The goal was to build a rotating, dynamic LED display. On either end of two horizontally rotating arms, a short ledge with 16 LEDs is placed vertically, forming a low, flat cylinder while rotating. If the LEDs are switched on and off at the right position, a standing text or graphics can be seen at the outer surface of that cylinder. It can visualize up to about fourty big letters. The text can also rotate to the left or right or even scroll up and down. In addition, there are options to let the display blink or to invert it. Furthermore, we have eight such lines at our disposal, each of them can be programmed with different attributes. Alltogether they form a whole operating sequence.

This model can be used for effectful, 'eye catching' advertising i.e. at a bus stop or wherever people are waiting and gazing around.

First we needed a mechanical construction, for which we did the whole design. Also all the electronics was designed by us. We devided our software into two parts. One of us was responsible for the window application (running on the operating system Windows95) which makes it easy for the user to enter and modify all kinds of different graphics and texts, varying in style and size. We used the Borland C++ Builder for that. The other did the programming (in C) of the microcontroller 80C166 that coordinates the output.

A particular problem was to find solutions to transmit the energy and the data from the static to the rotating part without using rotating contacts.A static primary coil of a transformator generates a flux, which induces the voltage over a U-iron and two ball-bearings in the rotating secondary coil, located on the rotating, hollow shaft.The data is transferred through the hollow shaft with two infrared transmitter/receivers (one rotating, one static).

Even though one single LED lights up at one of the 500 positions only for a brief moment, the optical effect is astonishing and surely worth a glance when exhibited.