Erik van Zijst writes about the design of a 24-hour digital quartz clock with self-dimming LED display:

A digital quartz clock from scratch

After 20+ years of programming, I wanted to get some understanding of the electronics that make my career possible.

I had built the basic individual logic gates with transistors on a breadboard, but to build anything meaningful I needed loads of them and so I bought a somewhat random collection of logic chips on Amazon which introduced me to the 7400-series and the concept of datasheets.

After a few simple projects I wanted to build something more useful: a quartz clock with LED display.

Here is a video of the clock:

The board is shared on OSH Park.