Controlling the speed of a Delta fan via PWM?
The way i learn is hands on, and having a goal. Since i want to learn the basics of Pulse Width Modulation, i started looking around for a project, and had found one after my brother, a person who works in the International part of Technology (IT Guy.) gave me a project to work on, The project being, to control a 12 volt, 4 amp, 48 watt delta fan and the speed it spins at. His reason being, "I have two delta fans that do a wonderful job at cooling my ridiculously overkill of a computer. My problem, is that the amount of noise they make is too loud, and i would like to be able to adjust the speed of them in order to reduce noise." Since his motherboard cannot control the speed of the fans, he is looking of a manual way of doing it, sticking some sort of device in between the ATX power supply, and the input for the fan(s). The fans have three cables: Red(Positive) Black(Negative) and Blue(With minimal research, i believe this is a censor for the CPU to know at what speed the fan is running at. I also heard it is used for speed control? Someone please clarify.) Looking into methods of reducing speed, adjusting the Pulse width looked like the best idea. Now, for my question. How would i make a device capable of controlling the PWM of such device listed above? I would like to adjust speed via a potentiometer.
Thank you for your time and support,