Roman Numeral Clock

——under construction——

This clock is an homage to my 1970s fascination with LEDs, which at the time were new and magical. I've been feeling a lot of nostalgia for the 70s lately, reminded of them often since I work at the local University and all the kids lately are rediscovering 70s “fashions”. I've even seen a couple of early episodes of The Dukes of Hazzard while working on this project on my laptop in front of the TV. If that doesn't give this clock some 70s-cred, I don't know what will.

Why this project?

I've long held that the entire point of hobbyist electronics is making LEDs blink. Before there were LEDs, neon or incandescent bulbs filled the bill, and before they came along there wasn't really such a thing as electronics.

But the creation of circuitry is a hard enough task that there ought to be some purpose to our blinking lights. There are a lot of uses for them but one of the most accessible purposes for them is to be a visual display of information. And one of the most useful and convenient pieces of information to display is the current time.

I'm hardly the first one to notice this, and the modern industrialized-nation household is already jammed with digital clocks. The pressure is on to come up with some kind of clock that's different, and talented hobbyists have come up with some very cool variations: two notables are the Nixie tube clocks and the propeller clocks.

So what other novel ways are there to show the time? I'm hoping for something that a) uses LEDs, b) looks cool, c) is within my modest ability to build, and d) is more or less readable. How about Roman numerals?

LED alphanumeric segmented displays can render any number or letter, at least in English, though some of them take some squinting to figure out. So, certainly they could display Roman numerals. Consider the number 38 in Roman numerals (XXXVIII):

As you can see, nothing about the displays themselves limits the ability to show Roman numerals in their correct form, but there are a few reasons for trying to tighten the display up a bit:

1. The clock ends up pretty big – as shown above, the number 38, which is the longest you'd have to display for minutes, takes 6 characters. The number 23, which would be the longest hours value (assuming a 24-hour format clock), would take another 5. So, you'd have 11 displays, and if they're of a size to be readable across a room, that's a physically large clock. That might be OK on a wall, but I'd rather build a bedside alarm-clock sort of clock.

2. 11 displays is an awful lot to accomodate in circuitry and software.

3. If you do it another way, there's a better chance that the clock will end up looking like something built by aliens. That's a design plus.

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