One day, [Samy]’s best friend [Matt] mentioned he had a wireless doorbell. Astonishing. Even more amazing is the fact that anyone can buy a software defined radio for $20, a small radio module from eBay for $4, and a GSM breakout board for $40. Connect these pieces together, and you have a device that can ring [Matt]’s doorbell from anywhere on the planet. Yes, it’s the ultimate over-engineered ding dong ditch, and a great example of how far you can take practical jokes if you know which end of a soldering iron to pick up.

Simply knowing [Matt] has a wireless doorbell is not enough; [Samy] needed to know the frequency, the modulation scheme, and what the doorbell was sending. Some of this information can be found by looking up the FCC ID, but [Samy] found a better way. When [Matt] was out of his house, [Samy] simply rang the doorbell a bunch of times while looking at the waterfall plot with an RTL-SDR TV tuner. There are a few common frequencies tiny, cheap remote controls will commonly use – 315 MHz, 433 MHz, and 900 MHz. Eventually, [Samy] found the frequency the doorbell was transmitting at – 433.8 MHz.

After capturing the radio signal from the doorbell, [Samy] looked at the audio waveform in Audacity. It looked like this doorbell used On-Off Keying, or just turning the radio on for a binary ‘1’ and off for a binary ‘0’. In Audacity, everything the doorbell transmits becomes crystal clear, and with a $4 434 MHz transmitter from SparkFun, [Samy] can replicate the output of the doorbell.

For the rest of the build, [Samy] is using a mini GSM cellular breakout board from Adafruit. This module listens for any text message containing the word ‘doorbell’ and sends a signal to an Arduino. The Arduino then sends out the doorbell code with the transmitter. It’s evil, and extraordinarily over-engineered.

Right now, the ding dong ditch project is set up somewhere across the street from [Matt]’s house. The device reportedly works great, and hopefully hasn’t been abused too much. Video below.

[Christopher Mitchell] has given Texas Instruments calculators the ability to capture images through a Game Boy Camera with ArTICam. First introduced in 1998, The Game Boy Camera was one of the first low-cost digital cameras available to consumers. Since then it has found its way into quite a few projects, including this early Atmel AT90 based hack, and this Morse code transceiver.

TI calculators don’t include a Game Boy cartridge slot, so [Christopher] used an Arduino Uno to interface the two. He built upon the Arduino-TI Calculator Linking (ArTICL) Library  to create ArTICam. Getting the Arduino to talk with the Game Boy Camera’s M64282FP image sensor turned out to be easy, as there already are code examples available. The interface between the camera sensor and the Arduino is simple enough. 6 digital lines for an oddball serial interface, one analog sense line, power and ground. [Christopher] used a shield to solder everything up, but says you can easily get away with wiring directly the Arduino Uno’s I/O pins. The system is compatible with the TI-83 Plus and TI-84 Plus family of calculators. Grabbing an image is as simple as calling  GetCalc(Pic1) from your calculator program.

So, If you have an old calculator lying around, give it a try to enjoy some 128×123-pixel grayscale goodness!

[Greg] implemented a simple ray tracer for Arduino as a fun exercise and a way to benchmark the processor. He started out with the Moller-Trumbore algorithm, a common ray-tracing algorithm that calculates the intersection of a ray with a triangular plane without doing any pre-calculation of the planes. His code supports one static light and one static camera, which is enough to render a simple scene.

[Greg] started out with a small scene composed of a few polygons, but just finished up a scene with 505 vertices, 901 faces, and reflective surfaces (shown above). He made the above render on his PC emulator, but estimates that it would take just over 4 days to render on the Arduino. [Greg]’s project supports multiple bounces of light, which differentiates his ray tracer from some we’ve covered before (and which explains why it takes so long to render).

The ray tracer is implemented entirely with double-precision floats. This translates to a ton of software float emulation instructions, since the Arduino doesn’t have a floating-point unit. While this ray tracer can’t render anything near real-time graphics due to the slowness of the microcontroller, it’s still a great proof of concept.

The title image for this post was rendered on a modern PC, taking 263 seconds to complete. The same scene, at 64×64 resolution, was rendered on the Arduino, taking 4008 seconds to complete. That render is below.

Who should chip in the most to restock the community coffee supply at work is a common point of contention at some offices. This RFID infused coffee brewer called Juraduino by [Oliver Krohn] solves the issue at his workplace once and for all by logging how much is being consumed by each person and how often; quite the diplomatic hack.

[Oliver] donated his old Jura Coffee maker to his office with some added hardware cleverly hidden underneath the faceplate of the machine. An Arduino mounted within runs the show, powered through mini USB from the logic unit of the coffee maker itself. Once a co-worker swipes their RFID card over the front of the machine, a real-time clock module stamps when the coffee was requested, and then logs the amount selected by that person on a mini SD card. The data stored is sent via an additional bluetooth module to a custom app [Oliver] created with MIT App Inventor for his phone which displays the information. These details can then be exported in the form of an email addressed to everyone in the office at the end of the week, announcing definitively who can be counted on to restock the bulk of the community supplies.

Though there isn’t a link available with further documentation, [Oliver] mentions in the ‘details’ portion of his video that he’d be happy to share that information with anyone who contacts him regarding the project. You can see the Jura at work below:

[psgarcha] took a year-old Arduino Uno on an international trip and upon returning found something was wrong. Every time he would try to upload, he would get the dreaded avrdude error, ‘stk500_getsync(): not in sync resp=0×00′. The Rx light would blink a few times during the attempted upload, but the tx light did not. Somehow, something was terribly wrong with the ‘duino, and [psgarcha] dug deep to figure out why.

To test the quality of the Arduino’s serial connection, [psgarcha] performed a loopback test; basically a wire plugged into the Tx and Rx pins of the Arduino. Sending a short message through the serial port showed the problem wasn’t the USB cable, the ATmega16u2 on the ‘duino, or any traces on the board. This would require more thought.

The main reason for the error would then be no communication between the computer and the ‘duino, the wrong COM port selected, the wrong board selected in the Arduino text editor, or timing errors or a corrupt bootloader. The first three errors were now out of the question, leaving timing errors and a corrupt bootloader. Troubleshooting then moved on to ordering a new programmer, and still this didn’t work with the broken Uno.

Frustrated with one of the greatest failures to become an Arduino tinkerer, [psgarcha] took a good, long look at the Uno board. He glanced over to an Arduino Mega board. Something looked different. On the Uno, the resonator had blown off. Problem found, at least.

Replacing the blown part with a hilariously large can crystal oscillator, [psgarcha] was back in business. This isn’t how you would fix 99% of getsync() errors, and it’s difficult imagining a situation where a this part would randomly blow, but if you’re ever looking at a nearly intractable problem, you need to start looking at what really shouldn’t fail.

Awesome rework, though.

This is a post about workbenches, but not the benches you’re probably thinking about. Workbenches meant for electronics development are simple matters – just about any flat surface, a few shelves for equipment, and an anti-static mat will be fine for every conceivable use.  Workbenches for woodworking are a separate matter entirely. There’s actually quite a bit of history behind the development of the woodworking workbench, but the basic idea is a thick laminated wood top, integrated vices, holes in the work surface for bench dogs, and ergonomics that allow for comfortable use of hand tools. The basic design of these benches hasn’t changed much in several hundred years, and [Dirk] thought the design was ready for a modern update.

Yes. This one moves on its own. It’s a robotic woodworking workbench that lifts the workpiece and table up to a comfortable position. The lifting mechanism is a quartet of Acme threaded rods all powered by an Arduino-controlled stepper motor linked together with sprockets and chain. There’s a remote control to raise and lower the bench, and a few batteries tucked behind the mechanics to allow for off-grid operation.

A bench must be sturdy, and this one has clamps on the frame of to clamp the ‘elevator car’ securely to the bench. Leveling casters make this bench mobile, giving [Dirk] the ability to move it around the shop, or from site to site. An integrate face vise and a twin-screw end vise securely hold the workpiece to the table, and a linseed oil finish make scratches and gouges easily repairable.

The majority of the frame is constructed out of birch plywood cut on a CNC, so if you have a Shopbot or other large router available to you at the local hackerspace, building this bench for yourself is a much simpler matter than the mortise and tenon joinery of a more traditional woodworking workbench. If you end up building this bench, be sure to pick up the casters [Dirk] used; this thing weighs 800 pounds. Massive, heavy, and an excellent bench that can be passed down to your grandkids. Video below.

Surely you need yet another way to charge your lithium batteries—perhaps you can sate your desperation with this programmable multi (or single) cell lithium charger shield for the Arduino<! Okay, so you’re not><em>hurting</em> for another method of juicing up your batteries. If you’re a regular around these parts of the interwebs, you’ll recall the <a href="http://hackaday.com/2014/09/21/a-li-ion-battery-charging-guide/">lithium charging guide</a> and that <a href="http://hackaday.com/2014/09/05/an-obsessively-thorough-battery-and-more-showdown/">rather incredible, near-encyclopedic rundown of both batteries and chargers</a>, which likely kept your charging needs under control.</p> <p>That said, this shield by Electro-Labs might be the perfect transition for the die-hard-’duino fanatic looking to migrate to tougher projects. The build features an LCD and four-button interface to fiddle with settings, and is based around an LT1510 constant current/constant voltage charger IC. You can find the schematic, bill of materials, code, and PCB design on the Electro-Labs webpage, as well as a brief rundown explaining how the circuit works. Still want to add on the design? Throw in <a href="http://hackaday.com/2014/07/16/finally-an-easy-to-make-holder-for-lithium-ion-batteries/">one of these Li-ion holders</a> for quick battery swapping action.</p> <p>[via <a href="http://embedded-lab.com/blog/?p=9644">Embedded Lab</a>]</p><br />Filed under: <a href="http://hackaday.com/category/arduino-hacks/">Arduino Hacks</a>, <a href="http://hackaday.com/category/microcontrollers/">Microcontrollers</a> <a><img src="http://feeds.wordpress.com/1.0/comments/hackadaycom.wordpress.com/138748/" /></a> <img src="http://pixel.wp.com/b.gif?host=hackaday.com&blog=4779443&post=138748&subd=hackadaycom&ref=&feed=1" />

So, what do you do when your Arduino project needs to operate in a remote area or as a portable device? There are LiPo battery shields available, and although they may work well, recharging requires access to a USB port. You can also go the 9v battery route plugged into the on-board regulator of the Arduino but the low mAh rating of a 9v won’t allow your project to stay running for very long. [AI] needed a quick-change battery option for his Arduino project and came up with what he is calling the AA Undershield.

As the name implies, AA sized batteries are used in the project, two of them actually. Yes, two AA batteries at 1.5v each would equal only 3 volts when connected in series. The Arduino needs 5v so [AI] decided to use a MAX756 DC-to-DC step-up regulator to maintain a steady stream of 5v. This article has some nice graphs showing the difference in performance between a 9v battery being stepped down to 5v verses two AA’s being bumped up to 5v.

The ‘under’ in Undershield comes from this shield being mounted underneath the Arduino, unlike every other shield on the planet. Doing so allows use of a standard 0.100″-spaced prototype PCB and is an easy DIY solution to that odd-sized space between the Arduino’s Digital 7 and 8 pins. The Arduino mounts to the Undershield via its normal mounting holes with the help of some aluminum stand offs.

[AI] did a great job documenting his build with schematics and lots of photos so that anyone that is interested in making one for themselves can do so with extreme ease.

We’re well past the time when Halloween costume submissions stop hitting the tip line, but like ever year we’re expecting a few to trickle in until at least Thanksgiving. Remember, kids: documentation is the worst part of any project.

[Troy] sent us a link to his wearable Game Boy costume. It’s exactly what you think it is: an old-school brick Game Boy that [Troy] wore around to a few parties last weekend. This one has a twist, though. There’s a laptop in there, making this Game Boy playable.

The build started off as a large cardboard box [Troy] covered with a scaled-up image of everyone’s favorite use of AA batteries. The D-pad and buttons were printed out at a local hackerspace, secured to a piece of plywood, and connected to an Arduino Due. The screen, in all its green and black glory, was taken from an old netbook. It was a widescreen display, but with a bezel around the display the only way to tell it’s not original is from the backlight.

Loaded up with Pokemon Blue, the large-scale Game Boy works like it should, enthralling guests at wherever [Troy] ended up last Friday. It also looks like a rather quick build, and something we could easily put together when we remember it next October 30th.

[Troy] wasn’t the only person with this idea. A few hours before he sent in a link to his wearable Game Boy costume, [Shawn] sent in his completely unrelated but extremely similar project. It’s a wearable brick Game Boy, a bit bigger, playing Tetris instead of Pokemon.

[Shawn]‘s build uses a cardboard box overlaid with a printout of a scaled-up Game Boy. Again, a laptop serves as the emulator and screen, input is handled by a ‘duino clone, and the buttons are slightly similar, but made out of cardboard.

Both are brilliant builds, adding a huge Game Boy to next year’s list of possible Halloween costume ideas. Videos of both below.

[A Raymond] had some free time at work, and decided to spend it on creating a wireless warning sign. According to his blog profile, he is a PhD student in Applied Physics. His lab utilizes a high-powered laser system. His job is to use said system, but only after it’s brought online by faculty scientists. The status of the laser system is changed by a manual switchbox that controls the warning signs wired around the lab entrances. Unfortunately, if you were in the upstairs office, you only knew this after running downstairs to check. [A Raymond's] admitted laziness finally got the better of him – he wanted a sign that displayed the laser’s status from the comfort of the office. He had an old sign he could use, but he wanted a way for it to communicate with the switchbox downstairs. After some thought, he decided Bluetooth was the way to go, using a pair of BlueSMiRF Bluetooth modules from Sparkfun and Arduino Uno R3’s.

He constructed a metal box that intercepted the cable from the main switchbox, mounting one BlueSMiRF and Uno into it. Upon learning that the switchbox sends 12V AC signals over three individual status wires, he half-wave rectified the wires and divided their voltages so that the Uno wouldn’t fry. Instead, it determined which status wire that had active voltage. and sent a “g(reen)”, “y(ellow)”, or “r(ed)” signal continuously via Bluetooth. On the receiving end, [A Raymond] gutted the sign and mounted the other BlueSMiRF and Uno into it along with some green, yellow, and red LEDs. The LEDs light up in response to the corresponding Bluetooth signal.

The result is a warning sign that is always up-to-date with the switchbox’s status. We’ve covered projects using Bluetooth before, from plush birds to cameras- [A Raymond's] wireless sign is in good company. He notes that it’s “missing” a high pitched whining noise when the “Danger” lights are on. If he decides to add an accompanying (annoying) sound, he couldn’t go wrong with something like this. Regardless, we’re sure [A Raymond] is happy that he no longer has to go back and forth between floors before he can use the laser.