Persistence Of Vision Death Star

Death Stars were destroyed twice in the Star Wars movies and yet one still lives on in this 168 LED persistence of vision globe made by an MEng group at the University of Leeds in the UK. While Death Stars are in high demand, they mounted it on an axis tilted 23.4° (the same as the Earth) so that they can show the Earth overlaid with weather information, the ISS position, or a world clock.

More details are available on their system overview page but briefly: rotating inside and mounted on the axis is a Raspberry Pi sending either video or still images through its HDMI port to a custom made FPGA-based HDMI decoder board.  That board then controls 14 LED driver boards mounted on a well-balanced aluminum ring. All that requires 75W which is passed through a four-phase commutator. Rotation speed is 300 RPM with a frame rate of 10 FPS and as you can see in the videos below, it works quite well.

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DIY Thermal Imaging Done Low-Tech Style

[Niklas Roy] has always wanted to try out thermal imaging and saw his opportunity when he received one of those handheld IR thermometers as a gift. But not content with just pointing it at different spots and looking at the temperatures on the LCD display, he decided to use it as the basis for a scanning, thermal imaging system that would display a heat map of a chosen location on his laptop.

DIY thermal imaging system
DIY thermal imaging system

He still wanted to to be able to use the IR thermometer as normal at a later date so cutting it open was not an option. Instead he firmly mounted a webcam to it pointing at the LCD display. He then wrote software on his laptop to process the resulting image and figure out what temperature was being displayed.

Once he got that working, he next put the thermometer on a platform with servos connected to an Arduino for slowly rotating it in the horizontal and vertical directions, also under control of the software on his laptop. Each time the thermometer measures the temperature of a spot, the software decodes the temperature on the LCD display and then tells the Arduino to use the servos to point the thermometer at the next spot to be measured. Each measurement takes a little time, so scanning an entire location as 70×44 spots takes around a half hour. But the end result is a heat map drawn on the laptop, done by a device that is low-tech. [Editor’s Snark: Because attaching a webcam and processing the images is “low-tech” these days.] He can overlay the heat map on a normal photo to see at a glance where the hot spots are.

The software he wrote is available on GitHub and the video below shows it in action. We’ve got to admit, it’s pretty awesome to watch. You can even see the heat map being filled in one measurement at a time.

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Good Penmanship With A 3D Printer

[Chris Mitchell] was going to make his own plotter for doing cursive writing for cards but realized he might be able to use his 3D printer to do the writing instead. But then he couldn’t find any suitable software so he did what you’re supposed to do in this situation, he wrote his own called 3DWriter. He even 3D printed a holder so he could attach a pen to the side of the extruder. When not in use as a plotter he simply retracts the pen tip.

The software is written in C# for Windows and is available on GitHub along with a detailed write-up. He clearly put a lot of thought into what features the software offers. After selecting the font, you type in whatever you want printed and then preview it to make sure it looks good. There’s also a bunch of G-Code settings you can fill in such as bed size, the horizontal and vertical offsets of the pen tip from the extruder tip, drawing speed and so on. There’s even an option to do a dry run with the pen raised so you can make sure it’ll draw on the bed where you expect it to.

The code itself is quite clean and easy to understand. If you’re curious like we were at what information is in the font files and how it’s translated into G-Code then download the source from the GitHub page and have a look. [Chris] settled on a font set called Hershey fonts since they’re primarily stroke based fonts as opposed to outline fonts which are what other programs he’d looked at used.

This makes us think of all those 3D printers with busted extruders we’ve seen collecting dust on hackerspace shelves or simply ones considered obsolete. Using them as a plotter gives them new life — even if just as a fun way to learn about writing code for CNC machines. It makes us wonder what other 2D uses they can be put to… cutting vinyl? laser printing? Ideas anyone?

In any case, have a look at the video below to see it in action as a 2D plotter. As a bonus, you’ll also see line art it drew using an Inkscape plugin.

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CNC-Telescope With Semi-Nasmyth Mount

[GregO29] had a 10″ GoTo telescope but at 70lbs, it wasn’t really portable. And so he did what any self-respecting CNC enthusiast would do, he put his CNC skills to work to make an 8″ Newtonian reflector, semi-Nasmyth mount telescope of his own design. It also gave him a chance to try out his new Chinese 6040 router/engraver with 800W water-cooled spindle.

What’s all that fancy terminology, you say? “Newtonian reflector” simply means that there’s a large concave mirror at one end that reflects a correspondingly large amount of light from the sky to a smaller mirror which then reflects it toward your eye, preferably along with some means of focusing that light. “Semi-Nasmyth mount” means that the whole thing pivots around the eyepiece so that you can keep your head relatively still (the “semi” is because the eyepiece can also be pivoted, in which case you would have to move your head a bit).

We really like the mechanism he came up with for rotating the telescope in the vertical plane. Look closely at the photo and you’ll see that the telescope is mounted to a pie-shaped piece of wood. The curved outer circumference of that pie-shape has gear teeth on it which he routed out. The mechanism that moves these teeth is a worm screw made from a 1″ spring found at the hardware store that’s on a 3/4″ dowel. Turn the worm screw’s crank and the telescope rotates.

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Why the Wright Brothers Succeeded

The types of steps and missteps the Wright brothers took in developing the first practical airplane should be familiar to hackers. They started with a simple kite design and painstakingly added only a few features at a time, testing each, and discarding some. The airfoil data they had was wrong and they had to make their own wind tunnel to produce their own data. Unable to find motor manufacturers willing to do a one-off to their specifications, they had to make their own.

Sound familiar? Here’s a trip through the Wright brothers development of the first practical airplane.

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Alexa Robot Coffee Maker Brews Coffee, Speaks For Itself

To keep hackers fueled and hacking, why not hack a coffee maker into a coffee brewing robot? [Carter Hurd] and [David Frank] did just that at The Ohio State’s Hack OHI/O 24 hour Hackathon. They even won the “Best Hardware Hack”. The video below shows it in action but the guys sent us some extra details on how it’s made.

To give it a voice they put Alexa on a Raspberry Pi. Using an audio splitter they have the voice go both to a speaker and to an Arduino. The Arduino then uses the amplitude of the audio signal’s positive values to determine how much to open the “mouth”, the coffee maker’s hinged cover. As is usually the case, there’s some lag, but the result is still quite good.

The brewing is also controlled by the Arduino. They plan to add voice control so that they can simply ask, “Alexa, make me coffee”, but for now they added a switch on the side to start the brewing. That switch tells the Arduino to work one servo to open the cover, another to insert a coffee filter, and two more to scoop up some coffee from a container and dump it into the filter.

They replaced the coffee maker’s on/off switch with a relay so that after the Arduino closes the cover again, it uses the relay to start the brewing. The result is surprisingly human-like. We especially like the graceful movement achieved by the two servos for scooping up and dumping the coffee. Full disclosure: they did admit that it would often either not scoop enough coffee or scoop enough but spill a bunch on the group.

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Blowing Out A Candle Flicker LED: The Death Of Flame

One day there will be no more need for flames. [slider2732] has put yet another nail in the coffin of this most ancient of all technology by making a candle that uses a flicker LED that you blow out. A little more miniaturization and we’ll have them fully integrated into the size of birthday cake candles (Hint hint, hackers!).

You may have seen these candle flicker LEDs.  They have a small chip inside them that modulates the LED’s light to flicker like a candle. We’ve even reported on what [Cpldcpu] found when he reverse engineered them first here and then here.

What [slider2732] did was to buy an electronic candle that used one of the LEDs actually shaped like a flame, and to drill a hole near the ‘flame’. He them embedded a microphone behind the hole. That goes to an LM386 amplifier circuit and from there to an Arduino Pro Mini all powered by a LiPo. As you’d expect, the Arduino code is very simple, just watch the pin from the amplifier and based on an internal variable, turn the LED on or off. We really like how none of the electronics is visible and how you actually have to lean over and blow into the top of the candle to blow it out. You can see this demonstrated in the video below.

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