Christmas POV Display Makes Viewer Do The Work

December 9, 2018 by 12 Comments

Hackaday readers have certainly seen more than a few persistence of vision (POV) displays at this point, which usually take the form of a spinning LED array which needs to run up to a certain speed before the message becomes visible. The idea is that the LEDs rapidly blink out a part of the overall image, and when they get spinning fast enough your brain stitches the image together into something legible. It’s a fairly simple effect to pull off, but can look pretty neat if well executed.

But [Andy Doswell] has recently taken an interesting alternate approach to this common technique. Rather than an array of LEDs that spin or rock back and forth in front of the viewer, his version of the display doesn’t move at all. Instead it has the viewer do the work, truly making it the “Chad” of POV displays. As the viewer moves in front of the array, either on foot or in a vehicle, they’ll receive the appropriate Yuletide greeting.

In a blog post, [Andy] gives some high level details on the build. Made up of an Arduino, eight LEDs, and the appropriate current limiting resistors on a scrap piece of perfboard; the display is stuck on his window frame so anyone passing by the house can see it.

On the software side, the code is really an exercise in minimalism. The majority of the file is the static values for the LED states stored in an array, and the code simply loops through the array using PORTD to set the states of all eight digital pins at once. The simplicity of the code is another advantage of having the meatbag human viewer figure out the appropriate movement speed on their own.

This isn’t the only POV display we’ve seen with an interesting “hook” recently, proving there’s still room for innovation with the technology. A POV display that fits into a pen is certainly a solid piece of engineering, and there’s little debate the Dr Strange-style spellcaster is one of the coolest things anyone has ever seen. And don’t forget Dog-POV which estimates speed of travel by persisting different images.

[Thanks to Ian for the tip.]

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Hackaday Links: December 9, 2018

December 9, 2018 by 28 Comments

SpaceX launched a rocket this week, and things did not go as planned. The hydraulics on the grid fins were stuck when the first stage started its atmospheric recovery, and the booster became a fish. The booster landed about a mile or so offshore, which meant we got some great footage of a failed landing, and there are even better shots of the guts of a landed booster. [Scott Manley] whipped out a video showing the ‘new’ discoveries of what’s going on inside a Falcon 9 booster. Interestingly: the weight of the upper stage is carried through the thrust plate of its engine (which makes sense…). There’s a lot of pneumatic stuff going on, and while the composite interstage is very strong along the long axis of the rocket, it doesn’t like being slammed into the ocean.

Winter is coming, and that means you should take your car out during the first snow, drive out to an empty parking lot, and do donuts. I am not kidding this is how you learn to drive in the snow. How do they do it in Russia? They weld 3000 nails to a steel wheel. Does it work? For a while, then the nails bend. We’ve seen this done by drilling screws through a tire, and that works much better; it’s less length for the screws to fulcrum over.

Aaay, we got a date for Sparklecon! It’s February 1-3rd in the endless suburban wastes of Fullerton, California. It’s in an industrial park, there’s a liquor store around the corner, and there’s a remote-controlled couch. Get on it.

Do you wish you had a hassle-free and affordable way to get scorpions delivered straight to your mailbox? Enter Dollar Scorpion Club. Dollar Scorpion Club makes a great gift for all ages. Just enter your friend’s shipping address during checkout, and the extra-special scorpion supply chain management will mean your scorpions are delivered fast to their door.

Regular Car Reviews finally reviewed a Pontiac Aztek. The takeaway is that it’s a bug-out car for Boomers, designed in that episode of The Simpsons where Homer finds out he has a brother.

Want to see something weird? It’s a G3 iMac running Windows 8. This is… weird. Either someone is doing a remote desktop into a Windows 8 machine, someone is just using screenshots, or this machine is way cooler than the craigslist seller is letting on. If you’re in Dallas, it might be worth picking this up.

Bose Wants You To Listen Up For Augmented Reality

December 9, 2018 by 21 Comments

Perhaps it is true that if all you have is a hammer every problem you see looks like a nail. When you think of augmented reality (AR), you usually think of something like the poorly-received Google Glass where your phone or computer overlays imagery in your field of vision. Bose isn’t known for video, though, they are known for audio. So perhaps it isn’t surprising that their upcoming (January 2019) AR sunglasses won’t feature video overlays. Instead, the $200 sunglasses will tell you what you are looking at.

The thing hinges on your device knowing your approximate location and the glasses knowing their orientation due to an inertial measuring system. In other words, the glasses — combined with your smart device — know where you are and what you are looking at. Approximately. So at the museum, if you are looking at a piece of art, the glasses could tell you more information about it. There’s a video showing an early prototype from earlier this year, below.

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Stove Alarm Keeps The Kitchen Safe

December 9, 2018 by 70 Comments

Gas cooktops have several benefits, being able to deliver heat near-instantly, while also being highly responsive when changing temperature. However, there are risks involved with both open flames and the potential of leaving the gas on with the burner unlit. After a couple of close calls, [Bob] developed a simple solution to this safety issue.

The round PCB sits neatly behind the knobs, affixed with double-sided tape.

Most commercial products in this space work by detecting the heat from the cooktop, however this does not help in the case of an unlit burner being left on. [Bob]’s solution was to develop a small round PCB that sits behind the oven knobs. Magnets are placed on the knobs, which hold a reed switch open when the knob is in the off position. When the knob is turned on, the reed switch closes, powering a small microcontroller which beeps at regular intervals to indicate the burner is on.

It’s a tidy solution to a common problem, which could help many people – especially the elderly or the forgetful. It integrates neatly into existing cooktops without requiring major modification, and [Bob] has made the plans available if you wish to roll your own.

On the other end of the scale, you might want an alarm on your freezer, too.

Generating Power With Wind, Water, And Solar

December 9, 2018 by 22 Comments

It is three weeks after the apocalypse. No zombies yet. But you do need to charge your cell phone. How do you quickly make a wind turbine? If you’ve read this project, you might reach for a few empty water bottles. This educational project might not charge your phone without some extra work, but it does illustrate how to use water bottles to make a workable air scoop for turning a crank and possibly generating electricity.

That takes care of the wind and water aspects, but how did we get solar? According to the post — and we agree it is technically true — wind power is a form of solar power since the wind is driven by temperature differences created by the sun. Technically true!

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FPGA Used VHDL For Fractals

December 9, 2018 by 9 Comments

Over on GitHub, [ttsiodras] wanted to learn VHDL. So he started with an algorithm to do Mandelbrot sets and moved it to an FPGA. Because of the speed, he was able to accomplish real-time zooming. You can see a video of the results, below.

The FPGA board is a ZestSC1 that has a relatively old Xilinx Spartan 3 chip onboard. Still, it is plenty powerful enough for a task like this.

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Easily Deboss Notebooks With A 3D Printed Stamp

December 9, 2018 by 14 Comments

While it’s arguably a bit closer to the “Arts & Crafts” region of the making spectrum upon which we don’t usually tread on account our l33t sense of superiority, we’ve got to admit that the quick and easy notebook customization demonstrated by [Sean Hodgins] is very compelling. We don’t put ink to dead trees with nearly the frequency we used to, but when we do it might as well be Hemingway-style with a little black Hackaday emblazoned notebook.

As demonstrated in the video after the break, the process starts by designing the stamp in your CAD package of choice. For optimal results [Sean] suggests fairly large capital letters, but with practice you should be able to get into some more creative fonts. Potentially you could even use the logo of your favorite hacking blog, but who are we to dictate what you do?

Whatever you chose, it needs to be mirrored and placed on a relatively thick backing. He recommends a 2 mm thick “plate” with the letters raised on top. You’ll want to print it at a high infill percentage, but even still it shouldn’t take more than 30 minutes or so to run off. Remember there tends to be diminishing returns on infill past 50%, so taking it all the way to 100% is not going to do much but expend more time and plastic.

Once printed, [Sean] hot glues the stamp to a block of wood since putting pressure on the printed piece directly would likely crack it. Then it’s just a matter of getting your notebook, printed stamp, and blocks of wood lined up in to a suitably beefy bench vise. Getting everything aligned is one of those things that easier said than done, so expect to mess up the first couple until you get the hang of it.

When the alignment looks good, crank it down and let it sit for a few minutes. If you’re embossing the design into actual leather, wetting it a bit before putting the pressure on should help. The final effect is understated but undeniably very slick; and with the Holidays rapidly approaching this might be an excellent way to knock out some legitimately thoughtful gifts.

Ultimately the idea here is something of a lightweight version of the 3D printed press break dies used to bend aluminum or the punch and die set used for steel plates. At this point it seems there’s enough evidence to say that 3D printed objects are certainly strong enough (in compression, at least) to put some legitimate work in.

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