(This is the original index page for the LED sign. Since the page has been updated, this page has been moved to a different location for posterity. Enjoy (or not)). Again, this is an OLD PAGE. Perhaps you were looking for current page?
Project History:I have always wanted a scrolling LED sign that I could program with whatever message I wanted. I had schemed about various ways to design one using a ton of logic circuitry and LED buffer/drivers. Fortunately, at a not-so-recent trip to the first Saturday sale in Dallas, I managed to pick up a junked one for $10US. There's both a positive and negative side to this. On the upside, I have a sign that appears to be in quite good condition, and I feel quite confident that the LEDs themselves and the buffers are in good shape. Unfortunately, I have no technical specifications on the sign and therefore have to do some hardware hacking. I guess that's the fun part.
ImagesNote: Some of these images are rather large in order to preserve detail. They may or may not fit completely within your browser window. Either scroll around or save them and view them in a graphics viewer.
Plans/Plan of Attack:Decypher power connector and apply 110VAC to see what the sign does - 5/19/99 - Done! I took a long hard look at the power connector (with the help of my new Fluke multimeter!) and decided where the power lines and ground lines were to go. Unfortunately, when power was applied, nothing happened! I was at least hoping for a default message or perhaps some depressing blue smoke...but alas, the sign failed. See below for more details.
Attempt to find keyboard interface specificationsElse
Figure out what signals to send over the keyboard interface to change the display
Design interface from PC serial/parallel port to keyboard connector
Design PC software API for driving the sign and/or controller.
Decode the lines that go from the the controller board to the LED driver board (completed)Naturally, I'm hoping that the sign will power up properly and that I can use it with minimal hardware modifications.
Supply power and test control signals to the control lines in attempt to change the display (accomplished)
Design custom microcontroller-based driver circuit (in-progress)
Sign Specifications:As discussed below, I haven't had much time yet to do any serious hacking