Hi there,
unfortunately the hollow plug of the power supply (Reichelt MCP 1800101) does not fit for the core board.
It has a hollow plug, Ø 5.5 / 2.1 mm which seems just not to fit in.
Therefore I search in my old boxes to find another plug and I am happy to have one.
I assume there´s a diode protecting the circuit, but to be sure, the pin assignment is plus for the inner pin and minus for the outer ring, right?
According to the BOM, PJ-079BH is a 2.5mm part, so the DC plug should match this.
There is an alternative 2.1mm (listed as 2.0mm…) DC jack on Mouser: 490‑PJ‑079AH
The center pin is +V, the outer sleeve is 0V, but all would be protected by a series diode. You can also see this printed on the case:
We found this to be a good power supply (2.5mm barrel):
This one:
Hi,
perfect. I was so focussed on the pcb that I didn´t see the print on the housing.
Thanks for the quick reply.
You’re welcome! Have fun! 
