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damaging fans

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andy257

Member
Hi,

Can anyone explain why using pwm on a 2 wire fan could possibly damage the fan?

I have been looking into pwm control on 2 wire fans and it looks like it can be done but the frequency has to be extreamly slow. Why is this?
 

Boncuk

New Member
PWMing a PC fan at 250 to 500Hz won't do any harm to the motor.
 

KMoffett

Well-Known Member
Wonder how that works for BLDC fans...which most of the small ones seem to be now.

Ken
 

bountyhunter

Well-Known Member
Hi,

Can anyone explain why using pwm on a 2 wire fan could possibly damage the fan?

I have been looking into pwm control on 2 wire fans and it looks like it can be done but the frequency has to be extreamly slow. Why is this?
If it's a DC fan, it has an IC inside to control speed andlimit current if the blades are stalled. Feed if square waves and I have no idea what will happen since it was designed to run on DC.

If you wire straight to the motor terminals inside, maybe PWM could work.
 
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
If it's a DC fan, it has an IC inside to control speed andlimit current if the blades are stalled. Feed if square waves and I have no idea what will happen since it was designed to run on DC.

If you wire straight to the motor terminals inside, maybe PWM could work.

If the fan has electronics it's most probably a BLDC one, so there's no motor to connect directly to.
 
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