LED Printers: The Quiet Achievers You May Not Have Heard Of

Many different types of printers have entered the market over the years. Most of us are intimately familiar with the common inkjet and laser, both of which can be found in homes and offices all over the world. Then there are those old dot matrix printers that were so noisy in use, thermal printers, and even solid ink printers that occupied a weird niche for a time.

However, very little attention is ever paid to the LED printer. They’re not actually that uncommon, and they work in a very familiar way. It’s just that because these printers are so similar to an existing technology, they largely escaped any real notability in the marketplace. Let’s explore the inner workings of the printer tech that the world forgot.

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Hackaday Links: March 1, 2026

We’ll start this week off with a bit of controversy from Linux Land. Anyone who’s ever used the sudo command knows that you don’t see any kind of visual feedback while entering your password. This was intended as a security feature, as it was believed that an on-screen indicator of how many characters had been entered would allow somebody snooping over your shoulder to figure out the length of your password. But in Ubuntu 26.04, that’s no longer the case. The traditional sudo binary has been replaced with a one written in Rust, which Canonical has recently patched to follow the modern convention of showing asterisks on the password prompt.

As you might expect, this prompted an immediate reaction from Linux greybeards. A bug report was filed just a few days ago demanding that the change be reverted, arguing that breaking a decades-old expectation with no warning could be confusing for users. The official response from a Canonical dev was that they see it the other way around, and that the change was made to improve the user experience. It was also pointed out that those who want to revert to the old style of prompt can do so with a config change. The issue was immediately marked as “Won’t Fix”, but the discussion is ongoing.

Speaking of unexpected changes, multiple reports are coming in that the February security update for Samsung Galaxy devices, which is currently rolling out, removes several functions from the Android recovery menu. After the update is applied to phones such as the S25 and Fold 7, long-standing features, such as the ability to wipe the device’s cache partition or install updates via Android Debug Bridge (ADB), disappear.

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Art of 3D printer in the middle of printing a Hackaday Jolly Wrencher logo

The Joys Of 3D Printing

Al and I were talking on the podcast today about a sweet 3D printed wide-format camera build, and we got to musing on why we 3D-print.

For Al, it’s an opportunity to experiment with 3D printing itself: tweaking his machines to get the best performance out of them. Other people make small, functional objects that they need in their daily life, like bag clips or spare parts for broken appliances. Some folks go for the ornamental or the aesthetic. The kids in my son’s class all seem obsessed with sci-fi props and fidget toys. The initial RepRap ideal was to replace all commercial fabrication with machines owned by the individual, rather than by companies – it was going to be Marxist revolutionary.

But there’s another group of 3D printer enthusiasts that I think doesn’t get enough coverage, and I’m going to call them the hobbyist industrial designers. These are the people who design a custom dog-poop-bag holder that exactly fits their extra-wide dog leash, not because they couldn’t find one that fit in the pet store, but because it’s simply fun to design and fabricate things. (OK, that’s literally me.)

It’s fun to learn CAD tools, to learn about how things are designed, how they work, and how to manufacture them at least in quantity one. Dreaming, designing, fabricating, failing, and repeating until you get it right is a great joy. And then you get to use the poop-bag holder every day for a few years, until you decide to refine the design and incorporate the lessons learned on the tough streets of practical use.

Of course none of this is exclusive to 3D printing. There were always people who designed-and-built things in the metal machine shop, or made their creations out of wood. In that sense, the 3D printer is just another tool, and the real fun isn’t in using the 3D printer, but rather in the process of bringing things out of your mind and into the world. So maybe there is nothing new here, but the latitude that 3D printing affords the hobby designer is amazing, and that makes it all the more fun, and challenging.

So do you 3D print for necessity, to stick it to the man, to pimp your printer, for the mini-figs, or simply for the joy of the process of making things? It’s all good. 3D printing is a big tent.

Hackaday Podcast Ep 359: Flying Squids, Edible Passwords, And A CAD Automaton

Hackaday editors Elliot Williams and Al Williams met up to trade their favorite posts of the week. Tune in and see if your favorites made the list. From crazy intricate automata to surprising problems in Peltier cooler designs, there’s a little bit of everything.

Should bikes have chains? What’s the hardest thing about Star Trek computers to duplicate? Can you make a TV station from a single microcontroller? The podcast this week answers these questions and more. Plus, weigh in on the What’s That Sound contest and you might just score a Hackaday Podcast T-shirt.

For the Can’t Miss segment, Elliot had airships on his mind, while Al’s sick of passwords. But is he sick enough to take electronic pills that transmit his password?

Or download the bit stream and decrypt it by XORing each byte with zero.


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Building An Interactive Climbing Wall

Climbing is a cool sport. With that said, like everything, it’s even better if you integrate lots of glowing colorful LEDs. To that end, [Superbender] worked up this fun climbing wall that features interactive lighting built right in.

Structurally, there’s nothing too wild going on here. It’s a wood-framed climbing structure that stands 10 meters long and 2.5 meters high, and can be covered in lots of climbing holds. It’s the electronic side of things where it gets fun. An Arduino Due is installed to run the show, hooked up with a small TFT display and some buttons for control. It’s then hooked up to control a whole bunch of LEDs and some buttons which are scattered all across the wall. It’s also paired with an Arduino Nano which runs sound feedback, and a 433 MHz remote for controlling the system at a distance.

[Superbender] uses the lighting for fun interactive games. One example is called Hot Lava, where after each climbing pass, more holds are forbidden until you can’t make the run anymore. Chase the Blues is another fun game, where you have to climb towards a given hold, at which point it moves and you have to scamper to the next one.

We’ve featured similar projects before from other inventive climbers. Video after the break.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Uni-body That Does The Splits

Personally, I love a monoblock or uni-body split. You’ll pry this Kinesis Advantage from under my cold, dead hands. But on the go, I really like the Glove 80, a true split that can be completely wireless in case you want to put the halves really far apart.

A triple-black split keyboard without a case, for now.
Image by [thehaikuza] via reddit
[thehaikuza] is the opposite, preferring a full split at the desk, but finding it troublesome when using it on the couch or at a cafe or co-working space, and so created dǎ bāo (打包) — a uni-body split that can also be a distant split. And this best-of-both worlds creation is remarkably [thehaikuza]’s first keyboard.

The name means to take out food, and if you click the picture you can see a cute little take-out container on the silkscreen of the right half. Directly below it, there’s a track point nubbin to be used with the thumb.

It does its split-in-half trick via a magnetic four-pin connector for when you want the halves stuck together. When the halves are separated, they can instead talk over a USB-C cable. One half has the microcontroller, and the other has a GPIO expander.

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Tech In Plain Sight: Projection Clocks

You wake up in the middle of the night. Is it time to get up? Well, you can look at the nightstand clock. Unless your partner is in the way. Whoops. Even then, without your glasses, the time is just a fuzzball of light. You could ask Alexa, but that’s sure to wake your partner, too. The answer is a projection clock. In its modern form, it shoots a digital time display on a wall or ceiling with digits so large that you don’t need your glasses. If you can see the ceiling, you can tell what time it is.

New Tech

A modern invention, of course. No, not really. According to [Roger Russel], a UK patent in 1909 used an analog clock face and lightbulbs to project the clock face and hands on the ceiling. Unfortunately, [Roger’s] website is no more, but the Wayback Machine is on the job. You can see a device of the same type at the British Museum.

A modern projection clock on the ceiling.

In 1938, [Leendert Prins] filed for a patent on a similar projection clock. Sometimes known as “ceiling clocks” or “night clocks,” these devices often have a regular clock visible as well as a way to project the time. In the old days, this was often an image of a translucent analog clock lit up by light bulbs. In the modern era, it is almost always either LEDs or an LCD with a halogen backlight. Of course, there are many variations. A clock might use numbers on a rotating drum with a lamp behind it, for example.

Development

It isn’t hard to imagine someone putting a pocket watch in a magic lantern as a prototype. In general, some bright light source has to pass through a condenser lens. The light then travels through the LCD or translucent clock face. Finally, a projector lens expands the image.

We couldn’t find much about the actual history of old projection clocks outside of [Roger’s] defunct website. But if you can project an image and build a clock, all you need is the idea to combine them.

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