Cargo Culting And Buried Treasure

December 3, 2022 by Elliot Williams 55 Comments

I have no idea how true the stories are, but legend has it that when supplies were dropped on some Melanesian islands during WWII, some locals took to replicating runway signs in order to further please the “gods” that were dropping them. They reportedly thought that making landing strips caused laden airplanes to visit. Richard Feynman later turned this into a metaphor about scientific theory – that if you don’t understand what you’re doing deeply, you may be fooling yourself.

I’d like to be a little bit more forgiving of adherents of technological cargo cults. Because the world around us is very complicated, we often just take things as they are rather than understanding them deeply, because there’s simply only so deep you can go into so many fields.

Is someone who doesn’t know the i386 machine language cargo-culting their way through a job as a web backend developer? Probably not. But from the perspective of an assembly-language programmer, any of us who write in compiled or interpreted programming languages are cargo-culting coding. You don’t need to understand a cell phone to dial home, but can you really say that you understand everything about how one works? Or are you just going through the motions?

So while some reliance on metaphor and “well, it worked last time” is perfectly normal, I think noticing when you cargo-cult is also healthy. It should also be a warning sign, or at least a flag to remind yourself that there may be dragons here. Or maybe just a buried learning opportunity, the X that marks the spot where digging deeper might be productive.

Bring Out The Fine Detail In Small Objects With This Coaxial Lighting Rig

December 3, 2022 by Dan Maloney 11 Comments

All things considered, modern photography is pretty easy. It’s really just a matter of pointing the camera at the thing you want to take a picture of and letting the camera do the rest. But that doesn’t mean good photographs are easy to make, especially when fine detail is required. And that’s the reason this 3D printed coaxial lighting setup was built — to make quality photographs of small objects a snap.

The objects of [Peter Lin]’s photographic desire are coins, no doubt of the collectible variety. Since the condition of a coin is essential to determining its value, numismatic photographers really need to be meticulous about the quality of their work. The idea here is to keep the incoming light parallel to the optical axis of the camera, for which purpose ring lights around the camera lens are often used. But they can result in lighting artifacts, and can be awkward to use for such smaller subjects.

So for this setup, [Peter] essentially built a beam-splitter. The body is a printed block that’s painted matte black to keep reflections down; a little self-adhesive flocking paper helps with that too. The round aperture on the top is for the camera lens, with the square window on the side admitting light. The secret is a slot oriented at 45 degrees to both of those openings, into which the glass element from a cheap UV filter is inserted. The filter acts like a beam splitter which reflects light down onto the coin on the bottom of the block and lets it pass up into the camera lens directly above the coin, parallel to the optical axis. Genius!

The video below shows it in use with both DSLR and smartphone cameras, and the image quality is amazing. While most of us probably aren’t photographing coins, we do enough high-resolution photography of small objects that this seems applicable. In a way, it reminds us of [Big Clive]’s “TupperCam” method of high-res PCB photography (final item).

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Hanging Christmas Lights With No Ladder And No Fuss

December 3, 2022 by Lewin Day 25 Comments

Getting up on a ladder to hang Christmas lights is a great way to hurt yourself if you’re not careful, and winter conditions only add to the peril. One enterprising hacker has whipped up a neat way to avoid ladders entirely, by hanging their lights while planted safely on the ground.

The build uses hefty magnets and triangle eye bolts, attached at regular intervals to the string of Christmas lights. The magnets are used to hold the lights to metal roof siding, while the hooks allow the lights to be lifted into place using a hook on a large extendable pole. Washers, spacers, and screws are used to attach the magnets and hooks to the lights.

For a layout that follows the lines of a simple peaked roof, this hack works great. For more complicated installations, you might still have to climb up a ladder. We’ve featured great primers on getting started with advanced Christmas light displays before, if you’re looking to up your game.

Meanwhile, no matter how much you enjoy seasonal decoration brinkmanship, don’t even think about watching Deck the Halls (2006). Danny Devito has saved a lot of films, but he couldn’t save this. Happy holidays!

Stack Trace From The 1950s Punches Again

December 2, 2022 by Chris Lott 4 Comments

This repair/tutorial video by the telephone Connections Museum of Seattle features an amazing piece of electro-mechanical technology from the 1950s — the 5XB trouble recorder. Museum volunteer Sarah the “Switch Witch” has a deep passion for old phone equipment, and gives an excellent description of the trouble recorder, the problems it solved, and how it works, and how they went about fixing it.

As central office switching became more complex and more dense, the manual methods of hunting down faults became unmanageable. Semi-automatic approaches using trouble lamps, but even that had its limits. This “stack trace”, which could have hundreds of indicators, had to be frozen while the technician recorded the status on a form. If another fault came along during this time, it was lost. The solution, using the available technology of the day, was a mind-boggling punched card apparatus that punches over a thousand bits of information when an switching error is detected or when various watchdog timers expire.

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Hackerboards: Making Finding The Right Single-Board Computer Easy

December 2, 2022 by Maya Posch 18 Comments

The great thing about the wide availability of single-board computers (SBCs) is that it offers such a large selection of options, in terms of CPU performance, GPU features, RAM size, I/O options and much more. This is however also the largest issue, especially with the annual surge of new boards with new feature sets. Trying to make sense of all these offerings is the recently overhauled Board-DB, also known as Hackerboards.

As [Martijn Braam] explains in the blog post on the changes, a major upgrade over the old Hackerboards (which we covered in 2016) is a far more extensive set of parameters that can be filtered against. This makes a fine-grained selection of detailed features significantly easier, which is also reflected in the technical specifications comparison feature. With over 450 active entries there are a lot of boards that can already be filtered on, but manufacturers are invited to take up contact to add further entries, which should keep the list up to date.

Incidentally, if you’d like to know how [Martijn] gets those gorgeous PCB photographs, he wrote a whole a separate write-up that goes over his camera setup.

Thanks to [Vlad] for the tip.

Converting A Porsche 944 To Run A MAF

December 2, 2022 by Lewin Day 28 Comments

Electronic fuel injection was a big leap forward for engine control. However, early implementations often left something to be desired. This was the case for [Rob] and his Porsche 944, which had relied on an old-fashioned mechanical air flow meter (AFM). He decided to replace this with a modern mass air flow (MAF) sensor instead, and documented the process online.

The output of the sensors was compared with a rig built using a vacuum cleaner to create air flow.

AFMs are often a target for replacement on old cars. They’re usually based on a flap that moves a potentiometer wiper across a carbon trace which wears out over the years. They can also present an air flow restriction in some cases, limiting performance. MAF sensors instead measure the amount of air flowing through with a hot wire. The amount of current required to maintain the temperature of the wire indicates the amount of air flowing through the sensor. They’re less restrictive and readily available as they’re used in many cars today.

To run a MAF in place of the AFM requires a circuit to emulate the AFM’s output. [Rob] used a STM32 Cortex-M0 to read the MAF, and then output the relevant voltage to the Porsche’s engine computer via PWM and a low pass filter. To figure out how to map the MAF’s output to match the AFM, [Rob] built a rig to blow air through both devices in series, and measuring their output on an oscilloscope. This data was used to program the STM32 to output the right emulated AFM voltage for the given MAF signal.

It’s a great piece of work from [Rob] that has his Porsche running happily on new parts. We’ve seen similar hacks done to other cars before, as well! Video after the break.

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Is That A Typewriter In Your Pocket Or Are You Just Pleased To See Me?

December 2, 2022 by Dave Rowntree 16 Comments

Don’t have the right milling tool? Just make one!

[Attoparsec] wondered what if you could carry a typewriter in your pocket, then followed through with that and built one. (Video, embedded below.) Kind of. The plan was to use an existing set of striker bars, but not wanting to destroy a perfectly good typewriter, they realised that you can easily source just the bar set on eBay.

The first problem was that the striker bars are shaped to allow the typewriter mechanism to operate, but that would not make for a compact arrangement. After a spot of straightening in a big vice, and drilling in a custom jig, they were in a suitable state to be arranged inside the case. The casing is milled from a chunk of aluminium, complete with a nice recess to hold an ink-impregnated felt pad. To prevent this pad from drying out when stowed, and to keep the whole thing clear of pocket lint, a U-shaped metal cover was bent from some sheet. This slides into a set of slots that are milled near the edges, in a very satisfying manner. This last bit was causing them a little trouble, so a custom slotting tool was created especially for the job. And a good job was indeed done. The final results look as you might expect from a manual ‘typewriter’ quirky, a bit wonky, but fabulous all the same.

If you have an old typewriter that needs some attention, here’s a quick guide for giving it a once-over. Some of you of a certain age may remember electronic typewriters with some fondness. They died a rapid death, but if you’ve still got one lurking, you could convert it into a Linux terminal for some clackity nostalgic fun.

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