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    Generic pin for PWM

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    • janjohundefined
      janjoh
      last edited by

      Hello!

      Basically, I want to connect a PWM controlled pump to act as a fan. And if possible i would like to avoid using a PWM fan output as it is 12V (and yes, i know i can use a simple voltage divider). But i thought that there must be a more elegant way to do this.

      I found https://forum.duet3d.com/topic/3372/map-general-pwm-i-o-pins-on-extension-header-as-fan but am unable to figure out how to actually do this?

      Any pointers?

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      • dc42undefined
        dc42 administrators
        last edited by

        The fan and heater outputs are open drain (i.e. the fan mosfets connect the FAN- pin to ground), so you can make them whatever voltage you want, by not using the VFAN pin.

        Duet WiFi hardware designer and firmware engineer
        Please do not ask me for Duet support via PM or email, use the forum
        http://www.escher3d.com, https://miscsolutions.wordpress.com

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        • janjohundefined
          janjoh
          last edited by

          Ah, yes. However, since i want 12V PWM to the other fans. That complicate things a bit for me. Well, unless i create a driver stage that handles all fans, but that seem overly complicated 🙂

          dragonnundefined dc42undefined 2 Replies Last reply Reply Quote 0
          • dragonnundefined
            dragonn @janjoh
            last edited by

            @janjoh 12V on 24V power supply? Is that your problem?
            If yes you can simple remove the V_FAN jumper and supply 12V to the middle pin in this header. Then all you fans will be get 12V.
            And easiest way to get 12V from 24V is using a step-down module.

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            • dc42undefined
              dc42 administrators @janjoh
              last edited by

              @janjoh said in Generic pin for PWM:

              Ah, yes. However, since i want 12V PWM to the other fans. That complicate things a bit for me. Well, unless i create a driver stage that handles all fans, but that seem overly complicated 🙂

              If you want (say) a 5V PWM output, just connect a resistor (e.g. 1K) between the FAN- pin of your chosen fan connector and +5V. Do not connect anything to the V_FAN pin of that connector.

              Duet WiFi hardware designer and firmware engineer
              Please do not ask me for Duet support via PM or email, use the forum
              http://www.escher3d.com, https://miscsolutions.wordpress.com

              janjohundefined 1 Reply Last reply Reply Quote 0
              • janjohundefined
                janjoh @dc42
                last edited by

                @dc42 said in Generic pin for PWM:

                If you want (say) a 5V PWM output, just connect a resistor (e.g. 1K) between the FAN- pin of your chosen fan connector and +5V. Do not connect anything to the V_FAN pin of that connector.

                Groaaaaaaaannnnnn... now i feel so.. INCREDIBLY stupid.... GAAAh..

                But thank you. 🙂

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