TomThings I've Built
Triple time zone clock using a Z80
Having built one clock purely out of transistors, I figured the next logical step was a more capable clock that could also display more than one time zone. https://github.com/tomstorey/Z80_clock
Discrete transistor NOR logic clock
This is a clock (and calendar) with logic inspired by the Apollo Guidance Computer - that is, NOR gates only (and inverters). I covered this in a blog which you can find here: https://ornotblog.blogspot.com/2017/03/discrete-nor-logic-clock-intr