A solid state switching circuit for energizing a lamp (L) is connected around a fuse (12) across an AC supply for detecting a voltage differential at the opposite sides of a blown fuse and applying that differential across the control (g) and switching (c) electrodes of the solid state switch (SCR) to...http://www.google.co.uk/patents/US4691197?utm_source=gb-gplus-sharePatent US4691197 - Blown fuse indicator
