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AN ELECTRONIC LITESHOW DISPLAY

Part 1ýThe Electronics Behind the Lights
by James Antonakos

Start ý The Big Picture ý Inside a Panel ý The Driver Board ý The 64-Bit Shift Register Board ý Interfacing with the PC ý A Little Math ý The Real Thing ý Sources and PDF

INSIDE A PANEL

Each panel of 64 lamps contains a 64-bit shift register board and eight 8-bit driver boards. The 8 ý 8 matrix of lamps is organized as shown in Figure 2. A particular lamp pattern is formed by clocking 64 bits of data into the panel. The first bit loaded into the panel is the MSB and the last bit is the LSB. Each row of lamps is controlled by its own driver board, which contains optically-isolated TRIACs that control the 120-VAC power fed to each 25-W lamp. Figure 3 shows the overall structure of the panel electronics.

Figure 2ýThe light panel bit assignments for each lamp can be seen here.

Figure 4 shows additional detail, indicating that each panel contains its own GFI receptacle (for safety), DC power supply, and fuses on the driver boards for protection and troubleshooting. Photo 1 shows a back view of one panel. Ribbon cables are used to connect the shift register board to the eight driver boards.

Figure 4ýThe light panel wiring details can be seen here. Note the GFI receptacle and fuse used for safety and troubleshooting purposes.

Photo 1ýHere is a rear view of a light panel showing several driver boards, the 64-bit shift register board (on the right), and DC power supply.

For a student project, the Electrical Engineering Technology Department at Broome Community College asked groups of students to design their own version of a printed circuit board for the driver board. One design was chosen and sent to a production house for fabrication. Many students then helped solder the components onto the driver boards, and others wired up the 64 lamp sockets on each panel. Other students were involved in making the wooden frames for each panel and mounting the eight driver boards onto the aluminum panel holding the lamps. Overall, the faculty and students of our department spent six months building the six panels.

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