How does a 4 pin fan work?

A 4-pin fan is designed for control a different way, by giving it a fixed voltage supply and then a special signal called PWM on Pin #4. The 4-pin fan has its own internal circuit to apply that PWM signal to its power supply to adjust its speed. This means of control is called “PWM Mode”.

How do I power a PWM fan with Arduino?

Connecting the fan to the Arduino If you have a 12V fan, the best way to power it is to put the Arduino and the fan in parallel, using the VIN pin to power the Arduino. It’s a good idea to put a diode in front of the VIN pin if you have it, that way you can connect both the 12V and the USB without damaging anything.

What kind of PWM do I need for Arduino fan?

The PWM pin accepts 5V input, and sources no more than 5mA, so it should be fine. Many fans should work with Arduino´s default PWM. The Norm says you have to use 25 kHz PWM frequency though, which is a bit tricky. See AKA’s post in the Control PWM Fan Thread. Yes, Arduino and the 12V power supply for the fan need to have common ground.

Where is the PWM pin on a 4 wire fan?

Intel specification (July 2004, Rev 1.2) defines the intended operation of a fan that implements the Pulse Width Modulation (PWM) control signal on the 4-wire fan interface. The following requirements are measured at the PWM (control) pin of the fan cable connector:

How is a 2 wire PC fan controlled?

A 2-wire fan is controlled by adjusting either the dc voltage or pulse width in low-frequency PWM. A 3-wire fan can be controlled using the same kind of drive as for 2-wire fans – variable dc or low-frequency PWM.

How does the Arduino fan control system work?

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 PC communicates with the arduino via the serial port.