Add A Little Quindar To Your Comms For That Apollo-Era Sound

April 30, 2023 by Dan Maloney 9 Comments

If there’s one thing that ties together all the media coming out of the Apollo era, it’s probably the iconic Quindar tones. These quarter-second beeps served as control tones for the globe-spanning communications network needed to talk to the Apollo astronauts, and any attempt to recreate the Apollo-era sound would be glaringly wrong without them. And that’s why [CuriousMarc] whipped up this Quindar tone system.

The video below starts with a detailed treatment of what Quindar tones are and why they were used, a topic we’ve covered ourselves in the past. To recap, Quindar tones are a form of in-band signaling, with a 2,525-Hz pure sine wave intro tone that signaled the transmitters connected to Mission Control in Houston over leased telephone lines to key up. The 2,475-Hz outro tone turned off the transmitters and connected the line to the receivers.

To recreate the sound quality of the original circuitry, and to keep in the retro vibe, [Marc]’s Quindar homage avoided digital circuitry as much as possible, opting instead to generate the two tones with an XR-2206 function generator chip. The chip can rapidly switch back and forth between two frequencies, making it perfect for FSK applications or, in this case, reproducing the two slightly different tones. [Marc] added a dual mono-stable multi-vibrator to pulse the tone, giving the 250-ms pulse, and an audio gate, which uses a MOSFET to switch the tone into an audio stream. All this got soldered up to a piece of perf board and stuffed in the base of a cheap intercom microphone, which while not period accurate still has a cool retro look — and now, a retro sound, too.

Hats off to [CuriousMarc] and his merry band for probing the mysteries of Apollo-era comms and keeping the accomplishments of all those engineers alive. The methods they used are still relevant after all these years, and there seems to be no end to what we can learn from them.

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The Nixie Clock From Outer Space

March 13, 2023 by Al Williams No comments

Nixie clocks are nothing new. But [CuriousMarc] has one with a unique pedigree: the Apollo Program. While restoring the Apollo’s Central Timing Equipment box, [Marc] decided to throw together a nixie-based clock. The avionics unit in question sent timing pulses and a mission elapsed time signal to the rest of the spacecraft. Oddly enough, while it had an internal oscillator, it was only used during failures. It normally synched to the guidance computer’s onboard clock.

There is a detailed explanation of the unit, along with some of the ancillary equipment and panels. Much of what the output from the unit is driving counters to display timers, although some of the clocks drive other pieces of equipment, like the telemetry commutator, which time stamps each telemetry frame.

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NASA Aces Artemis I, But The Journey Has Just Begun

December 12, 2022 by Tom Nardi 51 Comments

When NASA’s Orion capsule splashed down in the Pacific Ocean yesterday afternoon, it marked the end of a journey that started decades ago. The origins of the Orion capsule can be tracked back to a Lockheed Martin proposal from the early 2000s, and development of the towering Space Launch System rocket that sent it on its historic trip around the Moon started back in 2011 — although few at the time could have imagined that’s what it would end up being used for. The intended mission for the incredibly powerful Shuttle-derived rocket changed so many times over the years that for a time it was referred to as the “Rocket to Nowhere”, as it appeared the agency couldn’t decide just where they wanted to send their flagship exploration vehicle.

But today, for perhaps the first time, the future of the SLS and Orion seem bright. The Artemis I mission wasn’t just a technical success by about pretty much every metric you’d care to use, it was also a public relations boon the likes of which NASA has rarely seen outside the dramatic landings of their Mars rovers. Tens of millions of people watched the unmanned mission blast off towards the Moon, a prelude to the global excitement that will surround the crewed follow-up flight currently scheduled for 2024.

As NASA’s commentators reminded viewers during the live streamed segments of the nearly 26-day long mission around the Moon, the test flight officially ushered in what the space agency is calling the Artemis Generation, a new era of lunar exploration that picks up where the Apollo left off. Rather than occasional hasty visits to its beautiful desolation, Artemis aims to lay the groundwork for a permanent human presence on our natural satellite.

With the successful conclusion of the Artemis I, NASA has now demonstrated effectively two-thirds of the hardware and techniques required to return humans to the surface of the Moon: SLS proved it has the power to send heavy payloads beyond low Earth orbit, and the long-duration flight Orion took around our nearest celestial neighbor ensured it’s more than up to the task of ferrying human explorers on a shorter and more direct route.

But of course, it would be unreasonable to expect the first flight of such a complex vehicle to go off without a hitch. While the primary mission goals were all accomplished, and the architecture generally met or exceeded pre-launch expectations, there’s still plenty of work to be done before NASA is ready for Artemis II.

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Hackaday Links: August 21, 2022

August 21, 2022 by Dan Maloney 3 Comments

As side-channel attacks go, it’s one of the weirder ones we’ve heard of. But the tech news was filled with stories this week about how Janet Jackson’s “Rhythm Nation” is actually a form of cyberattack. It sounds a little hinky, but apparently this is an old vulnerability, as it was first noticed back in the days when laptops commonly had 5400-RPM hard drives. The vulnerability surfaced when the video for that particular ditty was played on a laptop, which would promptly crash. Nearby laptops of the same kind would also be affected, suggesting that whatever was crashing the machine wasn’t software related. As it turns out, some frequencies in the song were causing resonant vibrations in the drive. It’s not clear if anyone at the time asked the important questions, like exactly which part of the song was responsible or what the failure mode was on the drive. We’ll just take a guess and say that it was the drive heads popping and locking.

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A Deeper Dive Into Reverse Engineering With A CT Scanner

August 10, 2022 by Dan Maloney 6 Comments

We’ve recently got a look at how [Ken Shirriff] used an industrial CT scanner as a reverse engineering tool. The results were spectacular, with pictures that clearly showed the internal arrangement of parts that haven’t seen the light of day since the module was potted back in the 60s. And now, [Ken]’s cohort [Curious Marc] has dropped a video with more detail on the wonderful machine, plus deep dives into more Apollo-era hardware

If you liked seeing the stills [Ken] used to reverse engineer the obscure flip-flop module, you’re going to love seeing [Marc] using the Lumafield scanner’s 3D software to non-destructively examine several Apollo artifacts. First to enter the sample chamber of the CT scanner was a sealed module called the Central Timing Equipment, which served as the master clock for the Apollo Command Module. The box’s magnesium case proved to be no barrier to the CT scanner’s beam, and the 3D model that was built up from a series of 2D images was astonishingly detailed. The best part about the virtual models is the ability to slice through them in any plane — [Marc] used this feature to hunt down the clock’s quartz crystal. Continue reading “A Deeper Dive Into Reverse Engineering With A CT Scanner” →

CT Scans Help Reverse Engineer Mystery Module

August 7, 2022 by Dan Maloney 15 Comments

The degree to which computed tomography has been a boon to medical science is hard to overstate. CT scans give doctors a look inside the body that gives far more information about the spatial relationship of structures than a plain X-ray can. And as it turns out, CT scans are pretty handy for reverse engineering mystery electronic modules, too.

The fact that the mystery module in question is from Apollo-era test hardware leaves little room for surprise that [Ken Shirriff] is the person behind this fascinating little project. You’ll recall that [Ken] recently radiographically reverse engineered a pluggable module of unknown nature, using plain X-ray images taken at different angles to determine that the undocumented Motorola module was stuffed full of discrete components that formed part of a square wave to sine wave converter.

The module for this project, a flip-flop from Motorola and in the same form factor, went into an industrial CT scanner from an outfit called Lumafield, where X-rays were taken from multiple angles. The images were reassembled into a three-dimensional view by the scanner’s software, which gave a stunningly clear view of the components embedded within the module’s epoxy body. The cordwood construction method is obvious, and it’s pretty easy to tell what each component is. The transistors are obvious, as are the capacitors and diodes. The resistors were a little more subtle, though — careful examination revealed that some are carbon composition, while others are carbon film. It’s even possible to pick out which diodes are Zeners.

The CT scan data, along with some more traditional probing for component values, let [Ken] reverse engineer the whole circuit, which turned out to be a little different than a regular J-K flip-flop. Getting a non-destructive look inside feels a little like sitting alongside the engineers who originally built these things, which is pretty cool.

Reverse Engineering An Apollo-Era Module With X-Ray

June 29, 2022 by Dan Maloney 9 Comments

The gear that helped us walk on the Moon nearly 60 years ago is still giving up its mysteries today, with some equipment from the Apollo era taking a little bit more effort to reverse engineer than others. A case in point is this radiographic reverse engineering of some Apollo test gear, pulled off by [Ken Shirriff] with help from his usual merry band of Apollo aficionados.

The item in question is a test set used for ground testing of the Up-Data Link, which received digital commands from mission controllers. Contrary to the highly integrated construction used in Apollo flight hardware, the test set, which was saved from a scrapyard, used more ad hoc construction, including cards populated by mysterious modules. The pluggable modules bear Motorola branding, and while they bear some resemblance to ICs, they’re clearly not.

[Ken] was able to do some preliminary reverse-engineering using methods we’ve seen him employ before, but ran into a dead end with his scope and meter without documentation. So the modules went under [John McMaster]’s X-ray beam for a peek inside. They discovered that the 13-pin modules are miniature analog circuits using cordwood construction, with common discrete passives stacked vertically between parallel PCBs. The module they imaged showed clear shadows of carbon composition resistors, metal-film capacitors, and some glass-body diodes. Different angles let [Ken] figure out the circuit, which appears to be part of a square wave to sine wave converter.

The bigger mystery here is why the original designer chose this method of construction. There must still be engineers out there who worked on stuff like this, so here’s hoping they chime in on this innovative method.