[Raffi] needed a birthday present idea but he wanted to do something extra special. He realized that a big part of gift giving is the anticipation and excitement of opening the present. In order to prolong this experience, [Raffi] built an electronic puzzle box. The box contains the final gift, but first a series of puzzles must be solved in order to open the box.

The project runs on an Arduino Mega. This is hooked up to several sensors, including a temperature sensor, GPS unit, and CO sensor. There is also an LCD screen and numeric keypad for user input and output. The project page contains a flow chart that shows all of the puzzles and their solutions. One of the more interesting puzzles requires the user to blow tobacco smoke into a tube. The CO sensor detects the smoke and unlocks the next puzzle.

Some of the puzzles require interacting with outside systems. For example, one puzzle requires the user to send an email to the fictional Captain Hermano’s email address. If the correct keyword is included in the email, the user will receive a reply with the code to enter into the box. Another puzzle requires the user to call a particular phone number and listen for another riddle. We’ve included the video demonstration below.

This isn’t the first puzzle box we’ve seen, but each one has its own special flair. This one is very well made and looks like a lot of care was put into it. We’ve seen another that uses only discrete components. We’ve seen yet another that uses Morse code.

[Thanks Simon]

[Oliver] is back with an update to his recent coffee maker hacks. His latest hack allowed him to add a coffee payment system to an off-the-shelf coffee maker without modifying the coffee maker itself. This project is an update to his previous adventures in coffee maker hacking which logged who was using up all of the coffee.

The payment system begins with an Arduino Uno clone inside of a small project enclosure. The Arduino communicates with the coffee maker via serial using the coffee maker’s service port. This port is easily available from outside the machine, so you won’t have to crack open the case and risk voiding your warranty.

The system also includes an RFID reader and a Bluetooth module. The RFID reader allows each user to have their own identification card. The user can swipe their card over the reader and the system knows how many credits are left in their account. If they have enough credit, the machine will pour a delicious cup of coffee.

The Arduino communicates to an Android phone using the Bluetooth module. [Oliver’s] Android app was built using MIT’s app inventor. It keeps track of the account credits and allows the user to add more. The system can currently keep track of up to forty accounts. [Oliver] also mentions that you can use any Bluetooth terminal program to control the system instead of a smart phone app.

We have a pretty good guess where [Krizbleen] hides away any seasonal presents for his family: behind his shiny new secret library door. An experienced woodworker, [Krizbleen] was in the process of finishing the attic in his home when he decided to take advantage of the chimney’s otherwise annoying placement in front of his soon-to-be office. He built a false wall in front of the central chimney obstacle and placed a TV in the middle of the wall (directly in front of the chimney) flanked on either side by a bookcase.

If you touch the secret book or knock out the secret sequence, however, the right-side bookcase slides gently out of the way to reveal [Krizbleen’s] home office. Behind the scenes, a heavy duty linear actuator pushes or pulls the door as necessary, onto which [Krizbleen] expertly mounted the bookcase with some 2″ caster wheels. The actuator expects +24V or -24V to send it moving in one of its two directions, so the Arduino Uno needed a couple of relays to handle the voltage difference.

The effort spent here was immense, but the result is seamless. After borrowing a knock-detection script and hooking up a secondary access button concealed in a book, [Krizbleen] had the secret door he’d always wanted: albeit maybe a bit slow to open and close. You can see a video of its operation below.

We’ve seen capacitive touch organs manifest in pumpkin form. Though they are a neat idea, there’s something about groping a bunch of gourds that stirs a feeling of mild discomfort every time I play one. [mcreed] probably felt the same way and thus created this light-up Jello organ, so he can jiggle-slap Christmas carols, removing any sense of doubt that touching food to play music is weird…

This take on the capacitive tone producing instrument makes clever use of the transparent properties of Jello as well as its trademark wiggling. [mcreed] fills several small mold forms with festively colored strawberry and lime mix. One end of a wire connection is submerged in the liquid of each cup before it has a chance to solidify along with a bright LED. Once chilled and hardened, the gelatinous mass acts as a giant light emitting contact pad. An Arduino is the micro-controller used for the brain, assigning each Jello shape with a corresponding note. By holding onto a grounding wire and completing the acting circuit, one can play songs on the Jello by poking, spanking, or grazing the mounds.

Though I’m not entirely sure if the video is Jello propaganda or not, the idea is applaudable. I prompt anyone to come up with a more absurd item to use for a capacitive organ (zucchinis have already been done).

Like many mobile gamers, [Daniel] has found himself caught up by the addictive “White Tiles” game. Rather than play the game himself though,  [Daniel] decided to write his own automatic White Tiles player. While this hack has been pulled off before, it’s never been well documented. [Daniel] used knowledge he gleaned on Hackaday and Hackaday.io to achieve his hack.

The basic problem is sensing white vs black tiles and activating the iPad’s capacitive touch screen. On the sensing end, [Daniel] could have used phototransistors, but it turned out that simple CdS cells, or photoresistors, were fast enough in this application. Activating the screen proved to be a bit harder. [Daniel] initially tried copper tape tied to transistors, but found they wouldn’t reliably trigger the screen. He switched over to relays, and that worked perfectly. We’re guessing that changing the wire length causes enough of a capacitance change to cause the screen to detect a touch.

The final result is a huge success, as [Daniel’s] Arduino-based player tears through the classic game in only 3.9 seconds! Nice work [Daniel]!

Click past the break to see [Daniel’s] device at work, and to see a video of him explaining his creation.

When [William’s] thermostat died, he wanted an upgrade. He found a few off-the-shelf Internet enabled thermostats, but they were all very expensive. He knew he could build his own for a fraction of the cost.

The primary unit synchronizes it’s time using NTP. This automatically keeps things up to date and in sync with daylight savings time. There is also a backup real-time clock chip in case the Internet connection is lost. The unit can be controlled via the physical control panel, or via a web interface. The system includes a nifty “vacation mode” that will set the temperature to a cool 60 degrees Fahrenheit while you are away. It will then automatically adjust the temperature to something more comfortable before you return home.

[William’s] home is split into three heat zones. Each zone has its own control panel including an LCD display and simple controls. The zones can be individually configured from either their own control panel or from the central panel. The panels include a DHT22 temperature and humidity sensor, an LCD display, a keypad, and support electronics. This project was clearly well thought out, and includes a host of other small features to make it easy to use.

[Connor] was working on a project for his college manufacturing class when he came up with the idea for this sleek desk lamp. As a college student, he’s not fond of having his papers glowing brightly in front of him at night. This lamp takes care of the problem by adjusting the color temperature based on the position of the sun. It also contains a capacities touch sensor to adjust the brightness without the need for buttons with moving parts.

The base is made from two sheets of aluminum and a bar of aluminum. These were cut and milled to the final shape. [Connor] found a nice DC barrel jack from Jameco that fits nicely with this design. The head of the lamp was made from another piece of aluminum bar stock. All of the aluminum pieces are held together with brass screws.

A slot was milled out of the bottom of the head-piece to make room for an LED strip and a piece of 1/8″ acrylic. This piece of acrylic acts as a light diffuser.  Another piece of acrylic was cut and added to the bottom of the base of the lamp. This makes for a nice glowing outline around the bottom that gives it an almost futuristic look.

The capacitive touch sensor is a pretty simple circuit. [Connor] used the Arduino capacitive touch sensor library to make his life a bit easier. The electronic circuit really only requires a single resistor between two Arduino pins. One of the pins is also attached to the aluminum body of the lamp. Now simply touching the lamp body allows [Connor] to adjust the brightness of the lamp.

[Connor] ended up using an Electric Imp to track the sun. The Imp uses the wunderground API to connect to the weather site and track the sun’s location. In the earlier parts of the day, the LED colors are cooler and have more blues. In the evening when the sun is setting or has already set, the lights turn more red and warm. This is easier on the eyes when you are hunched over your desk studying for your next exam. The end result is not only functional, but also looks like something you might find at that fancy gadget store in your local shopping mall.

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.