The Etch-a-Sketch was a hugely popular toy in the days before video games and the Internet became ubiquitous. These days, they’re a fun amusement, but can still be difficult to master. Rather than learn the necessary skills himself, [Martin Fitzpatrick] decided to build a machine to draw for him. Enter the Etch-a-Snap.
The build starts with a Raspberry Pi Zero, equipped with the requisite camera. Images taken are processed into a 100×60 pixel image with 1-bit color. At this stage, a network graph representation is built of the image and used to generate commands for the plotting mechanism to draw the scene. Plotting is achieved with stepper motors that turn the knobs through 3D-printed gears. Plotting is slow, with images taking 15 minutes to an hour to “develop”. The system can also be used to draw manually processed images, which can improve results when images are chosen carefully.
When Microsoft announced the Xbox adaptive controller earlier this year, many were pleasantly surprised at how adaptive it truly was. The controller features 3.5mm jacks for easily connecting any external input device and sports an impressive build quality given its price tag, but the most impressive part was the fact that the design was so open in nature. Rather than seeking to create a specific design solution tailored to a subset of users the adaptive controller acts more as a hub for the community’s designs. One of those brilliant designs comes from [Colton] who posted a five-part series on his custom controller build for his daughter.
His daughter, Ellie, has Cornelia de Lange syndrome which prevents her from being able to use more conventional pressure sensitive input devices. So [Colton] devised a way for buttons to be pressed using an alternate range of motion. By attaching foam massage inserts to standard paint rollers, the buttons could be triggered by allowing the peaks and valleys of the foam to roll over the top of each button. He could achieve even better accuracy by attaching braided ribbon over the buttons in order to prevent binding.
After finding that setup to be successful, [Colton] went about designing a frame. He arrived at using PVC pipe and utilizing tees as anchor points for the rollers. A couple of steel hose clamps are enough to hold each of the foam rollers in place, and the contact distance can be dialed in with buttons housed in threaded PVC adapters (shown right). After the addition of a little colored wrap here and there the build has a decidedly cheery exterior.
However, the build was not complete without a custom piece of software to match. [Colton] reached out for help from his nephew to program a “RGB Etch-a-Sketch” they called Sundoodler. The game runs on a small form factor PC hooked up to a projector so Ellie can play lying down. [Colton] has some future plans for his daughter’s custom Xbox adaptive controller build, but for now you can see the results in the video below.
Electronic things are often most successful when they duplicate some non-electronic thing. Most screens, then, are poor replacements for paper. Except, of course, for E-paper. These displays have high contrast even in sunlight and they hold their image even with no power. When [smbakeryt] was looking at his daughter’s Etch-a-Sketch, he decided duplicating its operation would be a great way to learn about these paper-like displays.
You can see a video of his results and his findings below. He bought several displays and shows them all, including some three-color units which add a single spot color. The one thing you’ll notice is the displays are slow which is probably why they haven’t taken over the world.
The displays connect to a Raspberry Pi and many of the displays are meant to mount directly to a Pi. The largest display is nearly six inches and some of the smaller displays are even flexible. It appears the three color displays were much slower than the ones that use two colors. To combat the slow update speeds, some of the displays can support partial refresh.
The drawing toy uses optical encoders connected to the Raspberry Pi. The Python code is available. Even if you don’t want to duplicate the toy, the comparison of the displays is worth watching. We were really hoping he’d included an accelerometer to erase it by shaking, but you’ll have to add that feature yourself. By the way, in the video, he mentions the real Etch-a-Sketch might work with magnets. It doesn’t. It is an aluminum powder that sticks to the plastic until a stylus rubs it off.
Introduced in 1960 for the princely sum of $2.99 ($25.00 today), Etch A Sketch was to become a standard issue item for the Baby Boomers’ toy box. As enchanting as the toy seems, it’s hard to see why it had staying power: it was hard for young fingers to twirl the knobs, diagonal lines and smooth curves required a concert pianist’s fine motor control, and whatever drawings we managed to make were erased at the slightest jostle of the tablet.
Intent on righting these wrongs, [Sunny Balasubramanian] not only motorized an Etch A Sketch, but he’s also given it a mind of its own in a way. For those unfamiliar with the toy, it’s basically a manual X-Y plotter that drags a stylus across the underside of a glass screen, scraping off a silver powder clinging to the glass to make dark lines. Replacing the knobs with steppers is straightforward, of course, but driving them is the trick. [Sunny] hooked his up to a Raspberry Pi and wrote some Python code to drive them. The Pi also accepts input image files and processes them for rendering through the plotter, first doing Canny edge detection in OpenCV, then plotting a single path through the largest collection of connected pixels in the image. From there it’s just a matter of spinning the motors to create surprisingly detailed images. Check out the short video below to see it in action.
It’s hardly the first automatic Etch A Sketch we’ve seen – here’s one that automates everything including the shake to erase the drawing. That one cheats a little though, in that it rasters across the screen like a CRT. We really like how this one just does a single path. Pretty clever.
Stick a 10kΩ pot in the left-side header and you can play a space shooter game, or make line drawings by twisting the knob like an Etch-A-Sketch. Be sure to check out the detailed walk-through after the break, and a bonus video that shows off Multiduino’s newest functions including temperature sensing, a monophonic music player for sweet chiptunes, and a virtual keyboard for scrolling text on the OLED screen. [Danko] has a few of these for sale in his eBay store. They come assembled, and he ships worldwide. The code for every existing function is available on his site.
Curves are a breeze to draw with a stylus instead of joysticks, but it’s still a 2-D plotter and must be treated as such. The Touch-A-Sketch system relies on the toy’s stylus starting in the lower left hand corner, so all masterpieces must begin at (0,0) on the knobs and the touch screen.
The BOM for this project is minimal. A PIC32 collects the input coordinates from the touch screen and sends them to a pair of stepper motors attached to the toy’s knobs. Each motor is driven by a Darlington array that quickly required a homemade heat sink, so there’s even a hack within the hack. The team was unable to source couplers that could deal with the discrepancy between the motor and knob shaft sizes, so they ended up mounting the motors in a small plywood table and attaching them to the stock knobs with Velcro. This worked out for the better, since the Etch A Sketch® screen still has to be reset the old-fashioned way.
In bringing suitable illustrations to our articles, we Hackaday scribes use a variety of sources that offer images featuring permissive licences. Among the usual free image libraries there is one particularly rich source, the line drawings contained within the huge archives of patents granted by the various countries around the world. These are the illustrations used as part of the patent itself to describe the working of the patent being claimed. We use them because though the items they depict are legally protected from copying by the patents they are part of, they as part of the patents themselves are in the public domain. Thus we can easily find detailed hand drawn pictures of all kinds of technical innovations from the last couple of hundred years or so, and from time to time you as our readers reap the benefit.
If you spend a while browsing old patents through a search engine such as Google Patents, you can quickly become engrossed in these beautiful images of inventions past. Though their purpose is a functional one to convey the workings of an invention, the anonymous artists have often poured all of their skill into rendering them as considerably more than mere draughtsmanship. In those dusty Government archives lurk masterpieces, just waiting to be found.