Hi Qiaozhi,
If I am not mistaken, the schematic Robert posted was the amazing Robertoro LRL. This was a static detector with a noise filter, kind of an advanced Zahori. I think this is not the same exact circuit that the Iconos uses. Maybe the Iconos uses coils, because I see no telescoping antenna on the Iconos like the amazing Robertoro.
But where is the amazing Robertoro schematic? It was removed from the forum when the old Robert screen name was banned. Maybe Robert can post the schematic for this amazing Robertoro so we can all build it and see in our own hands if LRLs work to find treasure or not.
Best wishes,
J_P