The Warm-up Time of the Sensor at 500 ppm , for 60 secs ...acc Datasheet.
Every measures are show at T - 90 Secs - acc Datasheet .
The Unit " Learn " the environment conditions at the time, so is a must to sometimes calibrate at clean air for at least 20 minutes at Auto-zero On setting.
A Wellcome Screen .

Step 4: Schematics

The Schematics and connections are simple !

You can Change the Two Leds for a Bi-Collor Led ( Red & Green )

You need measure the Coil Resistance ( Normally between 100 - 500 Ohms ) and then calculate the Resistor (R-1) Between 100 - 680 ohms ) for your Coil ( of the Watch ) the Brands and Specs. of these Coils differs ...but you can use Ohms Law .. to determine the Pulses from the Arduino ( 5.0 v ... at High condition ) ;..must be lower to 1,3 ~1,5 volts !!! For two reasons : to avoid destroy the coli and for the correct Lenght for the pulses which moves the pointer forward & backwards ...it can be done with a Multimeter ( lower the voltage) at This pulses at High condition . the Maxximum value of 1,5 volts ( 1,3 can be set too ) .... or the Backwards & Forwards movements don't runs ...be patient to set this.

some tries can be need ! ...This is only for The Analog Display = The Retroffited Watch .

Everything was set for this range ( 1,3~1,5 volts ) at coil terminals ... so you only need set this resistor ( you can use a variable resistor to find the right value ) then change to the fixed one .

The power supply is recommend be 5v1 200 ma.( +/- 0.1% ) , by supplier ...however i tested 5.0 v ( +/- 10 % ) and for mine needs it's all right .

I used a " Salad Box " From ( Daiso Store ) made with Polystyrene ( easy to cut and make little holes for air Passage to the sensor)

Step 5: "Burning " the CHIP With AvrDudess"

The Compilation could be a little trouble for Newbees sometimes ... i felt this in the beggin ...and thats not a trouble for every one after some practice...none the less this fact and thinking about this fase which quickly pass ....sometimes yes ....sometimes no ... pass quickly.....Thats the code ( READY ) to " Burn" the Chip ( Arduino ). :

" Burn " = ( record into the Chip ...without Compilation ) mainly for Newbees into Programming World ....

The Summit you you need :

The Code ( .hex ) + UsbASAP ( A Cheap Hardware to Programmer any ATmel Chips Directly ...without compilation...) + AVRDUDESS (A Software which "Burns" any Atmel Chip )

The use of AVRDUDESS ( 2.14 ) is an easy way to replicate the first Projects. and after some time, even if the Compilation is within Domain of any " Maker"... this tool can be util in many ways ...

Attention : The AVRDUDESS can be used direct in the Arduino IDE , with only few steps in the Panel of The AVRDUDESS and " Burn' the .hex code ...without Compilation any way !!!

CO2_Meter_Instructables.hex
Download

Step 6: Setting the Times

1- Press the " ENTER " switch at same time at turn on Switch of The UNIT .

...Pre-set screen shows up...

2 - Press the " SELECT" switch to choice the time ...

...Options shows up in sequency ...

3 -Press the " ENTER " switch again to record the Option .

.... the Unit resets AUTOMATICALLY.......

Done !

The Meter is ready to run !

Put the Analog Pointer ( the pointer whose originaly marks the minutes onto the clock )...

M a n u a l y ...at 400ppm mark...( the zero point for the Sensor ) ...Every Time The Start of Gadget you must

to do this action at first time ... just at turn on for the first time ..rearrange the Pointer at 400 (ppm) point.

Let the Meter at least a half hour ( 30 ' ) at more fresh Environment Possible, the Sensor came Calibrated however , transport ...travel cares ...can modify the pre calibrated from the supplier . And the ABC Mode( Auto-zero ) is set on the Firmware .

You just let sometimes at Fresh Air , for these " Auto- recalibration Automatically ,,,That All !!!

Have Fun with your Project !!!