If you have installed at least one auxiliary fan in your PC, you must have noticed that it became a lot noisier. Extra fans are great to improve the air circulation in the case and to avoid overheating of the machine, but their greatest inconvenience is their noise level, that is, your computer becomes noisier. Depending on the type and quantity of fans you have added to your case, working at the computer may often become an impossible task due to the noise it makes.

The solution for this problem is very simple: to reduce the rotation speed of the auxiliary fan when the computer is not operating at full power. The slower the fan turns, the less noise it makes. When you need greater thermal dissipation (for instance, when you are playing your favorite 3D game and/or when you are doing overclock), then you may have the fans turning at full speed. But how can we do that?

Some high-end fans line have speed control, and some manufacturers developed circuits to control the speed of the fan, such as Cooler Master (visit http://www.coolermaster.com and see the Aerogate and the Musketeer).

The problem is that those products are expensive. So, what to do? Today we will teach you how to assemble a fan speed control system. You will see that it is much simpler than it seems, and that its cost is much more accessible than the ready-made solutions in the market. You will need to have experience in soldering electronic components; If you don't, as a friend who knows how to use a soldering iron to help you.

The only component you will need to buy is a 100-ohm linear potentiometer, which can be easily found at electronic parts stores. You will also need to buy two feet of wire (~0.50 m) to make the necessary connections. You may also want to buy a knob to put in the central pin of the potentiometer.

The connection is simple. The fan feeding wire will have to be cut in half in order to fit the potentiometer. That wire is red in fans directly connected to the motherboard (three-pin plugs) or yellows in fans connected directly to the power source (four-pin plugs).

Peel the end of each part of the wire and make the connection to the potentiometer, as shown in the figure. The wire numbered 1 should be connected to one end of the wires resulting from the cut, and the one numbered 2 should be connected to the other one. Don't forget to isolate all connections with isolating tape.

Figure 1: How to wire the potentiometer.

To improve control, the potentiometer may be installed at the front of the case, in one of the 5 1/4" bays that is not in use. All it takes is making a hole on the plastic cover and installing the potentiometer there.

If you have more fans that you want to control the rotation speed, you will have to repeat the operation, installing one potentiometer per fan.