Fan speed controller using LM2941


Many electronic circuits related to fan speed controlling have been published here and this one is just another approach. The circuit diagram shown here is of 12V DC fan speed controller using the IC LM2941CT which is a low drop out 1A voltage regulator. The IC has a dropout voltage as low as 0.5 and has also many useful features like power supply reverse protection, thermal protection, short circuit protection etc. The maximum output current the IC can source is 1A.
The 12V DC supply is connected between the Vin (pin4) and ground (pin3) of the IC. The load, which is the fan, is connected across the Vout (pin5) and ground (pin3) of the IC. The network comprising of potentiometers R1, R2 and resistor determines adjust current (Iadj) of the IC. By varying the Iadj using the POT R2 we can adjust the output voltage of the IC and hence the fan speed.
Circuit diagram.

fan speed controller using LM2941


  • The circuit can be powered from 12V DC.
  • The maximum possible load current is 1A.
  • A heat sink is recommended for the IC.
  • POT R1 can be used to adjust the minimum fan speed.
  • POT R2 can be used to adjust the fan speed.

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29 thoughts on “Fan speed controller using LM2941

  1. mahes

    sir,will u please send the explanation for this project to me( i will try to made the project in our college.

  2. sivakumar

    i am trying to make the circuit to my college project. How to make the project and please send the layout the circuit and explanation of the circuit. . . .
    Please to help me for to complete the project. . .

  3. gerrit

    hi, i am trying to build a 12v 50A variable speed controller for my car. can you tell me what i need to replace to get that results. the fan is pulsed with a square impulse from the computer(ecu)

  4. seetharaman

    Hi Gerald use thick copper (10 to 20 mm) strips used as link in high current cable links or thick aluminium bars. donot use without heat sink.

  5. gerald

    is it ok not to put a heat sink for the IC?? In case there is no heat sink available, what can I can use as an alternative?

  6. Ankil

    Hello guys, I am trying to make this circuit as my college project. I got the required output on breadboard but fail to get output on pcb when layout done on eagle software; I guess I dont know to use the eagle software. So can any1 please mail me the layout of this circuit on ? It will be of tremendous help. thank you

  7. soji

    sir in this experiment( fan speed controller using the IC LM2941CT) ,,sir which type of motor is to be used whether a 12 volt motor…or something else

  8. seetharaman

    Hi Probir the maximum current through R1 & R2 cannot be more than 6mA. Hence any potentiometer available in the market can be used.(Miniature pots are 100mw std ones are 250mw)


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