A glowing pocket watch with Roman numerals.

What Is The Hour? It’s XVII O’ Clock

February 4, 2025 by Kristina Panos 18 Comments

When live-action role playing, or LARPing, one must keep fully in tune with the intended era. That means no digital watches, and certainly no pulling out your fantastic rectangle from the future to find out if you’re late picking up the kid.

So what do you do when you’re LARPing at 2 PM, but you gotta be back at the soccer practice field by 5 PM? Well, you fashion a period-appropriate timepiece like [mclien]’s 17 o’ Clock. Visually, it’s about as close to a pocket sundial as you can get. It’s deliberately non-connected, and its only function is to tell the time.

But how? If you visually divide the watch across the top and bottom, you get two sets of Roman numerals. The top half handles the hour, and the bottom half the minute. [mclien] started designing this in 2018 and picked it back up in the second half of 2024.

Back to the non-connected part. The only permanently-powered part of the project is a high-precision real-time clock (RTC). The rest uses a power latching circuit, which turns on the Adafruit Trinket M0 to show the time using a NeoPixel ring. Be sure to check out the awesome project logs with fantastic pictures throughout.

Looking for a smarter pocket watch? It’s time you built one yourself. And speaking of pocket sundials…

Color Coded Clock Runs On Roman Numerals

December 24, 2019 by Lewin Day 2 Comments

Roman numerals are, by modern standards, a bit unusual. By virtue of using designations for both 5 and 10, and not scaling well to higher numbers, they’ve fallen out of favor outside of some specific uses. One of those is in time keeping, in which many clocks use the classical numerals instead of the more popular Arabic replacements. [Nicola]’s clock does too, albeit in a rather unusual way.

A diagram of the clock displaying the times 18:40 and 23:04.

The build begins with a faux-neon palm tree LED decoration, which is gutted and refitted with a WS2812B LED strip, run by an Arduino Nano. An RTC is used to keep accurate time, and the time is set by running a one-off program to initialise the clock.

To tell the time, the LEDs are color coded. However, instead of using a binary representation that many can find unfamiliar, colors are chosen instead to correspond to Roman numerals. Blue, green, red and yellow are chosen to represent 1, 5, 10, and 50, or I, V, X, and L respectively. The Github has more details for the curious. The clock uses 24 hour time, and we think we’ve figured out how the display works – with hours on the left and minutes on the right.

It’s fun to see an LED clock that takes a different bent on the usual themes. We’ve seen plenty over the years, from the byte clock to this stunning blinkenlights build. If you’ve cooked up your own special timepiece, be sure to let us know.