VLB

VLB may mean:

VLB - Vinblastine antitumor alkaloid isolated from the plant Catharanthus roseus (formerly Vinca rosea), Apocynaceae family. Merck Index

VRB-25

The VRB-25 is a lighthouse optical system designed and built by Vega Industries Ltd. in Porirua, New Zealand. It was originally designed in 1993-95 with the assistance of the United States Coast Guard to meet USCG requirements for a robust mechanism requiring minimum maintenance. It has become the Coast Guard's standard 12 volt rotating beacon. The company's literature says there are more than 400 installations worldwide. More than a quarter of the active lighthouses in Maine have one installed.

Components

A microprocessor controlled 12 volt DC motor drives an array of six or eight acrylic Fresnel lenses around a bulb at one of 248 speeds ranging from 0.5 to 15.9 revolutions per minute (RPM). In the simplest case, all six lenses are used, so that for Boon Island Light, which shows one flash every five seconds, the mechanism rotates at two RPM. Eight lenses are used only when required to achieve more complex characteristics.

Maximum range is achieved by using the slowest possible speed, but for grouped flashes, it is necessary to blank off lenses and rotate the mechanism faster. So, for example, for The Cuckolds Light, whose characteristic is group flashing two every six seconds, all but two of the six panels are blanked off and the mechanism rotates at ten RPM.