Introduction: PC Fan Controller

Hello everyone! Here is my new Instructable.

CPU coolers have been getting more and more efficient over the last years. However, this higher performance usually has a price: More noise. This noise is annoying and reduces well-being and productivity.

In this tutorial, we are making a Temperature controller for PC using Thermistor.

It regulates the speed of the FAN attached to it according to the measured temperature. Temperature is sensed using a simple NTC thermistor.

Step 1: Problems With Conventional Temperature Controls

Temperature controls for fans aren't exactly a new idea. Temperature-controlled fans are widely available. However, the most commonly used fan temperature controls have some major limitations:

● The temperature at which the CPU (or case) should be kept cannot be adjusted by the user. This is a major problem: The maximum operating temperature varies greatly between CPU types, so it's unlikely that the control will provide the best possible regulation for your particular CPU. Also, coolers with temperature control that can't be adjusted by the user are totally unsuitable for overclocking, since an overclocked CPU must usually be kept below a very precise temperature, at which it crashes.

Most conventional temperature controls only regulate fan speed, but don't turn the fan off. Especially for case fans, this doesn't make sense. It is much better if the fan is totally off when it's not required. Certain types of CPUs will produce so little heat when idle, that the CPU fan can be turned off when the CPU is not busy.

● Each fan needs its own sensor - with must current fan temperature controls, each fan needs its own sensor; it is not possible to control more than one fan with a single sensor.


In most PCs, the fan runs constantly, which may not be necessary. A simple circuit can regulate fan speed according to temperature. This not only saves energy, but it also reduces fan noise. Only three components are needed to allow the fan speed to be controlled according to the actual temperature: one adjustable voltage regulator (LM317T) and two resistors that form a voltage divider. One of the resistors is an NTC thermistor (temperature-sensitive resistor), while the other is a normal resistor. The circuit and its connections are shown in the above image.


– 1X LM317T

– 1X 100K POTENTIOMETER 3296W 3296

– 1X 15K NTC

– 1X 100UF 16V Capacitor


– 2X Latching Pin Headers 0.1″ Pitch 3 Way.

Step 4: DESIGN

I have designed the PCB using EAGLE tool and uploaded the design on LionCircuits. They are the best PCB manufactures and provide low-cost prototyping. I always choose them for my PCB needs. Above are the images of my PCBs that I have uploaded on LionCircuits platform.

I have also shared the Gerber files below so that you guys can create and assemble the above circuit.