Cooling Fan for the Electronic

  • Hello Everybody,

    i wanted to use an fan to cool my electronics with an fan, it works but is way to powerfull (24V 1.1A),
    so i am trying to control it via PWM (4pol fan)

    current connection: +red and -black connected to always on fan, and pwm yellow to + of Fan 2 on DuetWifi (white one is not in use)

    tried different configurations but can not get the fan to slow down
    (if i unplug the yellow it stops, but cannot get it to stop or slow down using g-code or the slider in the machine control)

    any ideas what to change?




  • administrators

    @phil_ae the PWM signal is on the GND side of the PWM fans. The "+" side in VIN and is not modulated.

  • thank you very much


    edit: does not work, i start to wonder if there is something wrong with the fan
    edit2: my fault, it has 4 pins, but you can control it with the voltage combine +red/yellow and -black,
    then i can just use a voltage between 7 and 24v...

  • administrators

    It should work if you connect the PWM input wire to the FAN- side of a controlled fan output and the red and black to an always-on fan output. But you might have damaged by connecting the PWM input to +24V. Alternatively, if it stops when you disconnect the PWM input wire, you might need to connect a resistor between that wire and +5V or perhaps +24V, as well as connecting it to a FAN- output. You may also need to increase the PWM frequency to 25kHz.

    Where did you find a 24V PWM-controllable fan? They are not common.

  • that was my mistake, i thought is was a pwm fan because it has 4 wires, but it turns out to be a normal dc fan.
    It works as intended by connecting the red and yellow to the + and the black to the - and leave the white one unconnected.

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