Berd-Air to Duet3

  • Can give some advice on wiring a Berd-Air pump to a Duet3 board. Should I attach the pump directory to one of the higher current connections (such as OUT2 or OUT3), or use a lower current connector (OUT4 - OUT7)?

    The kit I bought also comes with a "E-Z Switch" that appears to be some kind of opt-isolated PWM controller. (

    I'd like to keep the wiring simple, and I don't have any addition components (diodes, etc) that I've seen mentioned in some of the berd-air duet2 threads.

    Thank you

  • If you use the EZ switch, you don't need any diodes, etc. Also, the input side of the EZ switch can be driven by any output, including the ion.out pins. Were it me, I'd absolutely use that EZ switch, especially given that some of the alternatives could damage the Duet.

    So... do you need a wiring diagram? Or did the berd/ez come with one?

  • @Danal

    Not really needing a wiring diagram, but was just trying to better understand the wiring options given the large number of connection options on the duet3.

    I was also hoping that the EZ switch wouldn't be needed in order to simplify things. Two wires (direct) vs six (2 from the duet3 board, + 2 wires from the PSU, +2 wires from the EZ switch to the pump.)

  • Gary did you get a 12V or 24V system?

  • @Dougal1957 Ordered 24V (to match the rest of my system.)

  • All of the OUT connectors except OUT0 have flyback diodes so they're at least protected from back-EMF. OUT4-9 can provide about 2.5A of Vin each so it depends on what the pump draws. OUT1-3 can obviously handle more. Does the pump itself accept a PWM Vin and are you planing to vary the speed of the pump?

  • @gtj0 said in Berd-Air to Duet3:

    Does the pump itself accept a PWM Vin

    I'm assuming so, but I really don't know. I ordered the pump from '' as part of a kit:

    and are you planing to vary the speed of the pump?

    I absolutely intend to vary the speed of the pump. My understanding is that 100% on the berd air is incredible overkill for part cooling (as well as being noisy.)

    All of the OUT connectors except OUT0 have flyback diodes so they're at least protected from back-EMF.

    Can you confirm this? The wiki page here: implies that only OUT7-9 have flybacks built in

  • This MIGHT work on various Duet outputs that can supply current that the pump needs, and have proper protection. It MIGHT damage the board.

    Me, I'd go with the included switch every time. I'm not willing to risk a several hundred dollar board for not having to connect two extra wires. And, the makers of that pump included the switch for a reason...

    YMMV, of course.

  • Gary

    What I can tell you is that my pump (Chinese one but suspect the same) works fine on PWM and in fact I never need to run it above 25% so far.

    I would measure the coil resistance (preferably at multiple positions of the motor rotation) take the lowest reading you get and calculate the possible inrush current (V/R will give the current) and as long as this is well within the Duet capability you should be fine but as you have the EZSwitch (which is effectively just a opt isolated misfit) then it is worth using that as Danal says just to add an extra layer of protection. You can keep the switch close to your Duet and PSU to keep the wiring to a minimum and it won't hurt to put a flyback diode on the pump even if there is one fitted to whatever is driving it!



  • @garyd9
    shows the flyback diodes.

    As others have said though, the EZSwitch is cheap insurance.

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