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  • Added on: Jul 02 2012 05:28 AM
  • Date Updated: Aug 03 2016 05:10 AM
  • Views: 27442
 


Making Your Own Computer Fan Controller

This tutorial will describe how to make a fan controller to regulate the computer fan speeds.

Posted by ajnl on Jul 02 2012 05:28 AM
This is part 1. Just showing how to make a controller and an example on how to mount it on the front of your desktop computer. Part 2 will include how I connected the fan controller to the computer fans.

I wanted to buy a fan controller for my computer, but found that they were pretty expensive. But thought that it couldn't be that difficult to make one myself. Considering all they are using are potentiometers to control the fan speed. Potentiometers are also used in radios and computer speakers to change the volume. Basically when they are turned they either increase or decrease resistance. For a fan controller, when the resistance decreases, the RPM of the fan increase.

To learn a bit more how potentiometers work, check out this site.

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What you need:
  • Potentiometers (the number depends on the number of fans you want to control. One potentiometer for one fan)
  • Computer fan (to test your set up before putting it in your computer)
  • Wire (22 Gauge is probably best to use)
  • Wire clippers
  • Solder and a Soldering Iron
*I am assuming that you know how to solder, it is pretty easy to learn. Here are two tutorials you could use: Link 1; Link 2*

Optional:
  • Switches (completely turn fans on/off)
  • Caps for the potentiometers
  • LEDs (which light up when the fan is on)
  • Heat Shrink
  • MOLEX connectors (to connect the wires to the PSU and fans) 4 pin female
*I could not find any MOLEX connectors in my area, so I am going to connect them differently. Which I will show in the second Tutorial.*


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Potentiometers

You will need to use some simple calculations to find the correct potentiometers for your fans.
Fans are usually 5V, 7V, or 12V. Mine are all 12V fans.
Vf = minimum fan voltage
Vs = power from PSU (power supply), which is 12V for yellow wire and 5V for the red wire
Rf = fan resistance in ohms
Rr = potentiometer resistance needed in ohms
Vf1 = fan voltage, 12V, 7V, or 5V (depends on your computer fans)
Va = fan amps, usually between 0.1 and 0.5 amps

Rf = Vf1/Va

Rr = ((Vs*Rf)/Vf) - Rf
Most of my fans are 230mm fans. The voltage is 12V and 0.16 amps (max 0.28 amps)

Rf = Vf1/Va = 12/0.16 = 75 ohms

Rr = ((Vs*Rf)/Vf) - Rf = ((12*75)/5) - 75 = 105 ohms
So in my case, I need a 105 ohm potentiometer. Because there is no 105 ohm potentiometer, I went with the 100 ohm potentiometer.

To find these electrical items, like potentiometers:
- In the Netherlands this is a good site to order from.
- In the United States of America, then go to Radio Shack.

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Here is the potentiometer I used (100 ohms). You can cut them to the required length:

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I decided to add a switch for each fan as well:

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Cap for the potentiometers:

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Soldering Unit:

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Soldering Time

So now the actual work can be done. You want one wire that leads from the power supply to your potentiometer, then to the switch, and then to the fan (red wire). The second wire will lead from the power supply straight to the fan (black wire).

First solder a wire to the left and middle part of the potentiometer, this wire will be attached to the yellow or red wire from the PSU. A second wire is solder to the right side of the potentiometer, this wire will lead to the switch.

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Second solder the wire coming from the right side of the potentiometer, to the left side of the switch. The white wire is then soldered to the middle part of the switch, this white wire will go to the fan's red wire.

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I hope the picture below will clarify how each are connected to each other. And that there has to be one wire that bypass everything, it links the black wire from the power supply to the black wire from the fan. Below the switch is in the OFF position:

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Mount the System

Next you want to mount this to the front of your computer. I mounted the potentiometer and switch to a plexiglass plate and then mounted those plates on the front of my computer.

Plexiglass plate with holes drilled for the switches. Use drill bits that are made for drilling through metal.

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Plexiglass plate with holes drilled for the potentioemters:

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You can then screw in the potentiometers and switches into the plate, an example is show below:

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Next, on the front of my computer I have these plastic rectangular pieces that are easily removed.

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Once you take out the metal "fence" out:

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The plexiglass plates are then mounted inside the plastic rectangular pieces, you can use glue or two sided tape. Then it is possible to put the plastic rectangles, with mounted plexiglass plates, and the potentiometers/switches screwed in place, back onto the computer (all these switches are in the OFF position)

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A quick recap:
  • Step 1: Determine the potentiometer you need and get all the supplies you need
  • Step 2: Solder the wires to the potentioemeters and switches show above
  • Step 3: Find a way to mount them (an example is shown above)
Recommendations:
  • Think about how you want to connect the system to the power supple and fans and plan accordingly
  • Find a good way to mount the system
  • Solder everything BEFORE mounting anything, because it would be much harder to solder the wires when the potentiometer is attached to the plexiglass plate
  • When you cut the wires that you solder on to the potentiometer and switch, make sure they are long. Because you can always cut them shorter if necessary.
I linked the photos from photobucket, because I could not upload them (upload file size limit).