A Tuning Fork Clock, With Discrete Logic

February 8, 2022 by Dave Rowntree 8 Comments

[Willem Koopman aka Secretbatcave] was looking at a master clock he has in his collection which was quite a noisy device, but wanted to use the matching solenoid slave clock mechanism he had to hand. Willem is a fan of old-school ‘sector’ clocks, so proceeded to build his ideal time piece — Vibrmatic — exactly the way he wanted. Now, since most time keeping devices utilise a crystal oscillator — which is little more than a lump of vibrating quartz — why not scale it up a bit and use the same principle, except with a metal tuning fork? (some profanity, just to warn you!)

A crystal oscillator operates in a simple manner; you put some electrical energy in, it resonates at its natural frequency, you sense that resonance, and feed it back into it to keep it sustaining. With a tuning fork oscillator, the vibration forcing and the feedback are both done via induction, coils act as the bridge between the electronic and mechanical worlds.

By mounting the tuning fork onto a shock mounting, the 257 Hz drone was kept from leaking out into the case and disturbing the household. This fork was specified to be 256 Hz, but [Willem] reckons the drag of the electromagnets pushed it off frequency a bit. Which make sense, since its a mechanical system, that has extra forces acting upon it.

The sector face was CNC cut from aluminium, the graphics engraved, then polished up a bit. Finally after a spot of paint, it looks pretty smart. Some nice chunks of upcycled wood taken from some building work spoils formed the exposed enclosure. On the electronics side, after totally ignoring the frequency error, and then tripping over a bunch of problems such as harmonics in the oscillation, and an incorrectly set-up divider, a solution which seemed to work was found, but like always, there are quite a few more details to the story to be found in the build log.

We’ve seen a tuning fork clock recently, like this 440 Hz device by [Kris Slyka] that the project above references, and whilst we’re talking about tuning forks, here’s a project log showing the insides of those ubiquitous 32.768 kHz crystal units.

A Simple 3D Printed Gear Clock Shows Off How It Works

December 23, 2021 by Lewin Day 15 Comments

Analog clocks are beautiful things inside, using ornate gear trains to keep track of time in a dance of mechanical beauty. However, all too often, the complexity is hidden inside. This gear clock design from [Tada3], however, proudly shows off its workings.

A small stepper motor is used to run the clock’s movement, a small part of the 28BYJ-48 variety. The motor is driven once per second, making the gear train tick along in a rather compelling way that is somehow more visually interesting. Of course, with some modification to the design, continuous motion could easily be done as well.

The stepper motor is driven by an Arduino Nano, which also handles the timekeeping. One thing that’s missing is a real-time clock, something that should be added to the design if you wish it to keep accurate time. As it is, the included Arduino sketch simply uses the delay() function to time the stepping of the motor. It makes the clock tick along, but will quickly drift out of sync.

The design was also recreated in a YouTube video by [Mirko Pavleski], showing that the files are of suitable quality for building your own at home. We’ve seen some gear clock designs before, too, from the laser-cut to the neatly-nested. Video after the break.

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A Nested Gear Clock

December 12, 2021 by Matthew Carlson 11 Comments

One of the most common projects we see here at Hackaday is a clock. It could just be that we as humans are fascinated by the concept of time or that making a piece of functional art appeals to our utilitarian sense. In that spirit, [Alexandre Chappel] set out to make a large mechanical clock with complex gears.

The initial design was made in Fusion360 over a week and then in a somewhat bold move, [Alexandre] started up the CNC and cut all the parts out of valchromat. The basic idea of the clock is that the numbers move on the clock, not the hands. So the clock should show 10:25 instead of moving hands to the 10 and the 5. Most of the clock is made of up stacked gear assemblies, geneva drives, and many bearings. A single stepper motor drives the whole clock, which [Alexandre] admits is a bit of a cheat since trying to add springs and an escapement would add complexity to an already complex clock. He did have to adjust and recut a few gears but most of the assembly came together nicely. Some 3d printed numbers dropped into the CNCed slots offers much-improved readability.

A few problems became apparent once the system was together. The numbers don’t quite line up perfectly, which is unfortunate. He mentioned that tighter tolerances on the gears would likely help there. A fatal design flaw on the smallest disk became apparent as it needs to turn a sixth of the circle whereas the outer circle is just turning a tenth of the circle. Mechanical advantage isn’t in [Alexandre’s] favor and the stepper skips some steps and it slowly makes its way towards the next second digit of the hour.

If you’re looking for more beautiful artistic clocks, why not check out this circuit sculpture one?

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A Flip Clock That Flips Up, Not Down

November 24, 2021 by Dan Maloney 3 Comments

The venerable flip clock has become an outsized part of timekeeping culture that belies the simplicity of its mechanism. People collect and restore the electromechanical timepieces with devotion, and even seek to build new kinds of clocks based on split-flap displays. Designs differ, but they all have something in common in their use of gravity to open the leaves and display their numbers.

But what if you turned the flip clock on its head? That’s pretty much what [Shinsaku Hiura] accomplished with a flip clock that stands up the digits rather than flipping them down. The clock consists of three 3D-printed drums that are mounted on a common axle and linked together with gears and a Geneva drive. Each numeral is attached to a drum through a clever cam that makes sure it stands upright when it rotates to the top of the drum, and flops down cleanly as the drum advances. The video below makes the mechanism’s operation clear.

The build instructions helpfully note that “This clock is relatively difficult to make,” and given the extensive troubleshooting instructions offered, we can see how that would be so. It’s not the first time we’ve seen a mechanically challenging design from [Shinsaku Hiura]; this recent one-servo seven-segment display comes to mind.

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Mesmerizing Mechanical Seven-Segment Display

October 25, 2021 by Adam Zeloof 14 Comments

Seven-segment displays are ubiquitous. From where I’m writing this, I can see several without even having to swivel my chair. We’re all familiar with their classic visage; slightly italicized numbers that are brought to life by LEDs. There are a boatload of variants available– you can get displays with a decimal point, ones with multiple numbers, and even versions in just about any color you desire, but at the core they’re all basically the same thing- an array of LEDs sitting behind a faceplate. Except for those ones that have some gears inside.

Wait, what?

You read that right– a seven-segment display that contains gears, along with a handful of cams for good measure. Artist [Kango Suzuki] created this stunning all-mechanical seven-segment display that sequentially counts up from zero to nine when a thumbwheel is spun. All of the components are cut from wood and mesh together beautifully, complete with a satisfying click when the display rolls into a new digit, which you can hear in the video at the above link. You may recognize [Kango]’s style from this incredible mechanical clock he made a few years back. Unlike his earlier work, the seven-segment display is tiny, relatively speaking. Maybe we’ll see it integrated into a larger project some day, like a mechanical-digital clock.

We just love when somebody uses intricate mechanisms to artfully emulate some piece of existing tech. This isn’t even the first time we’ve seen a mechanical seven-segment display; [Peter Lehnér] built one back in 2019, and judging by [Kango]’s twitter feed, it appears to have inspired his design. There have even been a few other 3D printed ones over the years, but as far as we know this is the first wooden one– and, in true [Kango] fashion, its beautiful.

Thanks to [J. Peterson] for the tip!

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Steppers And ESP32 Make This Retro-Modern Flip-Clock Tick

October 2, 2021 by Dan Maloney 8 Comments

Before LEDs became cheap enough to be ubiquitous, flip-card displays were about the only way to get a digital clock. These entirely electromechanical devices had their own charm, and they have a certain retro cachet these days. Apart from yard sales and thrift stores, though, they’re a bit hard to source — unless you roll your own, of course.

Granted, [David Huang]’s ESP32-based flip clock is worlds apart from the flip cards of the “I Got You, Babe” era. Unfortunately, the video below is all we have to go on to get the story behind this clock, but it’s pretty self-explanatory. [David] started the build by making the flip cards themselves, a process that takes some topological tricks as well as a laser cutter. 3D-printed spools are loaded with the cards, which are then attached to frames that hold a stepper motor and a Hall-effect sensor. The ESP32 drives the steppers via L298N H-bridge drivers, but it’s hard to say if there’s an RTC chip or if the microcontroller is just getting time via an NTP server.

[David] might not be the only one trying to recapture that retro look, but we’ve got to hand it to him — it’s a great look, and it takes a clever maker to not only build a clock like this, but to make a video that explains it all so clearly without a single word of narration.

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Retrotechtacular: Mechanical TV From The People Who Made It Happen

July 31, 2021 by Jenny List 12 Comments

If we have a television in 2021 the chances are that it will be a large LCD model, flat and widescreen, able to display HD images in stunning clarity. Before that we’d have had a CRT colour TV, them maybe our parents grew up with a monochrome model. Before those though came the first TVs of all, which were mechanical devices that relied on a spinning disk to both acquire and display the image. The BBC Archive recently shared a vintage clip from 1970 in which two of the assistants of [John Logie Baird], the inventor of the first demonstrable television system, demonstrated its various parts and revealed its inner workings.

We’ve covered the Nipkow scanning disk in a previous article, with its characteristic spiral of holes. We see the original Baird Televisor, but the interesting part comes as we move to the studio. Using the original equipment they show a dot of light traversing the presenter’s face to scan a picture before taking us to a mock-up of the original studio. Here there’s a surprise, because instead of the camera we’d expect today there is a Nipkow disk projector which traverses the subject sitting in the dark. A bank of photocells above the projector senses the reflected light, and returns a video signal.

The resulting low-resolution pictures had a low enough bandwidth to be broadcast over an AM radio transmitter, and for a tiny 30-line picture in the glowing pink of a neon light they provide a surprising amount of detail. With such a straightforward principle it’s not surprising that they’ve appeared in a few projects on these pages, including an Arduino driven colour video monitor, and a POV clock. Take a look at the video below the break.

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