Thermal Fan Speed Controller

Hi

Today, God willing, I will show a video in which an important circuit is explained to control the speed of rotation of the computer fan, or any fan running on a continuous current, By using LM7812 linear voltage regulator, With BD139 transistor which works as a key.

After the introduction, the diagram and a set of questions and explanation of the connection are displayed, after which the diagram is presented in an embodiment and the last part in which the circuit is tested in practice.

Here I will show you the components of the project :-

1. Transformer 12V, 1A transformer
2. Linear voltage regulator LM7812
3. Bridge rectifier
4. Capacitor 1000uF, 35V
5. 0.1Uf ceramic capacitor
6. transistor BD139
7. NTC 10K negative coefficient thermal sensor
8. The resistance of the variable Tremer is 5Kohms
9. Computer fan

I want to test the operation of the device on the bread board .

by changing the amount of variable resister i can adjust the critical point of the fan start .

to now more information about practical part you can watch the video .