PWM signal from four wire fan

Discussion in 'The Projects Forum' started by sumit123, Nov 12, 2014.

  1. sumit123

    Thread Starter New Member

    Oct 28, 2013
    11
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    I am trying to design a circuit that read the PWM signal from four wire fan & indicate us in a form of Led or sound ,when fan stop the working or if the fan motor not working.

    Anybody help us with the circuit diagram.
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    970
    Why not use a fan with a locked rotor alarm signal if your only intent is to see when its not turning?
     
  3. alfacliff

    Well-Known Member

    Dec 13, 2013
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    unfortunatly when the fan fails, it is usually the bearings, and the electro0nics that drive the motor keep going.
     
  4. sumit123

    Thread Starter New Member

    Oct 28, 2013
    11
    0
    So what do you think if i use locked rotor alarm signal fan.Is it save to use or not.
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    are you trying to sense if the motor has stopped,if so use a slotted opto pickup or current sense it.
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    yes its safe and its the easiest way
    They are used all the time to protect critical equipment from overheating if the fan dies.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Mitsubishi use these 3 wire type of fans on their CNC equipment, the third wire has to indicate a high, (fan running) in order to energize the system.
    Max.
     
    Johann likes this.
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