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IanBland · 30th Apr 2019, 7:52 pm

This isn't directly answering the question either; but you can build an extremely simple fan control circuit using nothing but a potentiometer and a mosfet connected as an emitter follower. Fan noise drops rapidly as you drop the fan speed.

I did some experimenting with this a while back for a project (using a microcontroller rather than a potentiometer) and concluded that if you don't mind losing some energy in the transistor, voltage control is much quieter than PWM for fan control.

30th Apr 2019, 7:52 pm	#12
IanBland Hexode Join Date: May 2015 Location: Northampton, Northants, UK. Posts: 380	Re: UPS in a wooden cupboard This isn't directly answering the question either; but you can build an extremely simple fan control circuit using nothing but a potentiometer and a mosfet connected as an emitter follower. Fan noise drops rapidly as you drop the fan speed. I did some experimenting with this a while back for a project (using a microcontroller rather than a potentiometer) and concluded that if you don't mind losing some energy in the transistor, voltage control is much quieter than PWM for fan control.