Connecting 10000uF capacitor (power failure resume)

[techworld]

Hi there..!

Requesting for support on where to connect the 10000uF capacitor in order to implement power failure resume.

Using Duet3 6XD mother board with Raspberry Pi SBC mode....
The RPi is powered using a DC-DC USB converter

I've gone through the documentation but couldn't figure out exactly how to connect the capacitor.

https://docs.duet3d.com/en/User_manual/Tuning/Resume here its given that we need to add a 10000uF capacitor across the VIN rail in order to get more time for the duet board and RPi to save the last data.

In this forum link it's bit confusing on where exactly to add the capacitor https://forum.duet3d.com/topic/19468/resume-from-power-outage-really-only-with-24v/13?_=1680523965649

I'm assuming that we can connect the capacitor as given below

thanks
techworld

[dc42]

@techworld yes that's how to connect it. If you are using a Meanwell or similar PSU that has several sets (typically 3) of output terminals all connected in parallel, you can connect it to a spare pair of terminals if you have one.

Note, a few types of PSU won't start up with such a large capacitor connected to the output.

[techworld]

Thanks...! @dc42
Do we need to connect resistor in series with the circuit or only capacitor is enough..?

[dc42]

@techworld just the capacitor is enough if the PSU can take it. If it can't handle it then you need a resistor and high-current Schottky diode as well.