An irregular shard of a crystal wafer is set on a table, with two wire probes contacting it. Between the probes, a bright blue-purple light glows, illuminating the rest of the wafer.

Making LEDs In The Home Fab

August 23, 2026 by Aaron Beckendorf 24 Comments

Impressive as it most certainly is when an amateur fabricates a semiconductor, most of the projects we’ve seen are more demonstrations than workable chips. [Dr. Semiconductor], however, is going much further with his fabrication process, and is already working on a method to bond chips to printed circuit boards. It’s difficult to align a PCB with the pads on the underside of an opaque silicon wafer, however, so as a trial run he’s made and bonded some transparent LED chips.

The starting material for these chips is a gallium nitride (GaN) LED epiwafer, a stacked structure of n-doped GaN, an indium gallium nitride quantum well layer, and p-doped GaN grown on a sapphire substrate. When current passes through the structure, electrons from the n-doped layer and holes from the p-type layer recombine in the quantum well layer, emitting blue light. To make a functional LED from this, [Dr. Semiconductor] needed to make electrical contacts to both the n-type and p-type layers. Making the n-type contact required cutting through the p-type and quantum well layers.

This would normally be done with reactive ion etching in chlorine, but [Dr. Semiconductor] came up with a new process: a 355-nm ultraviolet etching laser causes GaN to break down into gallium and nitrogen, with the resulting cut being cleaned up by a potassium hydroxide etch. To deposit the contacts themselves, [Dr. Semiconductor] formed a photoresist mask, deposited metal (nickel, silver, and titanium) in a sputtering chamber, and used a developer solution to dissolve the mask and lift off the unwanted metal regions.

A square, purple PCB is shown under a microscope. The PCB has four vias surrounding a transparent chip, which has a blob of translucent yellow material on top of it. — The LED after bonding and phosphor application.

When [Dr. Semiconductor] applied current between the two contacts, the LED glowed bright blue. The next step was to mount it to a PCB; to do so, he first sliced the wafer into individual LED chips with the ultraviolet laser. He then electroplated indium bumps onto a printed circuit board, positioned the chip above these bumps, added some rosin flux, and melted the indium bumps. This soldered the chip to the board and let the board power the LED.

Like most commercial LEDs, these were blue; most LED assemblies additionally include a phosphor layer which absorbs blue light and emits another color. To create a white LED, for example, [Dr. Semiconductor] mixed cerium-doped yttrium aluminium garnet phosphor powder with clear silicone and spread it over the LED. This absorbs some of the blue light and emits yellow light, and the resulting mixture of blue and yellow light looks white to human eyes.

We’ve previously covered some of the history of LEDs and the phosphors which make them useful. This seems to be the first inorganic LED we’ve seen, but we’ve also seen a few homemade OLEDs.

Thanks to [SpuriousIndices] for the tip!

Mini Blinking Barrels Keep Desktop Traffic In Check

August 19, 2026 by Tom Nardi 19 Comments

Your desk or bench is a work area, so why not make it look the part? That’s the idea behind the miniature blinking traffic barrels that [Glen Akins] recently put together. Of course, just a single blinking light doesn’t really sell the idea of a busy construction zone, so he spent a somewhat surprising amount of time and effort optimizing the design for small-scale production.

The end result is a fascinating write-up that dives into the design decisions [Glen] made. Every aspect of this project, from the overhang of the “handle” on the 3D printed barrel to the number of passive components on the PCB was carefully considered. Critics may say [Glen] put too much thought into something that didn’t need to be so complex, but projects like these are an excellent way to keep your skills sharp — there’s no such thing as practicing too much.

Starting with the design of the barrel itself, we appreciate that [Glen] kept the capabilities of his desktop 3D printer in mind. By breaking the design up into multiple pieces and avoiding overly steep angles, he produced a design that prints cleanly without the need for support material. His step-by-step documentation and screenshots also serve as a great introduction to designing parts in Fusion if that’s something you’re interested in.

From there, things switch over to the electronics. Some in the audience will bemoan that he’s using a PIC12F1612 microcontroller to blink a single LED instead of a 555, but [Glen] brought the receipts on this one. Not only does the PIC offer more flexibility in terms of getting the blinking to look the way he wants, but it requires fewer passive components on the board and is considerably more energy efficient than the iconic timer IC. Even if you ignore all the other advantages, he calculates that going with a 555 would have cut the battery life of the finished product by approximately 15%.

This is one of those projects that’s difficult to summarize in such a terse format, as every time you think the write-up must be about over it takes a new turn on you. We were mildly bemused when the second iteration of the PCB popped up, but by the time he introduced the custom programming adapter board, we knew [Glen] wasn’t messing around.

Unsurprisingly, this isn’t the first time we’ve seen [Glen]’s handiwork. You may recall seeing his RP2040-powered sound board earlier this year, but his name has been popping up on these pages for more than a decade now.

Addressable LEDs Make Giant 16×2 Character Display

August 5, 2026 by Tyler August 12 Comments

We’ve always taken a certain childlike joy in seeing tiny things made big, and big things tiny. Evidently [Uncle Stem] is the same way, if this 7x sized 16×2 “LCD” display is any indicator.

“LCD” is in scare quotes there, because while the original display is a character LCD, [Uncle Stem]’s embigginated recreation is not. Liquid crystal displays are beyond all but the most dedicated DIYers, so [Stem] recreated the whole thing with addressable LEDs instead — over a thousand of them. Each character got its own PCB, and rather than pay for assembly [Stem] used a 3D printed stencil to help apply solder paste, an idea we’ve seen before. His choice of long lengths of nickel strip — the stuff you spot weld to Li-ion batteries — to join the LED-holding PCBs is also worth noting.

In order to get his giant display to act like the I2C-operated module he loves, [Uncle Stem] equipped it with an RP2040 pre-programmed with the LCD character set. That way he can plug it into any Arduino project that uses the LiquidCrystal_I2C library and have the authentic 1602 experience. The green “PCB” the display is mounted to is actually laser-cut plywood, while some acrylic sits in front of his PCBs with office paper to act as as a diffuser. A 3D printed frame completes the illusion. He even goes so far as to replicate the pin headers at 7:1 scaling with brass rods.

He also connects it to a over-sized Arduino, with giant jumper wires. But for the record, not the giant Arduino we featured previously. Like we said, hackers like to mess with scale, and we’ve seen everything from giant benchies to a working Mac Classic for Barbie.

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The 16K Display That Ate Las Vegas

August 3, 2026 by Al Williams 37 Comments

You may have a 4K television. Perhaps you have even bought an 8K screen, despite the shortage of things worth watching in 8K. A 16K display is, today, a rarity. But even when those eventually become commonplace, yours probably will not cover 14,900 square meters, rise 73 meters into the air, or wrap over your head and behind your peripheral vision.

That is approximately what happens inside Sphere in Las Vegas. The venue’s interior display is quoted as having a resolution of 16K by 16K and an area of 160,000 square feet, or about 3.7 acres. Unlike most enormous movie screens, it is not illuminated by a projector. The entire surface is a direct-view LED display: an immense, curved video wall assembled from tens of thousands of smaller pieces.

After seeing The Wizard of Oz at Sphere, however, the most interesting part was not simply the screen’s size. It was how thoroughly the screen could disguise itself.

Where Did The Theater Go?

Radio City or the Sphere? (It is the Sphere; photo courtesy [DP])

Before the presentation began, the auditorium appeared to have a conventional architectural ceiling. Great orange ribs curved over the seating, while ventilation grilles, suspended loudspeakers, lighting fixtures, curtains, and video monitors completed the illusion. It looked like the Radio City Music Hall’s proscenium. Then the show started — and the apparent theater completely disappeared. The speakers, the TVs, even the stage.

The obvious first conclusion was that the LED surface must be optically transparent, allowing the audience to see the real roof behind it until the pixels illuminated. That explanation was attractive because Sphere’s audio system really is installed behind the display, and the surface must allow sound through it.

It was also, apparently, wrong. The only explanation that makes sense is that the ceiling, ribs, grilles, speakers, and monitors were already being displayed by the screen. It was like a holodeck impersonating a physical theater interior. When the Oz material began, the system simply replaced one complete visual environment with another.

That’s what happens when a display fills nearly all of your useful visual field. A normal screen announces itself with a bezel, a wall, or at least a clearly visible edge. Sphere’s display extends upward and around the audience, removing many of those references. Give the image credible perspective, texture, shadows, and familiar architectural details, and the brain accepts the pixels as a room.

The same effect makes the Oz landscapes seem less like scenes displayed in front of the audience and more like places into which the auditorium has been inserted. Of course, there are more special effects. For The Wizard of Oz, there is wind and smoke, along with paper leaves, flower petals, and foam-rubber apples that fall from the sky. All of this makes it even more immersive.

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Architectural LED Install Shows How To Do It With Style

August 2, 2026 by Zoe Skyforest 6 Comments

Anyone can string up some LED string lights in a space with mixed results. However, if you want to create a lighting environment that’s classy and stylish, it takes a little more finesse. [ipad.bendavid] has a great example of this, with a rather tidy architectural LED installation.

The final look is quite clean and evenly lit, without requiring the use of any diffuser material.

The electronic side of things is relatively straightforward. There’s an ESP32 running the show, commanding the colors for 928 individually-addressable WS2812 RGB LEDs. It uses the WebSocket API for real time control, integrates with Home Assistant, and even offers audio reactive lighting modes with the aid of an INMP441 I2S audio input module. A hefty 5 V, 60 A power supply ensures the LEDs are never short of juice. There was also careful attention paid to power distribution to avoid any dim spots or other issues.

Where it gets really cool, though, is the attention paid to the construction of the installation. The LED strips are installed in concentric square frames, which block light in specific areas to create a nice square pattern, with the LEDs facing the wall they’re installed on rather than projecting out to the viewer. This hides the strips themselves and eliminated the need for diffusers which can be a pain to get right.

Overall, the build is a pleasing one that plays with light and darkness and looks rather stylish in a way so many LED installs don’t. If you’re cooking up your own neat glowable projects, you know we’d love to see them on the tipsline.

A Brief History Of The Crazy Old 7-Segment Display

July 9, 2026 by Al Williams 17 Comments

How old is the seven-segment display? Surely it is a product of the 1970s. After all, calculators started showing up, and the height of junior high humor was plugging 7734 into your calculator and showing it to someone upside down. Of course, for it to go mainstream, maybe they really originated in the 1960s, but no earlier than that, right? Actually, no. Sure, the LED seven-segment display had to wait for LEDs. But the actual idea is much older than that.

The concept of building numbers from a small set of reusable segments predates LED displays by decades. In fact, the basic idea appears in patents from the early 1900s and may have roots in even older mechanical signs and printing techniques.

The history isn’t entirely straightforward. Unlike vacuum tubes or transistors, segmented displays evolved gradually through a series of practical ideas rather than one defining invention.

Blacking out the Eight

While looking into the history of segmented displays, I was reminded of something I’d seen years ago in retail stores: reusable price tags printed with rows of eights.

Rather than printing every possible price, the clerk simply used a marker to black out portions of each figure, transforming an 8 into whatever digit was needed. Cover a few strokes, and the eight becomes a three. Remove a different set, and it becomes a zero or a five. It was, in essence, a manual segmented display.

Finding the exact origin of these price tags is akin to finding out where Romans bought sponges. They were inexpensive commercial supplies, not the sort of products that historians carefully documented. My recollection is from the middle of the twentieth century, but the underlying concept is almost certainly older.

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A Light-Up Map Of Monaco

July 2, 2026 by Zoe Skyforest 4 Comments

If you want to get around Monaco, a map — digital or otherwise — is probably the best way to navigate. But if you just want to appreciate the city’s form in a more artistic way, you might enjoy [Terence Grover’s] latest project—a backlit topographic map of the unique principality.

The touch mode allows one to draw patterns across the map.

The project started with a QGIS mesh of Monaco, with the data fed through the Open-Meteo elevation API, which takes into account building heights. This was used as the basis for the heights of 179 pieces of 20 mm x 20 mm acrylic. These were assembled into a laser cut steel base, and were sanded on all sides but the base in order to allow them to diffuse light more effectively.

Strips of CS8812 LEDs are used to light the plastic towers, driven by a pair of Adafruit Feather RP2040 Scorpio boards. They’re fed pixel data from a Raspberry Pi 5, which runs a Flask panel accessed over an iPad. This allows control over the LED map display, showing things like civic data, highlighted events, and weather. There’s even a touch-sensitive mode that lets one paint fun patterns across the representation of the city.

We love a good artistic map, particularly when they’re full of LEDs and represent useful information.

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