Liquid Metal Changes Shape To Tune Antenna

August 31, 2015 by Dan Maloney 39 Comments

Antennas can range from a few squiggles on a PCB to a gigantic Yagi on a tower. The basic laws of physics must be obeyed, though, and whatever form the antenna takes it all boils down to a conductor whose length resonates at a specific frequency. What works at one frequency is suboptimal at another, so an adjustable antenna would be a key component of a multi-band device. And a shape-shifting liquid metal antenna is just plain cool.

The first thing that pops into our head when we think of liquid metal is a silvery blob of mercury skittering inside the glass vial salvaged out of an old thermostat. The second image is a stern talking-to by the local HazMat team, so it’s probably best that North Carolina State University researchers [Michael Dickey] and [Jacob Adams] opted for gallium alloys for their experiments. Liquid at room temperature, these alloys have the useful property of oxidizing on contact with air and forming a skin. This allows the researchers to essentially extrude a conductor of any shape. What’s more, they can electrically manipulate the oxidative state of the metal and thereby the surface tension, allowing the conductor to change length on command. Bingo – an adjustable length antenna.

Radio frequency circuits aren’t the only application for gallium alloys. We’ve already seen liquid metal 3D printing with them. But we need to be careful, since controlling the surface tension of liquid metals might also bring us one step closer to this.

Want To Create A FabLab In Your Garage? Start By Joining Your Hackerspace

August 31, 2015 by Sonya Vasquez 58 Comments

For many hardware enthusiasts, it’s hard to stop imagining the possibilities of an almighty fablab in our garage — a glorious suite of machines that can make the widgets of our dreams. Over the years, many of us start to build just that, assembling marvelous workbenches for the rest of us to drool over. The question is: “how do we get there?”

Ok, let’s say we’ve got a blank garage. We might be able to pick up a couple of tools and just “roll with it,” teaching ourselves the basics as we go and learning from our mistakes. With enough endurance, we’ll wake up ten years later and realize that, among the CNC mill, lathe, o-scope, logic analyzer, and the graveyard of projects on the shelves–we’ve made it!

“Just rolling with it,” though, can squeeze the last bits of change out of our wallets–not to mention ten years being a long journey while flying solo the whole time. Hardware costs money. Aimless experimentation, without understanding the space of “what expectations are realistic,” can cost lots of money when things break.

These days, the internet might do a great job of bringing people together with the same interest. But how does it fare in exchanging the technical know-how that’s tied directly to tools of the trade? Can we get the same experience from a chatroom as we might from a few minutes with the local ‘CNC Whisperer’ who can tell us the ins-and-outs about tuning the machine’s PID controllers?

I’d say that we just can’t. “Getting started” in any subject often seems daunting, but we’re at a compounded disadvantage in that the gurus on the forum have some shared implicit knowledge and jargon on the subject that we wont have if we truly are taking our first steps. (Not to fear, though; none of us were born with this stuff!)

Ruling out forums for taking our first baby steps, where can we find the “seasoned gurus” to give us that founding knowledge? It’s unlikely that any coffee shop would house the local hardware guru sippin’ a joe and taking questions. Fear not, though; there are places for hackers to get their sustenance.

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Core Memory For The Hard Core

August 31, 2015 by Elliot Williams 57 Comments

[Brek] needed to store 64 bits of data from his GPS to serve as a last-known-position function. This memory must be non-volatile, sticking around when the GPS and power are off. Solutions like using a backup battery or employing a $0.25 EEPROM chip were obviously too pedestrian. [Brek] wanted to store his 64 bits in style and that means hand-wired core memory.

OK, we’re pretty sure that the solution came first, and then [Brek] found a fitting problem that could be solved, but you gotta give him props for a project well executed and well documented.

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Beating The Casino: There Is No Free Lunch

August 31, 2015 by Voja Antonic 83 Comments

When you are a hardware guy and you live in a time of crisis, sooner or later you find yourself working for some casino equipment company. You become an insider and learn a lot about their tricks. I’ve been in touch with that business for about 30 years. I made a lot of projects for gambling machines which are currently in use, and I had a lot of contact with casino people, both owners and gamblers.

Now I’m sure you expect of me to tell you about the tricks they use to make you spend your money. And I will: there are no technical tricks. This isn’t because they are honest people, but because they don’t need it. Mathematics and Psychology do all the work.

Does the risk of gambling pay off? Mathematically speaking, no – but it’s up to you to decide for yourself. One thing is for certain – whether you decide to gamble or not, it’s good to know how those casino machines work. Know thy enemy.

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FCC Introduces Rules Banning WiFi Router Firmware Modification

August 31, 2015 by Brian Benchoff 212 Comments

For years we have been graced by cheap consumer electronics that are able to be upgraded through unofficial means. Your Nintendo DS is able to run unsigned code, your old XBox was a capable server for its time, your Android smartphone can be made better with CyanogenMod, and your wireless router could be expanded far beyond what it was originally designed to do thanks to the efforts of open source firmware creators. Now, this may change. In a proposed rule from the US Federal Communications Commission, devices with radios may be required to prevent modifications to firmware.

The proposed rule only affects devices operating in the U-NII bands; the portion of the spectrum used for 5GHz WiFi, and the proposed rule only affects the radios inside these devices. Like all government regulations, the law of unintended consequences rears its ugly head, and the proposed rules effectively ban Open Source router firmware.

The rules require all relevant devices to implement software security to ensure the radios of devices operating in this band cannot be modified. Because of the economics of cheap routers, nearly every router is designed around a System on Chip – a CPU and radio in a single package. Banning the modification of one inevitably bans the modification of the other, and eliminates the possibility of installing proven Open Source firmware on any device.

Building A Better Mousetrap With The Raspberry Pi

August 31, 2015 by Kevin Dady 25 Comments

Build a better mousetrap, and the world will beat a path to your door, but what about a smarter mousetrap? [Alain] decided to find out by making a Raspberry Pi-powered, Internet-connected smart trap. The brains of the operation is a Pi running Arch Linux. Connected to that is a IR trigger, a servo to unlatch the sliding door, and a camera to see your new friend.

The housing of the trap is CNC cut foam PVC board, which is both easy to cut and to clean. Once the IR beam is broken the Pi turns the servo, which pulls a pin on the front door. Once your new friend is settled in a LED light turns on to illuminate the subject, a picture is taken and sent via email.

With automated alerts you don’t have to manually check the trap, and you also don’t have to worry about a trapped animal being inside for too long. Join us after the break for a demonstration video showing off all the features, and a real world example.

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Hackaday Prize Semifinalist: A Smart Battery Analyzer

August 30, 2015 by Brian Benchoff 6 Comments

[K.C. Lee]’s entry for the Hackaday Prize won’t cure cancer, wipe a disease from the planet, stop an alien invasion, or save the world. His battery charger and analyzer is, however, a useful little device for determining the charge and discharge characteristics of batteries, and can also be used as dual channel electronic load, current source, or power supply.

Inside [K.C.]’s device are all the tools required for charging and discharging lithium-ion, lead acid, and NiMH batteries. He’s doing this with a few slightly unusual circuits, including a SEPIC DC to DC converter, and an ‘analog’ PWM controller. these two techniques together mean [K.C.] can get away with smaller caps and inductors in his design, which also means less ripple on the output. As far as battery chargers and dischargers go, this one is very well designed.

Control of battery discharging and charging happens through a SILabs 8051-based microcontroller with USB. The UI is a simple Nokia LCD and an app running in Windows. If you want to save the world, this isn’t the project for you. If you need to test a few rechargeable batteries, this is a great device to have on the workbench.