3D Bubble Display

January 9, 2014 by Marsh 14 Comments

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[Craig Shultz], a mechatronics grad student at Northwestern University, sent us a video of his group’s project from last winter: a 3D bubble display. We’ve seen some pretty impressive and innovative bubble displays around here—most recently the 60-tube RGB LED build—but [Craig’s] is the first we’ve seen that adds some depth to the project.

For the most part, its construction is what you’d expect: an acrylic case enclosing the 4×4 arrangement of tubes, 16 valves 16 individually controlled solenoids, and some small air pumps; all driven by a PIC microcontroller. In the video, however, you’ll have to strain your eyes if you want to see the tubes, which is a clever design choice on [Craig’s] part to showcase the display’s depth. Each of the bubbles was visually separated by pairing glycerin with a tubing material that had a similar index of refraction, Pyrex. As a result, the tubes blend seamlessly into the fluid. Check out the video after the break.

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A Simple (and Dirty) Bill Of Materials And Stock Management Utility

January 9, 2014 by Mathieu Stephan 36 Comments

As many readers may already know, when I’m not featuring your projects or working on the mooltipass I try to make simple things that may be useful to electronics enthusiasts. My latest creation is a simple bill of materials generation tool, which can also do simple stock management. Unfortunately for Linux users, this utility is made using Visual Basic functions in an Excel file.

It works fairly simply: just enter your schematics’ components references in the excel sheet, along with the corresponding Digikey webpage address. Click on the “fetch” button and the script will automatically get all your component characteristics from the internet and tell you the component costs depending on the number of prototypes you want to make. Then click the “sort BoM” button and your BoM will automatically be sorted by component type and value. Another functionality allows you to check that all the components present in your BoM are also present on the (very simple) Kicad generated one. Finally, using another Excel sheet containing your current stock, the Bill of Materials will let you know if you have enough components for the assembly stage. A video of the tool in action is embedded after the break, and you can download the BoM template here (.XLSM file) and the corresponding stock file there (.XLSM file).

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Self-Balancing Robots Wobble, But They Don’t Fall Down

January 9, 2014 by Kristina Panos 7 Comments

[Trandi] can check ‘build a self-balancing robot’ off of his to-do list. Over a couple of weekends, he built said robot, and, in his own words, managed not to over-design it. It even kept the attention of his 2-year-old son for several minutes, and that’s always a plus.

He was originally going to re-purpose one of his son’s RC cars, but didn’t want to risk breaking it. Instead, he designed a triangular 3-D printed chassis to hold a motor and some cogs to fit both the motor shaft and some re-used Meccano wheels. [Trandi]’s design employs an MPU 6050 6-DOF IMU for the balancing act and is built on an Arduino Nano clone.

[Trandi] is controlling the motor with an L293D, which has built-in flyback diodes to minimize spikes. He found that the Nano clone was not powerful enough to handle everything, so he added an L7805CV voltage regulator. After the break, watch [Trandi]’s cute bot tool around on various types of terrain, with and without a payload.

Don’t have an IMU lying around? You don’t really need one to build a self-balancing bot, as this IR-based lilliputian bot will demonstrate.

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Fail Of The Week: Frying FETs With 500mA

January 9, 2014 by Mike Szczys 31 Comments

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When [Simon] fried his 3A rated FET with just 500mA of current he wrote it off to an inability of the SOT23 package to dissipate the heat without a heatsink. For the next iteration of the project he upgraded to a 12A rated part. Luckily he decided to test the circuit one more time before sending his board off for fab. He threw together this constant current load test which led him to discover his failure.

The switching circuit, which was for his home security system project that we’ve seen at least twice, worked just fine up to 500mA. But when he drove it above that threshold the package quickly warmed up. It got so hot that it actually reflowed its solder joints! The problem has to do with oscillation, but even with further testing he couldn’t get the FET to reliably shut off all the way. Take a look at his fail write-up linked at the top and then let us know some possible remedies for the situation.

Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Designing, Simulating And Testing A Simple Radio Duty-Cycling Protocol For Contiki

January 9, 2014 by Mathieu Stephan 1 Comment

A few days ago we featured [Marcus]’ Contiki port to the TI Launchpad, Contiki being an open source operating system dedicated to the Internet of Things created by [Adam Dunkels] at the SICS in Sweden. Part of [Marcus]’ work involved designing a simple radio duty-cycling protocol that achieves 3% idle listening duty cycle while allowing for an average 65ms latency with no prior contact or synchronization.

As a few readers may already know, it takes quite a lot of power for a wireless device to listen/send data. A platform therefore needs to have an algorithm that minimizes power consumption while allowing a (regular) planned data transfer. After creating his protocol named SimpleRDC, [Marcus] first simulated it using the Cooja simulator in order to check that it could perform as desired. He then implemented a real life test and checked the protocol’s performance by sniffing the SPI lines connecting his MSP430 to the wireless module and by monitoring the platform power consumption with his oscilloscope and a shunt resistor.

A Transparent 7-Segment Display

January 9, 2014 by Marsh 40 Comments

Though [Connor] labels it as a work in progress, we’re pretty impressed with how polished his transparent 7-segment display looks. It’s also deceptively simple.

The build uses a stack of seven different acrylic panes, one in front of the other, each with a different segment engraved onto its face. The assembly of panes sits on a small mount which is placed over seven rows of LEDs, with 5 LEDs per row. [Connor] left an air gap between each of the seven individual acrylic panes to clearly distinguish which was lit and to match the separation of the LED rows. To display a number, he simply illuminates the appropriate LED rows, which scatter light across the engraved part without spilling over into another pane.

You can find a brief overview and some schematics on [Connor’s] website, and stick around for the video demonstration below. We’ve featured [Connor’s] work before; if you missed his LCD data transfer hack you should check it out!

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OliveR The Programmable Cooking Robot

January 9, 2014 by James Hobson 46 Comments

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[Oak Robotics] is putting the finishing touches on their programmable cooking robot named OliveR.

It’s not about to make you a souffle (but where did it get the milk?), but it does aim to take the boring parts out of cooking — namely the tedious stirring, adjusting temperatures and the timing of ingredients. While that does make it significantly less impressive than the original title suggests, the team has a blog running of successful recipes — They’ve made some excellent chicken curry, Korean beef, and even Jambalaya!

The team is currently looking for beta testers, and while we’re not too sure what this even entails, you can certainly send them an email and find out! To see a demonstration of OliveR’s cooking skills, hang around after the break.

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