Decade Clock

The Decade Clock is a half-finished project I started as a pandemic past-time (and to use the CircuitStudio license I bought for myself as a graduation gift). The idea is very simple: modular boards that take in power + clock, count up some LEDs, and “spill” over to the clock on the output. The result is a neat visual effect where each column counts up 10x slower than the last. The project is perfectly impractical, but perhaps could be used as a teaching aid for middle or high school students learning about the differences between base 10 and other bases.

The design uses the CD4017BE decade counter, SN74AC32N quad OR-gate, and some jellybean parts for LEDs, resistors, etc.

Some issues I have found:

• I probably underspecced the power supply for anything more than 5 or so boards strung together
• The cascading design where each board powers the next is convenient for piecing them together. However, it requires the first board to have power traces beefy enough to supply all the power for all the boards. Even with a beefier power supply, the thin power traces would probably become a problem too.
• These on-board connectors are probably not intended to be directly connected to other on-board connectors. Small differences in tolerance lead to misalignment and they will likely break if I tried to both connect the boards together, and mount them on standoffs.

If I were to add some polish to this project, here’s what I’d do:

• Stronger power supply
• “Star” layout for power distribution, instead of cascading
• Remove the connectors and solder wires between boards. Or, leave the connectors, and create cable assemblies that attach to the existing connectors on the board

Here’s a video of a few boards strung together:

And the schematic and top view of the board: