Amazing 3D-Scanner Teardown and Rebuild

0_10ea1b_776cdc71_origPour yourself a nice hot cup of tea, because [iliasam]’s latest work on a laser rangefinder (in Russian, translated here) is a long and interesting read. The shorter version is that he got his hands on a broken laser security scanner, nearly completely reverse-engineered it, got it working again, put it on a Roomba that was able to map out his apartment, and then re-designed it to become a tripod-mounted, full-room 3D scanner. Wow.

The scanner in question has a spinning mirror and a laser time-of-flight ranger, and is designed to shut down machinery when people enter a “no-go” region. As built, it returns ranges along a horizontal plane — it’s a 2D scanner. The conversion to a 3D scanner meant adding another axis, and to do this with sufficient precision required flipping the rig on its side, salvaging the fantastic bearings from a VHS machine, and driving it all with the surprisingly common A4988 stepper driver and an Arduino. A program on a PC reads in the data, and the stepper moves another 0.36 degrees. The results speak for themselves.

This isn’t [iliasam]’s first laser-rangefinder project, naturally. We’ve previously featured his homemade parallax-based ranger for use on a mobile robot, which is equally impressive. What amazes us most about these builds is the near-professional quality of the results pulled off on a shoestring budget.

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Keytar Made Out Of A Scanner To Make Even the 80s Jealous

Do any of you stay awake at night agonizing over how the keytar could get even cooler? The 80s are over, so we know none of us do. Yet here we are, [James Cochrane] has gone out and turned a HP ScanJet Keytar for no apparent reason other than he thought it’d be cool. Don’t bring the 80’s back [James], the world is still recovering from the last time.

Kidding aside (except for the part of not bringing the 80s back), the keytar build is simple, but pretty cool. [James] took an Arduino, a MIDI interface, and a stepper motor driver and integrated it into some of the scanner’s original features. The travel that used to run the optics back and forth now produce the sound; the case of the scanner provides the resonance. He uses a sensor to detect when he’s at the end of the scanner’s travel and it instantly reverses to avoid collision.

A off-the-shelf MIDI keyboard acts as the input for the instrument. As you can hear in the video after the break; it’s not the worst sounding instrument in this age of digital music. As a bonus, he has an additional tutorial on making any stepper motor a MIDI device at the end of the video.

If you don’t have an HP ScanJet lying around, but you are up to your ears in surplus Commodore 64s, we’ve got another build you should check out.

Hackaday Prize Entry: Measuring 3D Magnetic Fields

Sometimes you have to start out with big goals. Ninth-graders [Finja Schneider] and [Myrijam Stoetzer] are aiming to make a magnetic field scanner that would be helpful in finding large underground metallic objects, like unexploded WWII bombs that pose a real threat whenever a new parking garage is excavated in Germany. But even big goals have to start out somewhere, so they’re gaining experience with the sensors and the math necessary to recreate 3D magnetic flux vector fields on household objects like sawblades and magnetized screwdrivers.

Magnetized screwdriver in the "valley"
Magnetized screwdriver in the “valley”

For their science-fair project, [Finja] and [Myrijam] took a mid-80s fischertechnik “toy” 2D scanner kit, mounted a 3D magnetic sensor to it, and wrote some firmware to scan around and pass the data back to a computer where they reconstructed the field lines and made some nice visualizations. Along the way, they tried a number of designs, from a DIY chassis on carbon-fiber rails to sensors with ferrofluid. They document their successes and failures equally nicely in their lab report (PDF, German). You can get a lot of the gist, however, from [Myrijam]’s blog and their entry.

You might also recognize [Myrijam] from her work with [Paul Foltin] on their eye-controlled wheelchair interface. These are some really cool projects! We’re excited to see how they develop, and are stoked that the future of hacking is in such capable hands.

GPS And SDR Combine Forces

Software-defined radio (or SDR) is a relatively new (to average tinkerers, at least) way of sending and receiving radio signals. The interest in SDR exploded recently with the realization that cheap USB TV tuner cards could be used to start exploring the frequency spectrum at an extremely reduced cost. One of the reasons that this is so advantageous is because of all of the options that a general-purpose computer opens up that go beyond transmitting and receiving, as [Chris] shows with his project that ties SDR together with GPS.

The goal of the project was to automatically tune a radio to the local police department’s frequency, regardless of location. To do this, a GPS receiver on a computer reports information about the current location. A JavaScript program feeds the location data to the SDR, which automatically tunes to the local emergency services frequencies. Of course, this relies on good data for what those frequencies are, but this is public information in most cases (at least in the US).

There are a lot of opportunities here for anyone with SDR. Maybe an emergency alert system that can tune to weather broadcasts if there’s a weather alert, or any of a number of other captivating projects. As for this project, [Chris] plans to use Google’s voice recognition software to transcribe the broadcasts as well. The world of SDR is at your fingertips to do anything you can imagine! And, if you’re looking to get started in it, be sure to check out the original post covering those USB TV tuner dongles.

Build A Rhizotron: Image The World Beneath Your Feet

The world of the subsoil is a fascinating place. Our whole ecosystem depends on its variety of fungus, bacteria and detritivore creatures that break down and decay dead matter and provide the nutrients to sustain plants that bring in the energy from the sun.

It’s easy enough to study what is happening beneath the surface, just reach for a trowel. But of course, that’s an imperfect technique, for it only gives a picture of a world you have destroyed, and then at best only a snapshot.

Fungal hypha growth in action
Fungal hypha growth in action

What if you could image underground, take pictures and video of the decay process and the creatures that are its engine? [Josh Williams] was curious how this could be achieved, so after early experiments with buried webcams proved unimpressive he created the Rhizotron. A flatbed scanner waterproofed for burial with plenty of silicone, and driven by a Raspberry Pi. The result was particularly successful, and though he has lost several scanners to water ingress he has collected some impressive imagery which he has posted on the project’s blog. Below the break we’ve included one of his videos taken with the scanner in a compost bucket, in which you can see decomposition aplenty, mating millipedes, spreading fungal hyphae and much more.

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Digital Images And The Amiga

There was a time in the late 80s and early 90s where the Amiga was the standard for computer graphics. Remember SeaQuest? That was an Amiga. The intro to Better Call Saul? That’s purposefully crappy, to look like it came out of an Amiga. When it comes to the Amiga and video, the first thing that comes to mind is the Video Toaster, hardware and software that turns an Amiga 2000 into a nonlinear video editing suite. Digital graphics, images, and video on the Amiga was so much more than the Video Toaster, and at this year’s Vintage Computer Festival East, [Bill] and [Anthony] demonstrated what else the Amiga could do.

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DIY Single Pixel Digital Camera

[Artlav] wanted to build a digital camera, but CCDs are expensive and don’t respond well to all wavelengths of light. No problem, then, because with a photodiode, a few stepper motors, the obligatory Arduino, and a cardboard box, it’s pretty easy to make one from scratch.

The camera’s design is based on a camera obscura – a big box with a pinhole in one side. This is all a camera really needs as far as optics go, but then there’s the issue of digitizing the faint image projected onto the rear of the camera. That’s fine, just build a cartesian robot inside the box and throw a photodiode in there.

There are a few considerations when choosing a photodiode for a digital camera. Larger photodieodes have higher noise but lower resolution. [Artlav] has been experimenting with a few diodes, but his options are limited by export control restrictions.

Even with the right photodiode, amplifying the tiny amount of current – picoamps in some cases – is hard. The circuit is extremely sensitive to EMI, and it’s inside a box with stepper motors pulled from the scrap bin. It’s amazing this thing works at all.

Still, [Artlav] was able to get some very high resolution images across a huge range of wavelengths. He’s even getting a few images in mid-wave infrared, turning this homebrew digital camera into the slowest thermal imaging camera we’ve ever seen.