Know Thy Enemy: Open Vias In BGA Footprints

July 26, 2012 by Mike Szczys 14 Comments

[Andrew Zonenberg] has crossed a line in his electronic hobby projects. The Ball Grid Array (BGA) is a type of chip footprint which most hobbyists leave to the professionals. But he’s learned the skills necessary to use them in his projects. Recently he ran a test batch to show off his soldering process and illustrate one of the errors a novice might make.

For those that are unfamiliar, the BGA footprint is notoriously difficult to accurately solder because it consists of a large grid of tiny points covering the bottom of the chip. There’s no way to get in there with an iron, so soldering depends on accurate placement of solder paste and chip, as well as a near-perfect reflow cycle. Often times it’s difficult for the professionals too. Many blame the heat-failure of Xbox 360 on the complications of the BGA connects for one of the console’s chips.

For this experiment [Andrew] wanted to show what happens if you include vias in the BGA footprint. It’s fine to do so, as long as they’re capped. But if a standard via is included, capillary action ends up pulling the solder down into the via instead of making a connection with the chip. The image above is a cross-section of one such uncapped via, seen on the far right.

[Thanks George]

Visualizing Heat With Schlieren Photography

July 26, 2012 by Brian Benchoff 12 Comments

[Kevin] wanted to check out the air patterns present when his 3D printer is in action. This is useful research; slight differences in temperature can affect the quality of his prints. Instead of something like a thermometer, [Kevin] decided to use Schlieren photography to visualize the air around his 3D printer.

If you’ve ever seen very old-school pictures of supersonic research, you’ve seen Schlieren photography. It’s a way of visualizing the density of transparent objects using only mirrors, lenses, and a point light source. The resulting pictures are usually black and white, although some amazing color pictures exist of bullets traveling through the air next to soap bubbles and candles.

The process of creating a Schlieren photograph is actually pretty easy. [Kevin] pointed a light at a used a 4-inch parabolic mirror placed behind his printer. A knife edge is placed at exactly twice the focal length of the mirror, and after putting a camera behind this knife edge, differences in the density of the air are visible.

From [Kevin]’s video of his Schlieren setup (available after the break), you can see the air is extremely turbulent around his print. That might have been obvious given the presence of a cooling fan, but it’s still very, very cool to look at.

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Measuring How Components React To Extremely Cold Temperatures

July 22, 2012 by Mike Szczys 8 Comments

[Shahriar Shahramian] is playing with some liquid nitrogen in order to see how various components react to extremely low temperatures. After the break you will find forty-one minutes of video in which he conducts and explains each experiment. This does have practical applications. If you’re designing hardware for use in space you definitely need to know how the hardware will be affected. We’ve actually seen test rigs built for this very purpose.

During the presentation he doesn’t water down the concepts observed, including the equations governing each reaction to temperature change. If you’re in the mood for a little bit lighter faire you should check out some of the liquid nitrogen cooking hacks like this super-cold cocktail pops project.

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Building A Steam Punk Style Time And Weather Display

July 21, 2012 by Mike Szczys 8 Comments

This is [Pierre Cauchois’] digital weather display. Since weather displays are ubiquitous in this day of smart phones in every pocket he went out of his way to give it a unique look. He started with a wooden voltmeter case, swapping the ancient display for a modern LCD screen.

He used Gadgeteer components for the retrofit. The images for the LCD are stored on an SD card and displayed on demand. Since the digital bezel will be the same no matter what the time or environmental conditions [Pierre] used the power of the .NET framework that drives the system. He made up an image using magenta for all of the dial openings. This way a sprite can be used just for the changing numbers, weather icon, and graphing area.

Looking at all that went into coding the project we think the Gadgeteer components are perfect for those that are well-versed in upper-level languages and don’t really want to deal with low-level microcontroller issues.

[Thanks George]

DMG Lib: Digital Mechanism And Gear Library

July 18, 2012 by Gerrit Coetzee 9 Comments

Reader, [klemens], suggested DMG Lib to us when we posted about a similar site. DMG-Lib is an amazing source of information. It’s primary downside is that a great portion of the text is in a language other than English, though in some ways this is a plus. Latin, Italian, German, and many other languages held the position of being the chief scientific language of the world long before English, and this repository holds entire books about mechanisms in those languages. Some of the books range all the way back to the 1500s. The mechanism animations are very good on this site and play smoothly. While it’s a little harder to search than KMODDL due to the language oddities, it’s still an extremely useful and interesting site to add to the hacker’s information toolbox.

Scratch-built Railroad Crossing Signal

July 16, 2012 by Mike Szczys 7 Comments

At first glance you would think this is the real thing, but [Kevin] built this railroad crossing signal from parts you can find at the home store. We keep seeing traffic lights used as web-connected signaling devices. This would be right at home for that type of setup, but [Kevin] built it with railroad enthusiasts in mind.

He used Google SketchUp to design the frame for the signal, then purchased all of the PVC parts to match those specifications. Some grey spray paint goes a long way to making it look like steel tubing. But this is much easier to work with and he should have no trouble internalizing the wiring later on. The lights themselves are tail lights for a trailer with a decorative trim piece added. He designed his own driver board to switch the lights and ring the doorbell which give the signal some sound. His first version used a 555 timer, this one upgrades to microcontroller. We like what he’s doing in the video after the break, but think the bell speed needs to be doubled for it to mimick the real thing just about perfectly.

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Repurposing Old HDD Components

July 12, 2012 by Mike Nathan 32 Comments

hdd-stepper

[IronJungle] had an old hard drive taking up space in his workshop, so he took it apart and wrote in to remind us how useful these old pieces of hardware can be. Aside from offering up incredibly strong magnets and donut-shaped mirrors, HDDs also come with a reliable stepper motor in tow.

He pulled theold drive apart, wiring up two of the stepper motor pins to a pair of the drive’s header pins. This allowed him to easily access the signals produced by the stepper simply by hooking up a small JST connector to the back of the drive.

From there, he can use the drive for any number of purposes. For the sake of discussion, [IronJungle] used it to flash an LED as seen in the video below – something he willingly admits is no great feat. However, stepper motors can be used for in a wide array of projects, both simple and complex. Be sure to share your favorite use for salvaged HDD motors in the comments.

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