7×10 LED Moving Sign

The project uses no microcontroller, its only based on an EPROM and multiple counters. As in most electric signs, the LEDs are matrixed, and strobed very quickly to make it possible for all 70 LEDs to appear lit. This sign is strobed horizontally, unlike most large signs which are strobed vertically. It was built this way because electrically its much simpler. The eprom has 8 outputs, 7 of them are used to drive the 7 horizontal rows.

The EPROM outputs are not strong, so they are buffered. The 10 vertical columns are activated in sequence, giving a 1/10 duty cycle. The 8th output of the EPROM is used to drive the reset for all the counters, so the circuit loops when empty memory is reached, allowing for short or long messages. With a 27C512 eprom(64k bytes), messages and animations can be almost a minute long!

LED Moving Sign: [Link]