PSU for running only 4 external fans

[NAS]

I want to wire up 4 spare fans i have to a cabinet. The cabinet has only a 240V AC supply so i need to beg/borrow/steal/buy a power adaptor /PSU

 

The fans are Xilence Red Wing 120mm Quiet Fan

 

http://www.quietpc.com/gb-en-gbp/products/120mmfans/x-rw-120r

 

Fan size (edge to edge) 120 mm

Manufacturer Xilence

Model XPF120R

Air volume at full speed (12V), CFM ±10% 44.7

Noise level at full speed (12V), dB(A) 20.5

Fan speed at full speed (12V), RPM ±10% 1300

Power consumption, W 0.84

Weight, g 180

Approximate cable length, cm 25

Life expectancy @ 25°C continuous use 3 years

Power connector 3-pin, 4-pin

Bearing type Hydro Bearing

Mounting hardware included Screws

Fan depth 25 mm

Rated voltage 12 VDC

Accessories None

Warranty 24 months

 

 

I have a fan adaptor that allows 4 molex connection to one input molex. The fans Starting voltage is 7 VDC.

 

Can anyone tell me what size of PSU i need minimum to power these 4 fans in parallel. I hope to use a normal block type PSU (the type you get free with almost every cheap electrical device) as I can almost certainly find one of them free and it would make fitting/placement easy.

 

Appreciated

[terrastrife]

tiny pwoerbrick from something like a external hdd enclosure would do. maybe one from a usb to hdd converter kit, these came with a brick which pins out in a 4 pin hdd/molex connector.

 

or buy some 240vac fans.

[NAS]

Currently there are two 240VAC fans. Even though they are supposed to be quiet on paper according to the cabinet manufactirer the reality is they are not. No where close.

 

So the plan is to change to 4 DC quiet fans. The sum total will be slightly less cfm but a massive drop in dB. I need less colling now I have gone to solely Eco Greens.

 

Interesting I actually tried a USB enclose power brick. Wouldnt even make the fan turn.

[queeg]

The Xilence you chose use .09A.  So if you hook them up on a single power supply it needs to supply their combined current draw.  

 

I just happened to be on this subject today.  I had to find something around the house that didn't need it's power supply any more.  I found this one.  I think it came off an older IDE external hardrive enclosure.  This one supplies 2A on the 12v line.  That would be many of the fans you are planning on using.

It has one of those multipin connectors.  I cut 3 inch pieces of 3 wires (red,black,yellow) loosened them up by jabbing a pointy thing into the wire then and jammed them end first down around the pins in the powersupply connector.  The insulation was not peeled back from around the wires.  I filled up the end of the connector with hotglue so the wires couldn't come loose and soldered the other ends on a string of molex plugs.  This power supply has pins for 12v, 5v and ground.  I connected the red wire to the 12v, black to ground and the yellow to 5v.

 

http://www.newpowersupply.com/leadman_ky_05036s_12_5_pin_ac_to_dc_power_adapter_bulk_pack-pr-224.html

 

You probably have some old 12v powersupply laying around.  If not, try to find a PC recycle center where they probably have piles of them for a few bucks.

[NAS]

Excellent stuff.

 

So essentially i am looking for a PSU kicking about "must have dozens of the damn things about the houses" that is rated at 12V and >= 500mA if i want 100% ish spare overhead.

 

i.e. there is magical complicated factor here there normally turns out to be on all PSU discussions on this forum

 

If for instances i found one rated 2A that wouldnt be an issue either i.e. it being so so over spec?

[queeg]

You'll probably find one that supplies more than 500ma.  Especially if it was from an old external enclosure the hard drive needed more than that.

 

Being overspec is all good.  I would test power-on with 2, then with 3 ... to make sure the startup power is sufficient.

[NAS]

Looks like you answered my question"If for instances i found one rated 2A that wouldnt be an issue either i.e. it being so so over spec?" before i even edited to ask it.

 

Kudos

 

Normally I am gung ho with stuff but since this is on 24*7 thought it best to gain a sanity check

[queeg]

Looks like you answered my question"If for instances i found one rated 2A that wouldnt be an issue either i.e. it being so so over spec?" before i even edited to ask it.

 

Kudos

 

Normally I am gung ho with stuff but since this is on 24*7 thought it best to gain a sanity check

 

No problem.  I did the same thing.  It was Joe L. who suggested the wall wart power supply as a solution to my external fan problem.

 

Here's one I just found: http://www.coolerguys.com/840556029977.html  that does exactly what you want.

[NAS]

Holy thread resurrection batman....

 

for one of 5 reason I never got around to this (mainly because the PSU i got didn't work and I got fed up).

 

So question. I can find at a good price a 2Amp laptop style PSU with a MOLEX but:

 

"Please note: These adapters are originally made for powering hard drives / disc drives outside your computer so pin #2 is not grounded. Some devices (I.E cathodes) require pin 2 to be grounded. Please check your device before purchasing."

 

Given that my last PSU didn't work for some reason unknown to me will this lack of pin 2 grounding matter?

 

Cheers

[lionelhutz]

I have no idea what they are meaning but it should not matter for fans as long as you get the positive and negative connected correctly.

 

I'd suggest you find a universal AC adapter with a voltage selector switch. Then, you can adjust the fan speed and sound level by just lowering the voltage. Here's an example I just found quickly though it's by far not the only option;

 

http://www.amazon.com/exec/obidos/ASIN/B0042X8XOG/randomize0d-20

 

Peter

 

[NAS]

I am taking a bit of a risk moving from AC to DC fans because of the drop in cfm ratings. Even full pelt these DC fans are 100 times quieter than the current AC ones so I wont be slowing them down.

 

I think I will just take the risk of the laptop type supply since it means everything plugs together without me having to DIY anything

[cyrnel]

Did someone already shoot down the idea of using any standard ATX supply? (well, almost any)

 

http://wiki.xtronics.com/index.php/ATX_Pinout

 

Short pins 14 and 15 to turn it on.

[NAS]

I did think about that but they are physically big. I would prefer to attach it to the cabinet door. But that could be a good backup plan.