Of course, there’s nothing unusual about using 7-segment displays, especially in a clock. However, [Edison Science Corner] didn’t buy displays. Instead, he fabricated them from a PCB us… ...

We’re used to seeing all manner of seven-segment displays, be they mechanical, electronic, or something in between. But what all these displays have in common is that they’re, you know, displays.

Output devices: Motors, solenoids, bulbs, buzzers, relays, LEDs, 7-segment displays. Circuit diagrams show connections. Relays: Electrically operated switches ...