The Impending CRT Display Revival Will Be Televised

September 23, 2025 by Maya Posch 98 Comments

Until the 2000s vacuum tubes practically ruled the roost. Even if they had surrendered practically fully to semiconductor technology like integrated circuits, there was no escaping them in everything from displays to video cameras. Until CMOS sensor technology became practical, proper video cameras used video camera tubes and well into the 2000s you’d generally scoff at those newfangled LC displays as they couldn’t capture the image quality of a decent CRT TV or monitor.

For a while it seemed that LCDs might indeed be just a flash in the pan, as it saw itself competing not just with old-school CRTs, but also its purported successors in the form of SED and FED in particular, while plasma TVs made home cinema go nuts for a long while with sizes, fast response times and black levels worth their high sale prices.

We all know now that LCDs survived, along with the newcomer in OLED displays, but despite this CRTs do not feel like something we truly left behind. Along with a retro computing revival, there’s an increasing level of interest in old-school CRTs to the point where people are actively prowling for used CRTs and the discontent with LCDs and OLED is clear with people longing for futuristic technologies like MicroLED and QD displays to fix all that’s wrong with today’s displays.

Could the return of CRTs be nigh in some kind of format?

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Computer Has One Instruction, Many Transistors

September 20, 2025 by Bryan Cockfield 22 Comments

There’s always some debate around what style of architecture is best for certain computing applications, with some on the RISC side citing performance per watt and some on the CISC side citing performance per line of code. But when looking at instruction sets it’s actually possible to eliminate every instruction except one and still have a working, Turing-complete computer. This instruction is called subleq or “subtract and branch if less-than or equal to zero“. [Michael] has built a computer that does this out of discrete components from scratch.

We’ll save a lot of the details of the computer science for [Michael] or others to explain, but at its core this is a computer running with a 1 kHz clock with around 700 transistors total. Since the goal of a single-instruction computer like this is simplicity, the tradeoff is that many more instructions need to be executed for equivalent operations. For this computer it takes six clock cycles to execute one instruction, for a total of about 170 instructions per second. [Michael] also created an assembler for this computer, so with an LCD screen connected and mapped to memory he can write and execute a simple “hello world” program just like any other computer.

[Michael] does note that since he was building this from Logisim directly he doesn’t have a circuit schematic, but due to some intermittent wiring issues might have something in the future if he decides to make PCBs for this instead of using wire on a cardboard substrate. There’s plenty of other information on his GitHub page though. It’s a unique project that gets to the core of what’s truly needed for a working computer. There are a few programming languages out there that are built on a similar idea.

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Old Phone Upcycled Into Pico Projector, ASMR

September 11, 2025 by Tyler August 29 Comments

To update an old saying for the modern day, one man’s e-waste is another man’s bill of materials. Upcycling has always been in the hacker’s toolkit, and cellphones provide a wealth of resources for those bold enough to seize them. [Huy Vector] was bold enough, and transformed an old smartphone into a portable pico projector and an ASMR-style video. That’s what we call efficiency!

Kidding aside, the speech-free video embedded below absolutely gives enough info to copy along with [Huy Vector] even though he doesn’t say a word the whole time. You’ll need deft hands and a phone you really don’t care about, because one of the early steps is pulling the LCD apart to remove the back layers to shine an LED through. You’ll absolutely need an old phone for that, since that trick doesn’t apply to the OLED displays that most flagships have been rocking the past few years.

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Generative Art Machine Does It One Euro At A Time

March 22, 2025 by Elliot Williams 14 Comments

[Niklas Roy] obviously had a great time building this generative art cabinet that puts you in the role of the curator – ever-changing images show on the screen, but it’s only when you put your money in that it prints yours out, stamps it for authenticity, and cuts it off the paper roll with a mechanical box cutter.

If you like fun machines, you should absolutely go check out the video, embedded below. The LCD screen has been stripped of its backlight, allowing you to verify that the plot exactly matches the screen by staring through it. The screen flashes red for a sec, and your art is then dispensed. It’s lovely mechatronic theater. We also dig the “progress bar” that is represented by how much of your one Euro’s worth of art it has plotted so far. And it seems to track perfectly; Bill Gates could learn something from watching this. Be sure to check out the build log to see how it all came together.

You’d be forgiven if you expected some AI to be behind the scenes these days, but the algorithm is custom designed by [Niklas] himself, ironically adding to the sense of humanity behind it all. It takes the Unix epoch timestamp as the seed to generate a whole bunch of points, then it connects them together. Each piece is unique, but of course it’s also reproducible, given the timestamp. We’re not sure where this all lies in the current debates about authenticity and ownership of art, but that’s for the comment section.

If you want to see more of [Niklas]’s work, well this isn’t the first time his contraptions have graced our pages. But just last weekend at Hackaday Europe was the first time that he’s ever given us a talk, and it’s entertaining and beautiful. Go check that out next. Continue reading “Generative Art Machine Does It One Euro At A Time” →

A TV With Contrast You Haven’t Seen For Years

March 5, 2025 by Jenny List 42 Comments

It’s something of a surprise, should you own a CRT TV to go with your retrocomputers, when you use it to view a film or a TV show. The resolution may be old-fashioned, but the colors jump out at you, in a way you’d forgotten CRTs could do. You’re seeing black levels that LCD screens can’t match, and which you’ll only find comparable on a modern OLED TVs. Can an LCD screen achieve decent black levels? [DIY Perks] is here with a modified screen that does just that.

LCD screens work by placing a set of electronic polarizing filters in front of a bright light. Bright pixels let through the light, while black pixels, well, they do their best, but a bit of light gets through. As a result, they have washed-out blacks, and their images aren’t as crisp and high contrast as they should be. More modern LCDs use an array of LEDs as the backlight which they illuminate as a low resolution version of the image, an approach which improves matters but leaves a “halo” round bright spots.

The TV in the video below the break is an older LCD set, from which he removes the backlight and places the electronics in a stand. He can show an image on it by placing a lamp behind it, but he does something much cleverer. An old DLP projector with its color wheel removed projects a high-res luminance map onto the back of the screen, resulting in the coveted high contrast image. The final result uses a somewhat unwieldy mirror arrangement to shorten the distance for the projector, but we love this hack. It’s not the first backlight hack we’ve seen, but perhaps it give the best result.

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LCD Stackup Repair: Not For The Faint Of Heart

February 23, 2025 by Elliot Williams 11 Comments

Coming straight to the point: [Ron Hinton] is significantly braver than we are. Or maybe he was just in a worse situation. His historic Acer K385s laptop suffered what we learned is called vinegar syndrome, which is a breakdown in the polarizers that make the LCD work. So he bit the bullet and decided to open up the LCD stack and replace what he could.

Nothing says “no user serviceable parts inside” quite like those foil-and-glue sealed packages, but that didn’t stop [Ron]. Razor blades, patience, and an eye ever watchful for the connectors that are seemingly everywhere, and absolutely critical, got the screen disassembled. Installation of the new polarizers was similarly fiddly.

In the end, it looks like the showstopper to getting a perfect result is that technology has moved on, and these older screens apparently used a phase correction layer between the polarizers, which might be difficult to source these days. (Anyone have more detail on that? We looked around and came up empty.)

This laptop may not be in the pantheon of holy-grail retrocomputers, but that’s exactly what makes it a good candidate for practicing such tricky repair work, and the result is a readable LCD screen on an otherwise broken old laptop, so that counts as a win in our book.

If you want to see an even more adventurous repair effort that ended in glorious failure, check out [Jan Mrázek]’s hack where he tries to convert a color LCD screen to monochrome, inclusive of scraping off the liquid crystals! You learn a lot by taking things apart, of course, but you learn even more by building it up from first principles. If you haven’t seen [Ben Krasnow]’s series on a completely DIY LCD screen, ITO-sputtering and all, then you’ve got some quality video time ahead of you.

A Web-Based Graphics Editor For Tiny Screens

February 22, 2025 by Tom Nardi 18 Comments

These days, adding a little LCD or OLED to your project is so cheap and easy that you can do it on a whim. Even if your original idea didn’t call for a display, if you’ve got I2C and a couple bucks burning a hole in your pocket, why not add one? Surely you’ll figure out what to show on it as the project develops.

But that’s where it can get a little tricky — in terms of hardware, adding a screen just takes running a few extra wires, but the software side is another story. Not only do you have to contend with the different display libraries, but just creating the image assets to display on the screen can be a hassle if it’s not something you do regularly. Enter Lopaka, a graphics and user interface editor for electronic projects created by [Mikhail Ilin].

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