Flashlight shining through gold leaf on glass

Shining Through: Germanium And Gold Leaf Transparency

January 5, 2025 by Heidi Ulrich 25 Comments

Germanium. It might sound like just another periodic table entry (number 32, to be exact), but in the world of infrared light, it’s anything but ordinary. A recent video by [The Action Lab] dives into the fascinating property of germanium being transparent to infrared light. This might sound like sci-fi jargon, but it’s a real phenomenon that can be easily demonstrated with nothing more than a flashlight and a germanium coin. If you want to see how that looks, watch the video on how it’s done.

The fun doesn’t stop at germanium. In experiments, thin layers of gold—yes, the real deal—allowed visible light to shine through, provided the metal was reduced to a thickness of 100 nanometers (or: gold leaf). These hacks reveal something incredible: light interacts with materials in ways we don’t normally observe.

For instance, infrared light, with its lower energy, can pass through germanium, while visible light cannot. And while solid gold might seem impenetrable, its ultra-thin form becomes translucent, demonstrating the delicate dance of electromagnetic waves and electrons.

The implications of these discoveries aren’t just academic. From infrared cameras to optics used in space exploration, understanding these interactions has unlocked breakthroughs in technology. Has this article inspired you to craft something new? Or have you explored an effect similar to this? Let us know in the comments!

We usually take our germanium in the form of a diode. Or, maybe, a transistor.

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Perfecting 20 Minute PCBs With Laser

January 5, 2025 by Al Williams 38 Comments

Normally, you have a choice with PCB prototypes: fast or cheap. [Stephen Hawes] has been trying fiber lasers to create PCBs. He’s learned a lot which he shares in the video below. Very good-looking singled-sided boards take just a few minutes. Fiber lasers are not cheap but they are within range for well-off hackers and certainly possible for a well-funded hackerspace.

One thing that’s important is to use FR1 phenolic substrate instead of the more common FR4. FR4 uses epoxy which will probably produce some toxic fumes under the laser.

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Hackaday Links: January 5, 2025

January 5, 2025 by Dan Maloney 4 Comments

Good news this week from the Sun’s far side as the Parker Solar Probe checked in after its speedrun through our star’s corona. Parker became the fastest human-made object ever — aside from the manhole cover, of course — as it fell into the Sun’s gravity well on Christmas Eve to pass within 6.1 million kilometers of the surface, in an attempt to study the extremely dynamic environment of the solar atmosphere. Similar to how manned spacecraft returning to Earth are blacked out from radio communications, the plasma soup Parker flew through meant everything it would do during the pass had to be autonomous, and we wouldn’t know how it went until the probe cleared the high-energy zone. The probe pinged Earth with a quick “I’m OK” message on December 26, and checked in with the Deep Space Network as scheduled on January 1, dumping telemetry data that indicated the spacecraft not only survived its brush with the corona but that every instrument performed as expected during the pass. The scientific data from the instruments won’t be downloaded until the probe is in a little better position, and then Parker will get to do the whole thing again twice more in 2025. Continue reading “Hackaday Links: January 5, 2025” →

Reverse-Engineering The Polynomial Constants In The Pentium’s FPU

January 5, 2025 by Maya Posch 5 Comments

Die photo of the Intel Pentium processor with the floating point constant ROM highlighted in red. (Credit: Ken Shirriff)

Released in 1993, Intel’s Pentium processor was a marvel of technological progress. Its floating point unit (FPU) was a big improvement over its predecessors that still used the venerable CORDIC algorithm. In a recent blog post [Ken Shirriff] takes an up-close look at the FPU and associated ROMs in the Pentium die that enable its use of polynomials. Even with 3.1 million transistors, the Pentium die is still on a large enough process node that it can be readily analyzed with an optical microscope.

In the blog post, [Ken] shows how you can see the constants in each ROM section, with each bit set as either a transistor (‘1’) or no transistor (‘0’), making read-out very easy. The example looks at the constant of pi, which the Pentium’s FPU has stored as a version with no fewer than 67 significand bits along with its exponent.

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Stacy’s Computer Has Got It Going On

January 5, 2025 by Al Williams 13 Comments

According to [ClassicHasClass], the best way to open an Atari Stacy is to not open an Atari Stacy. Apparently, these old computers were not pleasant to work on. The cables were not keyed and were prone to short against things. Screws easily strip out plastic holes. Of course, there wouldn’t be a story if there wasn’t a teardown and an upgrade that you can check out in the post.

The Stacy was one of Atari’s earliest portable systems and the first ST portable (that is, STacy). There’s a backlit LCD, a keyboard and trackball, and the usual ports. You could make do with a single floppy or spring for a second floppy or an internal SCSI hard drive. The 8 MHz 68000-based machine would set you back north of $2,300 back in 1989.

The original plan was to run the thing on C-cell batteries, but that would give you about 15 minutes of operation. They finally decided it was a luggable — you’d have to plug it into the wall. The battery compartment was there, but empty and glued shut.

Apparently, there were about 35,000 of these made, but they seem somewhat rare. But we do like a rare retrocomputer. Or even some that aren’t so rare.

Atari 65XE In Laptop Form

January 5, 2025 by Bryan Cockfield 1 Comment

For better or worse, Atari is no longer a household name in computing, but for a time in the 1980s, it was a huge mover in the industry. They not only produced PCs but also a huge number of video game consoles. Although they were a major contributor to the video game crash of the 1980s, they managed to limp along a few more years afterward and produce some interesting machines in the following years, even though they weren’t ultimately able to compete with Nintendo or Sega. One of those computers from that era was a PC-console hybrid of sorts called the Atari XE, and [Sideburn] was able to turn one into a laptop.

The retro laptop began life as an Arabic PAL version of the 65XE, the PC version of the ubiquitous 65-series computer. A large portion of the computer was reworked, including the removal of the power supply in favor of a rechargeable battery with a 6-hour life. Also among the list of scrapped components was the video and sound connectors as well as the RF modulator, which would have been common for displays at the time, but this laptop is getting a 1920×1080 LCD panel to replace all of that old hardware. A 1MB memory upgrade, new speakers and amp, a WiFi card, and an SD floppy card emulator round out the build.

The final part of the build is assembling it all into a custom 3D printed case, and the resulting laptop that [Sideburn] calls the XE Book is a faithful adaptation of this niche computer into what could have been a laptop we would have seen in the late 80s or early 90s similar to the Toshiba T3200SXC. It matches the original’s footprint and still uses all of the core components, so it’s not too difficult to imagine something like this having existed in the past.

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16-bit Linux-like Goodness

January 5, 2025 by Al Williams 15 Comments

We see many 16-bit retrocomputers around here based on Intel and Intel-like chips such as the 8086, 8088, V20, and similar. While they don’t seem very powerful by today’s standards, they were perfectly capable machines and, thanks to Elks (Embeddedable Linux Kernel Subset), you can run something fairly Linux-like on these devices.

The requirements are light: 512K of RAM is desirable, but you can do something with 256K. If you have ROM, you can even get by with 128K. Most importantly, the system doesn’t require a memory management unit to remap memory like many operating systems.

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