Laser Scanning A Cave With Homebrew Gear

June 24, 2026 by No comments

How do you measure the inside of a cave? You could do a bunch of hard work with classic surveying gear… or you could just use a laser scanner. [9nl] did the latter, with a scanning rig of his own creation.

The build is based around an Ouster VLP-16 mid-range lidar sensor. It shoots out pulses of light and measures how long it takes them to bounce back in order to determine the range of objects in the vicinity, and thus can be used to great effect for 3D scanning tasks. For [9nl], though, the sensor had a serious limitation. Since it only had a 40-degree field of view, it wasn’t ideal for the desired application of scanning a cave. However, by building a custom rig that could rotate the sensor, [9nl] ended up with a rig that could 3D scan an area through a full 360 degrees. There’s nothing wildly complex involved, just some good old mechanical engineering—putting the sensor on a shaft and spinning it with a belt drive. Then it’s just a matter of processing the data correctly. The hard part is then getting the rig in and out of the cave without breaking anything.

There are plenty of off-the-shelf 3D scanning solutions that can do this work, but few of them come cheap. Plus, rolling your own teaches you a great many things as you hone your solution to your particular needs. Video after the break.

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FLOSS Weekly Episode 872: I’m Not Satoshi

June 24, 2026 by No comments

This week Jonathan chats with Tristan Sherliker about the Craig Wright case, Open Source and the law, and Tristan’s own Open Source project, BunTool. How did Open Source help win the day at the Bitcoin trial? And why is right now such an interesting time to be in the legal field? Watch to find out!

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VFD Clock Runs On A Single AA

June 24, 2026 by 2 Comments

There are lots of different ways to build a clock. [Sciter_] came into the possession of some old calculator parts, and decided to reuse them for just such a project.

The heart of the build is an ATmega328P microcontroller, running off of a 32.768 kHz crystal. This allows the chip’s counters to neatly divide down the frequency to get a steady 1 Hz pulse for accurate timekeeping. Time is displayed on a vacuum fluorescent display (VFD) harvested from an old calculator. These displays need rather high voltages to run, which in this case are produced by a HV5812 driver chip and supporting circuitry. The display itself is neatly cradled in a pair of copper pipe elbows for a stylish look, with some addressable RGB LEDs present to provide some charming underglow.

Power for the device comes from a single AA battery, using a transformer-based low voltage converter. Alternatively, it can run off a USB 5 V power supply, which also charges the NiMH AA cell while available with the aid of an LM2576-ADJ buck converter.

Overall, it’s a neat homebrew clock that taught [Sciter_] plenty during its construction, and not the first time we’ve seen somebody put together a clock with second-hand VFDs. If you’re finding fun ways to reuse old display tech, don’t hesitate to let us know on the tipsline.

The Trains With Rubber Tires

June 24, 2026 by 13 Comments

The train was one of the game-changing inventions that defined the Industrial Age. No more would humanity rely on tempestuous animals to haul goods and passengers great distances across the land. Fire and steam came along to rapidly increase the speed of travel and transformed the very fabric of society itself.

To this day, the vast majority of train networks rely on the same basic principle—heavy locomotives and carriages running steel wheels on steel tracks. Yet, there is a curious alternative twist on this concept that sees trains of carriages riding on tires instead. But what would possess anyone to build a rubber tired train?

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Raspberry Pi Locator Website To Shut Down In July

June 24, 2026 by 23 Comments

As announced by [André] on Bluesky, next month the much loved Rpilocator.com website will cease displaying the stock status and pricing of Raspberry Pi computers from various online retailers.

One of the main reasons is that the indexing bot used by the site has been blocked by most shopping sites. It’s not clear whether this blocking is on purpose or just another consequence of website owners protecting themselves from the onslaught of obnoxious ‘AI’ scraping bots. But in any event, the effort of finding workarounds that may only work for a few days or weeks was becoming too much.

According to [André] there are still about 11,000 users of the site each month, which even when accounting for the human-bot ratio is still a sizable number of visitors who’ll now have to get their fix somewhere else. He also indicates that he receives numerous emails from presumably real people about the site to point out small issues they have noticed.

Although the site may still be back in the future, it’s also important to recognize how much the single-board computer landscape and raison d’être for this tracking site have shifted since the 2020s Chip Crisis days. Currently it’s less about finding where these boards are in stock, and more about taking the hits to one’s wallet as memory prices continue to spiral out of control. Making what were once fun, cheap little hobby boards into luxury items that cut into your rent-food-and-gas budget.

A T9 Keyboard For Your Smartphone

June 24, 2026 by 7 Comments

These days, most of us are fortunate enough to use smartphones with decent touchscreen keyboard capabilities. However, once upon a time, if you wanted to type something on a phone, you had to tap it out on the number keys instead. [Jarrett] is bringing that back with a custom T9 keyboard for modern phones. 

The build is designed around the keypad of the Nokia E52, a Symbian smartphone released in 2009—two years after Apple changed the game with the first iPhone. The phone keypad itself is laid over a custom PCB with Alps SKRK tactile switches corresponding to each individual key. Each is wired with a diode and the switches are scanned as a row/column array as is typical for keyboards. Reading the matrix is an ESP32-C6 microcontroller, which counts the keypresses and spits out the right letters over its Bluetooth connection to an attached smartphone or other device. Power is via a small lithium-ion battery, looked after by a TP4200 charger chip.

Overall, the keyboard works as you’d expect, allowing T9-style input to any compatible device that works with Bluetooth keyboards. [Jarrett] does have one regret, with the 0.98 N actuation force switches used leaving he keypad feeling a little mushy. The firmer 1.57 N switches were suspected to give a more satisfying response under thumb, which was a nice upgrade in the second revision build.

We’ve seen other builds in this vein before, too, albeit with bigger keys. If you’re coming up with your own esoteric input methods, don’t hesitate to notify the tipsline.

One Commodore, Five Displays

June 23, 2026 by 12 Comments

If you had one monitor back in the 8-bit era, instead of having to wait to use the family TV, you were already amongst the blessed. If you had five, maybe you worked at a computer store– but if you did, you could have done what [The 8-Bit Guy] demonstrates in a recent YouTube video and plug all five (5) monitors into a Commodore 128.

The computer isn’t modified in any way– well, except for the now standard use of an SD card disk emulator– so what gives? Well, you probably guessed he’s splitting up the colour signal into multiple monochrome images, but since the C128 actually has an RGBI, that I– intensity– actually gives another signal that can be broken out. That makes for four screens being driven from that port via composite, all sharing the same sync. The hardware for that was actually designed for [The 8-Bit Guy] by [Joe Burks] who open sourced the design on GitHub. He’s also selling them on Lectronz.

The fifth screen, of course, is driven by the VIC-II chip that Commodore provided for composite output to begin with. The interesting part is as much the software as the hardware, and while [The 8-Bit Guy] explains some of the thinking behind what he’s doing, he doesn’t link to any BASIC. If you know your way around a Commodore, you should be able to encode the multi-colour images required to do the splits.

For the people who prefer “real computers” — that is IBM compatible PCs– [The 8-Bit Guy] goes a bit outside of his 8-bit comfort zone to demonstrate that this same trick works quite well with the 16-color modes of EGA. With sixteen colours split between the two monitors, you of course get two colours each– combine the dithering with the blur of an old CRT, and it looks better than it has any right to. Just note that you need to have the right EGA card, as some blocked the 16-colour modes when set to output IRGB/CGA– he used a Trident card to good effect. The software here, though, was just Deluxe Paint, which can’t stop winning, even after four decades. 

The hack seems simple enough, and perhaps everyone knew about it back in the day, but this is the first time seeing it for this author. So we’ll leave it to the comments: have you ever seen a 5-display Commodore, or 4-screen EGA output done like this?

Of course CGA had some competition back in the 80s, and it would be fun to see how many retro standards this trick would work on; at the end of the video [The 8-Bit Guy] discusses splitting VGA signals, but that’s only three screens and way too new for him. If one of you takes up his challenge, please let us know.