|A few years ago I designed a 35x7 LED Dot Matrix display board and more recently wrote an Arduino stetch for it. I like it a lot but also desired a larger display for some applications. I was planning to design something when I ran across this board at Deal Extreme also known as DX.com. Do a search for the SKU: 196521|
This is a photo of the board.
There isn't much technical information on the website and no schematic. So I reversed engineered one. Here is the schematic.
Both the columns and rows are driven by 74HC595B1 latch IC's. There are no voltage dropping resistors or constant current circuits. The SPI signals and power are fed from the Arduino to the male pins. Use female to male DuPont jumper wires. The female socket on the other side of the board allows for easy daisy chaining.
The lack of current control results in slightly non-uniform dot illumination and perhaps not the greatest possible brightness but all-in-all the designers seem to get away with breaking conventional design rules in this case.
The software is a slightly modified version of by other Dot Matrix sketches. Get it here.
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This page written by Roger Schaefer. Last updated January 16, 2014