Film Negative Viewer Has Many Positives

February 18, 2020 by 8 Comments

Not so long ago, taking pictures was a much more sacred thing. Film and processing were expensive compared to the digital way, and since you couldn’t just delete a picture off the camera and get your film back, people tended to be much more selective about the pictures they took. Even so, for every roll of film, there was usually at least one stinker. If you’ve made it your quest to digitize the past, you’ll quickly realize that they’re not all gems, and that some can be left to languish.

[Random_Canadian] recently found himself knee-deep in negatives, but wanted an easy way to weed out the mediocre memories. With this film negative viewer and converter, he can step through the pictures one by one on a big screen and decide which ones to keep.

The Pi uses the negative image effect to turn the negatives positive, and then outputs them to the TV. If [Random_Canadian] finds one worth bringing into the 21st century, he pushes the green button to take a picture with the Pi camera and save it to that awesome cryptex USB drive. When he’s tired of walking down memory lane, he pushes the red button to exit the program.

We especially like that [Random_Canadian] made his own light panel by edge-lighting a piece of 6 mm Lexan. Fresh out of flat-topped LEDs, he made his own by grinding down some regular ones on a belt sander.

Got some old 8mm film you want to digitize? Check out this beautiful automated film scanner.

DNA Now Stands For Data And Knowledge Accumulation

February 18, 2020 by 33 Comments

Technology frequently looks at nature to make improvements in efficiency, and we may be nearing a new breakthrough in copying how nature stores data. Maybe some day your thumb drive will be your actual thumb. The entire works of Shakespeare could be stored in an infinite number of monkeys. DNA could become a data storage mechanism! With all the sensationalism surrounding this frontier, it seems like a dose of reality is in order.

The Potential for Greatness

The human genome, with 3 billion base pairs can store up to 750MB of data. In reality every cell has two sets of chromosomes, so nearly every human cell has 1.5GB of data shoved inside. You could pack 165 billion cells into the volume of a microSD card, which equates to 165 exobytes, and that’s if you keep all the overhead of the rest of the cell and not just the DNA. That’s without any kind of optimizing for data storage, too.

This kind of data density is far beyond our current digital storage capabilities. Storing nearly infinite data onto extremely small cells could change everything. Beyond the volume, there’s also the promise of longevity and replication, maintaining a permanent record that can’t get lost and is easily transferred (like medical records), and even an element of subterfuge or data transportation, as well as the ability to design self-replicating machines whose purpose is to disseminate information broadly.

So, where is the state of the art in DNA data storage? There’s plenty of promise, but does it actually work?

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How Many LEDs Can You Drive?

February 18, 2020 by 35 Comments

Driving more than a handful of LEDs from a microcontroller is often a feat that takes tedious wiring, tricking the processor, or a lot of extra external hardware. Charlieplexing is perhaps the most notorious of these methods, and checks two of those three boxes. This library for the Teensy 4.0 checks all three, but it can also drive a truly staggering 32,000 LEDs at one time.

The TriantaduoWS2811 library is able to drive 32 channels of LEDs from a Teensy 4.0 using only three pins and minimal processor resources. It uses the FlexIO and DMA subsystems of the i.MX RT1062, the particular ARM processor on the Teensy, to drive four external shift registers. Together, the system is able to achieve 30 frames per second on with 1,000 LEDs per channel, for a total of 32,000 LEDs. Whoah.

[Ward] aka [wramsdell] wondered what one would do with all of the horsepower of a Teensy microcontroller when he first saw its specifications, and was able to build this project to take advantage of its features. What’s surprising, though, is that it doesn’t use nearly everything the processor is capable of, so you can do other tasks at the same time as driving that giant LED display.

Insecure Surveillance Cameras Provide Dystopian Peep Show

February 18, 2020 by 29 Comments

It probably doesn’t surprise you to hear there are tens of thousands of web-connected cameras all over the world that are set to take the default credentials. Actually, there are probably more than that out there, but we can assure you that at least 70,000 or so are only a click away. With this project, [carolinebuttet] proves that it’s quite possible to make art from our rickety, ridiculous surveillance state — and it begins with a peephole perspective.

The peephole in your own front door grants you the inalienable right to police your porch, stoop, or patch of carpet in the apartment building’s hallway while going mostly undetected. In Virtual Peephole, the peephole becomes a voyeuristic virtual view of various corners of the world.

Slide aside the cover, and an LDR connected to an Arduino Micro detects the change in light level. This change makes the Micro send a key press to a Raspberry Pi, which fetches a new camera at random and displays it on a screen inside the box. You can peep a brief demo after the break, followed by a couple of short build/walk-through videos.

If you’re a peephole people watcher, put a camera in there and watch from anywhere.

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Wearable Cone Of Silence Protects You From Prying Ears

February 17, 2020 by 36 Comments

Careful,  the walls have ears. Or more specifically, the smart speaker on the table has ears, as does the phone in your pocket, the fitness band on your wrist, possibly the TV, the fridge, the toaster, and maybe even the toilet. Oh, and your car is listening to you too. Probably.

How does one fight this profusion of listening devices? Perhaps this wearable smart device audio jammer will do the trick. The idea is that the MEMS microphones that surround us are all vulnerable to jamming by ultrasonic waves, due to the fact that they have a non-linear response to ultrasonic signals. The upshot of that is when a MEMS hears ultrasound, it creates a broadband signal in the audible part of the spectrum. That creates a staticky noise that effectively drowns out any other sounds the microphone might be picking up.

By why a wearable? Granted, [Yuxin Chin] and colleagues from the University of Chicago have perhaps stretched the definition of that term a tad with their prototype, but it turns out that moving the jammer around does a better job of blocking sounds than a static jammer does. The bracelet jammer is studded with ultrasonic transducers that emit overlapping fields and result in zones of constructive and destructive interference; the wearer’s movements vary the location of the dead spots that result, improving jamming efficacy. Their paper (PDF link) goes into deeper detail, and a GitHub repository has everything you need to roll your own.

We saw something a bit like this before, but that build used white noise for masking, and was affixed to the smart speaker. We’re intrigued by a wearable, especially since they’ve shown it to be effective under clothing. And the effect of ultrasound on MEMS microphones is really interesting.

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What Does Your Necklace Say?

February 17, 2020 by 2 Comments

If we write about sound reproduction, there is a good chance we found a home-made amplifier or an upcycled speaker system. In this case, you don’t use your ears to appreciate the sound; you use your hands or eyes. [ElatisEagles] converted an amplitude sound graph into a wearable bead. Even without much background it should be immediately recognizable for what it is. Presumably, they converted a sound wave to vectors, then used the “Revolve” function in Rhino, their software of choice. Sometimes this is called a “lathe” function. Resin printers should be able to build these without supports and with incredible fidelity.

Some tattoos put a sound wave on the skin, and use an app to play it back, but if you want to wear a sound bite from your favorite show and not get branded as the “Pickle Rick” gal/guy at the office, maybe swap out the color and sound wave before it goes stale. We would wear a bead that says, “drop a link in our tip line,” but you can probably think of something more clever.

We have other high-tech ornamentation that leverages motion instead of sound, or how about a necklace that listens instead.

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Cable Operated Blast Door Needs No Power

February 17, 2020 by 34 Comments

Every well-equipped wood shop has a dust collection system, with blast gates at every tool to direct the suction power where you need it. If these gates are hard to reach they can be real pain to operate. [Cosmas Bauer] had this problem with his table saw, and created a convenient cable-operated mechanism.

The dust chute on table saw is on the back end, meaning he needs to walk around it to open it, and then walk back to the front to operate the machine. As we all know, laziness increased efficiency can be an excellent reason for projects. Electronics or pneumatics might get the job done, but [Cosmas] realised that a mechanical system might be simpler and more reliable.  Being a woodworker, he built most of the system out of wood.

The blast door itself is held in the closed position by a piece of elastic tubing. To pull it open, he attached a bicycle cable to the blast door, with the other side attached to a latching mechanism that is the star of the show. It’s a rotating disc, with the end of the cable and operating handle attached on the outer edge. A slot track is cut in the disc, in which a pin on the end of a short arm slides. It has a few sharp corners in the track, which forces the pin to only go around in one direction, and to latch in two possible positions when released. Check out the video after the break to see it in action.

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