Transmit FM Using Raspberry Pi And No Additional Hardware

December 10, 2012 by Mike Szczys 75 Comments

Now here’s a project that actually hacks the Rapsberry Pi rather than just using it as an embedded computer. [Londons Explorer] figured out how to turn the RPi into an FM transmitter. For now it’s done entirely in the user space, but we’re sure it could be improved if someone wanted to drill down further into the hardware. For those wanting to give it a try he’s rolled everything into a simple python package.

The technique requires nothing additional except a 20cm wire to serve as an antenna. The trick is to map GPIO pin number 4 to a position in memory. The clock generator is then used to toggle this pin at 100 MHz, which is the frequency to which your radio should be tuned. A fractional divider adjusts the frequency based on the sound file being transmitted.

The proof of concept for this was able to reliably transmit at a distance of about fifty meters through several walls. The problem is that this technique is limited in the amount of data which can be sent. Right now it’s only about 6-bit audio. But descending deeper through the abstraction layers to put DMA (Direct Memory Access) to use may be able to improve upon this.

[Thanks Owen via Reddit]

Morse Code Transceiver Based On Gameboy Color Camera

December 10, 2012 by Eric Evenchick 10 Comments

For their final project in a microcontrollers course, [Trudy] and [Josh] designed a pair of morse code transceivers. To send the message, they used an array of IR LEDs. The message is received using a Gameboy Color Camera, which takes care of basic image processing. This allows a 8-bit ATMega1284p microcontroller to handle transmitting and receiving messages.

The transmission LEDs form a square pattern with one LED in the center. The four outside LEDs are used to help the receiver locate the center LED, and the center LED is used for transmitting the message.

The Gameboy Color Camera is based on a M64282FP image sensor. This sensor uses an SPI-like protocol, which they implemented on the ATMega. It allows them to grab frames from the camera, and get the value of specific pixels. From this data they find the center LED and process the message.

The result can transmit messages of 200 letters at a time, but the speed is limited by the frame rate of the camera. If you have a Gameboy Color Camera lying around, their detailed write up might provide some inspiration and information on how to use it in a hack.

An Automat Of Wireless 3D Printers

December 10, 2012 by Brian Benchoff 17 Comments

vending

There’s a lot of really cool 3D printer stuff happening in the fashion district of NYC this month. It’s called 3DEA, and shows off the awesomeness of Shapeways, Ultimaker, and the Up! 3D printer to all the fashionistas, trend setters, and the caliphate of coolness that is midtown Manhattan. The folks at Ultimaker wanted to bring something awesome to this exposition and came up with the Vendingwall: a wall of 3D printers connected into a vending machine able to print multiple objects at once.

Ultimaker has made a name for themselves as the top open source 3D printer manufacturer with absolutely impressive build quality and even a 20-foot-high printer able to manufacture entire rooms. The Vendingwall is their next step in the commercialization of 3D printers; all you need to do to create your own 3D printed object is walk up to the Vendingwall, order a print, and later retrieve from one of the many Ultimakers.

To control these ranks of Ultimakers, a piece of software runs on a wireless router loaded up with OpenWRT. From there, the router serves up a website powered by JQuery-mobile for all the Android and iDevices at the 3DEA open house, turning a wall of 3D printers into a vending machine reminiscent of the automats of yore.

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10 Ways To Etch PCBs At Home

December 10, 2012 by Brian Benchoff 46 Comments

[youtube=http://www.youtube.com/watch?v=Q4tWEse2rDI&w=580]

There are a ton of benefits for etching your own circuit boards at home, chief among them the ability to design a circuit in the morning and have a prototype in your hand by lunch. There’s always the question of how to etch the board, but [NurdRage] over on Youtube has all the chemistry covered on ten different etchant solutions for DIY PCB manufacturing.

The peroxide-based methods use simple over-the-counter Hydrogen Peroxide to remove all the copper on a PCB. By combining H2O2 with either Hydrochloric (muriatic) acid or Sulfuric acid, you’ll get a relatively easy to acquire and somewhat safe etching solution.

Historically, the favorite etchant for the home PCB manufacturer has been Ferric Chloride and is still surprisingly available at a few Radio Shacks around the US. Another chloride etchant – Copper Chloride – is one of the most reusable etchants available, able to be regenerated by simply bubbling air through the solution. You can actually make Copper Chloride etchant by reducing down the products of an H2O2 + HCl etchant, making this a very good etchant for PCB pros.

In the ‘miscellaneous’ category, [NurdRage] goes over some alternative etchants such as Bleach and HCl, Nitric acid, and potassium nitrate and HCl; the potassium nitrate etchant is fairly similar to aqua regia, so if you’ve ever wanted a gold PCB, this is the way to go.

Balancing the ease of production and safety of all these etchants, we’ll stick with our Hydrogen Peroxide and HCl etchant for now, at least until we move up to CuCl for the best etching machine we’ve ever seen.

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FUBAR Labs Builds A Rocket Engine

December 9, 2012 by Brian Benchoff 27 Comments

engine

[Graham] over at FUBAR labs took it upon himself to build a rocket engine. This isn’t a simple solid-fuel motor, though: [Graham] went all out and built a liquid-fueled engine that is ignited with a spark plug.

The build started off with a very small ‘igniter’ engine meant to shoot sparks into a larger engine. This engine is fueled with ethanol and air – not the best fuel for a rocket engine by a long shot but save and cheap enough to do a few serious experiments with.

To test out this small engine, [Graham] made a test platform out of aluminum extrusion to remotely control the fuel and oxidizer valves. The valves are controlled by an Arduino and XBee for remote operation and a telemetry downlink for measuring the fluid flow into the engine.

After he had some experience with pressure, plumbing, valves, and engines, [Graham] upgraded his fuel and oxidizer to gaseous oxygen and ethanol. With proper safety protocol in place, [Graham] was able to a series of three 3-second burns less than a minute apart as well as a single burn lasting nearly 5 seconds.

Even though [Graham] eschewed the usual stainless steel construction of rocket engines (his engine is milled out of aluminum), he demonstrated it is possible to build a real liquid-fueled rocket engine at home.

The Burrito Bomber

December 9, 2012 by Eric Evenchick 40 Comments

The Burrito Bomber, created by the folks at Darwin Aerospace, claims to be “the world’s first Mexican food delivery system.” The delivery process starts with the customer placing an order through the Flask based Burrito Bomber webapp. The customer’s location is grabbed from their smartphone using the HTML5 Geolocation API and used to generate a waypoint file for the drone. Next, the order is placed into a delivery tube, loaded onto the drone, and the waypoint file is uploaded to the drone. Finally, the drone flies to your location and drops the delivery tube. A parachute deploys to safely deliver the tasty payload.

The drone is based on a Skywalker X-8 airframe and the Quantum RTR Bomb System. The bomb system provides the basic mechanism to hold and drop a payload, but Darwin Airspace designed their own 3D printed parts for the delivery tube. These parts are available on Thingiverse. The drone is controlled autonomously by ArduPilot, which uses the webapp’s waypoint output to guide the drone to the target and release the payload.

Unfortunately, this can’t be a commercial product yet due to FAA regulations, but the FAA is required to figure out commercial drone regulations by 2015. Hopefully in 2015 we’ll all be able to order burritos by air.

For all the source and models, check out the group’s Github. There’s also a video of the bomber in action after the break.

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USB NeXT Keyboard

December 9, 2012 by Eric Evenchick 24 Comments

[Ladyada] and [pt] had an old keyboard from NeXT, but since it used a custom protocol it wasn’t usable with modern hardware. So they built a custom device to convert the NeXT protocol to USB.

The device uses a Arduino Micro to read data from the keyboard and communicate as a HID device over USB. It connects to the keyboard using the original mini-DIN connector, and is housed in the classic Altoids tin enclosure.

Since the protocol used by NeXT isn’t standard, they had to figure it out and write some code to interpret it. The keyboard communicates bidirectionally with the computer, so they needed to send the correct frames to key data back.

Fortunately, they hit on a Japanese keyboard enthusiast’s site, which had protocol specifications. They implemented this protocol on the Micro, and used the Keyboard library to create a HID device.

The final product is an adapter for NeXT to USB, which allows for the old keyboards to be used on any computer with USB. It’s a good way to bring back life to some otherwise unusable antique hardware.