This project was designed in the '10s for the '80s.
Four 4026 decade counters drive the display modules. Their inputs were multiplexed, allowing a microcontroller to display any four-digit number in milliseconds with just four pins.
Everything is soldered together on a perf board and an atrocious mix of lead-free and leaded solder.
I would do so much differently next time, but perhaps my biggest mistake was placing components before worrying about their connections. It's a rat's next on the back!
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