DC Power Supply for PC Cooling Fans

[yeldarbj]

For those of you running 12V PC cooling fans above your tank, what type of 12V AC to DC converter are you using? Something you get at RadioShack or elsewhere? It seems that the cooling fans come with 3 or 4 pin cables for computer installation.

How many fans can you run on one power supply? I would assume as many as you want but that's just a guess.

 

[AZDesertRat]

Harbor Freight Tools has one on their website for $4.99, its a variable voltage DC power supply so you can vary the fans speed. Its a 500mA so you should be able to run 2 or 3 fans off of one supply. You can also find them at Radio Shack and WlMart for a little more $$ but basically the same thing.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46977
As far as the plugs, cut the plug off the fan and only use the red and black wires, ignore the yellow wire and any others it may have. Same with the power supply, cut all the adapters off and it only has two wires.

 

[yeldarbj]

Thanks, that's what I was looking for. I probably have several laying around somewhere in an old shoebox. If the fans use about 2 watts, what's the conversion to find the right mA adapter (the one you linked to was 500mA) some are 1000mA or higher?

 

[AZDesertRat]

I honestly don't know but I run two fans on one adapter no problem.

 

[Jefe12234]

Current = Watts / Voltage

2 watts / 12 volts (assuming they are 12v) = .167 amps = 167 mA

This means you need an adapter that can handle AT LEAST 167 mA to run one 2 watt fan or 334 mA for two of them, etc. You want to oversize the mA rating, not match it exactly. The voltage however should match, unless you want the fan to spin slower.

 

[reefer4sho]

thanks for the ohms law lesson jefe!

 

[badpacket]

BTW, just don't supersize the psu, as many of them actually put out a higher voltage when running equipment much lower than the psu's rated ma output.
Basically, if you need 200-300ma total, and slap a 1000-2000 ma (2 amp) psu on it, it may put out 14-15 volts if it is labeled a 12v supply, 10-11 if rated at 9v, etc. Better made psu's will not usually do this. Just test the psu voltage first without a load on it if you can.

BTW, if the psu says 'regulated' on it, then you most likely don't have to worry at all.

 

[TheGrog]

I have used old cell phone chargers with good success. They usually run 400-500 mA. Got several of them laying around.

Old power cables for computer peripherals (speakers, printers) work good too.