Persistent Displays With UV Light

This year’s Hackaday Prize has “Rethink Displays” as one of its first theme, and [Tucker Shannon] has given us his best shot on that subject with a set of impressive displays that “write” on glow-in-the-dark material using ultra-violet light. These materials glow for a while after UV illumination, so moving a light source like a UV LED over the surface draws glowing text or simple graphics which can be readily consumed.

One of the examples this a clock we were first smitten with back in 2018. It is a rather attractive 3D-printed affair with those servos mounted below the screen that moves a UV LED through a pair of linkages. Other offerings that play on the same UV stylus medium include a laser on an az-el mount controlled by a Raspberry Pi Zero. It’s a neat idea very effectively done, and we can see it has a lot of potential.

But the most impressively advanced so far is the model shown in the image at the top of the article and the demo video at the bottom. A loop of phosphorescent material is the display surface itself. This one moves that loop with two rollers to make up the X axis, and moves the UV source up and down for the Y axis. As with all of these designs, whatever is written will soon fade, leaving the surface ready for the next bit of information.

Interested in this project and think you could do a display of your own? The Hackaday Prize 2021 is live, and we’d love to see you enter it!

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Helmet Decal Charger Keeps Them Ready To Glow

When firefighters are battling a blaze, it’s difficult for them to find each other in the smoky darkness. To help stand out they wear glow-in-the-dark decals on their helmets, but since they spend so much of their down time stowed away in a dark locker, they don’t always have a chance to charge up.

[Bin Sun]’s firefighter friend inspired them to build a portable charging system that can stuff those helmet decals full of photons in a matter of minutes. Although phosphorescent materials will charge in any light, they charge the fastest with ultraviolet light. This uses a pair of UV LED strips controlled by an off-the-shelf programmable timer, and powered with an 18-volt drill battery stepped down to 12 V. The timer makes it easy for [Bin Sun]’s friend to schedule charge times around their shifts, so the battery lasts as long as possible while keeping the decals ready to glow.

We love that [Bin Sun] seems to have thought of everything. The light strips are nestled into 3D-printed holders that also house small magnets. This makes it easy to position the lights on either side of the locker so both the front and back decals soak up the light.

Phosphorescent materials are great as a reusable display medium, especially when they’re designed to look like Nixie tubes.

Appeasing Chicken Tastes With 3D Printing

Like most of us, [Hunter] and his partner [Katyrose] have been in quarantine for the past few months. Unlike most of us, they spun a 3D printed chicken playground design hackathon out of their self-isolation. The idea is simple: to build a playground full of toys custom-tailored to appease each chicken’s distinctive taste. The execution, however, can be proven a little tricky given that chickens are very unpredictable.

For each of the four select chickens in their coop, the couple designed separate toys based on their perceived interests. One, showing a fondness for worms, inspired the construction of a tree adorned with rice noodles in place of the living article, and moss to top it off. For late-night entertainment, the tree is printed in glow-in-the-dark filament. The others were presented with a print-in-place rotating mirror disguised as a flower, and a pecking post covered in peanut butter and corn. As a finishing piece, the fourth toy is designed as a jungle gym post with a reward of bread at the top for the chicken who dares climb it. Since none of the chickens seemed interested in it, they were eventually hand-fed the bread.

With no other entries to their hackathon, [Hunter] declared themselves as the winners. The 3D files for their designs are available for their patrons to print, should they have their own chicken coops they want to adorn. While the hackathon might’ve been a success for them, their chickens in particular seemed unimpressed with their new toys, only going to show that the only difference between science and messing around is writing it down, or in this case, filming the process. If you’re looking for other ways to integrate your chickens into the maker world, check out this Twitch-enabled chicken feeder, or this home automation IoT chicken coop door. Meanwhile, check out the video about their findings after the break.

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“Glixie” Puts A New Spin On Glow-In-The-Dark Displays

For as many projects as we see using Nixie tubes in new and unusual ways, there’s a smaller but often very interesting cohort of displays that fit into the “Nixie-like” category. These are projects where something other than the discharge of noble gasses is being used to form characters. This scrolling phosphorescent single-character display is one such project, and we think it looks fabulous.

Following the *ixie naming convention characteristic of these builds, [StephenDeVos] dubbed this the “Glixie.” This is on par with the size of a [Dalibor Farny] handmade Nixie, but not so big to be unwieldy. The display modality is glow-in-the-dark film that rotates past a vertical string of UV LEDs, which light up in turn as the cylinder rotates, building up the dot-matrix character column by column. There’s some fading of the first column by the time the whole character is built up, but not enough to be objectionable. We like the whole build, with laser-cut wood and the brass and steel hardware. Check it out in the video below.

If this phosphorescent display strategy seems familiar, it’s because we’ve seen it before. Remember this persistence of phosphorescence display? Or perhaps this time-writing robot clock? It’s not a new idea, but [Stephen]’s execution can’t be beat.

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Laser Draws Weather Report

Have you ever wished that a laser could tell you the weather? If you have, then [tuckershannon] has you covered. He’s created a machine that uses a laser and some UV sensitive paper to draw the temperature and a weather icon! And that’s not all! It’s connected to the internet, so it can also show the time and print out messages.

Building on [tuckershannon]’s previous work with glow-in-the-dark drawing, the brains inside this machine is a Raspberry Pi Zero. The laser itself is a 5mw, 405nm laser pointer with the button zip-tied down. Two 28BYJ-48 stepper motors are used to orient the laser, one for the rotation and another for the height angle. Each stepper motor is connected to a motor driver board and then wired directly to the Pi.

The base and arm that holds the laser were designed in SolidWorks and then 3d printed. The stepper motors are mounted perpendicular to one another and then the laser pointer mounted at the end. The batteries have been removed from the laser and the terminals are also wired directly to the raspberry pi. The Pi is then connected to Alexa via IFTTT so that it can be controlled by voice from anywhere.

The real beauty of [tucker]’s laser drawing machine is that is will draw out the temperature and weather icon, as well as drawing the time in either digital or analog forms! We’ve seen [tuckershannon]’s work before. The precursors to this project were his clock which uses a robotic arm with a UV LED on it to draw the time and another clock which uses similar robotic arm only with a laser attached. Let’s hope we get to see the rest of [tucker]’s progress!

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Rey’s Blaster Shoots Glow-in-the-Dark Bullets

Youtuber and rubber band enthusiast [JoergSprave] is a big fan of Star Wars, and he loved the look of the blaster that Han Solo gave to Rey. He’d seen a few replicas of Rey NN-14 gun, but hadn’t seen any that actually fired anything, so he set out to make one that did.

The build itself is from plywood, with a paint job to make it look like an old blaster. What makes the build really cool is the bullets used: glow sticks! [Joerg] created space in the magazine for three glow sticks, so you’ve got a couple of shots before you have to reload. Crack ’em, load them up and then fire away!

The glow sticks give the blaster fire a great look (especially in the dark!) and it’s really easy to find the shots after you’ve fired them. We’ve featured [Joerg]’s builds a few times on the site, and his build videos are a lot of fun. Check out his compressed air crossbow bolt gatling gun, or his machete shooting slingshot.

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Glow In The Dark Globe On A Spherical Screen

Terrestrial globes are almost a thing of the past in an era of Google Earth, but they can still be an exciting object worth hacking together, as [Ivan Miranda] shows with his glow-in-the-dark globe. It’s a globe, it’s a display, and it’s a great use of glow in the dark filament.

For the mechanical part of this build, [Miranda] used glow in the dark filament to 3D print a sphere and a reinforcing ring that hides inside. A threaded rod through the middle secured with screws and bearings make an appropriate spindle, and is attached to a stepper motor in the 3D printed stand. So far, it’s a sphere made of glowey plastic. Where’s the ‘globe’ part coming from?

To project a globe onto this sphere, [Miranda] used a strip of WS2812B LEDs stuck to the inside of the stand’s arc are programmed to selectively illuminate the globe as it rotates on its axis. After a brief hiccup with getting the proper power supply, he was ready to test out his new….. giant light ball.

It turns out, the filament was a bit more transparent than he was expecting so he had to pull it all apart and cover the interior with aluminium tape. [Miranda] also took the chance to clean up the wiring, code, and upgrade to a Teensy 3.1 before another test.

Despite the resulting continental projection being upside-down, it worked! [Miranda] added a USB cable before he closed it up again in case he wanted to reprogram it and display any number of images down the line.

[Thanks for the tip, olivekrystal!]