Digital Clock 1
I designed and built this digital clock when i was 17, and it still works. I used TTL chips so it requires 1,2 amp from the power supply! I did not use a Crystal oscillator because i did not find the value that i need for my project, so just for the "test", i built a 1Hz clock generator with a 555, the PCB on the back of the box.
One thing that i also did not build was a "antibounce circuit" to fix the hour an minutes, but just a 3 simple buttons, so it became very tricky to put the time right.