An automatic lamp changer (or lampchanger) is a device used to ensure that a navigational light such as a marine lighthouse or

aero beacon An aerodrome beacon or rotating beacon or aeronautical beacon is a beacon installed at an airport or aerodrome to indicate its location to aircraft pilots at night. An aerodrome beacon is mounted on top of a towering structure, often a control ...

stays lit even if a bulb burns out. Numerous types exist. The common design elements are an array of two or more lamps (or bulbs), installed on a mounting which can rotate to various positions. Each position brings a different lamp into the

focal point Focal point may refer to: * Focus (optics) * Focus (geometry) * Conjugate points, also called focal points * Focal point (game theory) In game theory, a focal point (or Schelling point) is a solution that people tend to choose by default in the ...

of an optical assembly. Since signal and navigational lights use sophisticated

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultra ...

to focus the beam, lampchangers are designed to position the new bulb at the focal point with high precision. The device automatically detects when the currently active lamp has ceased to function and moves the next lamp into place.

History

The automatic lampchanger was invented by Charles Wallace and patented in 1928. This original model held two headlight lamps from a

Model T The Ford Model T is an automobile that was produced by Ford Motor Company from October 1, 1908, to May 26, 1927. It is generally regarded as the first affordable automobile, which made car travel available to middle-class Americans. The relati ...

automobile. The

United States Lighthouse Service The United States Lighthouse Service, also known as the Bureau of Lighthouses, was the agency of the United States Government and the general lighthouse authority for the United States from the time of its creation in 1910 as the successor of th ...

had these in common use by the 1930s, as they moved to convert all navigational lights to electricity.

Types in current use

Lamp changers in current use may have two, four, or six lamps and use either a spring-loaded mechanism or an electric motor to change lamps when required. They are used in

aerodrome beacon An aerodrome beacon or rotating beacon or aeronautical beacon is a beacon installed at an airport or aerodrome to indicate its location to aircraft pilots at night. An aerodrome beacon is mounted on top of a towering structure, often a control ...

s and marine navigational aids. VRB-25 system diagram

References

{{Lighthouses Lighthouse fixtures