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How to: Wiring Case Fans

Joined
Apr 22, 2010
Messages
757
Location
Calgary, AB
I was taking pictures on how to wire a case fan (DC) to an AC wall plug for another member and figured I would just make a post for everyone to see. This is good for getting air circulation inside of a humid terrarium which is great for plants, or for placing at the end of a light fixture to cool it down. If using inside a terrarium with animals be sure to glue screen on the front and back of the fan so the animals can't get the the fan blades and injure themselves.

Materials

Case fan from CPU store, ebay etc.

Fan.jpg


110V AC/DC converter, I prefer the variable output ones so you can select how fast the fan spins. Make sure this puts out more amps than the fan requires, with 10-20% or more excess output. (Most cell phone charger will work too but will be a constant output of 5V usually)

converter2.jpg


Electrical tape
Wire cutters

Optional:
Soldering Iron
Solder

Step 1

Make sure your converter is unplugged from the wall. :) Cut off the plug on the end of the wire exposing the two wires. Do the same with the fan. Some fans have 2 wires and some have 3. Either are fine but if yours has 3 you wont need the yellow one so you can cut it short and get it out of the way. Split the two wires apart 2-3" down so you can split them nicely and have room to work on individual wires.

I do not have pictures of this because this fan was already wired and I took it apart for this How to post.

Step 2

Strip the 2 wires on both the converter and fan. I usually do about 1/2" to 3/4". Please excuse the glue on the wires, I had it glued into place prior to taking the pictures.

1.jpg


2.jpg



Step 3

Twist the wires from the converter to the fan. Pure black wire on the converter goes to the negative wire on the fan (black wire). Black wire with white stripe on converter goes with the positive wire on the fan (red wire).

3.jpg



Step 4

Plug converter into your wall outlet making sure to keep the two wires away from each other so it doesn't short. I do this to make sure the fan is working, and is spinning the correct way. If its spinning backwards, or isn't working flip the wires. If it is spinning the correct direction unplug.

Step 5 Soldering Method

If you dont have a soldering iron skip this step and go to the next step (taping method)

Solder your first wire together making sure to have a good connection. Now solder the other wire. Take electrical tape and tape each wire separately to insure it wont short out. Now tape the two wires together to clean it up.

4.jpg


5-1.jpg


6-9.jpg


7-10.jpg


8-11.jpg



Step 5 Taping Method

Take your first wire and take a small piece of electrical tape, approximately 1" and wrap it tightly around the twisted wire making sure to completely cover where the wire has been stripped. Now do your second wire separately the same as the first wire. Now take a larger piece of electrical tape, approximately 2" and tape the two wires together creating one wire to clean it up.

6-9.jpg


7-10.jpg


8-11.jpg



Step 6

Plug it in to make sure it is still working and you haven't made a mistake along the way. You are now ready to install it in your terrarium, vivarium, beside your lights to cool them off or whatever you are intending to do with the fan. Im lazy so I just take a little electrical tape and tape the fan in the corner of the aquarium making sure there is enough room behind the fan so air can be sucked in through the fan and out blowing over my plants.

12.jpg



Wiring more than 1 fan
Now if you want to hook up more than one fan you can do so on the same converter as long as the total input of amps of the fans is less than the output of the converter. Its always a good idea to leave 10-20% of room so you dont end up drawing too much amps from the converter on start up.

Ex: my converters output is 700ma or 0.7 amps.
0.7 x 0.20 = 0.14 amps

0.7 - 0.14 = 0.56 amps. This is how much amps I consider is safe to draw from the converter.

My fans are 0.06 amps.

0.56 / 0.06 =9.33333. So I can safely run 9 fans off this converter assuming all 9 fans draw the same amps.

If anyone has any questions feel free to post or send me a PM.
 

vraev

Carnivorous plant enthusiast
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Messages
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Location
Ontario, Canada
Good job! Nice guide for people trying to wire their first fan. :) I went the lazy route and got a adapter that was prewired to use these fans.
 
Joined
May 3, 2011
Messages
577
Location
Tidewater Virginia, USA
Nice tutorial!

Just a note on the splices - I always stagger the cuts, making the cut in the second wire about an inch down from the one in the first wire, that way if the tape peels off due to the humidity the wires won't be as likely to short together. At 12 volts DC it would only blow the adapter - at higher voltages (110 VAC)?
 
Joined
Apr 22, 2010
Messages
757
Location
Calgary, AB
No problem jpappy.

That is a good suggestion afrodisa. All my connections are outside the terrarium so I'm not too worried but if it was inside it could possibly be a problem. Another thing mentioned on another forum was use of heat shrink tubing instead of electrical tape. I find tape sticks very well if pulled tightly. Of course there is also liquid electrical tape too.
 

gill_za

Never Knows Best
Joined
Jan 30, 2011
Messages
996
Location
Philadephia, PA
You should also mention that if one connects more than one fan across the circuit one should connect the fans in parallel to make sure that the same voltage is applied across both fans. Simple computer fans are usually voltage driven and if one connects the fans in series the voltage across each fan will be equal to a half of a total voltage supplied by the PSU.

PS. that is the way fans, hdd, cd-roms and etc are connected in your PC :)
 

pappydew

I hate bugs. Carnivorous plants get me.
Joined
Apr 7, 2010
Messages
1,209
Location
Miami, FL
I feel bad...I broke down and bought some clip fans as the tanks are going "kaput!"

Still a nice write up to reference for future use. I'm sure I will give it a go someday...
 

gill_za

Never Knows Best
Joined
Jan 30, 2011
Messages
996
Location
Philadephia, PA
I feel bad...I broke down and bought some clip fans as the tanks are going "kaput!"

Still a nice write up to reference for future use. I'm sure I will give it a go someday...

I have a stash of fans I bought from newegg a while ago which i'm planning on putting on the wire shelf. I have to figure out how to fix them so that can be easily adjustable, some sort of a swiveling clamp or something :). I'll post pics when I'm done.
 
Joined
Nov 8, 2007
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1,070
Location
Aberdeenshire, Scotland
I also use switchable voltage power adapters, as above. Some of them are not voltage regulated though and are designed to deliver the specified voltage at the near the maximum current output; therefore, at lower currents such as those required by a fan, the voltage can actually be higher that that selected. Basically with these it is best not to run a 12V fan with the adapter set to 12V output, as it's likely to over-voltage the fan.
 
Last edited:
Joined
Jul 27, 2010
Messages
486
Location
Massachusetts, USA
What do you do when you have a four-pin fan? I have a MacBook Pro, and the fans just got replaced on it, but they're still good (just noisy) and I want to wire them up for my terrarium. A link to a picture from Amazon is below. I've wired case fans before, but all these wires are identical and I dont know which to hook up. I'm fairly hesitant to do trial-and-error, out of fear of electrocution or shorting a circuit or something.

http://ecx.images-amazon.com/images/I/41g6r3cGmJL._SL500_AA300_.jpg

Thank you for any input!
 

Not a Number

Hello, I must be going...
Staff member
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Nov 16, 2006
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7,642
Location
Los Angeles, CA
"Motherboard has open-collector type output. This construction guarantee, that with disconnected PWM signal will runs fan with maximum revolutions."
 
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