Inspired by Dumbledore's Army in the 5th Harry Potter.
There are two coins, the Dark Lord and the Death Eater.
When the Dark Lord is updated, by physically moving it into position, the Dark Lord transmits a time and a date.
The Death Eaters display that information when it is transmited, by physically moving into the correct position.
For communication, the RFM23BP is used, for high power, long range signal.
The schematics for this project can be found on Upverter, at https://upverter.com/rifkinni/795cc7315e6068cc/Bewitched-Galleons/