Powering fans from a dedicated external PSU

[NAS]

I am looking to power four 120mm 1W case fans from a dedicated PSU not connected to anything else.

 

Has anyone any experience of this? I was considering just taking a spare transformer form some random piece of deprecated kit that is rated above 5W and is 12V and powering it that way.

 

Any experience or advice would be appreciated.

 

Cheers

[jimwhite]

no experience with this precisely, but as an EE I can say you should have no problems as long as the wall-wart ahs the current rating you need...

 

[Joe L.]

no experience with this precisely, but as an EE I can say you should have no problems as long as the wall-wart ahs the current rating you need...

 

And as a technician I'd add as long as the wall-wart supplies DC (Direct-Current) and not AC (Alternating-Current.)

[jimwhite]

good call !!! 

 

[NAS]

So my basic math says as long as the transformer supplies DC 12V and can handle more than 0.35Amps as stated on the sticker I think I am fine runing four 1W fans in parallel or series?

[Joe L.]

So my basic math says as long as the transformer supplies DC 12V and can handle more than 0.35Amps as stated on the sticker I think I am fine runing four 1W fans in parallel or series?

In parallel, yes... Never in series...  The fans would probably not even start if all wired in series unless you used a much higher voltage wall-wart than usually found on consumer equipment.

 

If you do not know the difference between series wiring and parallel wiring... then get help...

 

Joe L.

[bubbaQ]

Go with a 1 amp PSU... you will have surge current, and I SERIOUSLY question a 1Watt rating for any 120mm fan that spins at more than 300rpm.

 

[NAS]

OK will do some more fan checking and digging around for a supply. I think i might have flat block one that came with a external SATA caddy.

 

Thanks again for all the replies.... finally i will banish my cabinet mains powered super noisy fans with something more sensible

[PhatalOne]

NAS, also remember that manufacturers tend to have a +/- 10% threshold on their fan ratings which could have some impact on your wattage/voltage as well.

[NAS]

NAS, also remember that manufacturers tend to have a +/- 10% threshold on their fan ratings which could have some impact on your wattage/voltage as well.

 

Will do.

 

I have actually just found a PSU from an old IDE docking rack with specs listed on it as:

 

 

Input: 100-240Vac ~ 56/60Hz 1A

Output: +5Vdc 2.0A

+12Vdc 2.0A

 

 

My only concern with this PSU is that I will be ignoring the 5Vdc line.

 

rest assured I am no where near trying this alot more reading needs completed first.

[PhatalOne]

NAS, if you really want to power some external finds with a power supply: find an old AT power supply.  Those power supplies were nice because they had a physical switch to turn to power off and on.  I sort of miss that. The other thing you could do is buy a cheap 80+ PSU and wire a switch that would complete the circuit necessary to trigger the soft on/off wires in an ATX supply.  Back in days of working for a small computer manufacturer, if we couldn't find the pin outs for the cheap motherboards the owner insisted using on his "specials", we'd run a screw driver across the pins until we closed the on/off circuit which would then trigger the power supply to turn on.

[NAS]

Holy resurrect old thread batman...

 

anyone know if LED transformers/driver are suitable for powering normal  DC fans. I cant see why not but i thought i would ask first.

 

Something like these:

 

http://www.discountelectricalcentre.co.uk/ourshop/prod_607681-ENSC60-2060wva-Dimmable-Transformer.html

 

or

http://www.ledhut.co.uk/led-driver-transformers/36-watt-led-transformer-driver.html

 

[S80_UK]

Interesting idea - cheap too.  Yes, I see no reason why they would not work.  The benefit over another PC supply is that many PC supplies require can require useful loads on some of the other supply rails before they can deliver useful power.  The possible down side would be that you would need to switch the mains power to the 12 volt supplies separately, but in a server that may be powered 24/7 that may not be much of an issue.

[NAS]

Agreed.

 

Some background to add context. I am trying and silence my cabinet. Its is 24U and acoustically shielded. Previously I just replaced failed fans with identical AC versions, however the AC dBA is high because their cfm is way way higher than i need (something like 150cfm x 4).

 

Using DC fans power consumption, noise and cost of replacement drops considerably.

[RokleM]

I don't see a voltage listed, but I believe most LED's run at 24v (twice what is required).

[NAS]

Most residential LEDs run at 12V. Only semi pro and above run at 24V i believe.

 

I will definitely check though before i take the plunge.

 

One thing i noticed is that some of these drivers have a minimum wattage rating. Not being an electrical engineer i would assume that excludes using a 20-60W supply on a 5-10W draw.

[RokleM]

Most residential LEDs run at 12V. Only semi pro and above run at 24V i believe.

 

I will definitely check though before i take the plunge.

 

That is certainly possible.  I'm use to dealing with fresh/reef tank lighting, which uses probably a bit different components.  Many of the drivers we use go up to 48v.