Photochromic Eggs: Not for Breakfast

Photochromic paint is pretty nifty – under exposure to light of the right wavelength, it’ll change colour. This gives it all kinds of applications for temporary displays.  [Jiri Zemanek] decided to apply photochromic paint to an egg, utilising it to create stroboscopic patterns with the help of a laser.

Patterns for the egg are generated in MATLAB. A Discovery STM32 board acts as a controller, looking after the laser scanner and a stepper motor which rotates the egg. A phototransistor is used to sync the position of the laser and the egg as it rotates.

The photochromic paint used in this project is activated by UV light. To energize the paint, [Jiri] harvested a violet laser from a Blu-ray player, fitting it to a scanning assembly from a laser printer. Instead of scanning the laser across an imaging drum, it is instead scanned vertically on a rotating egg. Patterns can then be drawn on the egg, which fade over time as the paint gives up its stored energy.

[Jiri] exploits this by writing a variety of patterns onto the egg, which then animate in a manner similar to a zoetrope – when visualised under strobing light, the patterns appear to move. There are also a few holiday messages shown for Easter, making the egg all the more appropriate as a billboard.

If you like the idea of drawing on eggs but are put off by their non-uniform geometry, check out the Egg-bot. Video below the break.

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An Eggcelent Eggspriment

After multiple iterations [Keef] has nailed down the fabrication process for an unusual component. Using only a heater water bath, some silicone and easily available reagents, [Keef] demonstrate how he manufactures a gastronomic enigma: the long egg.

The similarities between [Keef’s] process and the typical hacker iteration cycle are eggceptional. He starts out with a goal and iterates, modifying his methods until he gets the perfect long egg. Sound familiar? Cooking can be as much of a science as it is an art.

In his quest, [Keef] utilizes sausage casing, plastic bags, sticky tape, “lots of sweat and almost some tears” to hold eggs for cooking via an Anova Precision Cooker immersion circulator. However, [Keef] notes, the Anova is normally used for sous vide cooking so you might not have one sitting around. In that case, you can use a regular pan on a stovetop along with a digital thermometer, but you’ll have to be quite vigilant to keep the temperature steady.

But wait. Why would one want a long egg in the first place? I’ll leave this explanation to [Keef]. “Well, the main use is in a Gala Pie (a long pork pie baked in a loaf tin and often cut into slices for picnics). Or you could just slice the egg and lay it out on a platter and amaze your friends with how every slice is exactly the same size.”

Go check out [Keef’s] two videos. He has two, one that chronicles the eggciting initial attempts, and another that describes his final method. With [Keef’s] help, the number of long eggs outside of Denmark may substantially increase. But, if you’d rather have some pizza, we won’t be offended.

What Came First? The Chicken or the LASER?

If you’ve had a child in the last few decades, you’ve had a choice to make: if you want to know the sex of the baby ahead of time. With ultrasound you can find out or–popular these days–you can have the result sealed and have a baker create a reveal cake. Apparently, researchers at the Dresden University of Technology and the University of Leipzig wanted to do the same trick with unborn chickens.

You might wonder why anyone cares (we did). Apparently, chickens that are bred for egg laying don’t produce roosters suitable for food use. This leads to about half of the chicks being “culled” (a less ugly euphemism than gassed or shredded) and used in–among other things–animal feed. Worldwide, billions of chicks are culled each year and that’s not counting other similar situations like male turkeys and female ducks.

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Egg clock (it’s egg-ceptional)

Easter is over and with some plastic eggs still on hand, [Franspaco] was looking for something to do with them. He decided to use an egg as an enclosure for a digital clock.

You can see that the finished project uses just one 7 segment LED display to show the time. A scrolling number method is used to delineate each digit of the 24-hour time readout. The display will go blank, followed by two numbers for the hours, a dash as a separator, and finally two more digits for the minutes. A PICAXE microcontroller drives the clock, but for accuracy a DS1307 does the timekeeping.

[Franspaco] etched his own circuit board that is sized to fit perfectly, housing the two chips, an LED, and a programming header. The on-board LED blinks at 1 Hz, giving some inner glow to the plastic shell. He accomplished most of his goals, but was unable to fit the batteries inside of one egg, prompting the need for a tethered power-egg. If he moves to surface mount components for the next generation of this device we think he’ll have no problem fitting a small battery (like an A23) inside.

Easter egg hacking


Spring is upon us and Instructables user [Mischka] decided it was a good idea to combine two flavors we never considered putting together: The Easter Bunny and the A-Team.

He decided to build the egg as an Easter gift for his brother, who is a huge fan of the A-Team. He found a slightly larger than normal plastic egg, and proceeded to paint the shell white, adding a printed picture of Mr. T once the paint had dried.

The guts of the egg are made up of a Picaxe 08M micro controller mounted on a Picaxe protoboard. Rather fond of buzzing, beeping audio, he decided to forgo a normal speaker and opted to use a piezo instead. To activate the music when the egg is shaken, a tilt switch was added to the board as well. He uploaded his software to the Picaxe, sealed up the egg, and called it a day.

We can imagine his brother will be pretty pleased with the creation – who wouldn’t be? We only wish that there was video of the egg in action.

DIY Coffee Gripper

Here at Hackaday, we love it when people make home brew versions of elaborate, expensive, and technical equipment. By gathering up some coffee grounds, a balloon, some plastic tubing, and his lungs, [Carlos] has provided a good how-to on making your own coffee grounds robotic hand. Inspired by the U. Chicago, Cornell, and iRobot Collaboration we previously covered, he is one robot and a vacuum pump away from having their setup. Check out his blog for a list of components as well as a couple hints to help the build go smoothly. Be sure to check out the video after the break.

[via Make]

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CNC egg decorating

Lacking the patience to do it by hand, GeekPhysical built a CNC machine to decorate Easter eggs. We do mean eggs from chickens used to celebrate the Christian holiday of Easter, not hidden nuggets in technology used to amuse geeks. The results seen in their video (after the break) are quite impressive considering that the printing medium is not perfectly round nor perfectly smooth. The hardware design is ingenious; one servo rotates the egg, another is mounted on one side of the egg and moves a track in an arc so that a felt-tipped pen will follow the curve of the shell. The pen moves in an out along that track through the use of a third servo physically removed by a Bowden cable. We were able to get a closer look at the hardware via their Flickr set and the device is indeed Arduino powered. This fun build is a great way to celebrate the season!

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