The new sensing unit finally evolved from a breadboard prototype to a nice and shiny PCB.

The feedback works nice and sensitive. It is able to capture the raw water contact too. and reacts to tiny single discharges.

I won't go into details about the parts but the board offers a fully isolated high side shunt current feedback.  A linear optocoupler is used for isolation. The ESP is now fully disconnected from the pulseboard.

PS: Thanks to PCBway for the extra boards.