controlling moving sign display


Thread Starter

tee topsy

any idea how i can build a moving sign display, using light emmitting diodes? i find i hard to get LED array here, but i decided to use individual light emitting diodes for a max of 8 characters. Controlling it with my printer port.
You will need to be able to send Data in the form of 1s & 0s to the port. You can do this with Assembly language, C, or Basic, depending on your programing skills. I would not try to do this from windows, you will have problems talking to the parallel port directly. It will be alot easier if you use DOS (6.0 works well).

Interface some shift registers (CD4094 or others) to the port. It will take three bits, Data, Clock & Strobe. Hook up the shift registers (SR) in series. Each SR will give you eight lines.

Because the SR contain latchs your LEDs will stay lit until you turn them off. The 4094 will not drive LEDs directly so you need to buffer them with CD4050.

If you wanted to you could drive up to six strings of SR by using the remaining bits in the port the Strobe and Clock would be common to all six strings.

[email protected]