Straight from the Aerospace Controls Laboratory comes a variable-pitch quadrocopter designed by [Mark Cutler] and [Jonathan P. Howe]. While real, full-sized helicopters always have variable pitch rotors, changing the pitch of the blades on remote control aircraft is a fairly uncommon modification. When it’s done right, though, being able to easily change the thrust direction of a propeller leads to very cool flights, like having an airplane hover nose down.

[Mark] and [Jonathan] identified two interesting techniques that a variable pitch quadrotor can bring to the table. The first is trajectory generation  - because of the added maneuverability, their quadrotor can perform more aggressive banking turns when following a preprogrammed path. The second benefit to their design is quick deceleration. In the first video after the break, you can compare the deceleration rates of a variable pitch and fixed pitch quadrocopter. While the fixed pitch quad continues climbing after being commanded to stop, the quadrocopter outfitted with variable pitch rotors can stop on a dime.

We’re still waiting for the equivalent of the Red Bull Air Races for quadrocopter builds, but when it comes we know what would win the slalom event.

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[Adrian Bowyer] just posted his progress with multicolored printing to the RepRap blog.

The new developments are a continuation of [Adrian]‘s experiments with a mixer extruder that squirts four different colored filaments out of the same nozzle. [Myles Corbett] took this idea and ran with it producing the two-color print seen above. To squirt two different colored filaments out of the nozzle, [Myles] used two Bowden extruders mounted near the apex of the RepRap with tubes leading to the nozzle. Right now, the color of a print is controlled by loosening the grip screws of the extruder, but there are plans for moving that task over to electronic control of the extruders.

While it may be only black and white now, it’ll be a very interesting development once five extruders are loaded up with cyan, magenta, yellow, black, and white filament. Yes, it is now theoretically possible to print full-color 3D objects on a RepRap. While we’re not looking forward towards having to upgrade our one-motor extruder to a four- or five-motor model, the possibilities for desktop fabrication are becoming amazing.

Since [th3badwolf] realized a wrist watch is the ultimate men’s fashion accessory, he’s been trolling around eBay looking for a nice looking, but still inexpensive wearable chronometer. The Fauxlex brand isn’t normally regarded for accurate time keeping, so he decided measure the accuracy of his off-brand watches in a really clever way.

[th3badwolf] had a camera with a built-in intervalometer lying around and figured if the camera was set to take one picture a minute, the second hand would stay still while the minute and hour hands moved. An hour-long test confirmed his theory and he pointed his cameras towards his knock-off watches.

In the resulting time-lapse video available after the break, [th3badwolf] calculated that the first and third watches lose about 24 seconds a day. He attributes this fact to the watches having the same clockworks. The second watch gains nearly three minutes a day, and he’s trying to send that one back to the supplier. We’re not sure how that will end up, but at least [th3badwolf] has two reasonably accurate watches now.

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[Lewis] wanted to control MIDI devices with the huge touch screen that is his Android phone. After he couldn’t find a simple hardware implementation of MIDI out, he turned to an IOIO board to send MIDI notes to just about any imaginable musical hardware. It’s a clean build and fills a gap in the abilities of the Android platform.

Because of the woeful support of MIDI in Android, [Lewis] couldn’t find a good way to push MIDI notes from his phone to other devices. While there are a few high-overhead options like MIDI over wi-fi or a Bluetooth connection, there wasn’t much in the way of a straight-up hardware connection to other MIDI devices. [Lewis] got around this limitation by using an IOIO board and the right software to send MIDI notes though a DIN-5 connector.

Although the project works as intended, [Lewis]‘ build could be made more permanent by building one of these MIDI interfaces and wiring that to the IOIO. All the Android code is up and available, along with a neat demo of [Lewis] controlling the delay time of an effects unit in his guitar rig. You can check that video out after the break.

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Hackaday has seen dozens of Morse code keyboards over the years, but [Hudson] at NYC Resistor finally managed to give that idea the justice it deserves. He built a USB Morse code keyboard with the same type of telegraph key the pros use.

For his project, [Hudson] got his hands on a wonderful iambic paddle that is usually hooked up to CW rigs. Unlike previous Morse keyboards we’ve seen, [Hudson] used iambic paddles, a telegraph key with one lever for dits and another for dahs. Because the dits and dahs are separate electrical connections, it’s extremely easy for the microcontroller – a Teensy - to parse the Morse code and send the correct letter to the computer.

[Hudson] also added some audio feedback for the dits and dahs, and designed a laser-cut enclosure for the Teensy and speaker. Check out the video of the iambic keyer keyboard in action after the break.
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While having a great white shark as your spirit animal may sound cool, we’ve found walking around in public wearing a gigantic set of mechanical jaws to be a bit of a hindrance. [abetusk] doesn’t have that problem; he can wear his awesome animatronic cat ears anywhere he pleases.

The build was inspired by these extremely Japanese animatronic ears loaded with EEG hardware to read the emotional state of the wearer. [abetusk] decided that tearing apart some brain scanning hardware was too much work for not enough benefit, so he decided servos controlled by push buttons would be just fine.

On the electronic side of the build, servos attached to a head band are controlled by an ATtiny13. A single button goes through three states for the ears: a long button press is surprise, a tap followed by a long hold is angry or sad, and tapping three times is an ‘ear wink.’ All of the code is up on GitHub, and you can check out these cat ear emotions with [abetusk]‘s lovely assistant in the video after the break.

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[Kevin] has been working on reverse engineering the protocol used by the Arduino IDE and porting it to the Arduino platform. Now that his BootDrive project is nearing completion, he’s ready to give every Arduino the ability to program another Arduino over an SD card.

BootDrive isn’t terribly different from using an Arduino as an ISP, only now AVRdude runs on the Arduino itself and no computer is required to put new firmware into the target Arduino.  [Kevin] attached a MicroSD breakout board to an Arduino-compatible clone. When the clone starts up, it searches the SD card for a file called ‘program.hex.’ This file is sent over to the target Arduino and the new firmware is installed.

While it may not be extremely practical if you’ve only got a few Arduinos that never leave your workbench, we’re thinking this would be an invaluable tool if you need to update the software on a board already ‘in the field,’ serving as a weather station or homemade game camera. [Kevin] put up a demo of his BootDrive project; you can check that out after the break.

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After getting his hands on an Android-enabled wristwatch, [Paul] wanted to test the limits of his new hardware. We’ll assume he’s happy with his purchase because his finished build sends data from a Microsoft Kinect to his wristwatch, making it a night vision spy watch.

[Paul]‘s new toy is a WIMM One Android wristwatch that comes complete with wi-fi and a copy of Android 2.1. To get night vision onto his watch, a Kinect on [Paul]‘s desk streams depth data to his watch using OpenCV. The result is a camera that gathers depth data in the dark and sends it to [Paul]‘s watch.

Whenever the movement of an intruder is detected, [Paul]‘s watch vibrates and displays the depth image taken from the Kinect. If the intruder gets close to the Kinect, the face is picked up and also sent to the watch. To get the intruder out of the room, [Paul] can tap the face of his watch to turn on a remote alarm and sound an intruder alert. It’s a very neat project that would have been unimaginable a few years ago.