On December 12, 1891, the Lighthouse Board issued a "Notice to Mariners" announcing that a long-sought steam-powered fog signal had been installed at Point Betsie, featuring two 10-inch whistles like those then used on locomotives. The 22 by 40-foot building, made with corrugated iron siding and roofing and a smooth iron lining, housed two sets of boilers and machinery to guard against equipment breakdown. Its current exterior is a replica, while the interior walls are original. The boilers were wood- and coal-fired until the early 1920s, when electricity reached Point Betsie and the equipment was replaced by a more powerful compressor-driven diaphone. Mariners guiding ships through thick fog welcomed the greater protection of nearly instantaneous two-toned sound blasts every 30 seconds, and the change likely also eased the work of the light station's three-man crew. Another important technological innovation came in the mid-1920s, when a radiobeacon was installed using two tall antenna towers immediately north of the building; concrete blocks still visible at the northwest corner served as the base for the west tower. Advances in navigational technology gradually made the diaphone and radio beacon obsolete, and most of the equipment was removed in the mid-1970s.