This was my first original design project. I built this my sophomore year of college, before I had taken any design courses!
This digital clock uses all digital logic, no microcontrollers were used. The time is generated by a quartz crystal oscillator circuit, oscillating at 32,768 Hz. This is stepped down using a series of digital counters, and logic gates and more counters break it down into seconds, minutes, and hours. Seven segment display decoders are then used to output the binary numbers. There are also debounced switches to clear and set the time on the side. You can tell from the bottom there was a lot of tedious soldering involved in this project!