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1294 Articles

Neopixels? Try Liquid Nitrogen To Color Shift Your LEDs Instead

November 11, 2023 by 23 Comments

If you’re like us, you’ve never spent a second thinking about what happens when you dunk an ordinary LED into liquid nitrogen. That’s too bad because as it turns out, the results are pretty interesting and actually give us a little bit of a look at the quantum world.

The LED fun that [Sebastian] over at Baltic Lab demonstrates in the video below starts with a bright yellow LED and a beaker full of liquid nitrogen. Lowering the powered LED into the nitrogen changes the color of the light from yellow to green, an effect that reverses as the LED is withdrawn and starts to warm up again. There’s no apparent damage to the LED either, although we suppose that repeated thermal cycles might be detrimental at some point. The color change is quite rapid, and seems to also result in a general increase in the LED’s intensity, although that could be an optical illusion; our eyes are most sensitive in the greenish wavelengths, after all.

So why does this happen? [Sebastian] goes into some detail about that, and this is where quantum physics comes into it. The color of an LED is a property of the bandgap of the semiconductor material. Bandgap is just the difference in energy between electrons in the valence band (the energy levels electrons end up at when excited) and the conduction band (the energy levels they start at.) There’s no bandgap in conductive materials — the two bands overlap — while insulators have a huge bandgap and semiconductors have a narrow gap. Bandgap is also dependent on temperature; it increases with decreasing temperature, with different amounts for different semiconductors, but not observably so over normal temperature ranges. But liquid nitrogen is cold enough for the shift to be dramatically visible.

We’d love to see the color shift associated with other cryogens, or see what happens with a blue LED. Want to try this but don’t have any liquid nitrogen? Make some yourself!

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3D-Printed LED Wall Clock Does Lots With Little

November 6, 2023 by 14 Comments

This wall clock built by [Alf Müller] is lovely, using two NeoPixel rings to mark the time by casting light onto a 3D-printed ring. The blue shows the minutes, made more discrete by a grid inside the ring. The green shows the hours.  [Alf] has provided the code so you can rework the color scheme.  It might be interesting to add seconds with the red LEDs, or perhaps a countdown triggered by a touch sensor…

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A Tiny Board For Driving LEDs In…Whatever

October 26, 2023 by 19 Comments

Whether you’re into chiptune or just playing Tetris on original hardware, you might like rocking a heavily-customized Game Boy. Lovely flashing LEDs can only improve the aesthetic, so if that’s what you’re after, you might consider the ARCCore board from [NatalieTheNerd].

The board is a compact and easy way to drive some addressable LEDs, with a form factor designed to take up a small amount of space when stuffed into a Game Boy or other game console. It rocks an RP2040 microcontroller set up to drive a strip of WS2812B LEDs. Three buttons are used to configure the color and brightness settings. The board is designed to run on 3.3 to 5 V, thanks to an onboard buck converter. It’s capable of delivering enough juice to run up to 10 RGB LEDs, though you could potentially use more if you ran them from external power.

You can use just about any microcontroller on the market today to run addressable LEDs if you so desire. If you want a compact drop-in solution that takes up less space, though, you might find the ARCCore useful. If you’ve got your own nifty kit for running addressable LEDs, don’t hesitate to share it with the broader hacker massive — hit the tipsline!

Stage Lighting Hack Keeps La Bohème From Becoming A Dumpster Fire

October 22, 2023 by 20 Comments

With all due respect to the Utah Opera’s production of La bohème, we just couldn’t resist poking a little fun at master electrician [David Smith]’s quick lighting hack for the opera. And who knew an opera from 1896 would need a garbage can fire? Live and learn.

In what appears to be a case of “The show must go on,” [David] was called on to improve an existing fire effect for one scene in the opera, which was reportedly a bit “artificial and distracting.” This is a pretty common problem in live productions of all types; it’s easy to throw light at a problem, but it’s often hard to make it both convincing and unobtrusive. Luckily, he had both the time to come up with something, and a kit full of goodies to make it happen. A balled-up strip of Neopixels provided the light, with an Arduino running some simple code to randomize the intensity and color of the RGBs. [David] stuck with the warm white, red, and green colors, to keep the color temperature about right for a fire, and drove the LEDs with a couple of MOSFETs that he keeps in his kit to fix busted dimmer packs.

The overall effect worked well, but the holes knocked in the side of the greatly abused garbage can let too much light out, making the effect distracting on stage. The remedy was simple: a cylinder of printer paper surrounding the LED tape. The paper not only acted as a diffuser but held the tape in place inside the can. The electrical crew ran two circuits to the can — one to keep the Arduino running throughout the show, and one to power the LED tape. The former made sure the audience didn’t see the microcontroller boot sequence, and the latter gave the electrician a way to control the effect from the dimmer console. The brief video below shows it in action during a rehearsal.

Hats off to [David] and the whole crew for the stagecraft heroics and for getting this thrown together so quickly.

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Printed Upgrades Improve Cheap Digital Microscope

September 19, 2023 by 7 Comments

Digital microscopes used to be something that only labs or universities might have, but as image sensor technology has progressed, the prices have fallen to the point that any classroom or hobbyist can easily obtain a usable device. The only problem is that a lot of features and quality have been lost to make some of these digital microscopes more affordable. In an effort to add some of these creature comforts back into more inexpensive devices, [Marb’s lab] has created a special carriage for one of these microscopes.

The first addition to the microscope is improved lighting. To accomplish this, three LEDs were built into custom housings and wired to a purpose-built LED driver board coupled with a voltage regulator. Two of the LED housings were attached to the end of adjustable arms, allowing them to be pointed in whichever direction is needed. The third is situated directly below the microscope underneath the stage. These are all mounted to a large, sturdy PVC base which also holds an adjustable carriage for the microscope itself. This allows much more fine-tuning of the distance between the sample and the microscope than it otherwise would have had.

For just a few dollars and a little bit of effort, the usability of a device like this is greatly improved. If you want to take the opposite approach and really go all-out for your microscope, though, take a look at these microscopes used for PCB circuit construction and troubleshooting or even this electron microscope for viewing things at a much higher magnification than any optical system would allow.

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Backyard LED Sculpture Inspired By Las Vegas Sphere

September 15, 2023 by 19 Comments

The Las Vegas Sphere is a large building. It stands 112 meters high and 157 meters wide, and is covered in a full 54,000 square meters of LED displays. That’s a little difficult to recreate at home for the typical maker. A scaled-down version is altogether more achievable though, as demonstrated by [DrZzs & GrZzs].

The Pixelhead Megasphere, as it is known, is 1.98 meters high and 2.4 meters in diameter. That makes it altogether easier to fit in an average backyard, and it comes with a much smaller pricetag than the $2 billion used to build the Las Vegas Sphere. It runs 20,028 individual addressable LED pixels, and runs on four 12-volt 100-amp power supplies. As seen here, it’s only running at 15%, so it can go plenty brighter to really get those power supplies toasty. The sphere is controlled by Xlights, with the LEDs interfaced via Kulp controller boards. It’s able to run a variety of different animations at a good frame rate, with [DrZzs & GrZzs] busy whipping up different designs for Halloween. The eye of Sauron is a particularly nice example.

We’ve seen some other neat LED spheres before, too. Video after the break.

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Minimalist LED Lamp Is Circular Beauty Incarnate

September 4, 2023 by 8 Comments

Lamps used to be things built to provide light with specific purpose, whether as reading lamps, desk lamps, or bedside table lamps. Now we just build them for the vibes, as with this minimalist LED lamp from [andrei.erdei].

The build uses a 3D-printed frame printed in opaque grey, with a diffuser element printed in a more translucent white. This is key to allowing the LED to nicely glow through the lamp without ugly distracting hotspots spoiling the effect. The lamp mounts 36 WS2812B LEDs in strip form. These are controlled from an Arduino Nano running the FastLED library for lightweight and easy control of the addressable LEDs. Smooth rainbow animations are made easy by the use of the HSV color space, which is more suitable for this job than the RGB color space you may otherwise be more familiar with.

[andrei.erdei] does a great job of explaining the build, including the assembly, electronics, and code aspects. The latter could serve as a particularly good resource if you’re just starting out on your own builds in the blinky, glowable space. Video after the break.

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