How big a 5v power supply needed for Duet 3 and RPI4?
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I have edited my reply as i was working from memory and thought there was another protection diode where there is not (thanks oozebot for checking the voltage drop).
There is only one diode drop and its thus possible to have 5.x volts on the 5V exp header and then have 5V on the pi header (x depends on the exact diode drop).
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And regarding using the GPOI header to power the 5V on the Pi (like the Duet does). Connecting an unregulated 5V supply to those pins is not recommended (see a long discussion about it here)
https://raspberrypi.stackexchange.com/questions/1617/how-do-i-supply-power-through-the-gpio
In the case of the Duet powering the pi the internal 5V regulator is regulated with over current protection, however as has already been printed out a RPI4 with HDMI screen and other peripherals will be too high current for the internal regulator which it why powering the Pi from its own official supply is the safest option.
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OK, great! This makes me feel much better about the direction we took as we are not recommending any peripherals other than a webcam.
And to the OP - if interested, the 5v power supply we are using in the photo I posted is a Meanwell LRS-50-5
https://www.meanwell.com/productPdf.aspx?i=399
Thanks
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I use a meanwell RD-65a to supply 5/12v, combined with a meanwell 150w 24v psu (I have a ac heated bed). The Ed-65a works extremely well and is fanless so it’s quiet.
