A real-time clock that uses only one 7-segment LED to display the time. There are also four standard LEDs which tell you which digit you are looking at as the time is displayed. Two IC chips are used to control the clock.
It uses an Atmega 168 Microcontroller chip (learned how to program it via Nerdkits.com) to control the displays and to interface with the timekeeping chip. The timekeeping is done by the second chip, a DS-1302 Real-Time Clock chip. One pushbutton is used to set the time.
The electronics are all hand-soldered. There is a battery backup that maintains power to the timekeeping chip when AC power is not available. Power is by a "wall wart" standard 5V DC transformer.
The clock is housed in a wooden case, made of spalted (partially rotten) birch and curly maple, from trees that I felled and cut into boards.