color

42 Articles

Erasable Pen Ink Adds Colors To 3D Prints

September 28, 2021 by 8 Comments

Changing colors during a 3D print is notoriously difficult. Either you need multiple heads ready to go during the print which increases operating and maintenance costs for your printer, or you need to stop the print to switch the filament and then hope that everything matches up when the print is resumed. There are some workarounds to this problem, but not many of them are as smooth an effortless as this one which uses erasable pen ink to add colors to the filament on the fly.

Erasable pen ink is a thermochromic material that doesn’t get removed from paper when erased like graphite from a pencil. Instead the heat from the friction of erasing causes it to become transparent. By using this property for a 3D print, the colors in the print can be manipulated simply by changing the temperature of the hot end. Of course the team at [Autodrop3d] had quite a learning curve when experimenting with this method, as they had to run the extruder at a much lower temperature than normal to have control over the ink’s color, had to run the print much slower than normal, and were using a very sticky low-temperature plastic for the print.

With all of these modifications to the print setup, there are bound to be some limitations in material and speed, but the results of the project speak for themselves. This allows for stock 3D printers to use this method with no hardware modifications, and the color changes can be done entirely in software. While everyone catches up with this new technology, there are some other benefits to a 3D printer with multiple print heads, though, and some clever ways of doing the switching without too much interruption.

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Liquid Lite Brite Robot

March 3, 2021 by 2 Comments

Liquid handling workstations are commonly used in drug development, and look like small CNC machines with droppers on the ends which can dispense liquid into any container in a grid array. They are also extraordinarily expensive, as is most specialty medical research equipment. This liquid handling workstation doesn’t create novel drugs, though, it creates art, and performs similar functions to its professional counterparts at a much lower cost in exchange for a lot of calibration and math.

The art is created by pumping a small amount of CMYK-colored liquids into a 24×16 grid, with each space in the grid able to hold a small amount of the colored liquid. The result looks similar to a Lite-Brite using liquids instead of small pieces of plastic. The creator [Zach Frew] created the robot essentially from scratch using an array of 3D printers, waterjets, and CNC machines. He was able to use less expensive parts, compared to medical-grade equipment, by using servo-controlled valves and peristaltic pumps, but makes up for their inaccuracies with some detailed math and calibration.

The results of the project are striking, especially when considering that a lot of hurdles needed to be cleared to get this kind of quality, including some physical limitations on the way that the liquids behave in the first place. It’s worth checking out not just for the art but for the amount of detail involved as well. And, for those still looking to scratch the 90s nostalgia itch, there are plenty of other projects using the Lite Brite as inspiration.

Thanks to [Thane Hunt] for the tip!

Color E-Ink Display Photo Frame Pranks [Mom]

October 30, 2020 by 34 Comments

As a general rule, it’s not nice to prank your mother. Moms have a way of exacting subtle revenge, generally in the form of guilt. That’s not to say it might not be worth the effort, especially when the prank is actually wrapped in a nice gesture, like this ever-changing e-paper family photo frame.

The idea the [CNLohr] had was made possible by a new generation of multicolor e-paper displays by Waveshare. The display [Charles] chose was a generous 5.65″ unit with a total of seven colors. A little hacking revealed an eighth color was possible, adding a little more depth to the images. The pictures need a little pre-processing first, of course — dithering to accommodate the limited palette — but look surprisingly good on the display. They have a sort of stylized look, as if they were printed on a textured paper with muted inks.

The prank idea was simple — present [Mrs. Lohr] with a cherished family photo to display, only to find out that it had changed to another photo overnight. The gaslighting attempt required a bit more hacking, including some neat tricks to keep the power consumption very low. It was also a bit of a squeeze to get it into a frame that was slim enough not to arouse suspicion. The video below details some of the challenges involved in this build.

In the end, [Mom] wasn’t tricked, but she still seemed pleased with the final product. These displays seem like they could be a lot of fun — perhaps a version of the very-slow-motion player but for color movies would be doable.

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STM32 Gets Up Close And Personal With Mandelbrot

October 25, 2020 by 12 Comments

The Mandelbrot set is a curious mathematical oddity that, while interesting in its own right, is also a useful tool for benchmarking various types of computers. Its constant computing requirement when zooming in and out on the function, combined with the fact that it can be zoomed indefinitely, means that it takes some quality hardware and software to display it properly. [Thanassis] has made this a pet project of his, running Mandelbrot set visualizations in different ways on many different hardware platforms.

This particular one is based on an STM32 board called the Blue Pill, which [Thanassis] chose because he hadn’t yet done a continuous Mandelbrot zoom on a microcontroller yet. The display is handled by a tiny 16K IPS color screen, and some clever memory tricks had to come into play in order to get smooth video output since the STM has only 20 kB available. The integer multiplication is also tricky on a platform this small while keeping the continuous zoom function, so it’s limited to fixed point multiplication.

Even with the limitations of the platform, he is still able to achieve nearly double-digit FPS rates with this one. If you want to play around with graphics like this on an STM platform, [Thanassis] has released all of the source code on his GitHub page, but if you’d like to see more Mandelbrot manipulation you can check out one of his older projects where he built a similar project on an FPGA.

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Monochrome CRT And Liquid Crystal Shutter Team Up For Color Video

October 1, 2019 by 21 Comments

If you were tasked with designing a color video monitor, it’s pretty clear how you’d go about it. But what if you’d been asked to do so 20 years ago? Would it have been a cut and dried from an engineering standpoint? Apparently not, as this hybrid LCD-CRT video monitor demonstrates.

We’d honestly never heard of this particular design, dubbed “LCCS”, or liquid crystal color shutter, until [Technology Connections]’ partial teardown of the JVC monitor and explanation of its operation. The idea is simple and hearkens back to the earliest days of color TV in the United States, when broadcasters were busy trying to bring color to a monochrome world in a way that would maximize profits. One scheme involved rotating a color wheel in front of the black-and-white CRT and synchronizing the two, which is essentially what’s happening in the LCCS system. The liquid crystal panel cycles between red, blue, and green tints in time with the CRT’s images behind it, creating a full-color picture. “But wait!” you cry. “Surely there were small color CRTs back in the year 2000!” Of course there were, but they kind of sucked. Just look at the comparison of a color CRT and the LCCS in the video below and you’ll see why this system carved out a niche in the pro video market, especially for video assist monitors in the days before digital cinematography. A similar system was used by Tektronix for color oscilloscopes, too.

As usual, [Technology Connections] has managed to dig up an interesting bit of the technological fossil record and present it in a fascinating way. From video on vinyl to 1980s copy protection to the innards of a toaster, we enjoy the look under the hood of forgotten tech.

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Lithophanes Ditch The Monochrome With A Color Layer

August 20, 2019 by 10 Comments

3D printed lithophanes are great, if a bit monochromatic. [Thomas Brooks] (with help from [Jason Preuss]) changed all that with a tool for creating color lithophanes but there’s a catch: you’ll need a printer capable of creating multi-color prints to do it.

A video (embedded below) begins with an intro but walks through the entire process starting around the 1:26 mark. The lithophane is printed as a single piece and looks like most other 3D printed lithophanes from the front, but the back is different. The back (which is the bottom printed layer) is made of up multiple STL files, one for each color, and together creates something that acts as a color filter. When lit from behind, light passes through everything and results in an image that pops with color in ways that lithophanes normally do not.

The demo print was created with a printer equipped with a Palette 2, an aftermarket device that splices together filament from different spools to create multicolored prints, but we think a Prusa printer with an MMU (multi material upgrade) should also do the trick.

[Thomas] already has a lot of ideas on how to improve the process, but these early results are promising. Need a gift? Lithophanes plus LED strips make great lamps, and adding a cheap clock movement adds that little extra something.

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A PIC And A Few Passives Support Breakout In Glorious NTSC Color

March 29, 2019 by 27 Comments

“Never Twice the Same Color” may be an apt pejorative, but supporting analog color TV in the 1950s without abandoning a huge installed base of black-and-white receivers was not an option, and at the end of the day the National Television Standards System Committee did an admirable job working within the constraints they were given.

As a result of the compromises needed, NTSC analog signals are not the easiest to work with, especially when you’re trying to generate them with a microcontroller. This PIC-based breakout-style game manages to accomplish it handily, though, and with a minimal complement of external components. [Jacques] undertook this build as an homage to both the classic Breakout arcade game and the color standard that would drive the home version of the game. In addition to the PIC12F1572 and a crystal oscillator, there are only a few components needed to generate the chroma and luminance signals as well as horizontal and vertical sync. The game itself is fairly true to the original, although a bit twitchy and unforgiving judging by the gameplay video below. [Jacques] has put all the code and schematics up on GitHub for those who wish to revive the analog glory days.

Think NTSC is weird compared to PAL? You’re right, and it’s even weirder than you might know. [Matt] at Stand Up Maths talked about it a while back, and it turns out that a framerate of 29.97 fps actually makes sense when you think it through.

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