Pc/power supply fan is one of the most crucial components to ensure the smooth running of your computer. But often or not, many of us get annoyed because of the resultant noise.and very good overall functionality that makes it a perfect choice for very demanding users.
This
circuit will turn on/off 12V DC fan or CPU fan when temperature above
normal temperature.You can set turn on temperature by adjust VR1. This
circuit use an NTC (Negative temperature coefficient)which
is a thermistor is one in which the zero-power resistance decreases
with an increase in temperature. So If temperature increate the voltage
at pin 3 on LM311 will decreated .The resistance of NTC is about 10K at
25'c.
VR1 should be multi-turn potentiometer type such 10K/25 turn link
VR1 should be multi-turn potentiometer type such 10K/25 turn link