Can you guys help me on how to connect 6 fans of 12v each to my Arduino Uno Rev03 and the proper way of adding 12v power supply to my board
Not nearly enough information but in most cases it would require a relay or mosfet.
The 12 volt supply should be reduced 7 - 10 volts for the Arduino itself and the 12 volts only used for the fans.
A COMMON GROUND would be needed from the fans to the Arduino in this case too.
What are the fans being used for ?
Are they all the same make / model ?
What are the power supply details ?
Could you also take a few moments to Learn How To Use The Forum.
It will help you get the best out of the forum in the future.
Other general help and troubleshooting advice can be found here.
So I have 6 fans that are for air circulation for a hydroponic capsule. fans will give the right wind speed and enough O2 from bottom vents. What I want to do is to be able to connect 6 fans and make them work at the same time all 6 with the possibility of controlling their speed independtly as a stand alone mechanism
The fans that I am using is CFM-8015V-130-347 12 vdc , 4.5~13.8 vdc, 188mA, 2.26W 3000RPM 37.0CFM 0.14inch H2O, 34.7 dBA
And the power supply I am using is a dc 12 1amp with 2 wires, ground and voltage for output and 100-240v ac 50/60Hz 0.32 A max
The data sheet for all of the various versions of you fans do not ever mention the ability to vary the fan speed. In fact the data sheet states: "motor 4 pole DC brushless". That means the hub of each motor contains the electronics to power the motor, not your external circuit. Some of the fan versions have a tachometer signal so you can monitor if the fan motor is turning or is locked.
Paul
You can control the airflow by moving a slide across the INPUT side of the fan, but never the speed.
Those will control with PWM via MOSFET's.
That will allow you to vary the speed according to a sensor of your choosing.
Depending on the area to be utilised you may need more than one sensor( DHT series maybe ) and balance out the two sensor readings or apply more / less speed to that area.
That they are all the same helps with timing harmonics.
It is possible to use the fans sensor for speed but I have never found the need and rely on by MQ2 sensor to vary the RPM as needed.
Be aware that you would need logic level mosfets.
I use off the shelf Chinese modules which are available in single or multi device boards.
This negates having to do many of the calculations for gate resistors etc.
Whilst not used for your purpose my system kicks fans in based on solder fumes or my smoking and has been in use for almost 3 years with zero issues apart from an occasional fan failing but they were all reclaimed from computers anyway.
I think your PSU will be under powered so you may want to look for something a bit larger in the current department
EDIT...Just saw the CFM factor which is around 37 so you will probably only get a light draught even with 6 of them. But that would depend on the area and enclosure size.