At some spot (call it, say, S1) I have a 3-way switch with two incoming travellers from another 3-way switch downstairs (say, S2) and for some reason I cannot easily rewire things between S1 and S2.
I would need a (full) hot wire at S1 and there is none. So I thought: in theory, at any moment in time, exactly one of the two travellers is hot. Is there some device that I could wire at the end of the two travellers at S1 that would recover a permanent hot wire, switching automatically from one traveller or the other?
This is S1. The two black wires are the travelers, the two white wires go to two separate lamps (and are bridged).