Belt Gizmo

The "Belt Gizmo" is a device worn on the Ghostbusters' belts. While its true purpose has not been revealed, it is commonly thought by fans to be a type of warning or read-out system for the Proton Pack. Featured in both films and the 2009 video game, it is nonetheless an integral part of the Ghostbusters' equipment.
The main circuit board is from a 1972 Sanyo ICC-808D calculator, while the boards used in Ghostbusters II appear to be plastic replicas based on the original design. The motherboard sits in a modified tape measure holder that connects to a smaller "daughterboard" via a black coil cord. The display is normally comprised of eight nixie-tubes and a letter box, although some of the circuit boards used in the films had anywhere from 8-11 tubes. In Ghostbusters II, the nixie-tubes were replaced with ordinary plastic tubes inserted with rainbow ribbon cable. Ray's Belt Gizmo from the Ghostbusters Movie Poster Various Belt Gizmos from Ghostbusters II NOTE: Not every Sanyo ICC-808D circuit board is identical; Sanyo would frequently change the chipset and other electronics of the calculator without modifying the outer case. However, due to the rarity of nixie-tube calculators from this era, most fans opt to build their own replicas from scratch or existing components.