A color changing device for conventional theatre fixtures. Invented in the early 1980's by Keny Whitright (then working for Great American Market, now president of Wybron), with the "Colormax," and later "ColorWiz," products. Uses a gelstring, consisting of 10-32 frames, that rolls in front of the beam to change colors, controllable via DMX. Major manufacturers include Apollo, ChromaQ, and Wybron. Some, such as the Morpheus Colorfader, Wybron CXI, and Apollo MXR use two or more strings to allow for subtractive color mixing to achieve 100 or more discrete colors, see below. Color scrollers (with the exception of rare "stand-alone" units such as Wybron's discontinued The Scroller), are powered by a separate power supply (PSU) normally providing 24V DC to the scrollers via 4-pin color changer cable. DMX data is delivered from the lighting console to the PSU via 5-pin DMX cable, then travels along the "daisy-chained power/data circuit" to each scroller. The color scroller PSU is often positioned in the center of the pipe, allowing a group of scrollers to provide color changing capabilities to lighting instruments (ellipsoidals, PARs, etc) on the stage left as well as the stage right side of the PSU. Many manufacturers highly recommend using a 4-pin cable to "loop-back" the last scroller back to the PSU, so as to boost the line voltage available for all units on the circuit. As a secondary benefit, the returning 4-pin cable will terminate the DMX data when plugged back into the PSU. Copied directly from this post by [user]Icewolf08[/user]: Multi-String Units: 2-String: Includes units such as the Wybron CXI and Apollo MXR. Both use individual frames of cyan, magenta, and yellow (two per on each of the two strings) to subtractively mix the desired color. While a live color fade is possible, it will appear "steppy," due to the individual frames. 3-String: Morpheus ColorFader, three individual strings of graduated saturations of CMY. In theory, these provide 256^3= ~16 million different colors. Syncrolite OnmiColor, using DichroFilm colors. Pricy alternatives to conventional fixtures with any of the above scrollers are the: Ocean Optics Seachanger, Wybron Nexera, and HES/Barco ColorMerge, all of which are complete, non-moving, fixtures using variable glass dichroic flags. From the olde phart department: Here is an absolute truth that many of us have learned over a lot of years: Any moron can make one scroller that works. Now show me 100 scrollers that all go to exactly the same place, with the same DMX value, with old and new gelstrings, over a long period of time. That's harder--much harder! Sometimes the cheapest is not always the cheapest! Ever wonder why the ETC Revolution got a retrofit Wybron scroller more than two years after its introduction? Hmmmm... Lots more useful information in this thread: http://www.controlbooth.com/forums/lighting/11208-color-scroller-question.html.