CNC Zen Gardening

July 6, 2012 by Mike Szczys 9 Comments

The Harford Hackerspace in Baltimore, Maryland just went public with the zen garden they built for the Red Bull Creation contest. It’s a CNC creation that will help ease your frustration with that DIY 3d printer that you just can’t seem to get calibrated correctly.

On the hardware side the base of the machine serves as a sandbox. Finding the correct grain size of the medium was one of the more difficult parts of the build. The stylus is driven along three axes using a gantry common in CNC builds. The pulleys and some brackets were 3d printed, with the remained of the brackets being laser cut from wood. The Bullduino commands the stylus via a stepper motor control board, and drives the LEDs via a bank of MOSFETs. Limiting switches were also included to ensure an error didn’t result in damage to the device.

After the break you can see a build montage put to one of the greatest 8-bit game soundtracks of all time. The one thing we wish they would have shown is the built-in leveling bar that is responsible for “erasing” the garden.

Update: The Harford Hackerspace members came through with a new video that shows the ‘erasing’ process. You’ll find it after the break.

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Ancient Radio Repair

July 6, 2012 by Mike Szczys 39 Comments

They sure don’t build them like that anymore. [J.W. Koebel] managed to take this 1934 Simplex Model P radio and bring it back to life.

So where do you start with a repair job like this one? Being a ham radio guy he has a good idea of what he’s doing, and started by replacing the AC capacitor with one which will provide quality noise filtering. He tried to make fixes throughout that would improve functionality and declutter the wire mess. This led him to find a snapped solder connection on the volume knob. Next he tested out the speaker and found that the primary transformer needed replacing. After as replacing the A67 converter (we’ve got no idea what that is) he swapped out the rest of the original capacitors, most of the resistors, and fixed the mechanical problems with the tuning dial. The result is a working radio that looks fantastic!

[via Reddit]

Acrylic RPi Case You Can Make Without A CNC Machine

July 6, 2012 by Mike Szczys 15 Comments

[Simon Inns] is showing off the Raspberry Pi case which he built out of acrylic. It provides a lot more protection than a flimsy film case, but it is also a little bit more involved to fabricate. No, this doesn’t need to be laser cut, but to get the nice edges [Simon] used a band saw which many don’t already have in their shop. Ask around, or poke your head in at the local Hackerspace. It only takes a few minutes to cut out the parts.

It sounds like either 8mm or 6mm acrylic will work for this project. Aluminum pipe serves as a spacer to keep the two main sheets in place. The RPi board itself is held in position by a few well-place acrylic chunks super glued in place. You can see the entire build process, including rounding cut edges with a torch, in his video embedded after the break.

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Book Review: Eight Amazing Engineering Stories

July 6, 2012 by Mike Szczys 8 Comments

We’re big fans of [Bill Hammack], aka the Engineer Guy. His series of engineering videos dredge up pleasant memories of watching Mr. Wizard but spin to the adult science enthusiast. The most resent season (he calls it series #4) scratches the surface of the topics covered in his book Eight Amazing Engineering Stories, which was written with fellow authors [Patrick Ryan] and [Nick Ziech]. They provided us with a complimentary digital copy of the book to use for this review.

The conversational style found in the videos translates perfectly to the book, but as with comparing a novel to a movie, the written word allows for much more depth. For instance, we loved learning about how Apple uses anodization to dye the aluminum used for iPod cases. The same presentation style makes the topic easily understandable for anyone who took some chemistry and math in High School. But primers a sidebars offer an optional trip through the looking-glass, explaining the history behind the process, how it compares to natural materials, and what trade-offs are made in choosing this process.

Some of the other topics included are how CCD camera sensors, lead-acid batteries, mems accelerometers, and atomic clocks work. As the book progresses through all eight topics general concepts the complexity of the items being explained advances quickly. By the seventh story — which covers the magentron in a microwave oven — we’d bet the concepts challenge most readers’ cognition. But we still enjoyed every page. The book would make a great pool-side read. It would make a great graduation gift (too bad we missed that time of year) but keep it in mind for any science minded friends or relatives. You can see [Bill’s] own description of the book and all its formats in the clip after the break.

TLDR: Buy it or give it as a gift

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Reverse Engineering Silicon

July 5, 2012 by Mike Szczys 16 Comments

[John McMaster] is doing some pretty amazing work with figuring out how the circuitry in an integrated circuit works. Right now he’s reverse engineering a serial EEPROM chip one section at a time. This is a 24c02 made by ST, and he chose this particular portion of the die to examine because it looked like there were some analog components involved.

He removed the top metal using hydrofluoric acid in order to take this image. By continually removing layers this way he manages to work out the traces and even the components themselves. To help clarify the parts he uses the set of snapshots to generate a colored map using Inkscape. From there he begins labeling what he thinks the components might be, and like a puzzle the pieces start falling into place one by one. From the Inkscape drawing he lays out a schematic, then rearranges the components to make the design easier to understand. Apparently this is a Schmidt trigger.

[Thanks George]

The Cool Kids All File Their Resistors For Accuracy

July 5, 2012 by Mike Szczys 43 Comments

Here’s a tip to keep in your back pocket, you can use a metal file to adjust your resistors. [Gareth] shows off this technique in the video after the break. A metal file is literally all that you need to do some fine tuning. Just make sure you’re starting off with a carbon film resistor as this will not work with the metal film variety.

His example shows a 10k resistor which is reading just 9.92k on his multimeter. But he needs precisely 10k. After getting through the protective layer he makes just a couple of passes with a small file, each time adding about 20 Ohms of resistance. Now he does mention that excessive deep cuts can hurt the power rating of the resistor. But this certainly isn’t damaging it if done correctly. It turns out this is how they are tuned at the factory.

One possible use he mentions is trimming the balance on a hacked servo motor.

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Facedancer Board Lets Your Python Programs Pretend To Be USB Hardware

July 5, 2012 by Mike Szczys 9 Comments

This is the prototype board for [Travis Goodspeed’s] new USB development tool called the Facedancer. He took on the design with USB security exploits in mind, but we think it’s got a lot of potential for plain old development as well.

Kudos on the [Frank Herbert] reference when naming the project. Like the characters from the Dune mythology that can perfectly mimic any person they touch, this device let’s you mimic whatever you can imagine. One the USB ports connects to the victim (or host) the other connects to a development machine. Python can then be used to send USB commands in real time. Think of this as doing the same thing the Bus Pirate does for SPI and i2c, except that it’s doing it on the USB protocol itself. This way you can feel your way through all of the road-bumps of developing a new device (or testing an exploit) without the need to continually compile and flash your hardware.