PWM Computer Fan Controller Circuit Diagram Introduction Computers have been using PWM-controlled fans for ages now (they're the ones with a 4 pin connector). This allows the BIOS to change the fan speed according to the current temperatures using a PWM signal instead of changing the voltage of the fan, which means that motherboards are cheaper to make (less voltage regulators), but also that fans are much easier to control, since DC DIY PWM Control for PC Fans: This Instructable describes building a fully-featured 12 V PC fan PWM controller. The design can control up to 16 3-pin computer fans. PWM Phase Control The length or the pulse width of this delay pulse can be varied by suitably adjusting VR1 which also becomes the speed control knob for the discussed PWM controlled fan regulator circuit.
Even at low PWM duty cycles the fan runs at higher than expected speed, in my testing it was not possible to achieve quiet operation with 4 pin fans using an external PWM driver circuit.
A small circuit: PC fan PWM speed control Circuit Diagram
DC fan control circuits with speed control will use PWM driving to control average power delivery as described above. Depending on the required current delivery, control circuits for large and small fans could be designed from discrete components or from an integrated fan controller. This neat fan controller project requires only a little time, expense, and commitment, and the circuit is easy to build and satisfying to use!
Learn how to use the 12v PWM Fan (120mm) with detailed documentation, including pinouts, usage guides, and example projects. Perfect for students, hobbyists, and developers integrating the 12v PWM Fan (120mm) into their circuits. The HighPi Pro 5V Fan - Software-Controlled by PiHut is a PWM (Pulse Width Modulation) fan designed for precise speed control. By varying the duty cycle of the power signal, this fan provides efficient cooling with reduced noise, making it ideal for applications where thermal management and noise reduction are critical.
