Fan on only when drivers working?

  • Hi all,

    Is there any easy way to configure a given fan to turn itself on when the motor drivers are working? I know Marlin has something like that but I haven't seen anything similar on the Duet Wiki.

    My idea was to install a third themistor and fix it close to the X or Y driver and set up an additional fan to be temperature controlled in reference to that thermistor. But any better idea is welcomed, of course.


  • Moderator

    If this is on a machine with heaters that will be active you could tie the fan to the heater as an analogue for the drivers being used.

    Or tie it to the MCU temp, which also assumes that as the drivers and cpu heat up during use that a fan ties to the MCU should be able to keep the entire board cool enough.

    Or, you could add a fan command to the start gcode that enables a certain fan at the start of the job, and then another in the end gcode that turns it off again.

  • Great ideas and simpler solutions. Nice combo, thanks.

  • If you're actually worried about things getting too hot, simply run the fan any time the power is on- i.e. connect it to the power supply. If the noise concerns you, use a fan that is rated for higher voltage than your system (line or DC). I have a 127mm 208VAC fan blowing against the Duet board whenever the power is on. We have 117VAC line voltage here, so the fan turns slowly and quietly but moves more than enough air to keep things cool. 24VDC fans will usually start and run reliably, slowly, and quietly on 12VDC, or you can install a buck or boost converter with the fan to tweak the voltage to it a little as needed. Converters that can drive fans are very small and dirt-cheap.

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