STEAM Carnival Hacker Preview Day

Carney For LifeLast week we wrote about the guys over at TwoBitCircus and their upcoming STEAM Carnival. This Thursday we managed to make it down to the Hacker Preview day where they showed us all the toys and games that will be exhibited over the weekend.

The preview day went pretty well until the evening, when unexpected power problems occurred and the site lost power for a little while. But this is why you have a preview day right? Organizer [Brent Bushnell] even commented that he should have put a BETA badge on the ticket. Thankfully the outage coincided with the food truck arriving so everyone stopped for a burger.

Sadly all the fire based pieces were not active on the preview day since they didn’t have the appropriate safety measures in place yet, but they did get to show us most of their games. My personal favorites were the Hobby Horse Racing, and the Laser Foosball.

Here’s a quick run down of some of the stand out pieces.

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Building A Magnetic Levitating Quadcopter

hover Three days ago on October 21, 2014 it was announced to the world the Back to the Future hoverboard was real. It’s a Kickstarter, of course, and it’s trending towards a $5 Million dollar payday for the creator.  Surprisingly for a project with this much marketing genius, it’s a real, existing device and there’s even a patent. From the patent, we’re able to glean a few details of how this hoverboard/magnetic levitation device works, and in our post on the initial coverage, we said we’d be giving away some goodies to the first person who can clone this magnetic levitation device and put it up on

[jellmeister] just won the prize. It’s somewhat cheating, as he’s had his prototype hoverboard working in July, and demoed a more advanced ‘upside-down quadcopter’ device at the Brighton Mini Maker Faire in September. Good on ‘ya [jelly]. You’re getting a gift card for the hackaday store.

hoverLike the Kickstarter hoverboard, [jelly] is using an array of magnets rotating in a frame above a non-ferrous metal. For the initial test, eight neodymium magnets were arranged in a frame, suspended over 3/4″ aluminum plate, and spun up with a drill. With just this simple test, [jelly] was able to achieve 2kg of lift at 1cm and 1kg of lift at 1 inch of separation. This test also provided some valuable insight on what the magnets do to the aluminum or copper; the 3kg aluminum plate was nearly spinning, meaning if this device were to be used on small plates, counter-rotating pairs of magnetic lifters would need to be used.

The test rig then advanced to two pairs of rotors with standard hobby brushless motors, but stability was a problem; the magnetic rotors provided enough lift, but it would quickly fall over. To solve this problem, [jellmeister] took a standard quadcopter configuration, replaced the props with magnetic rotors, and successfully hovered it above a sheet of aluminum at the Brighton Maker Faire.

Since [jellmeister] has actually built one of these magnetically levitating hoverboards, he has a lot more data about how they work than an embargoed press release. The magnetic rotor hoverboard will work on aluminum as well as copper, but [jell] suspects the Kickstarter hoverboard may be operating right at the edge of its performance, necessitating the more efficient copper half pipe. The thickness of the non-ferrous plate also makes a difference, with better performance found using thicker plates. No, you bojo, hoverboards don’t work on salt water, even if you have pow-ah.

So there ‘ya go. That’s how you build a freakin’ hoverboard. [jellmeister]‘s design is a little crude and using a Halbach array for the magnetic rotors should improve efficiency. Using a 3D printed rotor design is a stroke of genius, and we’ll expect a few more quad-magnetic-levitating-things to hit the tip line in short order.

Demos of [jellmeister]‘s work below.

Oh. These things need a name. I humbly submit the term ‘Bojo’ to refer to any device that levitates though rotating magnets and eddy currents.

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Solid State Tesla Coil Plays Music


If you’ve ever wanted to build a Tesla coil but found them to be prohibitively expensive and/or complicated, look no further! [Richard] has built a solid-state Tesla coil that has a minimum of parts and is relatively easy to build as well.

This Tesla coil is built around an air-core transformer that steps a low DC voltage up to a very high AC voltage. The core can be hand-wound or purchased as a unit. The drive circuit is where this Tesla coil built is set apart from the others. A Tesla coil generally makes use of a spark gap, but [Richard] is using the Power Pulse Modulator PWM-OCXi v2 which does the switching with transistors instead. The Tesla coil will function with one drive circuit but [Richard] notes that it is more stable with two.

The build doesn’t stop with the solid-state circuitry, though. [Richard] used an Arduino with software normally used to drive a speaker to get his Tesla coil to play music. Be sure to check out the video after the break. If you’re looking for a Tesla coil that is more Halloween-appropriate, you can take a look at this Tesla coil that shocks pumpkins!

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High Altitude Balloon Keeps Going


Here’s a post from the AMSAT-UK high altitude balloon blog. It’s a great story about a balloon cruising at about 12km above the Earth completing its sixth circumnavigation of the planet. That post is from October 4th, and two weeks later the balloon is still going strong. Right now it’s over the Baltic heading into Russia with no sign of stopping or popping any time soon.

globeThe balloon was launched July 12, 2014 from Silverstone, UK. In the 100 days since then, this balloon has covered 144168 kilometers and has crossed its launching longitude six times. Even if this balloon weren’t trapped at high latitudes (including coming within 9 km of the pole), this balloon has still travelled more than three times the equatorial circumference of the Earth.

The balloon was built by [Leo Bodnar] a.k.a. [M0XER] with a self-made plastic foil envelope. The solar-powered payload weighs only 11 grams. It’s an exceptional accomplishment and one that has smashed all the amateur high altitude balloon distance records we can find.

Creating a 2D Film with 3D Printed Frames


In the early days of film, there was a time when French 3D Cinema was called “Relief Cinema”. The word, Relief, however brings the idea of something physical to mind when we hear it, which is why the name was later tweaked to include the more intangible term, 3D. Playing on this fact, French Artist [Julien Maire] has designed and built an over-sized projector for his installation titled “Relief“, that creates an animation by passing light through a series of individual 3D vignettes.

[Julien’s] intricately built projection reel in itself is an impressive mechanical feat, arguably out-staging the image it exists to produce on the wall of the gallery space. The eighty-five individual frames that create the short clip of a man digging a hole in the ground, consist of small figurines made with a stereo lithography printer. The semi-transparent nature of the resin used by the SLA printer gives the shadow cast by the projector a series of foggy-values that create a three dimensional appearance instead of merely casting a silhouette of the shape. This installation blends new and old technologies together to produce something we’re familiar with, but leaves us admiring an object that we’ve never seen before.


[Julien’s] “Relief” is currently being exhibited at iMAL (interactive Media Art Laboratory in Brussels) which will run throughout the month of October. If you happen to find yourself on a long stay in Europe before the Hardware Workshop in Munich, you could make a pitstop and check it out!

Open-Source Water Quality Tester

Open-Source Water Quality Tester

Contaminated water is a huge problem in many third-world countries. Impure water leads to many serious health problems, especially in children. Installing a water purification system seems like a simple solution to this problem, but choosing the right purification system depends on the level of contaminants in the water.

Water turbidity testers are often used to measure the severity of water contamination. Unfortunately most commercial water turbidity testers are very expensive, so [Wijnen, Anzalone, and Pearce] set out to develop a much more affordable open-source tester. Their tester performs just as well as commercial units, but costs 7-15 times less.

The open-source water tester was designed in OpenSCAD and 3d printed. It houses an Arduino with a custom shield that measures the frequency from several TSL235R light-to-frequency converters. An LED illuminates the water and the sensors measure how much light is diffused and reflected off of particles in the water. Another sensor measures the brightness of the LED as a baseline reference. The turbidity of the water is calculated from the brightness values, and is displayed on a character LCD. More details about the tester are included in a fairly extensive paper.

[Thanks Andrew]

Microbial Fuel Cell with a Side of Betta Fish

A betta fish swims in an MFC.

Move over, potato batteries: DIY microbial fuel cells are here to stay! A microbial fuel cell (MFC) is a device that uses bacteria in an anaerobic (oxygen-poor) environment to convert chemical energy into electricity. [drdan152] posted steps on how to make a soil-based MFC  with a neat twist: it’s also a fishbowl for a betta fish.

[drdan152] used soil from the wetlands, referred to as “muck.” This nutrient-rich soil provided a hearty supply of bacteria, especially Geobacter species, known for their uncanny ability to transport electrons outside their cells using bacterial nanowires. The proton exchange membrane (PEM) was made up of salt, water, and agar. After some initial runs, [drdan152] determined that flat char cloth made the best anode, while red copper wire served as the cathode. Assembling the MFC was as simple as surrounding the anode with a thick layer of muck on all sides, adding the PEM on top, followed by water. The cathode was situated halfway out of the water.

After a couple of days, the voltage increased in proportion to the amount of bacteria growing on the anode. The betta fish can happily live in this habitat for a short period of time(it still has to be fed, of course), and the bacteria certainly won’t mind – the fish’s excrement provides an additional food supply. As a bonus, the water is kept clean. However, like any aquarium, the water will need to be changed periodically as carbon dioxide byproduct accumulates from the fish’s respiration and the MFC (high carbon dioxide levels = dead betta fish).

The MFC generates 725 mV. [drdan152] is not satisfied with that number, and is testing out charge pump circuits to generate as much as 3V. We are looking forward to seeing the results. We also wonder if a small aquatic plant could help make it a more self-sustaining environment for the fish. In the meantime, [drdan152] is encouraging others to try larger-scale versions of this MFC. Perhaps MFC-powered carnivorous robots doubling as mobile aquariums are in our near future.


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