7V Fan slowdown mod!

[svol]

I got some real bad experience with PWM... it would create a very irritating whining noise with my Delta HP120 fan.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on 😱

 

[Teq]

Well, yes... looked inside a fan lately?

They aren't just an electric motor. There's a couple of active components in there to replace the normal brushes of a DC electic motor. Brushless fans need clean DC current to work correctly. The PWM method was probably driving them nuts.



<b>(</b>It ain't better if it don't work.<b>)</b>

 

[svol]

Ofcourse... now I know what that brushless means.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on 😱

 

[Teq]

If you have the chance, take a dead fan apart. It's really some very interesting technology, it's actually an inside out motor where the windings are on the stator and the commutator is a magnetic ring with several pole reversals around it's circumfrence.

What the chip does is reverse the polarity of the stator windings to cause the magnetic ring commutator to jump towards the winding's opposite pole, reverse it often enough and you get a spinning motor.

Fans with a tachometer in them also have a second small chip on the internal circuit board. This works by monitoring the stator windings for reverse pulses caused by the magnetic commutator, which are then cleaned up and sent back down the third wire.

Kewl stuff!




<b>(</b>It ain't better if it don't work.<b>)</b>

 

[svol]

The last time I disassembled a fan was before I learned how electric engine's work at school. Luckily I don't have any dead fans at the moment.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on 😱