A Raw Pixel Circuit Board



I built up one pixel by hand before sending the batch off for fabrication. Note that J1 is mounted from the rear of the unit. The design could definitely be smaller if SMT parts were used. The RS-485 transceiver, the PIC microcontroller and the drive transistors are available in SOIC packages.

A previous version of this design used a ULN2003 driver chip in place of the 2N3904 transistors. Board area is about the same, but the transistors only cost $.03.

Since the only thing on the board running off +5v are the chips, the 78L05 works well and takes up not much space at all.

The LEDs are made by SunLED and are high-flux 'spider' devices. Each pixel contains two each red, blue and green LEDs.

Each pixel attaches to the main wiring harness with 4 crimp connectors. The main harness contains +12, gnd, data + and data - signals. A future revision of this system will likely include separate in and out connectors on each pixel. However, these connectors add resistance and cost to the system.

The boards measure 1.25" x 2.00".



Posted: Thu - December 8, 2005 at 03:11 PM          

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