Noiseblocker BlackSilentPro PC-P Ultra Silent Fan

[chug]

Has anyone got this fan? Just fitted it to a power supply, and when you put your ear close to it seem to make a light clicking noise. It was recommended a a silent fan, and it is quiet, but there is this clicking noise. Just wondered if this is normal? I remmeber reading about fan bearings being designed to be upright or flat, could this be anything to do with it?

Cheers

 

[NiHaoMike]

It's an inherent limitation of square wave drive fans. Sine wave drive fixes that problem, but that's pretty much only found in higher powered fans. It might be worth a try hard wiring a variable speed fan for low speed.

 

[ATMINSIDE]

It's an inherent limitation of square wave drive fans. Sine wave drive fixes that problem, but that's pretty much only found in higher powered fans. It might be worth a try hard wiring a variable speed fan for low speed.

A square wave won't cause the fan to click.

OP, is the fan laying down or standing up?

 

[NiHaoMike]

The edges of the square wave can sound like a clicking or buzzing depending on speed.

 

[ATMINSIDE]

The edges of the square wave can sound like a clicking or buzzing depending on speed.

If that's true, every fan of that brand/model would have this issue.

 

[NiHaoMike]

It could also be a bad bearing. An easy way to check is to put in some way to instantly disconnect the power. If it stops as soon as power is off, it's definitely the square waves. If it continues, slowing down as the fan coasts to a stop, it's a bad bearing.

All of the cheap fans are going to be square wave. The circuits needed for sine wave (DSP or analog PWM modulator) cost a little more than a simple square wave drive and that's significant with the lower end products.

 

[magellan]

It could also be a bad bearing. An easy way to check is to put in some way to instantly disconnect the power. If it stops as soon as power is off, it's definitely the square waves. If it continues, slowing down as the fan coasts to a stop, it's a bad bearing.

All of the cheap fans are going to be square wave. The circuits needed for sine wave (DSP or analog PWM modulator) cost a little more than a simple square wave drive and that's significant with the lower end products.

What makes a sinusoidal waveform superior to a square wave? Is it the slower ramp up and ramp down from the waveform's peak? How much of a difference in DbA does a sinusoidal PWM fan make over the standard square wave?

 

[NiHaoMike]

An ideal sine wave has no harmonics (in practice, it's close), while square waves have lots of harmonics. The exact noise difference would depend on many factors, but it's generally more significant with lower speeds and larger motors. (At high speeds, the inductance of the motor windings tends to smooth out the torque pulsations.)

The digital motor drives also use what is known as field oriented control (FOC) to run the motor most efficiently. (The actual efficiency is not significant except in mobile computing, but it does mean you get a little more power out of a given motor.)

 

[Brando]

I had the same issue with noiseblockers on a fan controller. Thermalright fans seem to be silent regardless of speed. Pretty sure I got this kind.

http://www.amazon.com/Thermalright-TR-X-Silent-140-140mm-Black-Retail/dp/B002U4Z6NA