Description

A colour scroller, or colour changer, is an accessory fitted in the gel holder of a lantern which enables the colour to be changed remotely, nowadays via DMX but previously via Analogue Control systems. In addition some newer models (like the Wybron Coloram IT) gain additional functionality when controlled via RDM.

Scroller Types

Older Scrollers

Colour Wheel

The oldest form of colour scroller is probably the old colour wheel. This was a wheel which was attached to the front of a lantern and had the ability to change position, consequently chaning the colour. It rotated and stopped dependant on the signal which the motor was receiving. However this was not entirely accurate and didn't allow a choice of many colours.

Buckley comment needing cleanup: The oldest colour wheels I can recall are the Strand units that fitted Patt 23s, info in the Strand Archive http://www.strandarchive.co.uk/control/effects/colourwheel.htm I've never actually used one, so cant recall the control at all, but do recall that the wheel was rotated by a synchronous electric motor. I have definitely seen the motor connected to the same plug as the lamp, though to be fair the socket these were plugged into were non-dim, just switched, in village halls and the like.

Semaphore

The next advancment in colour changers was the semaphore. This was an attachment which had the ability to be controlled remotely via DMX. The way these worked were by placing gels which the person could choose into gel frames. These gel frames would then move dependant on the signal received. Sometimes they were linked up to a lighting desk, while other times they had their own little control box with buttons on and a green button which executed the move.

Buckley comment needing cleanup: The CCT semaphore units were popular, though these were definitely not DMX; they had their own control box which was connected to the changer by means of a dedicated per changer multicore cable. The unit fitted onto CCT SIL profiles. I didnt know (but I guess am not surprised) that Strand made the same sort of thing, but again, this stuff predates DMX by a ways.

Modern Scrollers

These are the scrollers which most people will be familiar with. They are the ones which are currently in production today.

Single String

This type of scroller has only one gel scroll which can be anywhere from 2 to 32+ frames (pieces of gel) long

Dual String

These scrollers use two gel scrolls. These allow, to a certain degree, CMY colour mixing. An example of these are the "Chroma Q Cascade Colour Mixing Scrollers" by AC Lighting on which the first scroll is from yellow - cyan and the second is yellow - magenta.

CMY

These are true CMY (Cyan/Magenta/Yellow) colour mixing scrollers which use three scrolls of gel.

Cabling and Control

Most scrollers use the DMX512 protocol. Traditionally each scroller unit is given an address which is set on the unit itself. The unit is then daisy chained with other scrollers via 4-pin XLR cable and the run back to a power supply often called a 'brain.' The power supply sends the DMX control signal from the lighting desk to each unit along with 24 volts DC. Power supplies can power anywhere from 2 to 64 units.

RDM Protocol

New models of scrollers are moving towards the RDM protocol and are using small LCD/LED screens for addressing and altering other settings on the unit (like the new line of Wybron scrollers). This new method of control allows for easier addressing and the ability to 'talk-back' to each scroller (to get diagnostic information for example).

Channels

Color scrollers utilize from 1 to 4 channels depending on their capabilities. One channel is required for every string of gel (up to 3) and one channel is required for optional control settings. Optional settings include: Remote fan control (ability to control the fan's speed and on/off status), preset color string mixed color positions (for scrollers with multiple strings), preset effects/times, and control over the speed the string moves.

With the newer RDM protocol many more options are available without taking up additional control channels. These can include: light sensor (to see if the fixture the scroller is attached to is on), temperature sensor, voltage sensor, timers, fan control, self test, gel string sensor (gives info on color, use, and if the string is broken).

Head-Feet Restriction

One major factor in the number of units that can be daisy chained together is due to head-feet restriction. Head-feet is defined as the total sum of the lengths of cable from each device to a single power supply. It is a way to account for the voltage drop in the power/signal cable due to the current drawn from each unit and the length of the cable.

Sizes

There are many sizes to fit the majority of lanterns.

• 4 inch (PAR 36)
• 7.4 inch (ETC Source 4 19°, 26°, 36° and 50° units)
• 10 inch (PAR 56 and 64)
• 12 inch (large Fresnel)
• 20 - 30 inch (Thomas 8 Cell Molefay and Thomas 9 units)
• Larger scrollers for ETC Multi-PAR