A few weeks ago I found an arduino micro controller board lying around doing nothing.
It happened to be around the time that I was wondering how to be able to automatically measure the energy usage.
We still have an old fashioned disc energy meter which is not compatible with any external read out.
some people tried with varying success to interface the disc with diodes and such.
I decided to introduce an extra energy meter which does have a S interface.
So after the read further you can read the “how it’s made”