AC Adapter & PC Fans - Questions

[NanoReefer53]

So I'm planning on modding my NanoReef to MH lighting so of course I'm going to need more circulation. My problem is hooking them up to an AC adapter. I could go out and get three of them but I'm wondering if there's a more simple way. Is there a way I could hook them up to one single AC adapter in parallel? I thought about using an old PC power supply but it's a little too bulky. Also, I read on a site that red wires meant +5V and black meant ground. On some fans though it's only a red and black wire so how does it get a negative voltage. Also, if red is 5v then how come the fan says 12v ?

I plan on hooking up these fans by the way:
3 of these - http://www.nexfan.com/galaxy606025b.html
1 of these - http://www.nexfan.com/syexbl.html

Thanks in advance

 

[BruiseAndy]

Get your voltage by the nameplate not by color (red is positive black is negative in the DC world usually). Yes if you have the amperage you could run the fans off the same adapter all in paralell. Just take your amp draws add them up then make sure you have an adapter powerful enough.

 

[itZme]

It is true that the red wires on an ATX power supply are 5V but the fan's red wires only indicate positive voltage. They are 12v fans and you need to wire them to the YELLOW wires of the power supply. If there are not enough YELLOW wires you can simply connect 2 or 3 red fan wires to a single YELLOW power supply wire.

The red power supply wires would not be used for your purpose.

I would STRONGLY caution AGAINST the fans you have chosen though as they have a noise rating of 34Db each and they are only 60mm, they only move 27cfm of air and run at 5,000 RPM.

Three of those will sound like a small jet engine in your house whenever they kick on. They will have a really high pitched whine. There are several places where you can find 120mm (or 80mm if you are cramped for space) fans that run at much lower RPM, move MORE air and will not drive you insaine from noise.

The prices are good on those fans you posted but it will be worth the $10 you may spend to buy 2 of the 120mm fans instead of the sets of ear plugs you will need to enjoy your tank.

Try searching for "quiet pc fans" on Ebay or Google and I would recommend getting the quietest you could afford. I see some 120mm fans are 20Db and flow 66cfm of air. That is almost twice the flow you would have and a SUBSTANTIAL reduction in noise. If you could use one fan or maybe two to do the same job you will not regret it.

Even if you must use 60mm fans you can find many with MUCH lower noise ratings. The 3 fans you linked to at 34 Db each would give you a total rating of around 43Db(A) which is quite noticable. I would shoot for something in the range of 20-28 Db(A) each.

As far as hooking them to an AC adapter, that would be perfectly fine as long as the amperage from the power supply was enough to supply what's needed the by fans. Say each of your 3 fans use 120ma "milliamps" (.12amps) the total needed would = 360ma or .36 amps at 12v. (3x.120=.360)

I would still get a bit larger power supply (in this case maybe .5a) so you aren't straining your power adapter. Please note that I did NOT find an amperage rating on your proposed fans so don't use those numbers for your power supply needs.

Good luck
-- itZme

 

[merlock116]

itzme is right about the noise issue. get larger fans. they run at lowerl rpm and move more air and are quieter.

why not get AC fans? Then u don't need to hassle of the DC power supply. mouser.com has a great selection of ac and dc orion fans for about $13 per fan.

 

[NanoReefer53]

Thanks for the clairification itZme. The reason I chose 60mm fans by the way because I'm going to be modifying a NanoCube which has it's own lighting enclosure and already has mounting spacers for 60mm fans. I wanted to get a good amount of cfm blowing through so those were the ones that pushed the most with lower db ratings than some of the others.

Here's what I plan on sticking the 70w MH bulb in. With such little airspace I need to push as much cold air in and and hot air out as possible (reason for scroll fan also).

 

[formula831]

DC fans use less energy...IMO DC fans are the way to go