Notes taken from Michael Gillette’s Designing With Light

 Company Switch  A disconnect box to which portable dimmers may be connected  Normally 240 VAC  Located in wings

 Every theatrical lighting system is made up of three components  Dimmers  Dimmer Control  Electrical Distribution

 Two kinds of Dimmers  Mechanical  Electronic

 Involved direct physical movement of mechanical components, not frequently used in theatre anymore

 Resistance Dimmer – Archaic dimmer using a variable-capacity resistor  Lights off - resistance increased energy converted to heat and does not reach the lamp  Lights on - resistance decreased and current reaches the lamps  Difficult to use, requires a lot of space,

 Saltwater Dimmer  Oldest type of dimmer  Involved dipping metal plates attached to one leg of a circuit into salt water with another set of plates already immersed in the water.  Current dependent on depth of metal plates being dipped.

 Use a low-voltage current to regulate the high- voltage current

 Autotransformer Dimmer  Rarely controls stage lights, but sometimes house lights  Control switch in booth regulates a mechanical linkage that controls the dimmer and enables it to raise and lower the lights  Motor runs a single speed so fades cannot be controlled

 Autotransformer Dimmer

 Silicon Controlled Rectifier Dimmer (SCR)  Operates on a gating principle  On for 1 second – full intensity  On for ½ second, Off for ½ second – 50% intensity  On for ¼ second, Off for ¾ second – 25% intensity  Solid state power transistor  No moving parts, reliable

 Silicon Controlled Rectifier Dimmer (SCR)

 Digital Control Systems for Electronic Dimmers  The new “Standard”

 Digital Control Systems for Electronic Dimmers  Analog  Requires a constant signal  Every dimmer in the system must be connected to the light board by its own control line  Line –The wires in low-voltage control systems

 Digital Control Systems for Electronic Dimmers  Digital  Discrete (separate and complete )steps  binary code, on, off, 0, 1  Multiplexing – can send multiple messages at the same time

Analog Digital

 Group Master  Individual dimmers controlled by a submaster, which is controlled by a grand master

 Preset  Two-scene Preset, Three-scene Preset  Controls for each dimmer are repeated for two or three scenes  Dimmers can be set up for each scene and using a fader can be shifted from scene one to scene two

 Combination  Combines preset and group master  Provides more options and flexibility

 Computer Memory  Most flexibility  Hard Drive – Device for storing and retrieving data  Back-up disk  Volatility – Nonpermanence

 Computer Memory  Channel Control – An electronic patching system in which one or more dimmers can be assigned to a control channel which in turn controls the intensity level of those dimmers  Group – grouping of two or more dimmers/channels under one controller

 Computer Memory  Timing capabilities  Fade-in – gradual increase in intensity  Fade-out – gradual decrease in intensity  Split time fade – Fade up and out are at different rates  Delay - Refers to the time interval that the second part of a split time fade follows the first