The Little Mechanism That Made Precise Time-keeping Possible

November 15, 2016 by Manuel Rodriguez-Achach 61 Comments

There are few things to which we pay as much attention as the passage of time. We don’t want to be late for work, or a date. Even more importantly, we don’t want to age and die. Good time keeping is an all important human activity, and we started to worry about it as soon as we abandoned our hunter-gatherer lifestyle and agriculture and commerce emerged.

By de:Benutzer:Flyout - own work, http://de.wikipedia.org/wiki/Bild:Kerzenuhr.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1783765 — A candle clock

Measuring time needs two things: a repetitive process to mark equal increments of time, and a way of tracking and displaying the result. The first timekeeping devices relied of course on the movement of the sun. Ancient Egyptians, around 3500 BC, built obelisks that, by casting a shadow on the ground at different positions, gave an approximate idea of the time. Next came the use of some medium that was consumed at a regular pace: candle, incense, water and sand clocks are examples. A great advancement came with the advent of the mechanical clock, and here is where the escapement mechanism appears.

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Make Water Bridges With High Voltages

November 15, 2016 by Richard Baguley 42 Comments

It’s generally a bad idea to mix high voltage electricity and water, but interesting things happen if you do. This video from [RWGResearch] shows one of them: water bridging. If you have two water sources (such as two beakers full of very highly distilled water) with a high voltage between them, the voltage can create a gravity defying bridge that flows between them.

The experiment starts with the pouring spouts from two beakers nearly touching each other. Water fills the beakers right up to the spout, but it’s the application of electricity that pulls the bridge between the positive and negative beakers. With care, this technique can create a bridge of up to 2cm (about 0.8 inches). [RWGResearch] shows that he is able to create a bridge of about a centimeter with a 5KV voltage, but which only carries a few milliamps.

What forces are at play here isn’t exactly clear, but one recent paper speculates that it’s down to a combination of the dielectric force caused by the differing charges of parts of water molecules and the surface tension of the water. Whatever it is, it is fascinating and makes for a neat trick.

Want to make your own contribution to the scientific body of knowledge? Prove or disprove the speculation mentioned in the Wikipeadia article: is this possible because of an H3O2 lattice formed by the high voltage? How would you formulate a test for this?

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RC receiver to arduino converter for BB-8

Ask Hackaday: How Do You Convert Negative Voltages To Positive?

November 14, 2016 by Steven Dufresne 81 Comments

I have a good background working with high voltage, which for me means over 10,000 volts, but I have many gaps when it comes to the lower voltage realm in which RC control boards and H-bridges live. When working on my first real robot, a BB-8 droid, I stumbled when designing a board to convert varying polarities from an RC receiver board into positive voltages only for an Arduino.

Today’s question is, how do you convert a negative voltage into a positive one?

In the end I came up with something that works, but I’m sure there’s a more elegant solution, and perhaps an obvious one to those more skilled in this low voltage realm. What follows is my journey to come up with this board. What I have works, but it still nibbles at my brain and I’d love to see the Hackaday community’s skill and experience applied to this simple yet perplexing design challenge.

The Problem

I have an RC receiver that I’ve taken from a toy truck. When it was in the truck, it controlled two DC motors: one for driving backwards and forwards, and the other for steering left and right. That means the motors are told to rotate either clockwise or counterclockwise as needed. To make a DC motor rotate in one direction you connect the two wires one way, and to make it rotate in the other direction you reverse the two wires, or you reverse the polarity. None of the output wires are common inside the RC receiver, something I discovered the hard way as you’ll see below.

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Electronica 2016: Too Much Electronics

November 14, 2016 by Elliot Williams 34 Comments

The Electronica trade show in Munich is so big that it only takes place once every two years. Every manufacturer, distributor, and maker of anything electronic is there. To get a feel for the scale of things, Electronica is spread out over twelve large exhibition halls and is served by two separate subway stations, one on either end. You wouldn’t think there would be so many inductor manufacturers in the world, but you’d be wrong.

It’s a hardware geek’s paradise, even if it is aimed more at facilitating industry contacts than at serving the humble hacker. But it’s great to see what is out there, quiz reps of all our favorite chip manufacturers about what they’ve got going on, and just generally wander around. You might not get to play with the multi-gigahertz scopes on a day-to-day basis, but you can get hands-on with them at Electronica. And as cool as it is to talk directly to the representatives of our mega-manufacturers, it’s maybe more fun to check up on the creative fringe of companies that you’ve never heard of before, but who nonetheless have great ideas.
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Linux On Your NES Classic Edition

November 13, 2016 by Jenny List 53 Comments

Nintendo look as though they may have something of a hit on their hands with their latest console offering. It’s not the next in the line of high-end consoles with immersive VR or silicon that wouldn’t have looked out of place in last year’s supercomputer, instead it’s an homage to one of their past greats. The NES Classic Edition is a reboot of the 1980s console with the familiar styling albeit a bit smaller, and 30 of the best NES games included.

You do not, however, get an original NES with a 6502 derived processor, and a stack of game cartridges. In the Classic Edition is a modern emulator, running on very modern hardware. We’re told it contains an Allwinner R16 quad-core Cortex A7 SoC, 256Mb of RAM, and 512Mb of Flash. That’s a capable system, and unsurprisingly any hacking potential it may have has attracted some interest. Reddit user [freenesclassic] for example has been investigating its potential as a Linux machine, and has put up a post showing the progress so far. It is known that there is already some form of Linux underpinning the console because Nintendo have released a set of sources as part of their compliance with the terms of the relevant open-source licences. That and the availability of a serial port via pads on the PCB gives hope that a more open distro can be installed on it.

We’re taken through the process of starting the machine up with the serial port connected to a PC, and getting it into the Allwinner FEL mode for low-level flashing work. Then we’re shown the process of loading a custom U-Boot, from which in theory a kernel of your choice can be loaded.

Of course, it’s not quite that simple. There is still some way to go before the device’s Flash can be accessed so for now, all that is possible is to use the RAM, and the current state of play has a kernel panic as it is unable to mount a filesystem. However this is a new piece of hardware in its first few days after launch, so this is very much a work in progress. We are sure that this device will in time be opened up as a fully hackable piece of hardware, and we look forward to covering the interesting things people do with it when that has happened.

If you are interested in the NES Classic, take a look at it on Nintendo’s web site. Meanwhile, here at Hackaday as a quick look at our past stories tagged “nes” shows, we’ve covered a huge number of projects involving the platform in the past.

Thanks [Doc Oct] for the tip.

Original NES console header image: Evan-Amos [Public domain], via Wikimedia Commons.

Transparent Rocket Engine

November 12, 2016 by Manuel Rodriguez-Achach 45 Comments

Rocket engines are undeniably cool. Experiencing the roar, seeing the fire, and watching the rocket blast off into the sky… what else can you ask for? Well, for [NightHawkInLight], a transparent rocket body is the answer.

Based on previous work by [Applied Science], he uses an acrylic rod as the rocket body and as the fuel. Bring a flame into the acrylic, apply oxygen from a canister at the other end of the body and voilà! The rocket engine starts nicely, and even better, the intensity of the burn can be controlled via the amount of oxygen provided.
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ArduWorm: A Malware For Your Arduino Yun

November 11, 2016 by Elliot Williams 24 Comments

We’ve been waiting for this one. A worm was written for the Internet-connected Arduino Yun that gets in through a memory corruption exploit in the ATmega32u4 that’s used as the serial bridge. The paper (as PDF) is a bit technical, but if you’re interested, it’s a great read. (Edit: The link went dead. Here is our local copy.)

The crux of the hack is getting the AVR to run out of RAM, which more than a few of us have done accidentally from time to time. Here, the hackers write more and more data into memory until they end up writing into the heap, where data that’s used to control the program lives. Writing a worm for the AVR isn’t as easy as it was in the 1990’s on PCs, because a lot of the code that you’d like to run is in flash, and thus immutable. However, if you know where enough functions are located in flash, you can just use what’s there. These kind of return-oriented programming (ROP) tricks were enough for the researchers to write a worm.

In the end, the worm is persistent, can spread from Yun to Yun, and can do most everything that you’d love/hate a worm to do. In security, we all know that a chain is only as strong as its weakest link, and here the attack isn’t against the OpenWRT Linux system running on the big chip, but rather against the small AVR chip playing a support role. Because the AVR is completely trusted by the Linux system, once you’ve got that, you’ve won.

Will this amount to anything in practice? Probably not. There are tons of systems out there with much more easily accessed vulnerabilities: hard-coded passwords and poor encryption protocols. Attacking all the Yuns in the world wouldn’t be worth one’s time. It’s a very cool proof of concept, and in our opinion, that’s even better.

Thanks [Dave] for the great tip!