The Engineering Case For Fusing Your LED Strips

January 29, 2018 by Lewin Day 47 Comments

Modern LED strips are magical things. The WS2812 has allowed the quick and easy creation of addressable RGB installations, revolutionizing the science of cool glowy things. However, this accessibility means that it’s easy to get in over your head and make some simple mistakes that could end catastrophically. [Thomas] is here to help, outlining a common mistake made when building with LED strips that is really rather dangerous.

The problem is the combination of hardware typically used to run these LED strings. They’re quite bright and draw significant amounts of power, each pixel drawing up to 60 mA at full-white. In a string of just 10 pixels, the strip is already drawing 600 mA. For this reason, it’s common for people to choose quite hefty power supplies that can readily deliver several amps to run these installations.

It’s here that the problem starts. Typically, wires used to hook up the LED strips are quite thin and the flex strips themselves have a significant resistance, too. This means it’s possible to short circuit an LED strip without actually tripping the overcurrent protection on something like an ATX power supply, which may be fused at well over 10 amps. With the resistance of the wires and strip acting as a current limiter, the strip can overheat to the point of catching fire while the power supply happily continues to pump in the juice. In a home workshop under careful supervision, this may be a manageable risk. In an unattended installation, things could be far worse.

Thankfully, the solution is simple. By installing an appropriately rated fuse for the number of LEDs in the circuit, the installation becomes safer, as the fuse will burn out under a short circuit condition even if the power supply is happy to supply the current. With the example of 10 LEDs drawing 600 mA, a 1 amp fuse would do just fine to protect the circuit in the event of an accidental short.

It’s a great explanation of a common yet dangerous problem, and [Thomas] backs it up by using a thermal camera to illustrate just how hot things can get in mere seconds. Armed with this knowledge, you can now safely play with LEDs instead of fire. But now that you’re feeling confident, why not check out these eyeball-searing 3 watt addressable LEDs?

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Interactive LED Table

January 21, 2018 by Al Williams 6 Comments

Some hackers make functional things that you can’t allow to be seen in polite company. Others make beautiful things that could come from a high-end store. [Marija] falls into the second category and her interactive LED coffee table would probably fetch quite a bit on the retail market. You can see a video of the awesome-looking table, below.

It isn’t just the glass, MDF, and pine construction. There’s also a Bluetooth interface to a custom Android application from [Dejan], who collaborated on the project. However, if you aren’t comfortable with the woodworking, [Marija’s] instructions are very detailed with great pictures so this might be a good starter project.

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Smartphone Controlled Periodic Table Of Elements

January 16, 2018 by Tom Nardi 14 Comments

It wouldn’t be much of a stretch to say that here at Hackaday, we’re about as geeky as they come. Having said that, even we were surprised to hear that there are people out there who collect elements. Far be it from us to knock how anyone else wishes to fill their days, but telling somebody at a party that you collect chemical elements is like one step up from saying you’ve got a mold and fungus collection at home. Even then, at least a completed mold and fungus collection won’t be radioactive.

But if you’re going to spend your spare time working on a nerdy and potentially deadly collection, you might as well put it into an appropriate display case. You can’t just leave your Polonium sitting around on the kitchen counter. That’s the idea behind the interactive periodic table built by [Maclsk], and we’ve got to admit, if we get to put it in a case this awesome we might have to start our own collection.

A large portion of this project is building the wooden display case itself as, strangely enough, IKEA doesn’t currently stock a shelving unit that’s in the shape of the periodic table. The individual cells and edge molding are made of pine, the back panel is MDF, and the front of the display is faced off with thin strips of balsa to cover up all the joints. Holes were then drilled into the back of each cell for the LED wiring, and finally the entire frame was painted white.

Each cell contains an WS2812B RGB LED, which at maximum brightness draws 60mA. Given the 90 cells of the display case, [Maclsk] calculated a 5.4A power supply would be needed to keep everything lit up. However, he found a 4A power supply that made his budget happier, which he reasons will be fine as long as he doesn’t try to crank every cell up to maximum at the same time. Control for the display is provided by an Arduino Nano and HC05 Bluetooth module.

The final piece of the project was the Android application that allows the user to control the lighting. But it doesn’t just change colors and brightness, it’s actually a way to visualize information about the elements themselves. The user can do things like highlight certain groups of elements (say, only the radioactive ones), or light up individual cells in order of the year each element was discovered. Some of the information visualizations are demonstrated in the video below, and honestly, we’ve seen museum displays that weren’t this well done.

We last caught up with [Maclsk] when he created a very slick robotic wire cutting machine, which we can only assume was put to work for this particular project. Too bad he didn’t have a robot to handle the nearly 540 soldering joints it took to wire up all these LEDs.

[via /r/DIY]

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A Mini Stacker Arcade Cabinet

January 7, 2018 by Kristina Panos 10 Comments

For [LumoW], what started as a school project turned into a passion project. He and his team made a hardware implementation of an arcade game called Stacker. Never heard of it? It’s pretty fun, kind of like an inverse Tetris. You can play the flash version here and see their mini arcade version after the break.

The game is based around the Mojo FPGA which the class required, and it’s programmed entirely in bitwise operators. It uses WS2812 RGB LEDs to represent the individual tower building blocks, and these are mounted on plywood in a matrix and separated into cells by a grid of foam board. After some trial and error, the team found the perfect shade of acrylic to diffuse the bright dots into glowing squares.

Since the game only needs one input, we don’t think [LumoW] should apologize at all for using the biggest, baddest button they could find. Besides, the game has that edge-of-your-seat action that can turn panic into heavy-handedness and cool DIY arcade games into shards of sadness.

Looking for something more advanced to do with an FPGA? Try your hand at vector games.

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Touch Panels Make This Christmas Tree Interactive

December 23, 2017 by Dan Maloney No comments

The city of Liverpool, famously known as both the home port of the Titanic and the birthplace of The Beatles, also seems to have a thing for interactive public art installations. Witness this huge interactive Christmas tree that can be played by passersby.

The display in the city’s busy Williamson Square was commissioned by a municipal business group and built by [Adrian McEwen]. The idea was to adorn the 10-meter natural tree with large geometric ornaments covered with Neopixel strips. [Adrian] documents the build process in some detail, including that fact that over 170 meters of WS2812b strips went into the ornaments for the tree. While the strips themselves at IP68 rated, the connections needed when attaching them to the custom-made frames were not, and that had to be overcome with ample application of heat-shrink tubing. OctoWS2811 adapter boards were dangled about the tree to control the lights and connected together with garlands of Ethernet cables. Pressure sensors were used to control the lights when the EMI from the beefy power supplies needed to run everything proved too much for the original touch sensors. After a lot of bench testing and a few long nights working with the city crew to hang the display, passing Liverpudlians can now play the tree and enjoy the Christmas season.

Would you rather a smaller display for your own Christmas tree? This somewhat hyperactive indoor light show might be what you’re looking for.

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Hackaday Links: April 16, 2017

April 16, 2017 by Brian Benchoff 10 Comments

Guess what’s going on at the end of the month? The Vintage Computer Festival Southeast is happening April 29th and 30th. The event is being held at the Computer Museum of America and is, by all accounts, a really cool show.

Walk into any package sorting facility or Amazon fulfillment center and you’ll find a maze of conveyor belts, slides, and ramps that move boxes from one point to another. Conveyor belts are so last century, so here’s a fleet of robots.

In 2017, the CITES treaty — an international treaty for the protection of endangered species — changed a lot. While the original treaty protected individual species, in 2017, enforcement of this treaty on tropical hardwoods changed to an entire genus. This is a problem when it comes to rosewood; previously only Dalbergia nigra was covered under CITES, now the entire Dalbergia genus is covered. This sucks for guitar makers, but a Dutch guy is making guitars out of newspaper. We’re probably looking at some sort of micarta thing here, but it sounds acceptable.

Where did Apple’s Spinning Beach Ball of Death come from? 1984, or thereabouts. The ubiquitous Apple ‘wait’ cursor is from the first versions of the Macintosh Toolbox, and it has remained mostly unchanged all this time. This is Apple Wait, a demonstration of this first spinny ball of death. It’s a Raspberry Pi connected to an Apple monochrome monitor that just displays a spinny wait logo. Check out the video.

How do you make strips of RGB LEDs turn a corner? Wire, usually. Here are some corner pieces for WS2812B LED strips. It looks very handy if you’re building a gigantic RGB LED matrix.

SHA2017 is an outdoor hacker conference that’s happening this summer. They’re working on a badge, but they need some help. They’re looking for some funding for their ESP32-powered, touch controller, sunlight-readable ePaper badge. If you have a job that likes to sponsor stuff like this, it’s a worthy cause.

A Wordsearch Twist On The Word Clock

March 16, 2017 by Donald Papp No comments

We love seeing new takes on existing ideas, and [Danny] certainly took the word clock concept in an unusual direction with his Wordsearch Clock. Instead of lighting up words to spell out the time, [Danny] decided to embrace the fact that the apparent jumble of letters on the clock face resembles a word search puzzle.

In a word search puzzle, words can be found spelled forward or backward with letters lined up horizontally, diagonally, or vertically. All that matters is that the correct letters are in a line and sequentially adjacent to one another. [Danny]’s clock lights up the correct letters and words one after the other, just as if it were solving a word search puzzle for words that just happen to tell the correct time. You can see it in action in the video, embedded below.

[Danny] went the extra mile in the planning phase. After using a word search puzzle generator tool to assist in designing the layout, he wrote a Processing sketch to simulate the clock’s operation. Visually simulating the clock allowed him to make tweaks to the layout, identify edge cases to address, and gain insight into the whole process. If you’re interested in making your own, there is a GitHub repository for the project.

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