duet 3 power sbc from dedicated power supply



  • I have a 24v power supply connected to the duet 3 and a 5v 10a buck converter I will use to power additional electronics.
    Its safe to power the sbc from the 5v buck converter removing the 5V->SBC jumper? I have read about ground loops in other threads but I'm not an expert so I tink its safer to ask.



  • You'll have to use a shared ground for the SPI signaling so faulty wiring could result in current flowing through the ribbon cable.

    dc42 posted something about potential (theoretical?) damage to the Pi if the Pi is connected to a unpowered Duet, as such the reccomendation is to always power both from the same 5v supply through the ribbon cable, be it internal or external to the Duet (and set jumpers accordingly)



  • Ground loops cover a very large topic... but the overwhelming "real world" problem starts with a PC providing the USB, where that PC is powered from a given wall (mains) socket, and the thing the USB is plugged into (Duet, Pi, other) being powered from a DC supply that is plugged into a different wall (mains) socket... and it turns out that a flaw in mains wiring (house or building) makes the ground (and/or ground and neutral in the USA) in those two different wall sockets be at wildly different voltages.

    Again, it is a very broad topic... but the above covers 95% of real world cases.

    The point being: If you have a SINGLE wall (mains) connection for the 24V supply, that implicitly means there is a single one for the 5V buck... and that is quite difficult (not impossible, but very very difficult) to create a damaging loop, because everything is tied together.

    So go for it.

    As an aside, personally, I avoid the USB problem by always using a laptop on battery.



  • @bearer said in duet 3 power sbc from dedicated power supply:

    You'll have to use a shared ground for the SPI signaling so faulty wiring could result in current flowing through the ribbon cable.

    dc42 posted something about potential (theoretical?) damage to the Pi if the Pi is connected to a unpowered Duet, as such the reccomendation is to always power both from the same 5v supply through the ribbon cable, be it internal or external to the Duet (and set jumpers accordingly)

    ok, so in my case is safer if the sbc provide the 5v to the duet.


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