Author: Dan Maloney

3373 Articles

Integrating sphere test setup

Cannonball Mold Makes A Dandy Integrating Sphere For Laser Measurements

February 6, 2022 by 9 Comments

It’s an age-old riddle: if you have a perfect sphere with a perfectly reflective inner surface, will light bounce around inside it forever? The answer is pretty obvious when you think it through, but that doesn’t mean that you can’t put the principle to use, as we see with this homemade Ulbricht sphere for optical measurements.

If you’ve never heard of an Ulbricht sphere, don’t worry — it’s also known as an integrating sphere, and that makes its function a little more apparent. As [Les Wright] explains, an integrating sphere is an optical element with a hollow spherical cavity that’s coated with a diffusely reflective coating. There are two ports in the sphere, one for admitting light — usually from a laser — and one for light to exit. The light bounces around inside the sphere and becomes perfectly diffuse, and creates a uniform beam at the exit port.

[Les]’ need for an integrating sphere comes from the desire to measure the output of some of his lasers with his Raspberry Pi-based PySpectrometer. Rather than shell out for an expensive commercial integrating sphere, or turn one on a lathe, [Les] turned to an unlikely source: cannonball molds. The inside of the mold was painted with an equally unlikely ultra-white paint concocted from barium sulfate and PVA glue. With a few ports machined into the mold, it works perfectly to diffuse the light from his dye lasers for proper measurements.

Lasers can be an expensive hobby, but [Les] always seems to find a way to make things more affordable and just as good. Whether it’s homemade doorknob caps for high-voltage power supplies or blasting the Bayer filter off a cheap CCD camera, he always seems to find a way.

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Hackaday Links: February 6, 2022

February 6, 2022 by 41 Comments

Last week, the news was filled with stories of Jack Sweeney and his Twitter-bot that tracks the comings and goings of various billionaires in their private jets. This caught the attention of the billionaire-iest of them all, one Elon Musk, who took exception to the 19-year-old’s feat of data integration, which draws from a number of public databases to infer the location of Elon’s plane. After Jack wisely laughed off Elon’s measly offer of $5,000 to take the bot down, Elon ghosted him — pretty childish behavior for the richest man on the planet, we have to say. But Jack might just have the last laugh, as an Orlando-based private jet chartering company has now offered him a job. Seems like his Twitter-bot and the resulting kerfuffle is a real resume builder, so job-seekers should take note.

Here’s hoping that you have a better retirement plan than NASA. The space agency announced its end-of-life plans for the International Space Station this week, the details of which will just be a run-up to the 2031 de-orbit and crash landing of any remaining debris into the lonely waters of Point Nemo. The agency apparently sees the increasingly political handwriting on the ISS’s aging and sometimes perforated walls, and acknowledges that the next phase of LEO space research will be carried out by a fleet of commercial space stations, none of which is close to existing yet. Politics aside, we’d love to dig into the technical details of the plan, and see exactly what will be salvaged from the station before its fiery demise, if anything. The exact method of de-orbiting too would be interesting — seems like the station would need quite a bit of thrust to put on the brakes, and might need the help of a sacrificial spacecraft.

“You break it, you fix it,” is a philosophy that we Hackaday types are probably more comfortable with than the general public, who tend to leave repairs of broken gear to professionals. But that philosophy seems to be at the core of Google’s new Chromebook repair program for schools, which encourages students to fix the Chromebooks they’re breaking in record numbers these days. Google is providing guidance for schools on setting up complete Chromebook repair facilities, including physical layout of the shop, organization of workflows, and complete repair information for at least a couple of popular brands of the stripped-down laptops. Although the repairs are limited to module-level stuff, like swapping power supplies, we still love the sound of this. Here’s hoping that something like this can trigger an interest in electronics for students that would otherwise never think to open up something as complicated as a laptop.

Back in July, we took note of a disturbing report of an RTL-SDR enthusiast in Crimea who was arrested for treason, apparently based on his interest in tracking flights and otherwise monitoring the radio spectrum. Now, as things appear to be heating up in Ukraine again, our friends at RTL-SDR.com are renewing their warning to radio enthusiasts in the area that there may still be risks. Then as now, we have little interest in the politics of all this, but in light of the previous arrest, we’d say it pays to be careful with how some hobbies are perceived.

And finally, aside from the aforementioned flight-tracking dustup, it’s been a tough week for Elon and Tesla. Not only have 817,000 of the expensive electric vehicles been recalled over something as simple as a wonky seatbelt chime, but another 54,000 cars are also being recalled for a software bug that causes them to ignore stop signs in “Full Self-Driving” mode. We’re not sure if this video of this Tesla hell-ride has anything to do with that bug, but it sure illustrates the point that FSD isn’t really ready for prime time. Then again, as a former Boston resident, we can pretty safely say that what that Tesla was doing isn’t really that much different than the meat-based drivers there.

Backpack COVID-19 lab

HDD Centrifuge Puts COVID-19 Testing Lab In A Backpack

February 5, 2022 by 11 Comments

Throughout this two-year global COVID-19 nightmare, one thing that has been sorely lacking is access to testing. “Flu-like symptoms” covers a lot of ground, and knowing if a sore throat is just a sore throat or something more is important enough that we’ve collectively plowed billions into testing. Unfortunately, the testing infrastructure remains unevenly distributed, which is a problem this backpack SARS-CoV-2 testing lab aims to address.

The portable lab, developed by [E. Emily Lin] and colleagues at the Queen Mary University of London, uses a technique called LAMP, for loop-mediated isothermal amplification. LAMP probably deserves an article of its own to explain the process, but suffice it to say that like PCR, LAMP amplifies nucleic acid sequences, but does so without the need for expensive thermal cycling equipment. The kit contains a microcentrifuge that’s fashioned from an e-waste hard drive, a 3D printed rotor, and an Arduino to drive the motor and control the speed. The centrifuge is designed to run on any 12 VDC source, meaning the lab can be powered by a car battery or solar panel if necessary. Readout relies on the trusty Mark I eyeball and a pH-indicating buffer that changes color depending on how much SARS-CoV-2 virus was in the sample.

Granted, the method used here still requires more skill to perform than a simple “spit on a stick” rapid antigen test, and it’s somewhat more subjective than the “gold standard” quantitative polymerase chain reaction (qPCR) assay. But the method is easily learned, and the kit’s portability, simple design, and low-cost construction could make it an important tool in attacking this pandemic, or the next one.

Thanks to [Christian Himmler] for the tip.

IoT toilet paper sheet counter

Keep Track Of Toilet Paper Usage With This IoT Roll Holder

February 3, 2022 by 51 Comments

Remember the Great Toilet Paper Crisis of 2020? We sure do, and it looks like our old friend [Vije Miller] does as well, while seemingly harboring a somewhat morbid fascination about how much paper every bathroom visitor is consuming. And to that end, we present his IoT toilet sheet tracker.

His 3D printed roll holder has a Hall effect sensor that counts revolutions of the roll and sends it to a NodeMCU. The number of sheets per roll is entered when the roll is changed, so some simple math yields the number of sheets each yank consumes. Or at least a decent estimate — [Vije] admits that there’s some rounding necessary. The best part of the build is the connection to Thingspeak, where sheet usage is plotted and displayed. Go ahead and check it out if you dare; at the time of writing, there was an alarming spike in sheet usage — a sudden need for 68 sheets where the baseline usage is in single digits. We shudder to think what might have precipitated that. The video below is — well, let’s just say there’s a video.

This isn’t the first time we’ve seen bathroom-based projects from [Vije Miller]. A few years back there was an attempt to freshen the air with plasma, and his IoT shower valve controller probably never scalded anyone accidentally.

Continue reading “Keep Track Of Toilet Paper Usage With This IoT Roll Holder” →

da Vinci-like quadcopter

Renaissance-Style Drone Would Make Da Vinci Proud Four Times Over

February 1, 2022 by 7 Comments

For as much of a genius as Leonardo da Vinci obviously was, modern eyes looking upon his notebooks from the 1400s tend to see his designs as somewhat quaint. After all, his concept of a vehicle armored with wood would probably only have survived the archers and pikemen of a Renaissance battlefield, and his curious helicopter driven by an Archimedes screw would certainly never fly, right?

Don’t tell that to [Austin Prete] and his team from the University of Maryland, who’ve built a da Vinci-style quadcopter that actually flies. Called the “Crimson Spin”, the quad is based on a standard airframe and electronics. Details are sparse — the group just presented the work at a vertical flight conference — but it appears the usual plastic props are replaced with lightweight screws made from wire and some sort of transparent plastic membrane. Opposing pairs of screws have the opposite handedness, which gives the quad yaw control. There’s a video embedded in the link above that shows the quad being tested both indoors and out, and performing surprisingly well. We’d imagine that Crimson Spin might not do so well on a windy day, given the large wind cross-section those screws present, but the fact it got off the ground at all is cool enough. It kind of makes you wonder where we’d be today if da Vinci had access to BLDCs.

For as fanciful as da Vinci’s designs can be, we’ve seen a fair number of attempts to recreate them in modern materials. His cryptex is a perennial favorite for hackers, and his bizarre piano-esque “viola organista” has been attempted at least once.

Thanks to [Peter Ryseck] for this tip.

Speed of motion test setup

Simple Setup Answers Complex Question On The Physics Of Solids

February 1, 2022 by 17 Comments

Thought experiments can be extremely powerful; after all, pretty much everything that [Einstein] came up with was based on thought experiments. But when a thought experiment turns into a real experiment, that’s when things can get really interesting, and where unexpected insights crop up.

Take [AlphaPhoenix]’s simple question: “Are solid objects really solid?” On the face of it, this seems like a silly and trivial question, but the thought experiment he presents reveals more. He posits that pushing on one end of a solid metal rod a meter or so in length will result in motion at the other end of the rod pretty much instantly. But what if we scale that rod up considerably — say, to one light-second in length. Is a displacement at one end of the rob instantly apparent at the other end? It’s a bit of a mind-boggler.

To answer the question, [AlphaPhoneix] set up a simple experiment with the aforementioned steel rod — the shorter one, of course. The test setup was pretty clever: a piezoelectric sensor at one end of the bar, and a hammer wired to a battery at the other end, to sense when the hammer made contact with the bar. Both sensors were connected to an oscilloscope to set up to capture the pulses and measure the time. It turned out that the test setup was quite a challenge to get right, and troubleshooting the rig took him down a rabbit hole that was just as interesting as answering the original question. We won’t spoil the ending, but suffice it to say we were pleased that our first instinct turned out to be correct, even if for the wrong reasons.

If you haven’t checked out [AlphaPhoenix] yet, you really should. With a doctorate in material science, he’s got an interesting outlook on things, like calculating pi using raindrops or keeping the “ultra” in ultra-high vacuum. Continue reading “Simple Setup Answers Complex Question On The Physics Of Solids” →

Floppy disks

Floppy Interfacing Hack Chat With Adafruit

January 31, 2022 by 44 Comments

Join us on Wednesday, February 2 at noon Pacific for the Floppy Interfacing Hack Chat with Adafruit’s Limor “Ladyada” Fried and Phillip Torrone!

When a tiny fleck of plastic-covered silicon can provide enough capacity to store a fair percentage of humanity’s collected knowledge, it may seem like a waste of time to be fooling around with archaic storage technology like floppy disks. With several orders of magnitude less storage capacity than something like even the cheapest SD card or thumb drive, and access speeds that clock in somewhere between cold molasses and horse and buggy, floppy drives really don’t seem like they have any place on the modern hacker’s bench.

join-hack-chatOr do they? Learning the ins and out of interfacing floppy drives with modern microcontrollers is at least an exercise in hardware hacking that can pay dividends in other projects. A floppy drive is, after all, a pretty complex little device, filled with electromechanical goodies that need to be controlled in a microcontroller environment. And teasing data from a stream of magnetic flux changes ends up needing some neat hacks that might just serve you well down the line.

So don’t dismiss the humble floppy drive as a source for hacking possibilities. The folks at Adafruit sure haven’t, as they’ve been working diligently to get native floppy disk support built right into CircuitPython. To walk us through how they got where they are now, Ladyada and PT will drop by the Hack Chat. Be sure to come with your burning questions on flux transitions, MFM decoding, interface timing issues, and other arcana of spinning rust drives.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 2 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Continue reading “Floppy Interfacing Hack Chat With Adafruit” →