I always wanted a binary clock, but none available was able to sync with the german radio clock signal (DCF77), so I had to develop my own solution. The basics are really simple, the leds are controlled by a max7219 multiplex led controller, which in turn is controlled by an atmega8. I bought a cheap dcf77 receiver, the microcontroller decodes the signal and sets the leds appropiate.
However, up to now I did not have the time to finish this project, but you can have a look at the schematic(pdf) and the SVN-Repository for the sourcecode.
