Wireless Pinball Controller For Tablet Gaming

March 4, 2013 by 6 Comments

wireless-pinball-controller

This wooden box is a wireless pinball controller and tablet stand. The idea is to set it on a workbench to give you some of the thrill of standing and playing the real thing. [Jeff] has been rather addicted to playing a pinball app on Android lately, and started the journey because he needed a way to give his thumbs some relief.

An Arduino monitors buttons on either side of this wooden controller. [Jeff] is new to working with hardware (he’s a Linux Kernel developer by trade) and was immediately struck with button debouncing issues. Rather than handle this in software (we’ve got a super-messy thread on that issue with our favorite at the bottom) he chose a hardware solution by building an SR latch out of two NAND gates.

With the inputs sorted out he added a BlueSMiRF board to the project which allowed him to connect a Nexus 7 tablet via Bluetooth. At this point he ran into some problems getting the device to respond to his control as if it were an external keyboard. His stop-gap solution was to switch to a Galaxy Tab 10.1 which wasn’t throwing cryptic errors. Hopefully he’ll fix this in the next iteration which will also include adding a plunger to launch the pinball, a part which just arrived in the mail as he was writing up this success.

We’ve embedded his quick demo video after the break.

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A Longboard Speed And Distance Computer

March 4, 2013 by 17 Comments

longboard-speed-distance-comptuer

Why should cyclists have all of the fancy toys? Bicycle computers are very common these days but you won’t find similar hardware for skateboards and longboards. [KobraX22] isn’t taking it lying down. He built this speed and distance computer for his longboard. It doesn’t use very many components and should be easy to install.

The device monitors the rotation of one of the wheels by mounting a reflectance sensor on one of the trucks. It points toward the inside of a wheel which has a piece of black tape on it. Every time the tape passes it prevents the IR led from reflecting back at its paired receiver. This lets the Arduino count the revolutions, which are then paired with the wheel diameter to calculate speed as well as distance traveled. Of course the wheels wear down over time to so frequent riders will have to take new measurements at regular intervals.

[KobraX22] went with a QRB1114 sensor. It costs less than $2 and doesn’t require him to embed a magnet in the wheel like a hall effect sensor setup would have. It also shouldn’t interfere with any other fancy wheel hacks you’ve done, like adding a POV display.

[via Reddit]

Retrotechtacular: Donner 3500 Portable Analog Computer

March 4, 2013 by 40 Comments

What if we told you we had a computer you can take with you? What if it only weighed 28 pounds? This is a pretty hard sell when today you can get a 1.5 GHz quad-core processor packing computer to carry in your pocket which weighs less than 5 ounces. But back in the day the Donner 3500 was something to raise an eyebrow at, especially for tinkerers like us.

The machine was unveiled in 1959 as an analog computer. Instead of accepting programs via a terminal, or punch cards, it worked more like a breadboard. The top of the case features a grid of connectors (they look like banana plugs to us but we’re not sure). The kit came with components which the user could plug into the top to make the machine function (or compute) in different ways.

We’re skeptical as to how portable this actually was. It used vacuum tubes which are not fans of being jostled. Still, coming during the days when most computers were taking up entire buildings we guess the marketing claim holds up. If you’d like to see a bit more about the machine’s internals check out this forum post.

Preserving Locomotives With 3D Laser Scanning And 3D Printing

March 4, 2013 by 3 Comments

[Chris Thorpe] is a model railroading aficionado, and from his earliest memories he was infatuated with the narrow gauge locomotives that plied their odd steel tracks in northern Wales. Of course [Chris] went on to create model railroads, but kit manufacturers such as Airfix and Hornby didn’t take much interest in the small strange trains of the Ffestiniog railway.

The days where manufacturing plastic models meant paying tens of thousands of dollars in tooling for injection molds are slowly coming to an end thanks to 3D printing, so [Chris] thought it would be a great idea to create his own models of these small locomotives with 3D laser scanners and high quality 3D printers.

[Chris] started a kickstarter to fund a 3D laser scanning expedition to the workshop where the four oldest locomotives of the Ffestiniog railway were being reconditioned for their 150th anniversary. The 3D printed models he’s able to produce with his data have amazing quality; with a bit of paint and a few bits of brass, these models would fit right in to any model railway.

Even better than providing scale narrow gauge engines to model railway enthusiasts around the world is the fact that [Chris] has demonstrated the feasibility of using modern technology to recreate both famous and underappreciated technological relics in plastic for future generations. There’s a lot that can be done with a laser scanner in a railway or air museum or [Jay Leno]’s garage, so we’d love to see more 3D printed models of engineering achievements make their way onto Kickstarter.

Using OpenCV With The Raspberry Pi

March 4, 2013 by 47 Comments

When we first heard of the Raspberry Pi we were elated that projects that once required a full-blown computer could now be done on a tiny, and cheap board running Linux. Unfortunately, we haven’t seen much in the way of using computer vision algorithms on the Raspi, but thanks to [Lentin] the world of OpenCV is now accessable to Raspberry Pi users everywhere.

[Lentin] didn’t feel like installing OpenCV from its source, a process that takes the better part of a day. Instead, he installed it using the synaptic package manager. After connecting a webcam, [Lentin] ssh’d into his Raspi and installed a face detection example script that comes with OpenCV.

It should be noted that [Lentin]’s install of OpenCV isn’t exactly fast, but for a lot of projects being able to update a face tracker five times a second is more than enough. Once the Raspberry Pi camera module is released the speed of face detection on a Raspi should increase dramatically, though, leading to even more useful computer vision builds with the Raspberry Pi.

Warming Seeds In An Outdoor Garden

March 4, 2013 by 16 Comments

resistor-string

Spring is almost here and with that the green thumbs out there are preparing for their summer gardens. It’s usually a good idea to get a jump on all your gardening activities by starting seeds indoors, but with this comes the problem of making sure juvenile plants get enough sunlight. Putting a few seeds on a window sill will keep seeds warm enough to start germinating, but that will drastically reduce the amount of sunlight available for any given day. The best solution is to make sure the seeds are kept warm outside, but for wont of a properly placed clothes dryer vent [Tim] decided to make a solar soil heater using junk he had lying around.

[Tim] constructed a simple heater cartridge using a few 5 and 10 Ω resistors. These were sealed inside a piece of copper pipe with heat shrink tubing and silicone. The solution to powering this heater cartridge, though, is an impressive display of thinking outside the box.

The cartridge is powered by a solar lantern – the same kind you’d find illuminating a garden path at night and recharging during the day. After inserting the cartridge in a hill of seeds, the heater provides a little bit of warmth to get the seeds through the night. During the day, the battery in the solar lantern recharges, providing just enough power to cycle through another night.

It works for [Tim] in his native New England, so we’re betting it’s good enough for just about any growing region.

DRM Chair Only Works 8 Times

March 4, 2013 by 104 Comments

chair

Download a song from iTunes, and you can only add that song to the music library of five other computers. Grab a copy of the latest Microsoft Office, and you’d better hope you won’t be upgrading your computer any time soon. Obviously DRM is a great tool for companies to make sure we only use software and data as intended, but outside planned obsolescence, there isn’t much in the way of DRM for physical objects.

This is where a team from the University of Art and Design in Lausanne, Switzerland comes in. They designed a chair that can only be sat upon eight times. After that, the chair falls apart necessitating the purchase of a new chair. Somewhere in the flat-pack furniture industry, someone is kicking themselves for not thinking of this sooner while another is wondering how they made a chair last so long.

The design of the chair is fairly simple; all the joints of the chair are cast in wax with a piece of nichrome wire embedded in the wax. An Arduino with a small switch keeps track of how many times the chair has been used, while a solenoid taps out how many uses are left in the chair every time the user gets up. When the internal counter reaches zero, a relay sends power through the nichrome wire, melting the wax, and returning the chair to its native dowel rod and wooden board form.

Melting wax wasn’t the team’s first choice to rapidly disassemble a chair; their first experiments used gunpowder. This idea nearly worked, but it was soon realized no one on the team wanted to sit on a primed and loaded chair. You can see the videos of the wax model failing after the break.

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