Advice On How to Lock RPM using PWM

Hi Guys... I have been trying this project for quite some time. Basically, running a fan using PWM. Its RPM usually goes all the way above 3000 RPM. Now I wanted to limit the RPM at 3500 and maitain it there steady by altering the PWM. I am not able to achive this. Please Help....

Read the how to use this forum-please read stickies to get advice on how to ask a question.

You have not provided any details. What exact components are you using? Can you post a schematic? What code have you tried? What does the code actually do?

Nicholas2020:
Hi Guys... I have been trying this project for quite some time.

That's good. So post the program you've tried that gets nearest to what you need. Then tell us what exactly it does and what it should do that's different.

Steve

Nicholas2020:
Basically, running a fan using PWM. Its RPM usually goes all the way above 3000 RPM. Now I wanted to limit the RPM at 3500 and maitain it there steady by altering the PWM.

Basically you have to monitor the fan speed, and reduce the PWM duty cycle as long as the speed is too high, and increase it again if the speed becomes too low.