A VIC-20 Emulator In Your Browser

February 3, 2026 by Lewin Day 11 Comments

The Commodore VIC-20 was a solid microcomputer that paved the way for the legendary Commodore 64 to come. If you’re a fan of the machine and want to revisit its glory days, you could hunt one down on an auction site and hope that it’s in working order. Or you could just emulate the VIC-20 in your browser thanks to the work of [Lance Ewing].

The project is called JVic—because it’s a VIC-20 emulator written in Java. It’s primarily intended for playing old VIC-20 games, and is designed with mobile devices front of mind—so it works well on a phone screen. You can enjoy the built-in library of games, or you can even direct JVic to boot up a ROM from a ZIP file hosted on a given URL or attached to a forum post. You can also install it on your own device rather than running it online, if so desired. [Lance] provides a range of setup options for running it locally or putting it on your own web server if that’s how you like to do things. Files are on Github for those eager to dive in.

We get lots of VIC-20 hacks around these parts. Even if it’s not the most popular machine that Commodore ever built, it’s certainly up there in the rankings. If you want to learn Forth, or even build a VIC-20 from scratch, we’ve explored that before. If you’ve got your own retrocomputer hacks kicking around, don’t hesitate to let us know!

[Thanks to Stephen Walters for the tip!]

Lego Typewriter Writes Plastic Letters

February 3, 2026 by Lewin Day 5 Comments

Some time ago, Lego released a beautiful (and somewhat pricey) typewriter set that was modeled after one used by company founder Ole Kirk Kristiansen. To the disappointment of some, it doesn’t actually work—you can’t really write a letter with it. [Koenkun Bricks] decided to rectify this with their own functional design.

Right away, we’ll state that this is not a traditional typewriter. There are no off-the-shelf Lego components with embossed letters on them, so it wasn’t possible to make Lego type bars that could leave an impression on paper with the use of an inked ribbon. Instead, [Koenkun Bricks] decided to build a design that was Lego all the way down, right to the letters themselves. The complicated keyboard-actuated mechanism picks out flat letter tiles and punches them on to a flat Lego plate, creating a plastic document instead of a paper one.

It’s not perfect in operation. It has some issues unique to its mode of operation. Namely, the round letter tiles sometimes rotate the wrong way as they’re feeding through the typewriter’s mechanisms, so you get sideways letters on your finished document. It looks kind of cool, though. Outside of that, sometimes the letter pusher doesn’t quite seat the letter tiles fully on the document plate.

Overall, though, it’s a highly functional and impressive build. We’ve seen some other great DIY typewriters before, too, like this 3D printed build. Video after the break.

Continue reading “Lego Typewriter Writes Plastic Letters” →

LED Interior Lighting Could Compromise Human Visual Performance

February 3, 2026 by Lewin Day 66 Comments

LED lighting is now commonplace across homes, businesses, and industrial settings. It uses little energy and provides a great deal of light. However, a new study suggests it may come with a trade-off. New research suggests human vision may not perform at its peak under this particular form of illumination.

The study ran with a small number of subjects (n=22) aged between 23 to 65 years. They were tested prior to the study for normal visual function and good health. Participants worked exclusively under LED lighting, with a select group then later also given supplemental incandescent light (with all its attendant extra wavelengths) in their working area—which appears to have been a typical workshop environment.

*Incandescent bulbs have a much broader spectrum of output than even the best LEDs. Credit: Research paper*

Notably, once incandescent lighting was introduced, those experimental subjects showed significant increases in visual performance using ChromaTest color contrast testing. This was noted across both tritan (blue) and protan (red) axes of the test, which involves picking out characters against a noisy background. Interestingly, the positive effect of the incandescent lighting did not immediately diminish when those individuals returned to using purely LED lighting once again. At tests 4 and 6 weeks after the incandescent lighting was removed, the individuals continued to score higher on the color contrast tests. Similar long-lasting effects have been noted in other studies involving supplementing LED lights with infrared wavelengths, however the boost has only lasted for around 5 days.

The exact mechanism at play here is unknown. The study authors speculate as to a range of complex physical and biological mechanisms that could be at play, but more research will be needed to tease out exactly what’s going on. In any case, it suggests there may be a very real positive effect on vision from the wider range of wavelengths provided by good old incandescent bulbs. As an aside, if you’ve figured out how to get 40/40 vision with a few cheap WS2812Bs, don’t hesitate to notify the tip line.

Thanks to [Keith Olson] for the tip!

CPU Scheduler Divines The Will Of The Heavens

February 1, 2026 by Lewin Day 17 Comments

Horoscopes are a great way to pass a boring lunchbreak, and an excellent excuse for ending a ill-considered relationship. They’re also a hilarious way to handle CPU scheduling under Linux, thanks to the work of [Lucas Zampieri].

The project is called scx_horoscope, and it’s a sched_Ext scheduler that makes its CPU scheduling choices based on what the heavens are doing in real time. Different tasks are handled based on different astronomical objects. For example, the Sun represents life force, and thus grants boons to key system processes. The Moon, an emotive influence, rules over interactive processes like shells and terminals. Mercury, as the god of communication, handles network and IO tasks, and so it goes from there. It’s not just a surface level thing, either—[Lucas] has implemented the influences of the elements of fire, air, earth, and water, and there are negative timeslice penalties on associated tasks when a given planet lands in retrograde.

You can argue whether or not the broader motions of the heavens have any impact on our lives based on the time and circumstances of our birth. But you can’t argue that scx_horoscope really will influence how your computer runs based on the dance of the planets in the sky. Mostly, though, we concern ourselves with astronomy rather than astrology around these parts!

[Thanks to Benjamin for the tip!]

A DIY Headset For SteamVR

February 1, 2026 by Lewin Day 1 Comment

The modern era of VR started a long time ago, and a wide range of commercial headsets have proliferated on the market since then. If you don’t want to buy off the shelf, though, you could always follow [Manolo]’s example and build your own.

This DIY headset is known as the Persephone 3 Lite, and is intended for use with SteamVR. It’s got the requisite motion tracking thanks to a Raspberry Pi Pico, paired with an MPU6500 inertial measurement unit. As for the optics, the headset relies on a pair of 2.9-inch square displays that operate at a resolution of 1440 x 1440 with a refresh rate up to 90 Hz. They’re paired with cheap Fresnel lenses sourced from Aliexpress for a few dollars. Everything is wrapped up in a custom 3D-printed housing that holds all the relevant pieces in the right place so that your eyes can focus on both screens at once. The head strap is perhaps the only off-the-shelf piece, sourced from a Quest 2 device.

If you’re eager to recreate this build at home, files are available over on [Manolo’s] Patreon page for subscribers. We’ve featured some other DIY headset builds before, too. Video after the break.

Continue reading “A DIY Headset For SteamVR” →

IPhone Becomes A Bluetooth Keyboard And Mouse

February 1, 2026 by Lewin Day 24 Comments

Sometimes you need to use a computer and you don’t have a spare keyboard and mouse on hand. [KoStard] figured an iPhone could serve as a passable replacement interface device. To that end, he built an adapter to let the phone act as a wireless keyboard and mouse on just about any modern machine.

To achieve this, [KoStard] grabbed an ESP32-S3 development board, and programmed it to act as a USB HID device to any machine attached over USB. It then listens out for Bluetooth LE communications from an iPhone equipped with the companion app. The app provides an on-screen keyboard on the iPhone that covers everything including special keys, symbols, and punctuation. You can also take advantage of the iPhone’s quality capacitive touchscreen, which emulates a nicely-responsive trackpad, with two-finger taps used for right clicking and two-finger drags for scroll. Latency is nice and low courtesy of the direct Bluetooth LE connection.

It’s a nifty build that is particularly useful in oddball situations where you might want a keyboard and mouse. For example, [KoStard] notes it’s a great way to control a Smart TV without having to do ugly slow “typing” on an infrared remote. We’ve seen his work before, too—previously building an adapter to provide Bluetooth capability to any old USB keyboard. Video after the break.

Continue reading “IPhone Becomes A Bluetooth Keyboard And Mouse” →

Limiting Battery Risk On Repurposed Smartphones With PostmarketOS

February 1, 2026 by Lewin Day 28 Comments

PostmarketOS is a Linux distribution specifically designed for those who wish to repurpose old smartphones as general-use computers, to a degree. This can be a great way to reuse old hardware. However, for [Bry50], it was somewhat discomforting leaving the phone’s aging lithium battery perpetually on charge. A bit of code was thus whipped up to provide a greater measure of safety.

The concept is simple enough—lithium batteries are at lower risk of surprise combustion events if they’re held at a lower state of charge. To this end, [Bry50] modified the device tree in PostmarketOS to change the maximum charge level. Apparently, maximum charge was set at a lofty 4.4V (100%), but this was reconfigured to a lower level of 3.8V, corresponding to a roughly 40-50% state of charge. The idea is that this is a much healthier way to maintain a battery hooked up to power for long periods of time. There’s one small hitch—the system will get confused if the battery voltage is higher than the 3.8 V setpoint when switching over. It’s thus important to let the device discharge to a lower level if you choose to make this change.

It’s a neat mod that both increases safety, but keeps the battery on hand to let the system ride through minor power outages. If you’re new to the world of repurposing old smartphones, fear not. [Bryan] also has a tutorial on getting started with PostmarketOS for the unfamiliar. If you’re working on your own projects in this space, we’d love to hear about them—so get on over to the tipsline!