PLL 101

June 21, 2011 by Kevin Dady 14 Comments

[Jeri Ellsworth] and former Commodore Computer engineer and current full time tinkerer [Bil Herd] have a little chat on skype covering the 101’s of Phase Lock Loops in this hour long video. PLL’s are handy for many applications, but their basic use is to keep clock signals in sync.

Topics covered include: Why we care, a basic explanation for the CD4046, capture ranges, and meta stability. Examples from analog tv, to clock recovery, finding falling edges and FPGA’s. This thing is jam packed full of information.

With talks of future episodes and a quick tour of [Bil’s] bench this is something to not miss. Join us after the break for the video!

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ChipKIT Sketch: Mini Polyphonic Sampling Synth

June 8, 2011 by Phil Burgess 20 Comments

In our hands-on review of the Digilent chipKIT Uno32, we posed the question of what the lasting appeal might be for a 32-bit Arduino work-alike. We felt it needed some novel applications exploiting its special features…not just the same old Arduino sketches with MOAR BITS. After the fractal demo, we’ve hit upon something unique and fun…

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Stripping DRM From OverDrive Media Console EBooks

June 7, 2011 by Mike Nathan 18 Comments

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[Armin Tamzarian’s] local library recently started lending eBooks via the OverDrive Media Console system. He checked out a couple of books, which got him thinking about how the copy protection scheme was implemented. He wondered what recourse users had if they wanted to view a book they have already checked out on a different, or unsupported piece of hardware.

His research centers around Adobe’s ADEPT digital rights management scheme, which is used to protect the books offered on loan by OverDrive. The topic is broken down into three parts, starting with an introduction to the EPUB file structure, the OverDrive Media Console, as well as the aforementioned ADEPT DRM scheme.

The second part takes a close look at the OverDrive Media Console itself, where he uses the ineptkey and ineptepub utilities written by [I♥CABBAGES] to pull the RSA cipher keys from the EPUB data he uncovered. When he then tries to strip the ADEPT DRM layer from his books however, he discovers that OverDrive is using a non-compliant version of the ADEPT standard, which renders existing tools useless.

The final part of [Armin’s] discussion digs even deeper into the OverDrive Console’s inner workings, where he finds that the OverDrive Media Console stores quite a bit of information in an SQLite database. After a bit of digging, he finds all the data he needs to strip the DRM from his books. [Armin] also took the time to wrap all of his findings up into a neat little tool called OMCStrip, which as you may have guessed, strips the DRM from ADEPT-protected eBooks with ease.

Cheap And Cheerful Arduino Breadboard Basics

June 1, 2011 by Jesse Congdon 8 Comments

For those less experienced folks looking to move their Arduino projects to more permanent installations, this is just for you! [Martyn] Posted a three part series, VeroBoardUino, over at his blog about moving your Arduino project to a soldered breadboard.

Part one kicks off with the appropriate breadboard requirements, modifications, and a simple 7805 power supply. In the guide [Martyn] is using strip board, so copper connections will have to be broken using a drill or just by scraping with a hobby knife. Strip board also saves a bit of wire routing in the end. Part two handles the reset button, serial connection and chip socket (Part 2.5 has also been added to include schematics of the breadboard). Finally, part three installs the crystal and connects your Atmega chip to power and ground.

Next post he will be covering more on the software end of things, burning the bootloader and uploading programs to your new board so stay tuned for updates!

Automated Hose Keeps Cats From Watering You

May 25, 2011 by Jesse Congdon 50 Comments

Commenter [TheCreator] reminded us of this fantastic video from [Craig Turner] who you may recognize from SBS’s Top Gear Australia Video Competition. You see, [Craig] has been struggling for some time with the problem of neighborhood cats relieving themselves pretty much all over his stuff. Through surveillance he identified (and named) around 9 separate cats sauntering into his yard during the wee hours of the night. The only issue now was to humanely discourage them from entering his yard.

The best solution, in this case, was a simple spray from the garden hose, but who is going to stay up all night to watch for cats? [Craig]’s ’75 Galant happens to have aftermarket door locks. These typically contain a simple powerful 12V actuator that will push or pull when given current. The actuator is strong enough, and has enough travel, to depress your typical garden sprayer handle. The lock actuators even include enough mounting hardware to tack everything together. The only irreversible part of the hack appears to be the hole drilled into the sprayer’s handle.

The job of cat detection is handled with a PIR sensor (sourced from his home security system) and a paper towel tube to narrow the detector’s field of view. Placed at animal height the PIR detector works like a trip line, and flips a relay connected to an array of devices: A bright LED lamp, a DSLR set to take several quick photos of the victim, An HD video camera, and the sprayer solenoid. This whole rig is placed at a convenient choke point and hilarity ensues! A schematic is included in the video but is pretty difficult to interpret, we transcribed it for you. Some details are unclear but essentially a few relays are stapled together to provide either high or low switching signals.

Check out the video, [Craig]’s schematic, and our interpretation of [Craig]’s schematic after the jump!

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The Ins And Outs Of Lithium-based Battery Packs

May 25, 2011 by Mike Nathan 10 Comments

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So, you’ve got your awesome project built and are ready to take it on the go, but how are you going to power it? You could use a couple alkaline cells or perhaps swipe a Litihium battery pack from some infrequently used portable device – however before you do that, why not check out what [Lady Ada] has to say on the subject?

The detailed tutorial on her site discusses the different types of Lithium-based batteries and their form factors, as well as the strengths and weaknesses of each type. Voltage ratings are covered, as well as why it is important to choose a Lithium battery pack that fits the task at hand. The dangers of improperly handling batteries are clearly noted, highlighting the importance of selecting a proper charger and resisting the urge to ever wire Lithium batteries together to increase capacity.

While the bulk of the information presented is nothing new to most of our readers, it’s definitely a worthwhile read for those just starting to use Lithium battery technology in their projects.

We Know “Mario’s Early Years” Was A Let Down, But This Takes It A Bit Too Far.

May 22, 2011 by Jesse Congdon 27 Comments

[JJ Hendricks] wrote in to tell us about his SNES cartridge urinal. The fully functional urinal is constructed with 40 SNES cartridges and sealed up with polyurethane. The base of the whole operation is actually not a puddle of festering urine, but instead poured polyurethane that ensures proper flow through the drain. You heard right, this urinal actually flushes! As a bit of consolation [Hendricks] plainly states in the directions: “No good games were damaged in the making of this video. All the video games used in this urinal were already broken or worthless sports games”. We have featured some SNES cartridge readers before, so now you have something to do with all the leftover hardware! Gross.

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