We hate to break it to [Rob Cai], but he’s built a VGA drawing toy, not an Etch-a-Sketch. How do we know? Simple, Etch-a-Sketch is a registered trademark. Regardless, his project shows how an Arduino can drive a VGA monitor using the VGAx library. Sure, you can only do four colors with a 120×60 resolution, but on the other hand, it requires almost no hardware other than the Arduino (you do need four resistors).

The hardware includes two pots and with the right firmware, it can also play pong, if you don’t want to give bent your artistic side. You can see videos of both the art toy and the pong game, below.

Because the device started as a pong game, [Rob’s] version has two boxes, each with a pot and a button. Of course, if you were really building it just for the drawing toy, you’d probably put it all in a box. Maybe even a red box. If we were building it, we’d be tempted to put a tilt sensor or an accelerometer in the box so you could shake it to erase the picture. Just saying.

If you want 640×480 resolution from an Arduino, it can be done, but it takes more hardware. If you were trying to get a kid interested in Arduino, you could do worse than start with two projects with video that are fun, use a handful of easy-to-source parts, and shares hardware. Then again, if you are in the “go big or go home” camp, we’d redirect to this pong game, instead.

[LDX] first noticed the odd sounds coming out of his ceiling fan, regularly, on the hour and half-hour. Then he noticed that the lights were flickering as well. Figuring something was up, he built a logging power-line monitor to see if he could decode the shadowy signals and figure out what cryptic messages were being transmitted over the power lines. Naturally, he suspected the Illuminati were behind it.

Even if you’re not prone to flights of fancy, you might want to keep track of your power line because it can serve as an accurate long-run timebase for projects, or because it can tell you something about the overall health of the grid.

[LDX]’s circuit is as simple as can be. A 10 V AC transformer reduces the mains power down to something reasonable. A resistive divider chops this down further to the range that an Arduino can handle, and then another voltage divider biases the signal to the Arduino’s ADC midpoint. The plus-minus 10 V signal thus swings between 0 and 5 V, just.

SPOILERS! After confirming that there was a higher-frequency wiggle superimposed on top of the power-line frequency, he contacted the folks at his power company in Denver. The system is called Decabit and it’s used to control street lights, hot water boilers, and other public infrastructure that might want to be coordinated to run when power is cheap or when it gets dark. The PDF that he links to explains it all, so you can take your tinfoil hat right back off.
But we still think it’s a fun project to look into the power lines. Who knows what other people will find? CON-spiracy!

[Marcelo Maximiano’s] son had a school project. He and a team of students built “The Pyramid’s Secret“–an electronic board game using the Arduino Nano. [Marcelo] helped with the electronics, but the result is impressive and a great example of packaging an Arduino project. You can see a video of the game, below.

In addition to the processor, the game uses a WT5001M02 MP3 player (along with an audio amplifier) to produce music and voices. There’s also a rotary encoder, an LCD, a EEPROM (to hold the quiz questions and answers), and an LED driver. There’s also a bunch of LEDs, switches, and a wire maze that requires the player to navigate without bumping into the wire (think 2D Operation).

In addition to the code and hardware diagrams, there is a PDF file on GitHub describing more about the game. It is in Portuguese, though, so most of us will probably need a little translation help. However, a Brazillian site did have an English post about the game, which might be a good place to start.

You might not want to replicate the game, but it is a great example of how much an Arduino can do with some simple externals devices and some attention to packaging.

Sadly, most of our projects look more like this game (no offense to that hacker). Projects like this are way more likely to spark young people’s interest than a blinking LED or a capacitor meter. If you are more in the mood for arcade play, you can also check out Arduinocade.

There’s an iconic scene from the movie Big where [Tom Hanks] and [Robert Loggia] play an enormous piano by dancing around on the floor-mounted keys. That was the first thing we thought of when we saw [jegatheesan.soundarapandian’s] PC joystick rug. His drum playing (see the video below) wasn’t as melodious as [Hanks] and [Loggia] but then again they probably had a musical director.

At the heart of the project is, of course, an Arduino. An HC-05 provides a Bluetooth connection back to the PC. We thought perhaps an Arduino with USB input capability like the Leonardo might be in use, but instead, [jegatheesan] has a custom Visual Basic program on the PC that uses SendKeys to do the dirty work.

The switches are more interesting made with old CDs, foil, and sponges. The sponge holds the CDs apart until you step on them and the foil makes the CDs conductive. He uses a lot of Fevicol in the project–as far as we can tell, that’s just an Indian brand of PVA glue, so Elmer’s or any other white glue should do just as well.

The glue also handles the fabric parts. When a project says “no sewing” we realize how some people feel about soldering. The CD/foil/sponge switches might be useful in other contexts. We’d be interested in how the sponges wear with prolonged use.

We’ve seen other giant controllers before. Of course, if you really want a big controller, you can’t beat a Nissan (the link is dead, but the video will give ou the idea).

A tachometer used to be an accessory added to the dash of only the sportiest of cars, but now they’re pretty much standard equipment on everything from sleek coupes to the family truckster. If your daily driver was born without a tach, fear not – a simple Arduino tachometer is well within your reach.

The tach-less vehicle in question is [deepsyx]’s Opel Astra, which from the video below seems to have the pep and manual transmission that would make a tach especially useful. Eschewing the traditional analog meter display or even a digital readout, [deepsyx] opted to indicate shift points with four LEDs mounted to a scrap of old credit card. The first LED lights at 4000 RPM, with subsequent LEDs coming on at each 500 RPM increase beyond that. At 5800 RPM, all the LEDs blink as a redline warning.  [Deepsyx] even provides a serial output of the smoothed RPM value, so logging of RPM data is a possible future enhancement.

The project is sensing engine speed using the coil trigger signal – a signal sent from the Engine Control Unit (ECU) which tells one of the ignition coilpacks to fire. The high voltage signal from the coilpack passes on to the spark plug, which ignites the air-fuel mixture in that cylinder. This is a good way to determine engine RPM without mechanical modifications to the car. Just make sure you modify the code for the correct number of cylinders in your vehicle.

Simple, cheap, effective – even if it is more of a shift point indicator than true tachometer, it gets the job done. But if you’re looking for a more traditional display and have a more recent vintage car, this sweeping LED tachometer might suit you more.

[via r/Arduino]

RC flying is one of those multi-disciplinary hobbies that really lets you expand your skill set. You don’t really need to know much to get started, but to get good you need to be part aeronautical engineer, part test pilot and part mechanic. But if you’re going to really go far you’ll also need to get good at electronics, which was part of the reason behind this Arduino servo tester.

[Peter Pokojny] decided to take the plunge into electronics to help him with the hobby, and he dove into the deep end. He built a servo tester and demonstrator based on an Arduino, and went the extra mile to give it a good UI and a bunch of functionality. The test program can cycle the servo under test through its full range of motion using any of a number of profiles — triangle, sine or square. The speed of the test cycle is selectable, and there’s even a mode to command the servo to a particular position manually. We’ll bet the build was quite a lesson for [Peter], and he ended up with a useful tool to boot.

Need to go even further back to basics than [Peter]? Then check out this primer on servos and this in-depth guide.

[via r/Arduino]

In the Red Dwarf TV series, Talkie Toaster wants to know if you want toast, and if not toast, then maybe a muffin or waffle, and it will pester you incessantly until you smash it with a 14lb lump hammer and throw it in a waste disposal. Now [slider2732] has actually gone and made one of the infernal machines!

He’s hidden a PIR sensor in the toaster handle to tell an Arduino Pro Mini when someone is unfortunate enough to be passing by. The Arduino then reads sound files from an SD card reader and plays them through a 3 watt amplifier out to a speaker. For that he uses the TMRpcm library available on github.

[slider2732] cleverly mounted the speaker to the side of the toaster along with some appropriately shaped bits and pieces, and some LEDs to make it appear and work much like the circular panel that lights up on the real Talkie Toaster. We dare you to watch the video after the break, unless you really are looking for toast. As a consolation, the video also walks through making it.

These links will take you to clips of Talkie Toaster in the TV series before he was smashed and after he was repaired.

And what else can you do with a toaster? Why not make a flying one. Of course what seems to be most popular here on Hackaday is making reflow ovens from toaster ovens.

What with wearable tech, haptic feedback, implantable devices, and prosthetic limbs, the boundary between man and machine is getting harder and harder to discern. If you’re going to hack in this space, you’re going to need to know a little about electromyography, or the technique of sensing the electrical signals which make muscles fire. This handy tutorial on using an Arduino to capture EMG signals might be just the thing.

In an article written mainly as a tutorial to other physiatrists, [Dr. George Marzloff] covers some ground that will seem very basic to the seasoned hacker, but there are still valuable tidbits there. His tutorial build centers around a MyoWare Muscle Sensor and an Arduino Uno. The muscle sensor has snap connectors for three foam electrodes of the type used for electrocardiography, and outputs a rectified and integrated waveform that represents the envelope of the electrical signal traveling to a muscle. [Dr. Marzloff]’s simple sketch just reads the analog output of the sensor and lights an LED if it detects a muscle contraction, but the sky’s the limit once you have the basic EMG interface. Prosthetic limbs, wearable devices, diagnostic tools, virtual reality — the possibilities are endless.

We’ve seen a few EMG interfaces before, mainly of the homebrew type like this audio recorder recruited for EMG measurements. And be sure to check out [Bil Herd]’s in-depth discussion of digging EMG signals out of the noise.

Someone once observed that the moon is a harsh mistress. But that doesn’t mean you can’t keep track of her, specially with this awesome moon phase clock that [G4lile0] designed and built.

It uses a 3D printed moon model combined with a series of LEDs to create the phases. These LEDs are driven by an Arduino that calculates the phase to show, as well as driving a small OLED display that shows the date and time. There is even a party mode for all of those lunar raves that you host.

[G4lile0] has done an excellent job of documenting the code that drives the lamp, so it would be easy to add features, or adapt this design to show the phases of another moon or add other features. It’s an excellent overall design, and kudos to [G4lile0] for doing it all with open source tools like FreeCAD.

Sometimes less is more. This is especially true when dealing with microcontrollers with limited I/O pins. Even if you have lots of I/O, sometimes you are need to pack a lot into a little space. [Hugatry] was inspired by the simple interface found on a lot of flashlights: one button. Push it and it turns on. Push it again, and it switches modes. You cycle through the modes until you finally turn it back off. One button provides mutliple functions. The question is how can you use a power switch as an I/O device? After all, when you turn the power off, the microprocessor stops operating, right?

[Hugatry’s] answer is quite simple. He connects a resistor/capacitor network to an I/O pin (or multiple pins). When the processor turns on initially, the pin will read low and the capacitor will charge up. If you turn the power off, the CPU voltage will fall rapidly to zero, but the voltage on the capacitor will discharge slower. If you wait long enough and turn the power on, there’s no difference from that first power on event. But if you turn the power on quickly, the capacitor voltage will still be high enough to read as a logic one.

What that means is that the processor as part of its start up can detect that it was recently turned off and take some action. If it remembers the previous state in nonvolatile memory, you can have the code cycle through multiple states, just like a flashlight. You can see a video of the setup, below.

[Hugatry] included some simple Arduino code that illustrates the concept. However, the technique is simple enough that you can adapt it to other projects easily.

Think one button isn’t enough to do anything interesting? Think again. Then again, Amazon probably has a patent on things with one button.