Get Twelve Charlieplexed PWM Outputs From An ATtiny85

February 24, 2019 by Donald Papp 8 Comments

Most of us are aware that charlieplexing can drive a large number of LEDs from a relatively small number of I/O pins, but [David Johnson-Davies] demonstrates adding another dimension to that method to create individually controlled PWM outputs as well. His ATtiny85 has twelve LEDs, each with individually-set brightness levels, and uses only four of the five I/O pins on the device.

Each LED can be assigned a brightness between 0 (fully off) and 63 (fully on). The PWM is done by using one of the timers in the ATtiny85 to generate a periodic interrupt, and the ISR for the interrupt takes care of setting the necessary ratios of on and off times for each charlieplexed output. The result? Twelve flicker-free LEDs with individually addressable brightness levels, using an 8-pin microcontroller and just a few passive components on a tiny breadboard. There’s even one I/O pin left on the ATtiny85, for accepting commands or reading a sensor.

[David] really wrings a lot out of the ATtiny series of microcontrollers with his compact projects, like his Tiny Function Generator (which recently got an update.) He also demonstrated that while charlieplexing is usually used with LEDs, charlieplexing can be used with switches just as easily.

Hexagonal Lamp Is A Stylish Application Of Plywood

February 21, 2019 by Lewin Day 10 Comments

Lamps are useful things, and can be a great way to add style and lighting options to a room. Where overhead lights have to provide enough illumination for all manner of tasks, a subtle table lamp can add a nice moody glow to a room when it’s time to kick back and relax. Oftentimes, a stylish lamp can be let down by having a run of the mill plastic switch hanging off the power lead, but it doesn’t always have to be the case. [Emiel] designed this hexagonal lamp with a hidden switch, which works remarkably well.

[Emiel] starts by laying out hexagonal paper templates on plywood and perspex sheet. The plywood is cut on the bandsaw, while the interior cuts on the perspex are made on a scroll saw to avoid unsightly cut entry lines. The outer half of the lamp slides up and down on a pair of steel rods. Springs hold the outer half up, and it can be pressed down to activate a switch inside to turn the lamp on and off.

The build has a clean and attractive aesthetic, with the LEDs hidden inside, glowing through the perspex slices built into the body. It looks like something you’d find in the rooms at the Tranquility Base Hotel & Casino. If regular lamps aren’t enough for you, however, you could always consider building something interactive. Video after the break.

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Infinity Icosahedron Is Difficult To Contemplate Even Looking Right At It

February 17, 2019 by Lewin Day 13 Comments

Cubes and pyramids are wonderful primitive three-dimensional objects, but everyone knows that the real mystical power is in icosahedrons. Yes, the twenty-sided polyhedron does more than just ruin your saving throws in tabletop RPGs – it can also glow and look shiny in your loungeroom at home.

[janth]’s build relies on semitransparent acrylic mirrors for the infinity effect, lasercut into triangles to form the faces of the icosahedron. The frame is built out of 3D printed rails which slot on to the acrylic mirrors, and also hold the LED strips. [janth] chose high-density strips with 144 LEDs per meter for a more consistent effect, and added frosted acrylic diffusers to all the strips for a clean look with less hotspots from the individual LEDs.

An ESP32 runs the show, and the whole assembly is epoxied together for strength. The final effect is very future disco, and it’s probably against medical advice to stare at it for more than 5 minutes at a time.

The infinity effect is a popular one, and we’ve seen a beautiful cube build by [Heliox] in recent times. Of course, if you do manage to build an actual portal through time and space, and not just a lamp that looks like one, be sure to send us a tip. Video after the break.

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COB LED Teardown

February 15, 2019 by Al Williams 15 Comments

[Big Clive] picked up some chip-on-board (COB) LEDs meant for hydroponics that were very unusual and set out to examine them on video. Despite damaging the board almost right away, he managed to do some testing on these arrays and you can see the results in the video below. He also compares it to older LED modules.

The 144 LEDs produce a lot of light. In addition to powering the device up, he also looks at the construction of the LEDs under a magnification, comparing the older style that used tiny bond wires to make connections versus the new version soldered on the board directly.

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This 3D Printed LED Softbox Really Shines

February 10, 2019 by Tom Nardi 8 Comments

Generally speaking, objects made on desktop 3D printers are pretty small. This is of course no surprise, as filament based printers are fairly slow and most don’t have very large beds to begin with. Most people don’t want to wait days for their project to complete, so they use 3D printed parts where it makes sense and supplement them with more traditional components such as aluminum extrusion wherever possible. But not always…

This 3D printed photography softbox created by [Nicholas Sherlock] doesn’t take the easy way out for anything. With the exception of the LEDs and the electronics to drive them, everything in the design has been printed on his Prusa i3. It wasn’t the easiest or fastest way to do it, but it’s hard to argue with the end result. Perhaps even more impressive than the final product is what it took to get there: he actually had to develop a completely new style of part infill he’s calling “Scattered Rectilinear” to pull it off.

Overall the design of the light itself isn’t that complex, ultimately it’s just a box with some LEDs mounted at the back and a pretty simple circuit to control their intensity. The critics will say he could have just used a cardboard box, or maybe wood if he wanted something a little bit stronger. But the point of this project was never the box itself, or the LEDs inside it. It’s all about the diffuser.

[Nicholas] forked Prusa’s version of Slic3r to add in his “Scattered Rectilinear” infill pattern, which is specifically designed to avoid the standard “ribs” inside of a 3D printed object. This is accomplished with randomized straight infill passes, rather than the traditionally overlapped ones. The inside of the print looks very reminiscent of fiberglass mat, which is perhaps the best way to conceptualize its construction. In terms of the final part strength, this infill is abysmal. But on the plus side, the light from the LEDs passing through it emerges with a soft pleasing look that completely obscures the individual points of light.

Anyone with a big enough 3D printer can run off their own copy of his light, as [Nicholas] has released not only his forked version of Slic3r but all of the STL files for the individual components. He’s also put together an exceptionally well documented Thingiverse page that has instructions and detailed build photos, something that’s unfortunately very rare for that platform.

If you’re in the market for a DIY softbox and don’t have a 3D printer handy, fear not. We’ve covered a few that you can build with more traditional methods, as well as several tips and tricks which you can use to get the most out of your photos and videos.

Hidden LED Video Wall At The Oregon Museum Of Science

February 10, 2019 by Lewin Day 10 Comments

Glowing and blinking things are some of our favourite projects around these parts, and the bigger, the better. [Thomas] wrote to us recently to share the design and construction of a large LED wall at the Oregon Museum of Science, and the results are nothing short of impressive.

The concept involved a large LED wall that would be completely hidden when switched off. The team decided to approach this by hiding high-brightness LED panels using APA102 strings behind milky-white plexiglass panels covered with a woodgrain print. The screen has a total of 90,000 pixels, arranged in a 408×220 resolution display.

A lot of bespoke LED displays have some pre-coded patterns, or perhaps some basic reactive features. In this case, FPGA grunt was brought to bear on the problem and the display accepts standard HDMI input. Four Spartan 6 Mojo FPGA boards split up the task of addressing the panels, each receiving the same HDMI signal, but only crunching the pixels relevant to their area of the display. To make sure clean SPI signals get to each panel, special RS485 driver chips are used to send the signal over a differential pair from the FPGA, before breaking the signal back out to standard SPI at the destination.

Building such a large display takes special techniques, and [Thomas] notes that the help of a local construction company was imperative to making the construction of the final video wall look easy. It’s always interesting to see what goes into these large installations. Sometimes, a major build can even clear out world stocks of important components.

3D Printed Diffusers Make More Natural Light

February 9, 2019 by Richard Baguley 11 Comments

A strip of LEDs may be a simple and flexible way to add light to a project, but they don’t always look natural. There is an easy way to make them look better, though: add a diffuser. That’s what [Nate Damen] did using a 3D printer. He created a diffuser using PETG giving a standard string of LEDs a softer and more natural look that makes them look more like older light sources such as fluorescent strips or EL wire, but with the flexible colors of LEDs. The PETG material he used has a naturally somewhat cloudy look, so it acts as a diffuser without needing any extra treatment.

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