The DCF-controlled LED clock design, published in the May 1998 issue of Elektor Electronics, is a radio-controlled electronic version of the clock mounted on the Rhine Tower in Düsseldorf. Inspired by the many positive reactions to this project, its designer has reworked the software to add new features. To make things even nicer, Elektor Electronics has designed a special circuit board in the shape of the actual tower in Düsseldorf.Building a circuit yourself is even more pleasant when the result is something unique. Those of you that have built the original DCF-controlled LED clock will certainly have experienced this first-hand. Anyone who sees such a clock for the first time will undoubtedly wonder what it is and how it works.The clock that is integrated into Düsseldorf’s Rhine Tower consists of a series of lights arranged in a vertical line. The 39 lamps that are used to indicate the time on the tower are replaced in this project by yellow LEDs.