Charging An Electric Supercar With Lemons, Kids, And The Sun

First things first: the tease on this video, that an electric supercar can be charged from a massive lemon battery array, is exactly that – a tease. Despite that, it makes for an interesting story and a great attempt to get kids exposed to science and engineering.

The story goes that [Mark] was approached by Volkswagen to help charge the batteries on their entry for the upcoming Pikes Peak International Hill Climb, the annual “Race to the Clouds” in Colorado. Racers are tortured by a 4,700′ (1,440 m) vertical climb over a 12.42 mile (20 km) course that features 156 switchback turns. Volkswagen’s entry is an electric supercar, and they sent [Mark] a portable battery cart to charge up the best way he saw fit.

Teaming up with [William Osman], the first attempt was a massive array of lemon cells, made with waterjet-cut strips of zinc and copper held in a plywood frame. Studded with 1,232 lemons, the battery performed just about as well as you’d expect it would. Plan B was cute, and another of [Mark]’s attempts to pad his “Funnest Uncle Ever” score a bit. He devised a zip line with regenerative braking to charge a cordless drill battery, and then indirectly harvested the energy in the battery by turning it into lemonade for a bunch of kids. The sugared-up kids rode the zip line till the battery was charged.

That was still a drop in the bucket, though, so Plan C saw [Mark] install a large solar array on his roof; the tie-in here was that the lemon-powered kids got to design a cleaning system for the solar array. A weak link, to be sure, but the kids had fun, and we can’t deny that the car will at least be partially lemon-powered when it heads up the hill.

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Free E-Book: Software Defined Radio for Engineers

We really like when a vendor finds a great book on a topic — probably one they care about — and makes it available for free. Analog Devices does this regularly and one you should probably have a look at is Software Defined Radio for Engineers. The book goes for $100 or so on Amazon, and while a digital copy has pluses and minuses, it is hard to beat the $0 price.

The book by [Travis F. Collins], [Robin Getz], [Di Pu], and [Alexander M. Wyglinski] covers a range of topics in 11 chapters. There’s also a website with more information including video lectures and projects forthcoming that appear to use the Pluto SDR. We have a Pluto and have been meaning to write more about it including the hack to make it think it has a better RF chip inside. The hack may not result in meeting all the device specs, but it does work to increase the frequency range and bandwidth. However, the book isn’t tied to a specific piece of hardware.

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Handmade Robot Brings Stop Motion to Life

Stop motion animation is often called a lost art, as doing it (or at least, doing it well) is incredibly difficult and time consuming. Every detail on the screen, no matter how minute, has to be placed by human hands hundreds of times so that it looks smooth when played back at normal speed. The unique look of stop motion is desirable enough that it still does get produced, but it’s far less common than hand drawn or even computer animation.

If you ever wanted to know just how much work goes into producing even a few minutes of stop motion animation, look no farther than the fascinating work of [Special Krio]. He not only documented the incredible attention to detail required to produce high quality animation with this method, but also the creation of his custom robotic character.

Characters in stop motion animation often have multiple interchangeable heads to enable switching between different expressions. But with his robotic character, [Special Krio] only has to worry about the environments, and allow his mechanized star do the “acting”. This saves time, which can be used for things such as making 45 individual resin “drops” to animate pouring a cup of tea (seriously, go look).

To build his character, [Special Krio] first modeled her out of terracotta to get the exact look he wanted. He then used a DIY 3D laser scanner to create a digital model, which in turn he used to help design internal structures and components which he 3D printed on an Ultimaker. The terracotta original was used once again when it was time to make molds for the character’s skin, which was done with RTV rubber. Then it was just the small matter of painting all the details and making her clothes. All told, the few minutes of video after the break took years to produce.

This isn’t the first time we’ve seen 3D printing used to create stop motion animation, but the final product here is really in a league of its own.

[Thanks to Antonio for the tip.]

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R/C Rocket-Beest Burns Up Fuses Out There Alone

We’re beginning to think the “S” in [Jeremy S Cook] stands for strandbeest. He’ll be the talk of the 4th of July picnic once he brings out his latest build—a weaponized, remote-controlled strandbeest that shoots bottle rockets. There are a bank of money shots up on Imgur.

This ‘beest is the natural next step after his remote-controlled walker, which we featured a month or so ago. Like that one, the locomotion comes from a pair of micro gear motors that are controlled by an Arduino Nano over Bluetooth. The pyrotechnics begin when nitinol wire cleverly strung across two lever nuts is triggered. All the electronics are housed inside a 3D-printed box that [Jeremy] designed to sit in the middle of the legs. We love the face plate he added later in the build, because those gumdrop LED eyes are sweet.

Can you believe that this vehicle of destruction began as a pile of innocent, pasta-colored pieces of kit? We dig the camouflaged battleship paint job, ’cause it really toughens up the whole aesthetic. And really, that’s probably what you want if you’re driving around a spindly beast that can just shoot rockets whenever. Let’s light this candle after the break, shall we?

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xLIDAR Is A Merry-Go-Round Of Time-Of-Flight Sensors

[JRodrigo]’s xLIDAR project is one of those ideas that seemed so attractively workable that it went directly to a PCB prototype without doing much stopping along the way. The concept was to mount a trio of outward-facing VL53L0X distance sensors to a small PCB disk, and then turn that disk with a motor and belt while taking readings. As the sensors turn, their distance readings can be used to paint a picture of the immediate surroundings (at least within about 1 meter, which is the maximum range of the VL53L0X.)

The hardware is made to be accessible and has a strong element of “what you see is what you get.” The distance sensors are on small breakout boards, and the board turns the sensor disk via a DC motor and 3D printed belt drive. Even the method of encoding the disk’s movement and zero position has the same WYSIWYG straightforwardness: a spring contact and an interrupted bare copper trace on the bottom of the sensor disk acts as a physical switch. In fact, exposed copper traces in concentric circular patterns and spring pins taken from an SD card socket are what provide power and communications as the disk turns.

The prototype looks good and sounds like it should work, but how well does it hold up? We’ll find out once [JRodrigo] does some testing. Until then, the board designs are available on the project’s GitHub repository if anyone wants to take a shot at their own approach without starting from scratch.

How Etak Paved the Way to Personal Navigation

Our recent “Retrotechtacular” feature on an early 1970s dead-reckoning car navigation system stirred a memory of another pre-GPS solution for the question that had vexed the motoring public on road trips into unfamiliar areas for decades: “Where the heck are we?” In an age when the tattered remains of long-outdated paper roadmaps were often the best navigational aid a driver had, the dream of an in-dash scrolling map seemed like something Q would build for James Bond to destroy.

And yet, in the mid-1980s, just such a device was designed and made available to the public. Dubbed Etak, the system was simultaneously far ahead of its time and doomed to failure by the constellation of global positioning satellites being assembled overhead as it was being rolled out. Given the constraints it was operating under, Etak worked very well, and even managed to introduce some of the features of modern GPS that we take for granted, such as searching for services and businesses. Here’s a little bit about how the system came to be and how it worked.

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When The Going Gets Tough, These Wheels Transform To Tracks

When we want to build something to go where wheels could not, the typical solution is to use tracks. But the greater mobility comes with trade-offs: one example being tracked vehicles can’t go as fast as a wheeled counterpart. Information released by DARPA’s ground experimental vehicle technology (GXV-T) program showed what might come out of asking “why can’t we switch to tracks just when we need them?”

This ambitious goal to literally reinvent the wheel was tackled by Carnegie Mellon’s National Robotics Engineering Center. They delivered the “Reconfigurable Wheel-Track” (RWT) that can either roll like a wheel or travel on its tracks. A HMMWV serves as an appropriate demonstration chassis, where two or all four of its wheels were replaced by RWTs. In the video (embedded below) it is seen quickly transforming from one mode to another while moving. An obviously desirable feature that looks challenging to implement. This might not be as dramatic of a transformation as a walking robot that can roll up into a wheel but it has the advantage of being more immediately feasible for human-scale vehicles.

The RWT is not the only terrain mobility project in this DARPA announcement but this specific idea is one we would love to see scaled downed to become a 3D-printable robot module. And though our Hackaday Prize Robotics Module Challenge has already concluded, there are more challenges still to come. The other umbrella of GXV-T is “crew augmentation” giving operators better idea of what’s going around them. The projects there might inspire something you can submit to our upcoming Human-Computer Interface Challenge, check them out!

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