FANS AC/DC help

[rainingshots]

Hi,
I have two 5" fans that are 12VDC that have a 3 pin connector. They are .52mA each. I want to know if I can make some sort of harness or something to get them connected with a AC adapter. I see them on the market so I know they can be connected to a AC/DC adapter. What kind of adapter would this require in terms of mA, volts etc. Please if anyone can give me some info on how to get them installed would be great.
Peace

[jdieck]

Use aindividual 1 Amp adapters for each one. (750 mA Minimumn).
From the three wires look fo black white (or yellow) and red, One of the three wires (the white or yelow) is for measuring the RPM by a computer board so you do not need to connect it.
Connect the red one to the center pole of the adapter connector or (+) and the black to the side pole of the connector or (-) terminal.

[rainingshots]

thats it? So I can just cut the connector off and do this with a salder iron? What if I get a 1500 mA or 2x 800 mA?
any other suggestions?
thanks a lot

[rainingshots]

could I not use 2x 500mA adapters? its not much of a difference is it?
thanks

[Rikko]

Actually that will give you problems. Worry about voltage first, not the current.
Let's say you have a fan that draws 12VDC and draws 510mA. You attach it to an adapter that provides 12VDC at 500mA. You *won't* get those 500mA because most adapters can't crank out what they're exactly rated at (cheap/small ones, at any rate) - you'll have less voltage because the current will "collapse". Beyond that, if you're sucking power very close to the adapter's practical limit, that sucker will be VERY hot and I'd be concerned about the casing melting/degrading over time.

Easiest thing to do would be to find an adapter that's in the neighbourhood of 10-14 volts and can push substantially more than you require.
Case in point:
last canopy I built has got two 12V (470mA) fans on it and I expect I might add some LEDs later. I connected them in parallel to a little "multi tap" I bought to quickly attach and remove more devices. The tap has got a 14VDC@1600mA adapter pushing it. I got the adapter for 6 bucks at Princess Auto and it's got more than I'll ever need.
Bear in mind that a little less voltage might be better for you, as pushing it at/beyond the rated voltage makes them spin pretty fast and they can be noisy.
The canopy I have running at 14V isn't in my house. :D

[rainingshots]

So I can run the 12V fans on a 13/14V adapter? Where can I find a good adapter for these 2 fans for a good price?
(12VDC .52mA each fan)
Rikko thanks for the info, do you have a pic of yours you can show me I want to see how you attached everything.
Thanks

[jdieck]

Not all adapters are born equal.... Fans will work within a voltage range say 10 to 14V. Many adapters like the ones used to charge batteries may not be fully DC. They call it DC because it has no negative component but the current may still be provided in positive half sine waves cycling 120 times per second. I will try to get adapters used for electronic equipment (Computer power supplies, adapters for radios or stereos etc.) Those adapters have further wave filtration (Usually trough capacitors) in order to provide a better continued DC voltage and current. Top adapters will also have electronic voltage regulation via a Zener diode to keep the voltage constant despite the size of the load but you do not need to be that fancy.
The reason I recomended the 1 Amp one is because that is not an expensive one, is something you can find at the Radio Shack and the most usuall will be 500 mA which will be too small and 1 Amp (1000 mA). You might find larger but are either too expensive if for electronic equipment or will not be fully rectified.

The connection is simple just cut the connector and solder directly to the fan wires, Of course you may want a switch. Ideally you may want the switch to turn off the 110 V outlet so you do not need to keep the power supply on all the time but you can also install the switch on the 12 V side is switching off the outlet is too dificult.

[Rikko]

Bad pic but all I have available:
http://www.aisle13.ca/rikko/aquaria/canopy/12.jpg

Basically, the fans are on either end of the canopy. You can only see the one on the left. I ran wire along to the silver/gold thingamagig in the middle, on which I slid normal boot connectors (You could just solder stuff into place... I designed mine with expansion in mind). The big adapter that's plugged into the power bar is likewise connected to the silver/gold thingamagig.

Circuit wise, you just need to combine all of your + wires and all of your - wires and you're done. Mine became a little complicated with the addition of the switch and thingamagig, but that's all that's going on.

And very soon I'll be adding a rheostat so that the fan speed can be controlled - at 14 volts it's a big noisy.

[rainingshots]

thanks for all the info people.