Testing 4pin PWM fas with a power supply, function generator and scope?

[dentaku]

I just got two 140mm 4pin fans. One is from be quiet! and the other from Noctua. They're actually the first parts I've gotten for the new computer I want to build.
Can I simply plug GND and 12V into pins 1 and 2 and have it spin at it's maximum RPM to check what they sound like?
ALSO... if I connect the function generator output of my Keysight DSOX1102G to pin 4 and send it a 25KHz PWM signal should it be 5V or 3.3V?
I want to test it a different speeds while I probe the output of pin3 and of course listen to them.

[NiHaoMike]

Default is to operate at full speed. PWM will work with either 5V or 3.3V.

[gnavigator1007]

This video might be helpful to you

[dentaku]

When I got back home today I decided to test out the fans.
I connected them to 12V to see what they were like at full speed then I pulled pin3 up to 5V with a 4.7k resistor and was able to measure the pulses.
Divide by 2 then multiply by 60 and they both turn at pretty much exactly the RPM they're rated for.

I then connected the function generator with a 3.3V square wave to pin4 and changed the duty cycle to see how slow they can go before they stop.
The Noctua will still spin steadily at around 6% but won't start from a dead stop that way.
The be quiet! doesn't like being spun at around 10 or 11% then stops below that.
It's not like anyone needs a fan that spins that slow but it's fun to test them out anyway.
It also make sense that at 80% the 1200RPM Noctua spins at the same speed as the 1000RPM be quiet! at 100%.

Noctua's "Low Noise Adapter" is just a heatshrunk 100R resistor that makes it spin about 200RPM slower but I already knew that.