How to Create a Three-Speed Fan Control without Spending a Dime

Connecting the Wires to the Power Supply

Now you will connect the wires from the fan to any unused peripheral power plug from the power supply. The way you will connect the fan wires to the power supply will depend on the speed with which you want to configure your fan. You have three options: low speed (+5 V), medium speed (+7 V) or full speed (+12 V). You may be asking yourself I can we get +7 V since the power supply doesn’t provide such voltage. Here is the trick. If you connect one wire to +12 V and the other wire to +5 V, you will have +7 V (12 V – 5 V = 7 V). It works like a charm.

For low speed, you will connect the black wire from the fan to the power supply black wire and the red (or yellow) wire from the fan to the red wire from the power supply. As previously mentioned, this will provide +5 V to the fan. We show how this is done in Figure 10.

Figure 10: Installation for low speed

For medium speed, you will connect the black wire from the fan to the red wire from the power supply, and the red (or yellow) wire from the fan to the yellow wire from the power supply. As previously mentioned, this will provide +7 V to the fan.

Figure 11: Installation for medium speed

For full speed, you have two options. One is to install the fan wires back to the fan connector. The other options is to connect the black wire from the fan to the black wire from the power supply and the red (or yellow) wire from the fan to the yellow wire from the power supply.

Figure 12: Installation for full speed