Solar Pi Zero E-Paper Photo Frame Waits For The Right Moment

December 21, 2020 by Tom Nardi 9 Comments

One of the biggest advantages of electronic paper is that it doesn’t require a constant power source to display a static image. Depending on the application, this can lead to a massive energy savings compared to more traditional display technologies. Of course, the electronics that actually drive the display are another story entirely. You need to reduce the energy requirements of the whole system if you really want to stretch your battery life.

So when [Giacomo Miceli] wanted to put together this solar powered e-paper photo frame, he had to come up with some creative ways to curb the energy consumption of the Raspberry Pi Zero that runs the show. While the 10.3 inch 1872 × 1404 panel would only require the occasional burst of power to flick over to a new image, the Pi would be a constant drain on the internal battery pack. Considering he wanted the frame to recharge from ambient light with an array of small solar panels, that simply wouldn’t do.

The solution came in the form of a PiJuice HAT and some scripts that decide how often the Pi is to be powered on based on the current battery level. If there’s enough power, it might be every hour or so. But the lower the charge, the longer the delay. When the energy situation is particularly dire, the Pi might only be turned on every couple of days. With the Pi off and the e-paper not drawing any power, all of the energy produced by the solar panels can be devoted to recharging the frame’s 1,000 mAh battery.

When the Pi does get booted up, it quickly connects to a server to download a new image and update the display. After that, it ascertains the current battery level and determines how long the PiJuice should wait before turning it back on. After these tasks are complete, it will turn itself off until the next scheduled event. All told, [Giacomo] says the Pi is only up and running for about a minute each time the image is refreshed on the e-paper. He says the system has been running for six weeks now, with the battery level occasionally dipping down to 40% or so before it climbs back up.

Admittedly the energy consumption of the frame could be cut drastically by replacing the Raspberry Pi with a simple microcontroller, but we appreciate the creativity. Besides, the power and flexibility afforded by the Pi means this frame could be taught quite a few new tricks with some updated software.

Bringing Full Colour PCB Art To Production

December 19, 2020 by Jenny List 6 Comments

One of the Holy Grails in the world of electronic badges has been full-colour PCB art as a logical progression from the limited palette of traditional PCB artwork. In the progression towards achieving this goal there have been a variety of techniques applied, and it’s become an expensive commercial possibility rather than an unachievable dream. Has it become practical for mere mortals then? [Tom Clement] has put together a write-up of his progression towards achieving full-colour PCB artwork on a limited production run , and it makes for a fascinating read.

The board in question is the Pixel badge, an improved commercial version of the CampZone 2019 I-Pane badge we reviewed last year. It’s a very bright large multicolour LED matrix that has caught the eye of campgoers at events ever since the original, and has generated enough demand for a new production run. As well as a few electronic enhancements it replaces the original’s dithered monochrome silkscreen rear art with a full-colour design, and it is that with which the write-up is concerned.

It starts with UV printing, and goes through the various iterations of the process until a satisfactory result is achieved. We learn about the effect of reflow temperatures on UV printing inks, it seems that white ink discolours with temperature and the inventive solution is to transfer all the whites to the PCB silkscreen layer. He closes with a discourse on alignment, and we start to appreciate the achievement behind producing this badge. A colour print isn’t necessary for the Pixel’s eye-searing light show, but the point of badges is as much to show off the cutting edge of the art.

As the regular Hackaday reader will know, colour PCB art is a long-time topic of interest here at Hackaday.

Tunes You Can Eat

December 14, 2020 by Chris Lott 15 Comments

This week retro-gadget collector and video blogger [Techmoan] featured perhaps the most delicious audio recording format that we know of — a chocolate gramophone record. (Video, embedded below.) Compared to his typical media format explorations, the chocolate record is of quite recent vintage. He first heard of them back in 2015 when Tasmanian artist [Julia Drouhin] offered chocolate recordings as part of her art project. The one that [Techmoan] finally obtained was from a UK chocolatier who offers them with custom labelling and your choice of two songs. There are some pointers in the video about how to playback your chocolate disk without ruining it (use the lightest stylus tracking force as possible). These disks are recorded at 45 RPM on one side only, and are about the same size as a standard single. But being about five times thicker, they pack a lot more calories than your typical phonograph disk.

No reflection on the Tewkesbury Town Band, but this is probably the lowest fidelity recording media ever, but at least you can eat it when you’re done listening — label and all. We hope the Mission Impossible movie producers are paying attention so we can see the secret audio briefing being eaten instead of going up in smoke next film.

Continue reading “Tunes You Can Eat” →

A 3D – To – 2D Converter To Make Plots From STLs.

December 13, 2020 by Jenny List 13 Comments

We’ve become used to finding models on websites such as Thingiverse and downloading them to print. After all, whose hackerspace doesn’t have a pile of novelty prints? How about printing them on paper? For the plotter enthusiast that can be particularly annoying. Never fear, [Trammell Hudson] is here with an online 3D to 2D converter just for plotters. [Trammell’s] creation makes a vector image suitable for a plotter while eliminating spurious behind-the-scenes lines.

Plotter drawings are the pen-and-paper equivalent of a vector CRT display, in which the graphics are printed as continuous strokes. Rendering a 3D model as a wireframe for a plotter requires the removal of any pen strokes that comes from the 3D space behind the surface in view. Loading various models into the web page seemed to do a pretty good job of this, though the ubiquitous Benchy 3d printer test model lived up to its billing as a torture test in taking several minutes to render.

As anyone who has followed the #PlotterTwitter social media hashtag will know, there is a considerable community of pen plotter enthusiasts who are pushing the boundaries of what their machines can do. [Trammell] has posted his plotter producing some of the work created with this tool, and we can see that it’s likely to work better with lower-poly models.

We’ve featured a lot of plotters over the years as they seem to be a popular project. If you’d like one then they can be made from the most available parts, including those scavenged from scrap DVD drives, or printers.

CNC Router Frame Repurposed For Colorful String Art Bot

December 11, 2020 by Dan Maloney 12 Comments

Pandemic lockdowns have been brutal, but they’ve had the side-effect of spurring creativity and undertaking projects that are involved enough and complex enough to keep from going stir crazy. This CNC string art robot is a great example of what’s possible with a little imagination and a lot of time. (Video, embedded below.)

According to [knezuld11], the robot creates its art through mathematical algorithms via a Python program that translates them into nail positions and string paths. The modified CNC router frame, constructed of laser-cut plywood, has two interchangeable tool heads. The first places the nails, which are held in a small hopper. After being picked up by a servo-controlled magnetic arm and held vertically, a gear-driven ram pushes each nail into a board at just the right coordinates. After changing to a different tool, the robot is able to pick up one of nine different thread dispensers. A laser sensor verifies the thread nozzle position, and the thread starts its long journey around the nails. It’s a little mesmerizing to watch, and the art looks great, with a vibe that brings us right back to the 70s. Groovy, man.

This reminds us a little of a recent [Barton Dring] project that makes art from overlapping strings. That one was pretty cool for what it accomplished with just one thread color, while this one really brings color to the party. Take your pick, place your nails, and get stringing.

Continue reading “CNC Router Frame Repurposed For Colorful String Art Bot” →

A PCB Diary

December 9, 2020 by Chris Lott 8 Comments

[Gijs Gieskes] has made another eye-catching PCB wonder, this time a diary built from several circuit boards which are assembled into a book, not unlike a PC/104 system. But with [Gijs]’s system you can easily open the stack-up to access single boards without disassembling the whole thing. We don’t see brass piano hinges on PCB assemblies very often, but [Gijs]’s PCB designs are anything but conventional. Hint: if you wanted to recreate this technique using more ordinary hardware, you can find hinged PCB standoffs from various suppliers.

Bicycle, soccer ball, smoke on the “No no no no no…” PCB

Apparently it’s more than a passive piece of art. Each board has several circuits, some of which (all?) are functioning is ways not clearly described, which seems to be intentional. According to his build log, different things happen when you mix and match the inter-board ribbon cables in various ways. We are told in the instructions “to just try and see what happens”. No schematics are posted, but there is a partial description of the circuits in the manual and parts on the two-layer boards are well-labeled. Although after spot checking a few circuits board photos, we’d guess that no small number of traces, and perhaps some parts, are wild goose chases.

The project claims to be a diary for the years 2018 and 2019, but we will leave it as an exercise for the reader to interpret the messages that [Gijs] has embedded into this fascinating piece. We have written about several of his projects over the years, such as this crazy bent Casio SK-1 from all the way back in 2005. And before dismissing this “book” style of circuit board stack-up as only for artists, check out this teardown of a Soyuz clock we covered back in January.