Repairing A Junked Signal Generator

October 15, 2012 by Mike Szczys 21 Comments

We must be walking past the wrong dumpsters because we certainly haven’t encountered equipment like this just waiting to be salvaged. [Shahriar] found an HP 8648C Synthesized Signal Generator while he was ‘dumpster diving’ and set out to fix the malfunctioning lab equipment. He posted a 1-hour video on the project, which you can find embedded after the break. The actual fix happens in the first half, the rest of the video is spent testing the resurrected device.

The back corner of the case has been dented, which may be the reason this has been thrown out. When it is first powered it emits an unpleasant screeching noise and the user interface doesn’t do anything. [Shahriar] says he recognizes the sound as a malfunctioning switch-mode power supply. Sure enough, when disconnected from the main board it still makes the noise. It turns out there’s a huge electrolytic capacitor the size of a stack of poker chips which has come loose from the PSU board. When it’s resoldered the device fires up as expected.

Now how are we going to find a digital capture oscilloscope that just needs to have its PSU reassembled?

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7400 Project Encrypts And Decrypts Data

October 15, 2012 by Mike Szczys 8 Comments

[Nakul], [Nikilesh], and [Nischal] just finished posting about their entry in the 2012 Open 7400 Logic competition. It’s an encryption system based entirely on 7400 logic chips. The device operates on 8-bit binary numbers, which limits its real-world applications. But we bet they learned a lot during the development process.

The encryption algorithm is based on a the concept of cellular automaton. This is a something with which we’re already familiar having seen many Conway’s Game of Life projects around here. What we’re not familiar with is this particular wing of the concept called ‘Rule 30‘. It works well with this project because a complex pattern can be generated from simple beginnings.

After conceptualizing how the system might work the team spent some time transferring the implementation to the chips they had available. The end result is a quartet of chip-packed breadboards and a rat’s nets of wires, but the system is capable of both encrypting and decrypting data.

Controlling A Robot With Your Mind

October 15, 2012 by Brian Benchoff 16 Comments

For [Ern]’s MEng group project, his group had to develop a robotics platform capable of achieving some end goal. Because innovation is a large part of the grade, [Ern] convinced his team members to work with a brain controlled interface and build a mind controlled robotics platform.

For wont of having an easy build, [Ern] and his team chose a Lynxmotion Tri-Track robot capable of moving around the classroom while receiving commands from a computer. The mind-control portion of the build comes from a NeuroSky MindWave Mobile, a cheap and fairly open EEG system that reads alpha, beta, and delta waves generated by a user’s brain and sends that data over to a computer for processing.

After a bit of testing that included an Arduino to move the robot forward if the MindWave’s ‘attention’ value was over 60%, [Ern] and his team looked for a way to implement multi-directional control.

In order to get the robot moving left, right, and backwards in addition to moving forwards, the team looked at the included ‘blink detection’ abilities of the MindWave to cycle through a few commands. This technique turned out to be far too sensitive – the blink detection of the MindWave is simply too good. To get around that problem, the team used the signal strength of the received EEG signals. The theory being when a user blinks their eyes, the EEG contacts will move slightly, degrading the signal received by the hardware.

The team finally got a reasonable mind-controlled robot up and working, as demonstrated in the video after the break. Check out how each blink allows [Ern] and his colleagues to cycle through driving modes. Pretty neat for controlling something with your mind.

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μJ, A Java Virtual Machine For Microcontrollers

October 15, 2012 by Brian Benchoff 78 Comments

[Dimitri] sent in a project he’s been working on that implements a Java Virtual Machine purely in C, and is easily portable between microcontrollers such as the AVRs and PICs we normally see, ARM devices, and even the lowly 386.

Before going into the ‘how’, [Dimitri] first covers why he wanted to run Java bytecode on a microcontroller. Basically, he found existing solutions like the Arduino environment too complex for people just wanting to program a chip. Arduino and PICAXE require C-like syntax and pointers; not the easiest thing when everyone and their mother can program in Java.

As for how [Dimitri] managed to pack a JVM into a microcontroller, that’s another story entirely. Everything in the JVM, from double, long, and float data types to exceptions, neat thread-related functions such as ‘synchronize’ and even methods such as String.charAt() and String.length() are completely optional. If your microcontroller is too small, just disable the functions you don’t need.

As for how well – and how fast – μJ is able to run, [Dimitri] threw up a demo of an ATMega644 and PIC24 running his JVM and a small Java app. You can check those videos out after the break, or just download the source for μJ on [Dimitri]’s site.

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Raspis With Double The RAM In The Wild

October 15, 2012 by Brian Benchoff 33 Comments

There is buzz all over the reddits and Element 14 discussion boards about an updated version of the Raspberry Pi that bumps the amount of RAM from 256 MB to 512 MB.

This new update comes after the announcement of an upgraded version of the yet-to-be-released Raspi Model A (from 128 MB of RAM to 256 MB), and a few slight modifications to the Model B that include fixing a few hardware bugs (nothing serious) and adding mounting holes.

After perusing the Element 14 and Raspberry Pi discussion boards, a few things become apparent. Firstly, it appears this new upgrade to double the amount of RAM was initiated by manufacturers. It seems 512 MB RAM chips are cheap enough now to include in the Raspi without impacting the cost of components. Secondly, 512 MB seems to be the upper limit for the Raspberry Pi, at least for this iteration of hardware. Not enough address lines, they say, but you’re welcome to try and hack your own RAM to a Raspi CPU.

So far, attentive Raspi enthusiasts have found Raspberry Pis with double the amount of RAM on the UK Farnell site and the Australian Element 14 site. Nothing so far on the US Element 14 site, although we’ll gladly update this post when a Hackaday reader finds the relevant link.

EDIT: Here’s the link for the US version of Newark. No, there aren’t any in stock. Also, Hackaday beat the official Farnell/Element 14/Newark press release and the Raspberry Pi blog to the punch. Woo, go us.

Cheap Spark Detector For Alpha Particles

October 15, 2012 by Jesse Congdon 14 Comments

[JAC_101] wrote in to let us know that the Truely Mad Scientist’s LVL1 Splinter Group just built a simple Alpha Particle detector. The detector is a high voltage DC spark gap that is triggered by ionizing radiation. Making one of these detectors involves gutting a cold cathode power supply for some high voltage AC, then bumping that source up to crazy high voltage DC with a Cockcroft-Walton generator. Once the spark gap distance is carefully adjusted it will light up brilliantly with the introduction of a radioactive source, we are told. There are no videos, or even pictures of the thing running, but we found this one that is pretty darn cool. Maybe all that spark-gap related RF killed their camera or something, their page at least promises videos soon.

In the mean time check out Truely Mad Scientist’s LVL1 Splinter Group’s ionizing cloud chamber for more radioactive fun.

Our First Election Hack That Doesn’t Involve E-ballots

October 15, 2012 by Brian Benchoff 47 Comments

Because some of Hackaday’s readers aren’t from America, let us fill you in on the US election process from the point of view as a voter. Over the next few weeks, political campaigns will dump millions of dollars into advertising, get-out-the-vote and canvassing efforts across the country. The airwaves will broadcast still more ads and political analyses until November 6th, when voters will go to the polls and pull the lever for whoever earned their vote back in July.

Despite how effectively public opinion can be swayed, there are still a lot of problems with the election process in the United States. A first-past-the-post, winner take all system guarantees there will only ever be two realistic choices for voters, but a group of philosophy students (and teachers) may have a solution to this problem.

The idea is fairly simple, really: take dissatisfied members of one party and match them up with dissatisfied members of another party. Normally, these voters would be inclined to vote the party line and not their conscience, for fear of throwing their vote away. After matching these voters up, they make a gentleman’s agreement with each other (either with a handshake or by mailing in their ballots together) to not vote the party line. The balance of power between (D)s and (R)s remains, but third-party candidates get a much-needed shot in the arm.

It’s an interesting idea with far more potential to effect some change than the numerous e-voting hacks that will pop up after the election. Sure, it may not be as effective as other voting systems such as the Condorcet method, but save for elected officials abdicating powers granted to them, this might be the best shot we’ve got.