APRS Repeaters Get The Signal Out Of Mammoth Cave

November 25, 2015 by Elliot Williams 55 Comments

APRS Cave-Link uses the amateur radio’s Automatic Packet Reporting System (APRS) inside caves to get their position data (and other messages) out.

Imagine that you’re coordinating a large scale search-and-rescue mission in a cave. You need to know where all your groups are, and whether or not they’ve found anything. But how do they all communicate to the command center?

You’d guess radio, but you’d guess wrong. Radio doesn’t propagate well at all in a maze of twisty passages, all alike; rocks absorb radio waves, especially in the VHF/UHF range that’s best suited for most small radios. In the past, you’d run wire and transmit along it. This article runs through the options in detail. But adding miles of wire to your already heavy caving and climbing gear is a nuisance or worse.

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“Hello Barbie” Under The Knife

November 24, 2015 by Elliot Williams 43 Comments

In February, Google and Mattel introduced their Hello Barbie Internet-connected toy. This Barbie has an internal microphone, a WiFi connection to Google’s voice recognition services, and a speaker to carry on a “conversation” with the targeted child.

Like the folks at Somerset Recon, we’d say that this is an Internet of Things (IoT) device that’s just begging for a teardown, and we’re totally looking forward to their next installment when they pore through the firmware.

On the hardware front, Barbie looks exactly like what you’d expect on the inside. A Marvell 88MW300 WiFi SoC talks to a 24-bit (!) audio codec chip, and runs code from a 16Mbit flash ROM. There’s some battery management, and what totally looks like a JTAG port. There’s not much else, because all the brains are “in the cloud” as you kids say these days.

From day to day we alternate between the promise of IoT and being anti-IoT curmudgeons, so it should come as no surprise that we’re of two minds about Hello Barbie. First, there’s the creepy-factor of having your child’s every word overheard by a faceless corporation with “evil” in their mission statement (see what we did there?). Next, we’re not sure that it’s OK to record everything your child says to a toy and listen to it later, even if you are the parent. Hackaday’s [Sarah Petkus] summarized this neatly in this article.

But mostly, we’re curious about how well the thing actually works and what it will do with naughty words. And who will take on the task of reviving the Barbie Liberation Organization? Now we totally want to go out and buy one of these things.

Doc Brown’s Security Briefcase Needs Speed

November 24, 2015 by Elliot Williams 16 Comments

If you just wait around long enough, the future becomes the past. And that’s happened to the “Back to the Future” future, as you probably all remember. But BttF-themed projects are still pouring in.

[ossum] sent us the link for his build of Doc Brown’s briefcase that only opens above 88 mph. His writeup is fantastically detailed, and worth a look if you’re interested in working with a GPS unit and microcontrollers, driving seven-segment LEDs with shift registers, or just driving too fast in an old Jetta. And there’s a video demo just below the break if you’re not a believer.

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The Ommatid Is An Awesome “Thing”

November 23, 2015 by Elliot Williams 7 Comments

[Jonathan Foote] made a really cool device: the Ommatid spherical display and controller. Part woodworking craft project, part art, and part tremendous hack, the Ommatid is something that we don’t really have a name for. But you can watch it in action, running demo code, in a video below the break.

The sphere design started out with a “20-sided regular polyhedron” with which D&D players should be familiar, and then divided each triangular face into four more triangles. An 80-sided die? Almost. One triangle’s worth was sacrificed for the part that mounts to the base.

Each facet contains an RGB LED and an IR sensor so that it can tell when a hand is nearby. All of this input and output is run through a Raspberry Pi, so both the sensing and display interactions are easily modified. [Jonathan] runs us through the electronics, programming, and interactivity in a separate Instructable. We really like [Jonathan]’s idea of turning this device into an OSC controller / display.

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The First Radio Sets: A Spark Gap And A Coherer

November 22, 2015 by Elliot Williams 33 Comments

[Ashish] let us know about his experiments in recreating the earliest type of radio set: a spark-gap transmitter and iron-filings coherer. He goes through the historical development of the kit in great detail, so we’re just going to skip that part. Go read it yourself!

Instead, we’re going to tease you with the coolest part of the rig: the coherer. In [Ashish]’s build, it’s a piece of tubing with some iron filings between two bolts. When a sufficiently strong EM wave hits the filings, they stick together and bridge the gap between the bolts, allowing electricity to flow and light up an LED, for instance. You can see this in [Ashish]’s video below the break, along with kmore discussion of that coherer.

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Laser-cut Cardboard Planetary Gearset Is Pretty, But Useless

November 22, 2015 by Elliot Williams 11 Comments

[Shane] made a project that speaks directly to our heart — combining laser cutting, cardboard, and gears. How could it be any better? Well, it could do anything. But that’s quibbling. It’s fun enough just to watch the laser-cut cardboard planetary gears turn. (Video after the break.)

It was made on a laser cutter using the gear extensions for generating gears in Inkscape, everybody’s favorite free SVG editor.

In his writeup, [Shane] touches on all of the relevant details: all of the gear pitches need to be the same, and the number of teeth in the sun gear (in the center) needs to equal the number of teeth in the ring (outside) divided by the number of planets (orbiting, in the middle). So far so good.

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Tiny Arcade, Based On Arduino

November 21, 2015 by Elliot Williams 16 Comments

Who can resist video games when they’re packed up in tiny, tiny little arcade machines? [Ken]’s hoping that you cannot, because he’s making a cute, miniature Arduino-based arcade game platform on Kickstarter. (Obligatory Kickstarter promo video below the break.)

The arcades are based on [Ken]’s TinyCircuits Arduino platform — a surprisingly broad range of Arduino modules that click together using small snap connectors in place of pin headers. The system is cool enough in its own right, and it appears to be entirely open source. Housing these bits in a cute arcade box and providing working game code to go along with it invites hacking.

There’s something about tiny video cabinets. We’ve seen people cram a Game Boy Advance into a tiny arcade cabinet and re-house commercial video game keyfobs into arcade boxes. Of course, there’s the Rasbperry Pi. From [Sprite_TM]’s cute little MAME cabinet to this exquisite build with commercially 3D-printed parts, it’s a tremendously appealing project.

But now, if you’re too lazy to build your own from scratch, and you’ve got $60 burning a hole in your pocket, you can get your own tiny arcade — and tiny Arduino kit — for mere money. A lot of people have already gone that route as they passed the $25k funding goal early yesterday. Congrats [Ken]!

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