A Word Clock, The Hard Way

We’ve all seen word clocks, and they’re great, but there are only so many ways to show the time in words. This word clock with 114 servos is the hard way to do it.

We’re not sure what [Moritz v. Sivers] was aiming for with this projection clock, but he certainly got it right. The basic idea is to project the characters needed to compose the time messages onto a translucent PVC screen, which could certainly have been accomplished with just a simple character mask and some LEDs. But for extra effect, [Moritz] mounted each character to a letterbox mounted over a Neopixel. The letterboxes are attached to a rack and pinion driven by a micro servo. The closer they get to the screen, the sharper the focus and the smaller the size of the character. Add in a little color changing and the time appears to float out from a jumbled, unfocused background. It’s quite eye-catching, and worth the 200+ hours of printing time it took to make all the parts. Complete build instructions are available, and a demo video is after the break.

We like pretty much any word clock – big, small, or even widescreen. This one really pushes all our buttons, though.

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Artistic Images Made With Water Lens

It’s said that beauty and art can be found anywhere, as long as you look for it. The latest art project from [dmitry] both looks in unassuming places for that beauty, and projects what it sees for everyone to view. Like most of his projects, it’s able to produce its artwork in a very unconventional way. This particular project uses water as a lens, and by heating and cooling the water it produces a changing image.

The art installation uses a Peltier cooler to periodically freeze the water that’s being used as a lens. When light is projected through the frozen water onto a screen, the heat from the light melts the water and changes the projected image. The machine uses an Arduino and a Raspberry Pi in order to control the Peliter cooler and move the lens on top of the cooler to be frozen. Once frozen, it’s moved again into the path of the light in order to show an image through the lens.

[dmitry] intended the project to be a take on the cyclical nature of a substance from one state to another, and this is a very creative and interesting way of going about it. Of course, [dmitry]’s work always exhibits the same high build quality and interesting perspective, like his recent project which created music from the core samples of the deepest hole ever drilled.

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Embiggen your Eclipse 2017 Experience with a Sun Funnel

As exciting as Eclipse 2017 is going to be this Monday, for some folks it might appear a bit — underwhelming. Our star only occupies about half a degree of the sky, and looking at the partial phase with eclipse glasses might leave you yearning for a bigger image. If that’s you, you’ll need to build a sun funnel for super-sized eclipse fun.

[Grady] at Practical Engineering is not going to be lucky enough to be within the path of totality, but he is going to be watching the eclipse with a bunch of school kids. Rather than just outfitting his telescope with a filter and having the kids queue up for a quick peek, he built what amounts to a projection screen for the telescope’s eyepiece. It’s just a long funnel, and while [Grady] chose aluminum and rivets, almost any light, stiff material will do. He provides a formula for figuring out how long the funnel needs to be for your scope, along with plans for laying out the funnel. We have to take exception with his choice of screen material — it seems like the texture of the translucent shower curtain might interfere with the image a bit. But still, the results look pretty good in the video below.

Eclipse 2017 is almost here! How are you planning to enjoy this celestial alignment? By proving Einstein right? By studying radio propagation changes? Or just by wearing a box on your head? Sound off in the comments.

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Unusual 72-Bulb Display Mechanism Found in Vintage Clock

It’s hard to beat a vintage clock for something that you can hack, and that your significant other might actually let you display in your home. It’s practical and it’s art all at the same time! But, finding that perfect vintage clock for restoration can be a bit tricky. A crowd favorite is to choose something with intricate mechanisms and gears — the motion of a mechanical display is just so fascinating.


[Gavin] managed to find a clock that is every bit as interesting without any moving parts. The clock uses a unique system of bulbs and screen masks to project each digit of the time onto glass, which creates a pretty cool look you’re not likely to see on other devices. As cheap as LCD and 7-segment displays are these days, it’s hard to imagine a time when an intricate solution like this — using 72 light bulbs — was considered practical.

Of course, what isn’t practical is replacing 72 incandescent bulbs, just to have them start the process of burning out all over again. [Gavin’s] solution to this problem was to replace the incandescent bulbs with LEDs. After getting the color temperature right (to replicate the vintage warm glow), he was able to use a jig system to get the LEDs positioned correctly to project the digits properly.

This certainly isn’t the first time we’ve seen a unique clock design, but there is something intriguing about seeing a design like this that never quite caught on. It’s a little bit of technological history that even your significant other will think is cool.

Get Subpixel Printing With a DLP 3D Printer

A DLP 3D printer works by shining light into a vat of photosensitive polymer using a Digital Light Processing projector, curing a thin layer of the goo until a solid part has been built up. Generally, the resolution of the print is determined by the resolution of the projector, and by the composition of the polymer itself. But, a technique posted by Autodesk for their Ember DLP 3D Printer could allow you to essentially anti-alias your print, further increasing the effective resolution.

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UV Laser Projector Shines With Glow-in-the-Dark Vinyl

Mirror galvanometers were originally developed in the 17th century to precisely measure very small changes in current. Unlike other instruments of the day, a mirror galvanometer could clearly show minute current variations by translating tiny movements of the mirror into large movements of the light reflected off of the mirror. Before clean electrical amplification became possible, this was the best means of measuring tiny differences in current. True mirror galvanometers are very sensitive instruments, but hobby servos can be used as a low-fidelity alternative, like with this project on Hackaday.io created by [robives].

Using a mirror galvanometer is by far the most common technique for laser projection shows – it’s really the only way to move the laser’s beam quickly enough to create the visual illusion of a solid line in real time. A mirror galvanometer works by using coils to attract magnets attached to the mirror, allowing the angle of the mirror to change when current is applied to the coils. This movement is extremely small, but is amplified by the distance to the projection surface, meaning the laser’s beam can move huge distances in an instance. If you’ve ever seen a laser show, it almost certainly used this technique. But driving galvos requires a beefy DAC, so we can’t blame [robives] for wanting to keep it digital.

[robives’s] project side-steps the need for galvanometers by using glow-in-the-dark vinyl and a UV laser. The result is a laser beam trail which lasts much longer, which means that solid lines are visible without the need for high-speed galvos. A build like this lets you experiment with laser projections without dealing with sensitive mirror galvos, and instead use components that you probably already have sitting on your workbench.

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Shedding Light on the Mechanics of Film Projection

Do you know how a film projector works? We thought we did, but [Bill Hammack] made us think twice. We have covered the Engineer Guy’s  incredibly informative videos many times in the past, and for good reason. He not only has a knack for clear explanation, the dulcet tones of his delivery are hypnotically soothing. In [Bill]’s latest video, he tears down a 1979 Bell & Howell 16mm projector to probe its inner workings.

Movies operate on the persistence of vision (POV) principle, which basically states that the human brain creates the illusion of motion from still images. If you’ve ever drawn circles and figure eights in the nighttime air with a sparkler or perused a flip book, then you’ve experimented with POV.

A film projector is no different in theory. Still images on a strip of celluloid are passed between a lamp and a lens, which project the images on to a screen. A device called a shuttle advances the film by engaging its teeth into the holes on the edge of the film and moving downward, pulling the film with it. The shuttle then disengages its teeth and moves up and forward, starting the process again.

shuttersFilm is projected at a rate of 24 frames per second, which is sufficient to create the POV illusion. A projector’s shutter inserts itself between the lamp and the lens, blocking the light to prevent projection of the film’s physical movement. But these short periods of darkness, or flicker, present a problem. Originally, shutters were made in the shape of a semi-circle, so they block the light half of the time. Someone figured out that increasing the flicker rate to 60-70 times per second would have the effect of constant brightness. And so the modern shutter has three blades: one blocks projection of the film’s movement, and the other two simply increase flicker.

[Bill] explains how the projector reads the optical soundtrack. He also delves into the mechanisms that allow continuous sound playback alongside intermittent projection of the image frames. You’ll never look at a projector the same way again.

Want to know more about optical soundtracks? Check out this Retrotechtacular that explores the subject in detail.

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