Control Power Supply Fan from Duet Wifi



  • Hi guys ☺

    I built an Hypercube Evolution controlled by a Duet Wifi instead of classic RAMPS solution: it's fantastic, another world 🙂

    I'm trying to find a solution to lower the noise of my printer and, after have changed the hotend fan (e3d v6) with a Noctua 40mm fan (powered by a dc dc step down), one of the noisest part that still remains is the power supply fan.

    My power supply is a classic 24V 500W and the fan inside is a normal 60mm that it's always on.

    I already tried to exchange the fan, but the silent ones like Noctua are too big to stay inside, so I have to find another solution.

    My idea is to use the DuetWifi to control the power supply fan.

    I think that the power supply fan inside is a classic 24v, so instead of modify the fan with resistors/potentiometers or others strange solution to modify the speed, maybe I can use one PWM port of the Duet to change the speed of the fan?

    The question is: is a problem connect the fan inside the power supply directly to the duet pwm port?

    The next step, it the first works, is to insert inside the power supply a classic thermostatic sensor to watch the temperature and regolate the speed of the fan on the fly.

    How should I modify the configuration in this situation? The temperature range will not be too much hot, so how I should set the PID in this scenario?

    Thanks to everyone 👍



  • I modified my PSU to have a thermostatic-controlled fan:
    https://www.youtube.com/watch?v=LNyZnfy3bRE&t=688s

    With a simple thermo-switch: KSD9700 in the normally-open variant, that closes at e.g., 50°C and turns on the fan.



  • @resam Yes, I know this solution, the only problem is that will works only at full speed and the temperature range on the KSD9700 is not so great (10°C degree for the switch from on to off is too much).

    I need something more customizable: more precision on temperature and fan speed variable, this is why I asked about PWM port 🙂



  • What about just getting a quieter fan?



  • @brisma

    You should be able to connect the fan to the Duet but you'll have to hack your power supply (cut or disconnect the wires from the PSU to the fan , then run extension wires from the fan to the Duet). Note, it may or may not run in PWM mode (some fans simply don't). To get it to run in thermostatic mode, varying the speed with temperature, you'll need to firstly be able to measure the temperature. That can be done by attaching a thermistor somewhere on the PSU with a dab of epoxy adhesive or some such. Then you use M305 to set up a virtual heater. This will also give you ability to monitor the temperature using the web interface. Then you map the fan to the virtual heater using M106.

    As an example, suppose you configure the thermistor to be something like this:
    M305 P103 X2 S"PSU Temp" Tnnn Bnnn Rnnn (use values for T, B and R to suit the thermistor)

    Then you could use something like this
    M106 P2 S255 I0 F250 H103 T30:50

    That example would mean the fan would start to come on at above 30 deg and reach full speed at 50 deg C but of course you can use whatever values you like.

    HTH



  • @phaedrux The problem is that all the silent ones are typically 15 or 20 mm thick, but the supply can contain only 10mm 😞



  • @deckingman said in Control Power Supply Fan from Duet Wifi:

    @brisma

    You should be able to connect the fan to the Duet but you'll have to hack your power supply (cut or disconnect the wires from the PSU to the fan , then run extension wires from the fan to the Duet). Note, it may or may not run in PWM mode (some fans simply don't). To get it to run in thermostatic mode, varying the speed with temperature, you'll need to firstly be able to measure the temperature. That can be done by attaching a thermistor somewhere on the PSU with a dab of epoxy adhesive or some such. Then you use M305 to set up a virtual heater. This will also give you ability to monitor the temperature using the web interface. Then you map the fan to the virtual heater using M106.

    As an example, suppose you configure the thermistor to be something like this:
    M305 P103 X2 S"PSU Temp" Tnnn Bnnn Rnnn (use values for T, B and R to suit the thermistor)

    Then you could use something like this
    M106 P2 S255 I0 F250 H103 T30:50

    That example would mean the fan would start to come on at above 30 deg and reach full speed at 50 deg C but of course you can use whatever values you like.

    HTH

    Ok, i will try with this solution... in the stock fan can support the PWM 🙂



  • @brisma

    ......or another option (but this might be a bit extreme for you) is to do what I do and use a mains powered bed heater. Then you can use a much smaller, fan less power supply (which of course is totally silent).


 

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