7400 competition entry: CD4000 digital alarm clock

Jvok’s open 7400 Logic Competition entry┬áis the CD4000 digital alarm clock. As the name suggests this is an alarm clock based on CMOS 4000 series logic ICs.

I designed this clock over the course of two weeks for the Open 7400 Competition. The clock, which is made from 25 CD4000 ICs, three 555/556 ICs and a handful of discrete components, includes an alarm and a way of setting the clock that until now I have only seen implemented using microcontrollers. All this makes for a rather involved circuit, but I have split the schematic into a number of pages, which will hopefully make it easier to follow

Build something that uses or abuses a logic chip and get amazing boards, tools, and other swag. The Open 7400 Logic Competition promotes awareness of the basic building blocks of modern circuits. Devious geeks ignited the computer revolution with discrete logic computers, what can you do? Details and entry form here.

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