GEMINI
MEMORY LIGHTING CONTROL
OPERATOR'S HANDBOOK
INTRODUCTION
1.1 GENERAL
Gemini is a new memory Lighting control system which is intended for
use in medium sized theatres and television studios. It offers many of
the sophisticated facilities previously available only on much more expensive
systems and has an added advantage in that it often may be incorporated
in an existing manual system with the minimum of rewiring.
The system consists of a Control Console which may be supplied for desk-top
mounting, as a free-standing console, or built into a desk assembly with
other equipment, and a colour monitor which provides the mimic display.
Gemini can control up to 180 Lighting channels and has a Channel-to-dimmer
patch facility which gives the flexibility often needed in the modern
theatre and television studio. The dimmer control outputs are multiplexed
and can drive any of the dimmers in the Rank Strand range, via a special
interface which must be fitted in each - dimmer rack; this interface is
supplied already fitted to the latest, multiplexed dimmers.
In addition, the system may be used with the Tempus M24 Multiplex Interface
unit. This produces the dimmer control signals for 24 - lighting channels
and will also accept inputs from another Lighting control system, e.g.
an AMC desk; the contribution from the second system combines with the
output of Gemini on a 'Highest-takes-precedence' basis and may be recorded
in the Gemini memories. Versions of the Multiplex Interface unit are also
available to permit Gemini to control dimmers from other manufacturers.
Gemini uses an intelligent memory packing system, whereby only those channels
which are On in a Lighting state are recorded, so that the amount of system
memory used for each memory depends on the number of channels which are
On in that cue. The number of memories available will therefore vary from
production to production, but will be found to be adequate for all but
the largest. The memory may be supplemented, if required, by the optional
floppy-disc unit, so that, on the rare occasions when additional memory
is required, cues may be loaded very quickly from floppy disc. The percentage
of the memory which is 'in use' is shown on the Video Mimic.
Gemini uses battery-maintained electronic memories which will retain their
data for at least a month if the system is not used. If longer term storage
is required, the floppy-disc unit must be used.
1.2 CONTROLS
The Gemini control console provides all the facilities necessary for effective
lighting control. The panel consists of six sections: Channel Control,
Red and Green Playbacks, Memory Control, Output control and Sub-masters.
1.2.1 Channel Control
Comprehensive facilities are provided to vary the intensity of any individual
channel or of a number of channels by means of a decimal keypad and a
fader-wheel. Levels may also be set by use of the '@' key. Groups of channels
may be controlled by directly calling up the channels, or by selecting
previously recorded groups or memories. To provide clear information to
the operator numeric displays above the keypad show the last number entered
and the level of the selected channel.
Any modifications made by the channel control may be effected in the system
output store (i.e. their effect will be seen live) or in any one of the
eight Sub-master stores.
It is possible, either for identification or special effect, to flash
the selected channel or channels to full or zero.
1.2.2 Playbacks
These controls provide the means by which memories are normally recalled.
Memories are selected on the MEMORY CONTROL keypad (see next section)
and recalled using either FADE button. The recall action takes place in
the time set on the associated Fade Duration controls (one for channels
fading up and the other for those fading down), the time being variable
between instant and 20 minutes. An infinity position on each control allows
either part of the associated fade to be stopped at any point.
Other facilities include the use of recorded fade times, manual fades
and automatic memory sequence.
1.2.3 Memory Control
Once a scene has been lit it may be recorded in the system's permanent
memory. This is done by allocating to the scene a unique number by which
the lighting state may be subsequently identified.
The memory numbers are called up using a decimal keypad on the Memory
section of the control panel. Numbers may be in the range 0.1 to 999.9
(0.0 is not available), but it is recommended that integers are used initially
and scenes recorded in the running order of the show. This allows memories
with decimal points (e.g 36.5) to be inserted Later if required. The number
of the currently selected memory is displayed in a window above the Memory
keypad.
It is possible at any time to record the current Lighting state or the
state set on any of the eight Sub-masters.
A Lockable keyswitch is provided to protect the memory from over- recording
and to allow all or some part of the memory to be cleared. If an attempt
is made to over-record an existing memory a warning will sound and the
recording will not take place. Should this be a deliberate action, the
record push should be pressed twice in rapid succession for a successful
recording.
A Link facility is provided whereby an existing memory may be linked to
the next memory required in the sequence of a performance. In this way
a show which has been recorded in random order may be strung together
to run as required. This facility is also useful for chase loops of memories.
The Gemini system allows the operator to record a fade type, fade times
and a wait time with each memory. When used in combination, these make
it possible to set-up complex fade sequences which take place completely
automatically.
1.2.4 Output Control
This section of the panel has a master fader which controls the output
of the Gemini system. There is also a blackout switch, a Record Total
('REC 
’) push-button
and a Memory Recall ('
MEM')
button.
1.2.5 Sub-masters
This section of the control panel provides eight stores, each of which
may hold a complete lighting scene. The stores each have a Sub-master
fader which proportionally fades the content of that store to the output.
The eight stores normally interact between themselves and with the main
system on a 'highest-takes-precedence' basis, i.e. if a channel is On
in two or more active stores the output Level will be the highest of them.
With these controls it is possible to preset up to eight Lighting scenes,
so that they are readily available. Each scene may then be introduced
by raising the appropriate fader - a very useful facility if rehearsal
time has been limited and it is necessary to 'Vamp' the performance. The
panel also allows channels or complete memories to be simultaneously balanced
against each other before the total effect is recorded.
An alternative method of using each Sub-master (Inhibit mode) allows
the operator to proportionally reduce the dimmer levels of the channels
which are On in the Sub-master store. A common use for this facility is
in the control of Front-of-house lighting.
Channels may be set or modified in any Sub-master store by the Channel
Control (operating in Sub-master mode). Any previously recorded memory
may be loaded into a store by calling up its number on the Memory keypad
and pressing the appropriate memory recall (‘MEM’)
button.
Facilities are provided to display and interrogate the contents of each
Sub-master store. A master fader (A-H) is also provided for this section
of the control panel.
1.2.6 Video Mimic
The standard mimic display is a colour Video Display Unit (VDU).
In normal operation the main part of the screen shows up to 180 channels
and if a channel is On, its number appears on the screen, together with
its level, expressed as a percentage; channels which are Off have their
channel number displayed dimly. Any channels under the control of a Channel
Controller are identified on the mimic by their entries appearing in inverse
video. If required, channels may be assigned numbers relating to their
geographic position in the installation.
The bottom section of the display shows the current status of the various
parts of the control panel, e.g. channels under control, memories fading,
selected memory, etc. Different colours are used for the different areas
on the screen in order to enhance the clarity of the display.
The mimic display may be used to show the current scene being output,
the contents of any of the eight Sub-master stores, the levels recorded
in a selected memory (so that it may be previewed before use), a list
of the memories recorded or the assignment of channels to dimmers. In
all of these cases the title of the display is shown on the top line of
the screen. Paging is provided for use when displaying a list of memories;
this will normally be too long to display in its entirety.
1.2.7 Memory Back-up System
A simple, independently powered control system with an electronic on/off
memory is available to act as a back-up to Gemini.
The control panel has eight patch master faders to which anyone of
ten eight-memory 'presets' may be assigned; a keypad is provided for the
selection of dimmers and presets. Dimmer may be set On or Off individually
or in groups using the keypad, or the On/Off states of the dimmers contributing
to the current Lighting may be copied into the selected memory.
1.3 OPTIONAL EXTRAS
1.3.1 Floppy Disc Unit
For Long term storage of Lighting states, e.g. for use in repertory theatre,
an optional floppy disc unit may be supplied. This enables some or all
of the memories recorded in the Gemini system to be duplicated on a 3.5"
magnetic disc. The disc may be removed from the drive unit and stored
until that production is next performed. The Gemini memory may then, of
course, be over-recorded.
Floppy discs may also be used to store the contents of the memories during
periods when the system ;s in infrequent use and the memory retention
period of one month may be exceeded.
1.3.2 Printer
A computer type dot-matrix printer is available for connection to the
Gemini system. This may be used to produce paper copies of memories, the
channeL-to-dimmer assignment and the recorded special effects.
1.3.3 Special Effects Panel
The increased use of Lighting to accentuate pop-music has produced a need
for a Lighting control system which may be used in variety entertainment
to provide programmable automatic Lighting effects. Such effects include
automatic chases, sound activated Lighting, automatic flashing and sequencing
effects. The use of these effects is not, however, restricted to variety
entertainment and the Gemini effects panel is very useful for dramatic
productions where continually changing Lights, such as a flickering fire
or a flashing neon sign, need not monopolize the operator's time.
The Gemini effects panel may be set-up to control both individual channels and, in conjunction with the Sub-master stores, complete memories. An effect may be one of several types (e.g. Chase, Regular or Pseudo-random Flash, Sound-to-Light) and may include instructions to Load new memories into the Sub-masters or to synchronise the effect with the start of a fade on a Playback. Each effect may be executed a specific number of times, may be set to run for a defined time, or may continue until stopped, either manually or by the start of a fade on a Playback. Up to 99 separate effects may be recorded and a number of different effects may be performed simultaneously.
1.3.4 Remote Control
Provision is included in Gemini to accept commands from the standard Rank
Strand Rigger's Control or from a portable Designer's Control. Details
of the operation of these units are published in separate handbooks, available
from Rank Strand.