Lord Vetinari from the Discworld series is known for many things, but perhaps most of all a clock that doesn’t quite keep continuous time. Instead, it ticks away at random increments to infuriate those that perceive it, whilst keeping regular time over the long term. [iracigt] decided to whip up a real world version of this hilarious fictional timepiece.
The clock itself is an off-the-shelf timepiece purchased from Target for the princely sum of $5. However, it’s been deviously modified with an RP2040 microcontroller hidden away inside. The RP2040 is programmed to tick the clock at an average of once per second. But each tick itself is not so exact. Instead, there’s an erraticness to its beat – some ticks are longer, some shorter, in the classic Vetinari style. [iracigt] explains the nitty gritty of how it all works, from creating chaos with Markov chains to interfacing the RP2040 electronically with the cheap quartz clock movement.
If you’ve ever wanted to build one of these amusements yourself, [iracigt’s] writeup is a great place to start. Even better, it was inspired by an earlier post on these very pages! We love to see the community riff on a theme, and we’d love to see yours, too – so keep the tips coming, yeah? Video after the break.
Should put that one in an exam hall to mess with the ‘Muggles’
I’m not actually that evil. Definitely thinking I should create a power optimized version for office hours though.
I thought he was best known for having mimes arrested and thrown into a scorpion pit, written on one wall of which was the command “LEARN THE WORDS”?
Frivolity aside, this is a clever project and a good way to kill time (that was a pune or play on words, as Vetinari was also an assassin… oh, please yourselves). Hats off to [iracigt]!
One man, one vote, he’s the man and he has the vote.
“Don’t let me detain you”
it would be fun if it took a half-step backwards to partially correct a double-step.
Clever idea, but I’m not sure if that’s canonical with the books.
If I may be permitted to quote from “Feet of Clay”…
“Someone very clever […] must have made the clock for the Partrician’s waiting room. It went tick-tock like any other clock. But somehow, and against all usual horological practice, the tick and the tock were irregular. Tick tock tick…and then the merest fraction of a second longer before…tock tick tock…and then a tick a fraction of a second earlier than the mind’s ear was now prepared for. The effect was enough, after ten minutes, to reduce the thinking processes of even the best-prepared to a sort of porridge…”
Alas, no mention of kcit’s or kcot’s or other backwards tick/tocks!
I must have misplaced my dried frog pills again! Was the clock made by Bloody Stupid Johnson?
Reminds me of a clock to get a longer lunch break past a strict supervisor
https://hackaday.com/2011/01/18/the-lunchtime-clock-gives-you-12-extra-minutes/
I’m sure I’ve also read about similar projects
I inadvertently paused the video and ended up staring at it for at least a minute and a half waiting for the second hand to leave the 30-second mark
IIRC there was reputed to be a bunch of smarty-pants students who rewired one of the old AC wall clocks at the back of a lecture hall so that it would progress at various speeds to drive the lecturer nuts. In the early -digital days this was quite a feat, involving generating what amounted to a variable/random-frequency drive for the thing that could produce a current enough to run the motor and then concealing it in the wall-box for the outlet behind the clock. The harder trick was to make it average out about right so that you didn’t get cumulative errors.
Challenge: do this with a pendulum clock. Bonus points for having the pendulum move smoothly.
Just use a motor (more ponus points for a ball screw assembly) to raise or lower the weight along the pendulum arm.
You don’t need to be that mechanically complex, hide an electromagnet close enough to the pendulum weight, drive it with a variable current then induced eddy currents will slow the pendulum, vary the current to vary the length of swing.
Presumably if you had an electromagnet at each end of the swing you could make the pendulum “pause” at one end or be propelled faster than gravity away from the end.
That’d work too but you’d need the pendulum to be magnetic or have a magnet attached.
I also realised my scheme would only slow the clock so yours is better
The Corpus Clock at Cambridge beat me to that.
https://en.m.wikipedia.org/wiki/Corpus_Clock
Fun fact: all clocks work like this, it’s just that the fraction is small enough to not be perceived by the mind’s ear!
A bold claim, given that some clocks are mechanical, others electric, and others (like this RP2040-powered one) are electronically controlled. Do you mean in that ina very subtle sense, that no two things are exactly alike? Otherwise I would say the clock escapements are one of the first cases of humans making something (nearly) perfectly consistent (at least to our senses, that is).
Well, that’s the thing, our senses can identify different ticks and tocks down to some ms at best. Our instruments down to 1e−20? There is no clock with a frequency precision of 0!
See also: https://www.youtube.com/watch?v=plYjatoHnlo
Too bad they can’t even spell Vetinari correctly.
It’s not exactly Vetinari science!
are you a vetinarian
Someone sells kits for this; I have one that plays shave and a haircut every now and then. Thing was in the bathroom for over a year nobody noticed. I was unhappy.
Very devilish. I too am morbidly curious about why a clock that doesn’t keep time is so frustrating.
I’m also really curious (having spent the last couple of months fault finding a particularly disobedient wall clock!) how you connected to the coil. Did you disconnect the existing driver? Did you have trouble routing wires out past the delicate mechanisms? Do you have any photos of that?