Non-PWM fan speed control

Hi all,

I have some non PWM 12V fans and by applying 5V they are nicely slow.

How can I control the speed of these fans?

Thanks in advance!

Do you want to speed them up or slow them down? If you want to slow them down even more hook them up to a pwm pin and adjust the frequency. If you want to speed them up you will need to use 12v. You can do that using a transister or relay so the microcontroller can switch the 12v signal.

I want to use arduino to control their speed according to a temperature.

I want to use 9 to 15 fans.

Or should I just get PWM fans? What I don't like with PWM fans is the pulse noise that some of the fans are producing.

Hey, I'm currently using 4 12V fans. i used MCP1407 mosfet driver for now, but even with mosfets, the fanx are making quite a noise if anything lower than 255 PWM signal is applied. What can I do to get rid of that noise?

These fans are not PWM fnas, just normal 12V fans.

Thanks in advance.