LED Princess Dress Also Lights Up Girl’s Face

We’re pretty sure that [Luke] took Uncle of the Year last Halloween when he made an RGB LED princess dress for his niece. He recently found the time to document the build with a comprehensive how-to that’s just in time for Halloween ’17.

[Luke] made the system modular so that his niece could use it with any dress. The RGB LED strips are actually fastened down the inside of a petticoat — a fluffy, puffy kind of slip that’s worn underneath the dress. The LEDs face in toward the body, which helps diffuse the light. [Luke] first attached the strips with their own adhesive and then spent a lot of time sewing them down so they stayed put. At some point, he found that hot glue worked just as well.

The coolest part of this project (aside from the blinkenlights of course) is the power source. [Luke] used what he already had lying around: an 18V Ryobi battery pack. He wired a step-converter to it using a printed cap from Shapeways that’s designed to connect metal clips to the battery contacts. This cap really makes these packs useful for a lot of projects that need long-lasting portability.

These batteries are rated for 240W, which is overkill considering the load. But there’s a reason: it keeps heat to a minimum, since the electronics are hidden inside a cute little backpack. Speaking of cute, you can see his niece model the dress after the break.

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Sense Hat Comes Alive

Remember the Raspberry Pi Sense Hat? Originally designed for a mission to the International Space Station, the board has quite a few sensors onboard as well as an 8×8 RGB LED matrix. What can you do with an 8×8 screen? You might be surprised if you use [Ethan’s] Python Sense Hat animation library. You can get the full visual effect in the video below.

The code uses an array to represent the screen, which isn’t a big deal since there are only 64 elements. Turning on a particular element to animate, say, a pong puck, isn’t hard with or without the library. Here’s some code to do it with the library:

for x in range(0,7):
 ect.cell(image,[0,x],[randint(0,255), randint(0,255), randint(0,255)],0.1)
 ect.cell(image,[0,x],e,0.1)
for x in range(7,0, -1):
 ect.cell(image,[0,x],[randint(0,255), randint(0,255), randint(0,255)],0.1)
 ect.cell(image,[0,x],e,0.1)

Each loop draws a box with a random color and then erases it before going to the next position. The second for loop makes the puck move in the opposite direction. You can probably deduce that the first argument is the screen array, the second is the position. The third argument sets the color, and the final argument sets an animation timer. Looking at the code, though, it does look like the timer blocks which is probably not going to work for some applications.

If that’s all there was, this wouldn’t be worth too much, but you can also draw triangles, circles, and squares. For example:

ect.circle(image,(4,4), 3, [randint(0,255), randint(0,255), randint(0,255)], 0.1)

We covered the Sense Hat awhile back. Of course, it does a lot more than just light up LEDs as you can see from this weather dashboard.

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Ask Hackaday: What About the Diffusers?

Blinky LED projects: we just can’t get enough of them. But anyone who’s stared a WS2812 straight in the face knows that the secret sauce that takes a good LED project and makes it great is the diffuser. Without a diffuser, colors don’t blend and LEDs are just tiny, blinding points of light. The ideal diffuser scrambles the photons around and spreads them out between LED and your eye, so that you can’t tell exactly where they originated.

We’re going to try to pay the diffuser its due, and hopefully you’ll get some inspiration for your next project from scrolling through what we found. But this is an “Ask Hacakday”, so here’s the question up front: what awesome LED diffusion tricks are we missing, what’s your favorite, and why?

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Beautiful Linear RGB Clock

Yup, another clock project. But here, [Jan] builds something that would be more at home in a modern art museum than in the dark recesses of a hacker cave. It’s not hard to read the time at all, it’s accurate, and it’s beautiful. It’s a linear RGB LED wall clock.

7512951486134540347You won’t have to learn the resistor color codes or bizarre binary encodings to tell what time it is. There are no glitzy graphics here, or modified classic timepieces. This project is minimal, clean, and elegant. Twelve LEDs display the hours, six and nine LEDs take care of the minutes in add-em-up-coded decimal. (It’s 3:12 in the banner image.)

The technical details are straightforward: WS2812 LEDs, an Arduino, three buttons, and a RTC. You could figure that out by yourself. But go look through the log about building the nice diffusing plexi and a very clean wall-mounting solution. It’s the details that separate this build from what’s hanging on our office wall. Nice job, [Jan].

Cheap LCD TV gets cheaper fix

Most hacks need some fair bit of skill and knowledge if you want to come out successful at the other end. Others, you just plunge in blindly with a “heck, it’s already broken so I can’t make it any worse” attitude. Throwing caution to the wind, you dive in, rip things up, and see if you can manage to catch the bull by the horns.

[Jim]’s cheap LCD TV, barely a few years old, died. It was purchased from the store whose blue polo-shirted cashiers can drive you nuts with their incessant questions. [Jim] just rolled up his sleeves and rather haphazardly managed to fix his TV while adding an extra feature along the way.

His initial check confirmed that the LCD panel worked. Using a flashlight, he could see that the panel was displaying video which meant it was the backlight that wasn’t working. Opening up the TV, he located the LED driver board whose output turned out to be zero volts. [Jim] happened to have a lot of WS2812B strips lying around, along with their power supplies and RGB color controllers. The obvious solution was to ditch the existing LEDs and power supply and use the WS2812B strips.

Surprisingly, the original backlight consisted of just 21 LEDs arranged in three rows. He ripped those out, put in the WS2812B strips, and taped the jumble of wires out of sight. After putting it back together, [Jim] was happy to see it worked, although the new strips were not as bright as the old ones, causing some uneven light bands. He solved this by adding a few more strips of LEDs. It took him a couple of hours to fix his TV, but by the end of it, he had a TV whose backlight could be adjusted to any color using the external color controllers — although we’re not too sure what good that would be.

World’s Smallest LED Cube – Again

There’s a new challenger on the block for the title of the “Worlds Smallest 4x4x4 RGB LED Cube“. At 13x13x36 mm, [nqtronix]’s Cube Pendant is significantly smaller than [HariFun’s] version, which measures in at about 17x17x17 mm just for the cube, plus the external electronics. It took about a year for [nqtronix] to claim this spot, and from reading the comments section, it seems [HariFun] isn’t complaining. The Cube Pendant is small enough to be used as a key fob, and [nqtronix] has managed to really cram a lot of electronics in it.

The LED’s used are 0606 RGB’s which are 1.6mm square, although he did consider using 0404’s before scrubbing the idea. There’s many ways of driving 192 IO’s, but in this case, Charlieplexing seemed like the best solution, requiring 16 IO’s. Unlike [HariFun]’s build, this one is fully integrated, with micro-controller, battery and everything else wrapped up in a case made entirely from PCB — inspired by [Voja Antonic]’s FR4 enclosure technique, and the LED array is embedded in clear resin.

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Another Desktop LED Xmas Tree!

We love it when someone takes inspiration from one of our posts and comes up with their own twist on it. [Matthew] liked one builds he saw on Hackaday so much, he built his own LED desktop Xmas tree!

[Matthew] was inspired by [designer2k2]’s DIY desktop Xmas tree that was posted in October. To get started, he found a set of concentric WS2812 rings over on Ali Express. The five rings total 93 LEDs, plus a single WS2812 for the top of the tree. He also got a laser cut tree model from Thingiverse and had it cut, combining the LED rings with the tree in the final product

The whole thing running on a Digispark USB Development Board from DigiStump, the same as the original project. There aren’t many details in the video, but [Matthew] has put links to where he got the rings and the tree, the laser cutting service, a link to the DigiStump website as well as a link to [designer2k2]’s original tree project. There’s no source code yet, but [Matthew] says a link to it is coming along with some more pictures.

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