Controlling a pwm fan outside of a computer

[Letgomyleghoe]

Hi,

     I’ve endeavored on a project creating my own air purifier, 120mm fans seem to be a decent choice since the room I’m using them in is rather small and doesn’t require a high cfm. I’m wondering if I will be able to strip the cables on a noctua NF-P12, and connect the hot and ground to this Controller using some copper lugs, leaving the speed sensor and speed control wires disconnected from the fan. This is one of my first diy projects involving any sort of electronics, so please excuse any incompetencies. Thanks!

[AbydosOne]

17 minutes ago, Letgomyleghoe said:

Hi,

     I’ve endeavored on a project creating my own air purifier, 120mm fans seem to be a decent choice since the room I’m using them in is rather small and doesn’t require a high cfm. I’m wondering if I will be able to strip the cables on a nocturnal NF-P12, and connect the hot and ground to this Controller using some copper lugs, leaving the speed sensor and speed control wires disconnected from the fan. This is one of my first diy projects involving any sort of electronics, so please excuse any incompetencies. Thanks!

It should work, but it's a) an extremely overkill controller (fans are like 10-20W most of the time) and b) you could save a few dollars by using non-PWM fans to start.

The slightly more advanced answer is to provide the PWM signal on the fourth pin, so you only need to provide 12V straight. You'd need something to generate the pulses, but that's not too complicated (555-timer or a microcontroller, and a transistor).

[OhioYJ]

Slightly more expensive but Noctua makes a PWM controller. Might be another option. 

[Letgomyleghoe]

2 minutes ago, AbydosOne said:

It should work, but it's a) an extremely overkill controller (fans are like 10-20W most of the time) and b) you could save a few dollars by using non-PWM fans to start.

The slightly more advanced answer is to provide the PWM signal on the fourth pin, so you only need to provide 12V straight. You'd need something to generate the pulses, but that's not too complicated (555-timer or a microcontroller, and a transistor).

Agreed it is extremely overkill but everything else I could find either required a little more diy than I was looking for, or was simply more expensive with a worse ship out time. I was also considering using non-pwm fans, but it is all I have on hand at the moment so it was the cheapest route. The controller is able to provide the pulse modulation, so theoretically I would still be able to control the speed just using the controller correct? 

[Letgomyleghoe]

16 minutes ago, OhioYJ said:

Slightly more expensive but Noctua makes a PWM controller. Might be another option. 

I was considering this as well but I would like to be able to only have one cord leaving the enclosed box, while still being able to control the speed of the fans. I should be able to cut a hole in the side of the case and mount the other controller where as it may be a tad more difficult with the Noctua.

[Gomo]

I can recommend you two solutions:

 

1. PWM signal generator where you can also adjust the frequency (if needed). Aliexpress URL here. It needs its own 12 volts (low current) to function, and sends out the PWM signal for your BLUE wire on the fan. Which means, you connect your fan to 12 Volts (red wire on the plus, black on minus) and blue one goes to the PWM pin on the generator. With "Duty Cycle" you can adjust the RPM.

2. PWM signal generator which is at the same time power source for the fan -> pulses 12 Volts without the need for the BLUE fan wire. Aliexpress URL here. All you need to do here is make sure you have a PWM fan, and connect its plus and minus on the corresponding spots of this PWM signal generator. No need to connect blue fan wire anywhere.
With this one, you can only adjust the duty cycle (via the knob), frequency cannot be changed. Benefit is that you don't need a special power supply for the fan, and it can handle up to 120 watt (DC) fans.

I've used both, for different use cases.