That is why I was interested in demagnetisation, since lighting might be sometimes unusual upward, not downward, so I'd like to be able detect three states of such ferrite toroid core, which was passed by lighting hit to/from ground
Well you had four years, so I went ahead and tried a square loop core, and a BBQ piezo igniter mechanism to simulate the current pulse to a real Earth rod in the ground, and all appears well
The toroid PCB is the only part that has to be mounted outside, and the reader/resetter is only used to read and/or reset the core's magnetisation state.
I’ve heard for some lightning can drive electron current from the Earth, upward too, so it might take two cores to read both types of lightning,
starting with both cores set in opposite directions, and looking for an event that sets them both in the same direction.
I’ll try a proper connection from an antenna mast, to shunt current normally, but I assume enough current would flow through an extra (and thinner) wire too.