Making Your Own Computer Fan Controller

[ajnl]

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:

 

 

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

 

 

Cap for the potentiometers:

 

 

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.

 

 

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.

 

 

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.

 

 

Plexiglass plate with holes drilled for the potentioemters:

 

 

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

 

 

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

 

 

Once you take out the metal "fence" out:

 

 

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). Edited March 30, 2018 by Fearless Staff

[Jefke]

Only spotted this tutorial now ^^

 

I'm almost as pro, I altered a fan controller which I took out of one of my previous build to fit 4-pin molex fans instead of the 3-pin fans and I made the connectors reach further in my case it was a disaster to connect the fans to it (after I done that I realised I could have changed to connector on my 2 scythe fans without problems. Problems would start if I put them on my mobo, but otherwise that solution would have worked to ^^)

 

Anyway nice tutorial (but basic fancontrollers aren't expensive so I will stick to altering them XD).

Edited September 4, 2012 by DrJoske

[MoAZeR]

yea really like this one i made something similar into mine comp but with out a switch

[ajnl]

Thanks guys, yeah I am planning on changing this one a bit. I bought some thicker wires and hopefully will get more power running through so I can get the fans to hit higher RPMs. Also, I replanning the connection system. Like you said, it can be tricky. I'll post a modified tutorial with the changes, once I have the time to make them.

 

You are right, it is cheap enough to buy one. But I enjoy making these things on my own.

 

yea really like this one i made something similar into mine comp but with out a switch

 

I was planning on putting LEDs as well, but they were sucking up too much power, plus didn't have space for them .

 

How did you connect yours?

Edited September 4, 2012 by ajnl

[daitallica]

Hi
 

Excellent tutorial!

 

I was wondering if you could help me with something.

Say I was using the same fans as in the tutorial, and I wanted to run 6 fans off one potentiometer. (for a radiator)
Would the same pot owrk or would I need a different one?

Thanks

[ajnl]

Hi

 

Excellent tutorial!

 

I was wondering if you could help me with something.

Say I was using the same fans as in the tutorial, and I wanted to run 6 fans off one potentiometer. (for a radiator)

Would the same pot owrk or would I need a different one?

 

Thanks

I'm sorry, I have no idea. Try attaching one battery to all the fans and see if it works. I wonder if enough power will reach each fan if you're only using one cable from the power supply?

[Metalchef1]

I wired everything exactly as you showed in the tutorial but I have an issue. The pot only slightly controls the fan. If it were to have numbers 1 thru 10.....1 through 8 is off and the 9 to 10 gives basically 2 speeds. I have 12v .3a fans. 100k ohm pots. Used the same wire....wired it the same way as shown....the power supply is 12v 1.0a.

Where did I go wrong? Did I go wrong? I would like to have full range of speed control if possible.

By the way.. im new here and have limited to no knowledge of electronics.

[ajnl]

I wired everything exactly as you showed in the tutorial but I have an issue. The pot only slightly controls the fan. If it were to have numbers 1 thru 10.....1 through 8 is off and the 9 to 10 gives basically 2 speeds. I have 12v .3a fans. 100k ohm pots. Used the same wire....wired it the same way as shown....the power supply is 12v 1.0a.

Where did I go wrong? Did I go wrong? I would like to have full range of speed control if possible.

By the way.. im new here and have limited to no knowledge of electronics.

Sorry about the late response, I just got back from vacation.

 

You should check your calculations. I used a 100ohm pot, you can see why in the tutorial.

 

For you:

 

Vf = min fan voltage = 5v

Vs = power from PSU = 12v

Rf = fan resistance = Vf1/Va

Rr = potentiometer resistance needed = ((Vs*Rf)/Vf) - Rf

Vf1 = fan voltage = 12v (in your case)

Va = fan amps = 0.3a (in your case)

 

Rf = Vf1/Va = 12/0.3 = 40 ohms (for my fans this was 75 ohms)

 

Rr = ((Vs*Rf)/Vf) - Rf = ((12*40)/5) - 40 = 56 ohms

 

So you need a pot that is around 56 ohms (just get one as close to that as possible)

 

Your 100k ohm pot is way too high.

[Ghobar]

Dear ajnl

Your tutorial is illuminating and instructing.

I am still acquiring knowledge.

I have some questions:

1. It seems that potentiometers have two other factor, watts and amperes. So what should be the watt and ampere of the potentiometer that is required?

2. You have spoken about "Vf = minimum fan voltage". How can the minimum fan voltage be known?

3. Can you specify wire in terms other than gauge?

 

Regards

Ghobar

Edited September 27, 2016 by Ghobar

[ajnl]

Dear ajnl

Your tutorial is illuminating and instructing.

I am still acquiring knowledge.

I have some questions:

1. It seems that potentiometers have two other factor, watts and amperes. So what should be the watt and ampere of the potentiometer that is required?

2. You have spoken about "Vf = minimum fan voltage". How can the minimum fan voltage be known?

3. Can you specify wire in terms other than gauge?

 

Regards

Ghobar

1. Potentiometers just increase/decrease the resistance. I = V/R; Current = Volts/Resistance

 

Current is measured in amperes

Resistance is measured in ohms

Volts is well volts...

 

Watts is work done and can be calculated various ways depending on the situation.

Watts = V*I (volts*ampere); this is in electromagnetism, it shouldn't be necessary here.

 

2. Voltage affects the speed of the fan. If its a 12V fan, then a lower voltage will slow down the fan. So the minimum is something you choose.

 

3. Not sure how else to specify it?

[Ghobar]

Under "Soldering Time", you said "First solder a wire to the left and middle part of the potentiometer,...".

The picture 0629, shows that you have used a double wire and you have soldered one cord of it to the left part of the potentiometer, and the other cord to the middle part of the potentiometer.

There arises some questions:

1. Can a single wire be used and be soldered to both the left and the middle parts?

2. According to the web page you have linked (Beginners' Guide to Potentiometers), there are different wiring plans. Can you explain your reasons in wiring as you do?

[ajnl]

Under "Soldering Time", you said "First solder a wire to the left and middle part of the potentiometer,...[/size]".

The picture 0629, shows that you have used a double wire and you have soldered one cord of it to the left part of the potentiometer, and the other cord to the middle part of the potentiometer.

There arises some questions:

1. Can a single wire be used and be soldered to both the left and the middle parts?

2. According to the web page you have linked (Beginners' Guide to Potentiometers), there are different wiring plans. Can you explain your reasons in wiring as you do?

1. Yep a single wire can be used. I ended up winding two together since they were so thin.

 

2. I'll get back to you on this question.

[Ghobar]

2. I'll get back to you on this question.

 

When will you get back?

[ajnl]

When will you get back?

I honestly don't remember (it was a while back). I think I just used a battery to test which connections to make so that the fan would increase/decrease speed with the turning of the pot.

 

The wiring that the website shows is for volume or lighting control. It assumes three wires, but we only have two for a fan. So I think one wire needs to be connected to two ports on the pot.

[Ag47]

2. According to the web page you have linked (Beginners' Guide to Potentiometers), there are different wiring plans. Can you explain your reasons in wiring as you do?

 

I can't access the webpage, but I will try to guess its content.

 

The difference is the configuration of the potentiometer, it can be used as a variable resistor (which will control current passing through the fan), or can be used as a voltage divider (which will control the voltage across the fan). Basically:

 

Variable resistor -> Potentiometer (also named rheostat only for this configuration) is connected in series with the fan, therefore, both of them will have the same current, but different voltages.

Voltage divider -> Potentiometer is in parallel with the fan, therefore, both of them will have the same voltage, but different currents passing through each one.