Powering PWM fans without a PC?

[lumencreative]

A bit of an odd one…

I’m trying to build a cooling solution for something at work consisting of 4-6 Noctua industrial 3000rpm PWM fans.

I’ve bought a Molex to 4x 4pin fan splitter and a 12v Molex power supply.

Plugged it all together and nothing. Tested the fan and the Molex to fan splitter in my PC and that worked fine so I think there’s an issue with the power supply, though I’m not sure whether I just bought the wrong thing or whether the power supply is faulty.

The pins on the power supply are correctly laid out, and the power supply can either do 5v or 12v at 2amps. The seller of the power supply suggested the 2amps might be too much for the fans but I don’t know enough to know if that’s true?

So, I wondered if anyone here could advise what I should buy in order to power the fans? Am I better buying a proper ‘external’ fan controller and then finding a way of powering that?

Any advice would be hugely appreciated.

 

[lumencreative]

Someone on here used to build a controller PCB for people to drive PWM fans - dunno if they still do - but may find information in those threads on it.

The amperage capability of the supply won't matter as long as it is high enough - the fans will only draw what they need.

Thanks, will see if I can find the threads.

Yeh, that’s what I thought, that the 2amps would be a ‘max’

 

[lumencreative]

It might have been me?

Get a 3-pin fan to use PWM?

Hi all, I recently bought the Zalman fan shown in my signature but it only has a 3 pin header. Is there any way I can get it to use PWM? Thanks :o)

forums.overclockers.co.uk

The fans are looking for a pulse on the PWM pin. No pulse, no spin. PWM works by switching the fan on and off very fast so it appears to run much slower. Because you don’t have a timing chip sending the pulses on the 4th pin the fan won’t spin. Even though it’s getting 12V

Can you not use 3-pin fans as they’ll spin up based on the voltage supplied, not the number of PWM pulses.

If you have to use PWM fans then yes, you’ll need a PWM fan controller with a timing chip to generate the PWM pulses.

So, the fans I bought are NF-A14 industrialPPC-3000PWM’s. I’d read that without the PWM control, they just run at the maximum of 3,000rpm.

When I tested them on my pc, I used the Molex splitter cable I had bought (which just has the 12v wire and the ground wire), and they powered up fine.

I guess the next step would be to buy some form of pwm controller and see if that works.

 

[lumencreative]

You linked to a thread of mine. I did build an external PWM unit but I don't think I went into any detail on how it was built in the threads as that wasn't really the topic.

The circuit itself was built to test the digital PWM to 3 pin fan circuit mentioned above and I built it into a small grey box, mostly. It consisted of a 555 timer IC, and a few other components. I had all the components to hand so was fairly easy for me to make but if you don't have electronics as a bit of a hobby building such a thing might be more difficult.

I've not checked but you can usually pick up little PWM or motor drive PCBs off ebay for a few quid.

Had a quick look online and thinking of getting the Akasa FC.Six. It’s not technically ‘external’ but says it can be powered by a Molex.

There are cheaper alternatives available but Akasa is a brand I know of.

I’ll also order a 3 pin fan as well just to test it out in comparison.

 

[lumencreative]

Buy a cheap psu and fan controller.

Problem with a psu is it needs some way of powering it on. I know you can jumper wire it to power it on but that’s not really a viable option long term.

I’ve got an Akasa FC.SIX arriving today so will see if that works, otherwise will be buying a multimeter (may get one anyway to be honest).

@lsg1r I did look at that Noctua controller but the reviews I read suggested it needed the pwm signal from the motherboard to control the fans. Not sure how true that is but that’s why I went with the Akasa as a first option.

 

[lumencreative]

Just an update, Akasa controller arrived today and works fine with the Molex power supply I’d bought.

Blimey these 3,000rpm fans are fast…now wondering whether they’re too fast haha but they’re only £2 more than the non ‘industrial ones’ at 1,500rpm and they’re the same price as the 2,000rpm industrial ones, though the 2,000rpm ones are 10db quieter.

Decisions decisions haha.