This is quite a simple project that saved me alot of time when assembling and installing twisted pair ethernet at the Presentation of Mary Academy computer lab.

It is very simple in concept, and is based on a Basic Stamp I. (actually programmed into a blank PIC with the ALT-I command from the Stamp Software)

There are 8 Stamp I/Os, and 8 lines. I connect each together, and then make a 2nd side that connects to the other end of the cable and has LEDS on it. By toggling the outputs of the Stamp one at a time (and making the others inputs) you can create an LED pattern that can be seen at the other end of the cable.

It all works even if the cable goes hundreds of feet into another room!

Look at the following PDF file, and I think it will all become clear.