There is some information out there.
Arduino pwm fan controller.
The system uses a temperature sensor to control four fans that are driven by an arduino controller.
There is a jumper for switching the power supply from arduino or the 12v input.
Temperature based fan speed control monitoring with arduino.
4 wired fan control pwm control a pwm fan with arduino.
The pwm controller accepts the control signal and adjusts the duty cycle of the pwm signal according to the requirements.
Getting temperature values from a digital or analog temperature sensor on an arduino is fairly simple.
So after that no electricity flows through it turning the fan off.
I o pin 9 on the arduino board is directly connected to fan control input and by reading the state of 3 push buttons on pins 2 3 4 different pwm values are sent to the fan.
Design schematic diagram is shown next.
An inexpensive single small pass transistor like 2n222 or bd139 can be used here.
Pwm waves with various duty cycle are shown in the figure below.
Pwm fan controller sketch can be downloaded here.
It is efficient because the pass transistor is used as a switch.
The frequency values can be adjusted between 125 hz 8 mhz as well as a variable duty cycle.
The pc communicates with the arduino via the serial port.
On the pcb there is a 5 12v input for the fan supply.
In the above wave forms you can see that the frequency is same but on time and off time are different two applications of pwm control using arduino is shown here.
As long as the cooling is on the red led is on when not cooling the green led is on.
The temperature and fan speed are reported through a 8 digit 7 segment display fitted on a rack mounted aluminium bar.
For this reason i used arduinos d6 pin pwm.
Firstly make sure that you fan s are pwm controller you can check this by making sure that your fan connector has 4 wires.
How to connect it.
Control the speed of the fan.
I have been wondering about this project and how to control my 4 pin pwm fans.
Many projects that use a temp sensor but never the most simple thing.
I had 5 laying around and thought mine as well give it a shot.
Beginner full instructions provided 24 154.
The system works by an application running on the pc checking the cpu temperature and checking whether to speed up or slow down the fans.
The ultimate project is to control the fan based on temperature.
A low frequency pulse width modulation pwm signal whose duty cycle is varied to adjust the fan s speed is used.
It then becomes a matter of telling the fan pwm to raise or lower the speed based on the temperature.
