“A Chorus Line” Strip Lights

Pennsylvania Shakespeare Festival | Center Valley, PA | June-July 2022

Overview

This project was completed for temporary installation and use during the two week run of “A Chorus Line” at the Pennsylvania Shakespeare Festival in Center Valley, PA.

The purpose of this project was to create a set of lights which looked like typical strip lights, but would only appear for the number “Music in the Mirror” and be fully hidden for the rest of the show. Due to the construction of the pit and the D-ring placement for the pit’s safety net, the space for these lights was limited. No standard lighting fixture would operate in the limited space as a moving strip light. Thus the need for a custom fixture presented itself.

For simple cue-to-cue programming, the unit needed to operate as if it was a chain of standard 3 circuit strip lights–with every third port operating as a single unit. Its motion also needed to be controlled from the lighting console for easy in-show operation.

Details

The project itself consisted of 8 “boxes” which would each fit in a slot between two of the pit D-rings, the safety net, and the stage edge. Each box had three ports in it which would emit light onto the stage similar to any other footlight. These boxes would then be connected together on one long beam which would raise and lower on three actuators allowing the lights to be seen for the single musical number and remain hidden for the rest of the show.

Each port held a 24 RGBW LED section of LED tape with the white LED at roughly 3200 Kelvin. These were controlled by 8 individually addressable chipsets onboard the LED tape. The interior of each port was covered in aluminum foil as a reflector and Roscolux R111 was used as diffusion over the port in order to homogenize the output.

The movement in and out of the pit was facilitated by three 4” actuators. Implementation of hall sensors for position detection was attempted, but not achieved due to the production timeline. Instead, the project utilized an auto-stop switch built in to each actuator. This allowed a continuous “extend” or “retract” command to be sent even when in a fully extended or retracted state without the risk of ruining the device or burning out the motor. The final product was able to be in two states: either fully extended or fully retracted.

The unit was controlled by DMX512 from the lighting console. This data was processed by an Arduino Mega which output data to the SK6812 LED chipsets. Using looping, every third port would be controlled as a group–24 ports total, 8 ports per group. The Arduino also sent control data to three H-bridge motor controllers for the actuators. See Table 1 below for the DMX chart.

DMX Channel	Control Parameters	DMX512 Ranges
1	Motor Control (Elevation)	000-127: Fully Retracted 128-255: Fully Extended
2	Red 1	000-255: 8-bit dimmable
3	Green 1	000-255: 8-bit dimmable
4	Blue 1	000-255: 8-bit dimmable
5	White 1	000-255: 8-bit dimmable
6	Red 2	000-255: 8-bit dimmable
7	Green 2	000-255: 8-bit dimmable
8	Blue 2	000-255: 8-bit dimmable
9	White 2	000-255: 8-bit dimmable
10	Red 3	000-255: 8-bit dimmable
11	Green 3	000-255: 8-bit dimmable
12	Blue 3	000-255: 8-bit dimmable
13	White 3	000-255: 8-bit dimmable