What’s the temp in your house? This Arduino-based Nixie tube thermometer will tell you

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Because every engineer loves a good Nixie tube thermometer.

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If you want to know the temperature, normal digital thermometers, or increasingly the Internet, are usually good enough. Visually though, it’s hard to beat the warm glow and retro look of a Nixie tube. What better way to display this than with a three-digit tube display like Luca Dentella’s build.

His process is outlined in a series of 10 posts that can be found here, or you can just skip to the completed version. The “brain” of this display is a Arduino Pro Micro (ATmega32U4). It uses a thermistor-style temperature sensor, which has a resistance than changes depending on the temperature, to tell how hot it is.

The display is, of course, three nixie tubes. The first thing that’s interesting about the setup is that the third tube shows “°C.” Dentella is using an “IN-19A” tube for this purpose, which can also reveal a number of other symbols. In this case, it shows the degrees Celsius value at all times.

The other interesting part of this design, besides the generally clean layout and printed circuit board use, is that each tube has a programmable LED under it. This allows for a unique coloring, and could certainly have produce many interesting visual effects. Perhaps in another life, this type of display could serve as a sound level meter, with the LEDs pulsing on and off to the beat of the music.

 

An Arduino MPPT solar charger shield

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This Maker decided to build his own MPPT (maximum point of power tracking) charge controller.

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Lukas was asked by a friend for help on a solar project. Inspired by an Instructables article, this friend wanted to make (or inspire someone else to make) a system to charge a battery to provide power in his garden. Charging a battery might seem like a simple task, but the a panel’s varying voltage output levels present a challenge. If this voltage spikes at too high of a level, there is a risk of damaging the battery.

If this over-voltage condition were constant, a DC-DC converter, commonly known as a “buck converter” would be well-suited to make the needed voltage conversion. However, since it’s not constant, a “switching converter” would have to be used. Normally a switching converter cycles much faster than an Arduino would be able to handle, but since voltage levels change relatively slowly in this instance, an Arduino’s speed would be quite sufficient. Since this slower speed minimizes switching losses, it would actually be an advantage.

The project is well-documented here, including available design files. Once this neat converter was built, the second step was to test it out. Lukas reports that it does its job with an efficiency of over 95% in the voltage range of interest. He plans to talk about the software involved next, so hopefully we will get to see the entire charging station come together soon!

The world’s tiniest RGB LED cube

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This 4x4x4 cube measures only 2cm on each side.

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If you read Atmel’s blog, chances are that you’ve seen a programmable LED cube. Given the amount of soldering involved, adequate space between each light would seem like a necessity. Hari Wiguna, however, decided that he could make a 4x4x4 cube measuring only 2cm on each side. In other words, as seen in the first video below, it would roughly fit on a quarter.

This build took Wiguna “months to build, but it’s finally done,” and, unless he hears differently, it is the smallest 4x4x4 LED cube in existence. Soldering, as shown in the second video, seems that it was quite a nightmare, but at least he had a custom PCB on which to set his LED stacks once they were assembled. For work that small, he needed a fine-tip soldering iron, but had to actually build his own set of jigs to assemble everything correctly.

The circuit, seen in the third video uses an Arduino Nano (ATmega328) to control the 64 RGB LEDs used. It’s a very clever setup, modeled after the Charliecube design found here. The four stacked LEDs are each rotated 90 degrees to each other, allowing its diode property to separate out each light’s signal.

The resulting animations are quite impressive — amazing for something this size! Check out the three clips below for even more background on this tiny wonder.

Unlock your car door with a fistbump

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Maker Pierre Charlier shows how he was able to add NFC control to his car door with a KeyDuino.

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In the year 2016, the idea of having to use an actual key to lock and unlock your car is as obsolete as listening to a cassette tape. Pretty much every vehicle these days comes with a remote, which lets you wirelessly control your doors from afar. Not to mention, some whips can even sense when you’re in close proximity and automatically unlock as you approach.

Pierre Charlier, on the hand, decided to retrofit his old ride with a KeyDuino and a relay shield, which enabled him to experience keyless entry in the form of a fistbump via an NFC ring. To accomplish this, the Maker removed his car’s internal lock switch and modified the wire harness to take the connection to the ‘duino. For a permanent 12V power supply, he plugged a wire directly on a fuse and another to the ground of the vehicle. (However, it should be noted that connections differ from car to car.)

As you can see in the video below, the system also works with a smartphone for those who rather not wear a ring. Charlier has shared all of the code and a step-by-step breakdown of the project for those interested in adding NFC-enabled entry to your set of wheels. Looking ahead, the Maker hopes to have an improved prototype with a BLE+NFC board right on the door handle.

The brainchild of Charlier himself, KeyDuino is Arduino-like board with built-in NFC capabilities that was successfully launched on Kickstarter late last year. Based on the ATmega32U4, the KeyDuino shares pretty much the same form factor and DNA as the Leonardo, and is compatible with most shields.

 

 

 

Dad builds a talking and transforming birthday cake for his son

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Maker Russell Munro created an Optimus Prime cake that actually transforms.

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While Jeff Highsmith may have been the unofficial Maker dad of the year in 2014 with his impressive mission control desk, it looks like we just found 2015’s undisputed champion. That’s because Russell Munro recently created the ultimate birthday cake for his six-year-old son: a talking Optimus Prime cake that actually transforms.

According to Munro, the animated cake consists of a 3D-printed skeleton: a chest, thighs, arms and lower legs. The thighs and the chest are the only animatronic pieces, as the lower legs remain in place to support all of the movement. Metal fishing wire is wound up by a stepper motor which pulls the chassis to a standing position. A pair of arms pop out from the chest once the robot is fully upright.

The entire operation is controlled by an Arduino, along with an EasyDriver from SparkFun, a 2A DC motor driver and an MP3 player module. The platform for the cake is made from 8mm MDF.

With the help of his wife, the chocolate mud cake was then baked around the mechanism and ultimately topped off with an amazing icing job. Safe to say, this Maker will probably be receiving countless invites to birthday parties in the very near future. Intrigued? Read all about the build on his log, as well as his latest writeup in MAKE: Magazine.

And now sans the cake…

Create your own smart heater for $15

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Just in time for winter, this Maker added smart temperature control to his infrared heater. 

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The IoT refers to the idea that things, in this case an infrared heater, can be connected to the Internet. Although at times this may seem like overkill, in this case, it seems like a very practical solution. As creator Yuvaltz puts it, “Both IR heaters I have at home have only two power levels. Without any control, it’s easy to get to either a too hot or a not hot enough situation.” Naturally the Arduino-compatible and Wi-Fi-enabled Cactus Micro (ATmega32U4) was used to take his heater into the 21^st century!

The Cactus module controls a relay, which turns the heater on when appropriate. The control scheme is based on something called a proportional-integral-derivitave (PID) loop, which allows for several factors to be taken into account when deciding on the appropriate heater state.

Since the Cactus is Wi-Fi-enabled, temperature variation as well as power output can be uploaded to a website. Yuvaltz setup a ThingSpeak channel for this device, and was able to generate two very interesting plots. One comparing the temperature data gleaned from two sensors that he tried, while the other plotted the temperature as well as how much power the heater put out at a certain time.

As Yuvaltz notes, don’t try something like this unless you’re familiar with high-voltage safety. A simple remote control is suggested as an alternative, but perhaps even that could be hacked for PID control! Check out his entire build here.

Make your own Arduino-powered laser engraver at home

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Instead of shelling out hundreds of dollars, a 16-year-old decided to build his own professional-looking machine. 

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If you don’t have a laser cutter, and would like one (after all, who wouldn’t?) you could buy one for thousands of dollars…. or build one yourself. 16-year-old “MichielD99” decided to do just that, and documented the entire process on Instructables.

Control is handled by an Arduino Uno (ATmega328) running the grbl CNC controller software. This, in turn, runs two stepper motors via driver boards, as well as a laser via its own separate driver. It’s noted that this configuration could even be used as a CNC router if a rotary tool and Z-axis was added.

What really sets this project apart is the beautifully-made physical structure. It’s constructed primarily from 18mm and 12mm sheets of MDF, which translates to roughly ¾” and ½” thick material. It’s been 3D-modeled, and the cutouts are available as PDF images and STL files. This means that if you want to replicate it, all you have to do is print the PDFs out, then use a bandsaw to cut out the appropriate pieces. STL makes it possible to replicate with a laser or CNC router. Some work with a Dremel tool will also be needed, though this could possibly be avoided if using a CNC router to make the cuts.

If you’re going to create one of these yourself, this engraver is a great place to start (right after you purchase a pair of safety goggles meant for your laser’s wavelength). For another take on this type of tool, check out this build using similar electronics with a frame made of aluminum extrusion.

Watch a robot solve a Rubik’s Cube in one second

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This Arduino-driven robot will unfix a Rubik’s Cube before you could even finish reading this sentence.  

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Last November, 14-year-old Lucas Etter set a new world record for the fastest time to solve a Rubik’s Cube, becoming the first person to ever break the five-second barrier for unravel the iconic 3 x 3 x 3 puzzle. As impressive as that may be, nothing may compare to this duo’s latest project. That’s because software engineers Jay Flatland and Paul Rose have devised an automated mechanism that can crack it in just over a second.

With an Atmel chip at its heart, the system is comprised of stepper motors, some 3D-printed parts and four webcams all connected to a Linux-based computer. The software engineers used the Kociemba algorithm to solve the puzzle, and have modified the Rubik’s Cube by drilling four holes into the middle of each of its six sides so the robot could manipulate it. Since the robot needs the cameras in order to function, the webcams are covered with a piece of paper until the cube is properly scrambled.

The team is now in the process of applying for the Guinness World Record. Pending all goes to plan, the robot will crush the current record holder’s time of 3.253 seconds.

This tennis racquet grunts like Sharapova (and others) when you swing it

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A racquet that makes quite the racket.

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Conventional wisdom says that tennis players grunt because it helps them apply the maximal force when they strike the ball. However, don’t be fooled, these noises are totally unnecessary and downright annoying. In fact, there are top names in the game like Maria Sharapova whose screams routinely top 100 decibels. This has led many, including the legendary Martina Navratilova, to call into question whether or not the behavior is actually a form of cheating.

Cognizant of this, Maker Seiya Kobayashi has come up with a hilarious solution for this problem: a racquet that does the grunting for you. You simply select one of four notable noisemakers — Serena Williams, Maria Sharapova, Novak Djokovic and Rafael Nadal — and the aptly named Grunting Racket will take care of the rest.

This allows you to focus on your footwork and hitting the ball, while the combination of an Arduino Pro Mini (ATmega328), an accelerometer and speaker emits the obnoxious sounds. Additional components include a LiPo battery, an Adafruit Audio FX Sound Board and a button on the grip that lets you choose the player. These electronics are all housed inside the racquet’s handle. Kobayashi employed both Arduino and Processing sketches along the way to prototype his idea.

How it works is fairly simple: When a value from the accelerometer exceeds a particular threshold, the sound board will play one of the four tones. You can see (and hear) it action below!

[s/o to fellow tennis players Artie Beavis and David Scheltema]

ATtiny85 helps breathe new life into a broken scale

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Rather than toss out a broken bathroom scale, this father-son duo decided to refurbish it with an all-new electrical system.

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What do you do when your scale breaks? If you’re like most people, you either buy a new one, or don’t weigh yourself hoping that you didn’t actually gain any weight over the holidays. If, however, you are Oxford doctoral student Ilias Giechaskiel, you simply design a new electrical system for it, then build it with the help of your dad.

As the Maker puts it, “The obvious solution…was to get rid of the internal components, reuse the case and the sensors, and build everything from scratch.”

One of the more interesting techniques employed in this project is the use of a Wheatstone bridge in conjunction with a load cell to measure weight. As the voltage change in this type of setup is quite small, a separate chip was needed to amplify the signal before it was passed to an ATtiny85’s analog input. Another neat design choice was the use of the ATtiny85 with its limited input/output (IO) capability (5 IO pins plus a reset pin).

Giechaskiel explains his selection of MCU,“I like its small form-factor, and did not want to have unused pins.” However, he does admit that more I/O would have been useful to implement more functionality in the scale.

If that wasn’t enough, he programmed the ATtiny with an Arduino, as outlined in these instructions, and his new display is a nice bright red. This would seem to be an improvement over the boring gray, though if you’re not happy with the reading, it might be harder to conceal!

There are several neat concepts in this build, so be sure to check out his code, library, and schematics on GitHub. if you think you might be able to use some of these ideas!