$50 Backyard Rollercoaster

December 8, 2013 by James Hobson 36 Comments

This is great. What happens when you bet a group of friends they can’t build a roller coaster in their backyard for under $50? They build one.

They built it almost entirely out of old forklift pallets, some wood from Home Depot, assorted nails and screws, some caster wheels and a folding seat from an old arena. It was built in just over 9 hours by three people. Once assembled they tested it with a 15lb cinder block — safety first right? The cinder block survived the ride, and by that logic, a 160lb+ person should be fine as well!

Well… they were right! To finish it up and get into the holiday spirit they also decked it out in Christmas lights and let the neighborhood kids use it all night. The total came to $49.27 from Home Depot for the wood and wheels.

Stick around after the break to see a .GIF of it in action!

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OpenMV: The Camera For Your Next Project

December 8, 2013 by Brian Benchoff 12 Comments

Last month we saw [Ibrahim] tackle the lack of cheap, high speed, high resolution serial cameras with full force. He designed a serial camera based on the STM32F4 microcontroller that’s the perfect solution to anyone wanting to add visual processing or machine vision to a project. It’s cheap, too: instead of the $100 or so you’d spend on a high-end serial camera, [Ibrahim]’s version only has about $15 in parts.

Now he’s back at it again, with 25 FPS face detection, 30 FPS color detection, a new board with a micro SD socket, and support for USB OTG full speed. [Ibrahim] has been hard at work deep in the bowels of the STM32F4 micro, playing around with the core coupled memory. This allows for some very fast image processing, combined with the micro running at 168 MHz makes for very fast face and color detection.

As for a few benchmarks for this camera, the maximum resolution is 1280×1024, and at 88×72 resolution this little board can output at 60 FPS. Of course everything is limited by the speed of the serial connection, but there’s a lot of potential in this small serial camera.

No word on how much this board will cost, but [Ibrahim] may be putting a few boards up on Tindie shortly. Here’s to hoping he’ll send us an email telling us when his store is open.

An Awesome Electric Bike

December 8, 2013 by Brian Benchoff 16 Comments

bike

Converting a motorcycle to electric is always a favorite project of ours, and [Peter]’s build is up there with the rest of them.

The bike is a 2002 ZX6E he bought from a salvage shop. It had been parted out over the years and for $250 this very light aluminum frame made the for the perfect electric conversion frame. After learning MIG welding from his brother, [Peter] cut up a few plates and built a motor mount for his new 4.2 kW power plant.

The controller is a 300 amp IGBT he found on eBay, with an extraordinarily sturdy looking circuit built into an ammo box. The motor from the bike was replaced with 16 60Ah LiFe cells providing 52 volts. [Peter] also built his own battery management system using a Cypress PSoC 3 microcontroller and a beautiful custom PCB.

It’s still a long way from being finished, but already [Peter] has a great looking bike and an awesome weekend project on his hands.

Four Cable Drawing Machine Pulls Our Strings

December 8, 2013 by Adam Fabio 22 Comments

sandplotter

[David] has created a four cable drawing machine for the Telus Spark Science Centre in Canada. Hackaday has featured [David’s] unconventional drawing contraptions before, specifically his center pivot pen plotter. The drawing machine is a new take on a drawbot, and could be considered to be close cousins with [Dan’s] SkyCam. The premise is simple: A stepper motor with a reel of string is placed at each corner of a square. The strings for all four motors come together at a center weight. When all four strings are taut, the weight is lifted off the drawing surface. When a bit of slack is added into the strings, gravity pulls the weight down to touch the sand.

It’s at this point that a simple premise becomes a complex implementation. Moving the weight in one direction is a matter of reeling out string on one motor, and reeling in string on the other. But what about the two “un driven” strings? They have to be slack enough to allow movement in the driven direction, but not so slack that the weight can dig in and tumble on the sand, causing a tangle. To handle some of these questions, [David] called on [Kevin] to write some software. [Kevin] created a custom kinematics module for LinuxCNC to control the drawing machine. The drawing machine runs on Gerber Code, similar to a CNC. Simply feed the machine Cartesian coordinates, and [Kevin’s] module converts to steps.

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Arduino RFID Car Starter

December 8, 2013 by James Hobson 29 Comments

[Pierre] recently bought his first car and decided to make his own RFID electric starter for it!

An Arduino Nano controls two relays which in turn can turn the car on, start it, and turn it off. Instead of adding a button for “push to start” he opted for a 13.56MHz RFID module. Now when he passes his RFID badge across the dash, the car turns on — if it’s held there for over a second, the car starts. Another pass and it will turn off.

His eventual goal is to relocate this circuit closer to the wheel and use an NFC ring to start it! He’s done an amazing job hiding all the components under the trim in his car so far, you can’t tell anything is amiss! Check out the demonstration in the video after the break.

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LED Concert Dress

December 7, 2013 by James Hobson 13 Comments

[Geri] has an awesome brother. He made this amazing LED dress for her to wear at the [Taylor Swift] concert last weekend!

As you may or may not know, she encourages her fans to bring “glowy” things to wave around at her concerts. A quick check of the exhibition arena’s conditions of entry, and it seemed like LEDs would be allowed, so [Patrick] got to work.

He’s using a set of waterproof red LED strips and a cheap controller ordered from China. They needed a rather beefy battery pack so [Patrick] threw together a switchmode buck converter to drop a 19.8V 4.5A/h battery pack to a constant 12V for the LED controller. Not wanting to mess up the red cocktail dress, their mom sewed the strips into place. The dress is super bright and looks great — it draws about 25W, so the battery pack should last for the entire duration of the concert.

Unfortunately about a week before the concert they discovered Vector Arena is not allowing LED lights into the concert, which as you can imagine, was quite heartbreaking.

Thankfully, someone reached out to the organizers and they made an exception for them! [Geri] even ended up on the front page of their local newspaper! Stick around after the break to see a video of the dress in action!

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Will Dance For Bitcoin

December 7, 2013 by Eric Evenchick 6 Comments

It seems that Bitcoin is all over the news nowadays, but the Bitcoin Bot is probably the first robot that will dance for Bitcoins.

[Ryan] at HeatSync Labs in Mesa, AZ, is a fan of the cryptocurrency, and decided to build something to accept it. He discovered that Coinbase, a popular hosted Bitcoin wallet service, has a callback API. This causes Coinbase to fetch a specified URL any time a wallet receives a transaction, and provides information on the transaction in the request. A Python script handles these requests and updates a running count of the BTC balance sent to the robot’s wallet.

On the hardware side, an Arduino with an Ethernet Shield checks the balance. If it has changed, it calls the dance function and the luau girl dances.

The robot sits in the window of the hackerspace, so anyone passing by can read about Bitcoin and make a donation. The source code is on Github, and a video follows after the break.

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