Raspberry Pi UPS Using Supercapacitors

April 3, 2014 by James Hobson 21 Comments

What happens when you want to integrate a Raspberry Pi into some kind of project that gets turned on and off with mains voltage? Do you power the Pi separately, or make a UPS for it?

[Lutz Lisseck] decided he wanted to turn his ambient-lamp (Rundbuntplasma) on and off with only the main power switch in his Hackerpsace. He could build a traditional UPS using a battery pack (it’s only 5V after all!) but decided to take it a step further. He picked up a pair of 50F supercapacitors. This way his UPS would last longer than his Pi would! The caps store just enough power that when the main supply is cut, a GPIO notices, tells the Pi, and it begins a shutdown sequence lasting about 30 seconds.

While [Lutz] is using two 2.7V supercapacitors, he mentions it would be a lot cheaper to use a step-up converter instead of putting them in series — but he had the caps on hand so decided to use both.

If you need it to last a bit longer, you could make one with rechargeable batteries…

40-Node Raspi Cluster

February 17, 2014 by Marsh 49 Comments

Multi-node RasPi clusters seem to be a rite of passage these days for hackers working with distributed computing. [Dave’s] 40-node cluster is the latest of the super-Pi creations, and while it’s not the biggest we’ve featured here, it may be the sleekest.

The goal of this project—aside from the obvious desire to test distributed software—was to keep the entire package below the size of a full tower desktop. [Dave’s] design packs the Pi’s in groups of 4 across ten individual cards that easily slide out for access. Each is wired (through beautiful cable management, we must say) to one of the 2 24-port switches at the bottom of the case. The build uses an ATX power supply up top that feeds into individual power for the Pi’s and everything else, including his HD array—5 1TB HD’s, expandable to 12—a wireless router, and a hefty fan assembly.

Perhaps the greatest achievement is the custom acrylic case, which [Dave] lasered out at the Dallas Makerspace (we featured it here last month). Each panel slides off with the press of a button, and the front/back panels provide convenient access to the internal network via some jacks. If you’ve ever been remotely curious about a build like this one, you should cruise over to [Dave’s] page immediately: it’s one of the most meticulously well-documented projects we’ve seen in a long time. Videos after the break.

Continue reading “40-Node Raspi Cluster” →

Self-Balancing Robot Keeps Getting More Features

November 10, 2013 by Mike Szczys 18 Comments

self-balancing-robot-gets-more-features

It’s a lot of fun to see a self-balancing robot project. Rarely do they go much further than being able to keep themselves upright while being piloted remotely and annoyingly shoved by their creator as proof of their ability to remain standing on two wheels. This little anthropomorphic guy is the exception to the rule. It’s the product of [Samuel Matos] who says he didn’t have a specific purpose in mind, but just kept adding features as they came to him.

Starting with a couple of carbon fiber plates [Samuel] cut the design by hand, using stand-offs to mount the NEMA 17 stepper motors and to connect the two halves of the chassis. It looks like he used some leftover material to make a nice little stand which is nice when coding at his desk as seen above. There’s also a carbon-fiber mask which makes up the face atop an articulated neck. It has two ultrasonic range-finding sensors as eyes, and the Raspberry Pi camera module as the nose. The RPi board powerful enough to run OpenCV which has kept [Samuel] busy. He set up a course in his living room containing tags directing where the little guy should go. It can also follow a tennis ball as it rolls around the room. What we found most impressive in the clip after the break is its ability to locate the next tag after making a turn.

Continue reading “Self-Balancing Robot Keeps Getting More Features” →

Web Connectivity And Other Addons For An Automatic Schnauzer Feeder

September 8, 2013 by Mike Szczys 9 Comments

web-enabled-automatic-dog-feeder

[Ben Miller] and his dad combined forces to create this automatic dog feeder. It not only keeps their two schnauzers happy, but gives them peace of mind as they can double-check that he feeding happened by pulling up an image on the Internet. Make sure you make it through all three posts of the build to get the entire picture.

The project started with some research which turned up a project that used a commercially available automatic feeder. That one used Arduino, but because of the cost the board plus a WiFi shield is a bit high, [Ben] went with a Raspberry Pi and a USB WiFi dongle instead. The Pi is much more powerful and adds the functionality for capturing images via a webcam.

After a convoluted process of connecting the Pi to the existing button traces on the automatic feeder it was time to start coding. The system runs from a Perl script which monitors a Gmail account for remote commands (in addition to a regular feeding schedule). The final touch is a bit of mechanical engineering which splits the output into two bowls so the dogs each have their own serving.

We still use the Autodine we built several years back but its single-serving limitation has always kept a second version on our project list. Hopefully seeing a well-executed system like this will motivate us to get building!

Build A File Server Inside An Old External Optical Drive Enclosure

September 1, 2013 by Mike Szczys 20 Comments

This one nearly ended up in today’s Links post, but on second look we think it deserves a feature of its own. [Profezzorn] designed some mounting brackets to house a file server inside of an external drive enclosure. Click on the instructions tab to get a bit more of the story.

The enclosure that he’s using is meant for a 5.25″ optical drive. It comes with a USB to SATA converter which is how he connects the hard drive to the Raspberry Pi serving the files. His mounting system uses the original holes in the enclosure, the threaded holes of the drive, and the holes in the RPi PCB to mount everything with just ten screws. The enclosure included a Molex power connector. He sacrificed an old connector to make a custom cable for the Pi’s power.

Add a portable power supply, do a little work with the Linux configuration, and you could easily turn this into a pirate box.

Spoofing WiFi AP Based Geolocation

August 27, 2013 by Mike Szczys 39 Comments

[Pierre Dandumont] just finished up a little project that will give Google Maps’ location feature a run for its money. It’s a technique that spoofs WiFi networks in order to relocate the positional data reported via WiFi networks.

He starts with an explanation of the different ways modern devices acquire location data. GPS is the obvious, and mobile network triangulation is pretty well know. But using WiFi networks may be a new trick for you. We’re not 100% certain but we think Google is able to look up location data based on known IP addresses for WiFi access points (this would be a good comments discussion). To trick the system all you have to do is feed some captured AP data into the computer before Google Maps tried to lock onto a location. The video after the break shows Maps with the legit location displayed. After running a quick script whose output is shown above the map position is changed to the spoofed location.

Continue reading “Spoofing WiFi AP Based Geolocation” →

Voice Controlled Home Automation Uses Raspberry Pi And LightwaveRF

August 11, 2013 by Mike Szczys 32 Comments

It’s not quite artificial intelligence, but saying “Jeeves, lights!” will switch on the bulbs in the room. [Chipos81] built the voice-activated home automation around a Rapsberry Pi board with LightwaveRF devices switching lights and outlets.

The LightwaveRF system offers a WiFi link which provides Internet connectivity for all of those devices in your house. This makes it a snap for [Chipos81] to control them from the RPi. To provide speech recognition he’s using CMU Sphinx. It’s an open source speech recognition library developed by researchers at Carnegie Mellon University and released under a BSD license. It seems to do a great job in the video of quickly parsing several sets of commands.

“Jeeves” will even talk back to you to confirm a command. This is generated by Festival, a package developed by the University of Edinburgh. This provides some entertainment in the last seconds of the video as we detect a distinct Scottish accent when it says “See you tomorrow”.

The GPIO pins provide a bit of feedback, using three colored LEDs to let you know what is going on with the system. There’s even an IR LED used to add voice control to your Television.

Continue reading “Voice Controlled Home Automation Uses Raspberry Pi And LightwaveRF” →