Mysterious Files PH

Even though GPS makes it possible for us to easily navigate around the planet in almost any vehicle we’d like, whether that’s a passenger vehicle, airplane, or cargo ship, it’s not really suitable for applications that require sub-meter accuracy. For that, some specialized hardware is needed, and [GreatScott!] shows us how to do it using a small robot as a platform.

The key to extremely accurate GPS signals in this case is using a receiver that supports real-time kinematic positioning (RTK). This type of system relies on a base station with a known position communicating with local mobile receivers to increase the precision of those mobile receivers by comparing the phase angle of the received signals. Of course these modules are much more expensive than the average standard GPS receiver, but for this kind of accuracy there is always a cost.

After getting a baseline accuracy of around two meters with a standard GPS receiver, [GreatScott!] installs the RTK GPS mobile receiver on a tracked robotic platform and a base station on a fence post. With the RTK system running, the limiting factor in accuracy became the robot’s steering system, as its turning radius and steering algorithms weren’t up to the task of hitting centimeter-sized targets out of the box.

But, as a proof-of-concept, it goes to show how accurate GPS can be as long as the right hardware is used, and for practical applications is good enough to mow a lawn with a robot or even do some amateur land surveying.

[Stefan] of CNC Kitchen has an informative video describing his experiences with trying to cleanly laser-mark 3D printed plastics using different methods, and it also happens to be a fantastic tour of all the different laser options available to hobbyists and workshops these days.

Laser marking is a fast and effective way to put things like product names, serial numbers, and other information on plastics. [Stefan] wondered whether laser options would be capable of creating clean and professional marks on 3D-printed items, and approached things with his usual attention to detail.

How does a laser mark plastic? When the laser hits the material, its energy is dumped into it and can cause pigment bleaching, microfoaming, charring, melting, or ablation (vaporizing) of the surface. The goal is to have a combination of laser and material that delivers a crisp, high-contrast result.

There are several kinds of laser technologies easily available today, and of course a variety of filament types. [Stefan] printed a whole bunch of different PLA, PETG, ASA, TPU, and polycarbonate samples in different colors and tested them with different laser machines, including:

• UV laser (355 nm wavelength)
• Blue diode laser (450 nm wavelength)
• MOPA fiber laser (1,064 nm wavelength)
• CO₂ laser (10,600 nm wavelength)

So is it possible? Yes, but it’s still a bit of a fussy process. There isn’t a one-size-fits-all solution for marking plastic, because results depend a lot on the the right combination of laser type, settings, and target material. That being said, [Stefan] was able to obtain some really great results.

Overall the UV laser was the most suited to marking 3D-printed plastics. [Stefan] says it produced the cleanest results on the widest range of materials with the least fiddling. The MOPA fiber laser also worked, but is clearly more of a metal-marking tool. We’ve seen them etch super-fine PCB traces and while great results are possible it isn’t quite in its element with plastics. Other lasers could get good results under just the right circumstances, but are overall best suited to cutting tasks rather than marking thermoplastics.

Check out the video below for the full details, including some really fantastic closeups.

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.

[Thanks to Kovy Jacob for the tip!]

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!

• • https://www.twobirds.com/en/people/t/tristan-sherliker
  • https://buntool.co.uk/
  • https://www.twobirds.com/en/insights/2024/global/a-different-way-to-defraud-the-lessons-from-the-trial-of-bitcoins-origins
  • Evidence Download

Full Ruling:

• https://www.judiciary.uk/wp-content/uploads/2024/05/COPA-v-Wright-Judgment.pdf

Did you know you can watch the live recording of the show right on our YouTube Channel? Have someone you’d like us to interview? Let us know, or have the guest contact us! Take a look at the schedule here.

Direct Download in DRM-free MP3.

If you’d rather read along, here’s the transcript for this week’s episode.

Theme music: “Newer Wave” Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

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.

No, this isn’t another product from [PeriFractic]’s revived company, though we hope he’s taking notes. This is, in fact, a hack on the beloved 1530 Datasette, using the tape mechanism and case to create a portable audio device for your precious remaining mix tapes. Well, [Jan Derogee]’s precious mix tapes, at any rate; we aren’t the government, we don’t know if you have any tapes, mixed or otherwise.

[Jan] started, obviously enough, with a Datasette, but they key was apparently to use a Made-in-Japan model–  the Made-in-Taiwan units are a later development and victims of the old Commodore’s infamous obsession with cost-cutting. The main difference is that the Japanese-built Datasettes have two sets of screws: one to hold the tape mechanism in place, and the other to hold two halves of the case together. The Taiwanese units make one set do double duty. Doubtless more was saved through streamlining assembly than the cost of four screws, but either way it made those models difficult to work with for [Jan]’s purposes.

As you likely can tell from the photo, he simply splits the case, allowing the tape transport to remain in place with those  Japanese screws, and inserts a 3D printed spacer to hold speakers, audio amplifiers, and a bay for AA batteries. For the people who really care about such things, the mod appears to be fully reversible, though you won’t be able to use it as data entry for your C64 until you do reverse it. Given how slow and dodgy tape loads could be, though, that’s not likely to bother many people, since it’s so much easier to load media onto the old breadbox from an emulated tapedeck.

If, on the other hand, you can’t stand the idea of using a Datasette for anything but data storage, maybe you should try connecting yours to a modern PC to remind yourself what it was really like. In either case, you can check out the 1530 Boombox at the link above or the video embedded below. For the actual Commodore product we didn’t see coming, click here for the phone. 

Some of our esteemed readers were not yet out of diapers back in 2013 when Microsoft decided to put MSN Messenger out to pasture, but the memories that this instant messenger’s (IM) interface and notification sounds have left are hard to erase. This also includes some of the weirdest accessories that this IM spawned, such as the USB-connected i-Buddy. Recently [Rayly Retro] got his mittens on a new-in-box one to revive alongside an era-appropriate Windows 7 PC.

What the i-Buddy gets you is the ability to light up the head in seven different colors, twist the torso and flap the butterfly wings, all of which can correspond to certain events in the MSN IM or for more general notifications, as set by software running on the connected PC. Interestingly, this i-Buddy is recognized by Windows as a USB HID, so no special driver is needed. A range of ways to program it exist too, including a .NET-based library from back when it was still being sold for around $20.

Although the MSN Messenger network’s servers have long since been dumped into an e-waste dumpster over at Microsoft HQ, an alternative exists in the form of the Escargot service using which a range of official clients can work again.

In the video it’s demonstrated how to create a user account with the Escargot site and how to patch the messenger – here Window Live Messenger 2009 – before signing in. With that step completed, getting the i-Buddy up and running is next. This took a lot of struggling, since the version of the i-Buddy software that comes with the device didn’t like Windows 7 much. Fortunately an old forum post led to a download of version 2.10, using which the gadget jumped to life, happily lighting up and flapping its wings.