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hrmes

Junior Member

Aquaero 5 PWM fan signal

Freitag, 13. Mai 2011, 15:07

Hi everyone, this is my first post.

I want to replace my T-Balancer with an Aquaero 5 but first I want to know a few details so that I can decide what fans to use with it.

What I want to know is, when you are using channel 4 in PWM mode, if the PWM signal is in any way calibrated to reflect the real percentage of maximum fan RPM, or if the PWM signal is simply a raw PWM signal.
I'm asking this because I have tested a Noiseblocker 120mm PWM fan with a speed of 1000 to 2000 RPM with the SpeedFan utility.

I connected it to a 4-pin motherboard fan header and saw that the fan spins at about 900 RPM when the PWM signal is at 0%, at about 1500 RPM at 50% PWM signal, and at about 2000 RPM at 100% PWM signal.
This may seem normal but look at page 14 of the attached 4-wire PWM Developer Specs PDF. developer_specs_4_Wire_PWM_Spec.pdf

There it states: "The fan RPM (as a percentage of maximum RPM) should match the PWM duty cycle within +-10%."

If I understand correct this means that when the PWM duty cycle is at 50% then the fan should spin at 50% of maximum RPM, so in the case of the fan I tested when the PWM signal is at 50% the fan should spin at 1000 RPM and not at 1500. Obviously this happens because the fan manufacturer does not fully comply to the PWM fan guidelines.
If Aquaero 5 can't calibrate the PWM signal to reflect the true percentage of maximum fan RPM, then in the case of the Noiseblocker fan when Aquaero 5 sets the fan to run at 50%, it will actually be running at 75% (1500) of max RPM (2000).
In that case I think that a calibration option could be added to the firmware of Aquaero 5. It could run the fan from 0% to 100% PWM duty cycle and read the corresponding fan RPM at each PWM duty cycle. Then it could use that RPM data to calibrate the PWM signal.

Dieser Beitrag wurde bereits 1 mal editiert, zuletzt von »hrmes« (14. Mai 2011, 18:38)

hrmes

Junior Member

Mittwoch, 1. Juni 2011, 17:54

No official reply... :( Can any Aquaero 5 owner test a PWM fan and see if 50% fan channel power means 50% fan RPM ?