I recently soldered up a Boarduino from Adafruit Industries. Boarduino is simply an Arduino clone with a smaller form factor, designed to plug directly into a breadboard rather than giving you the female headers of the original. I thought I’d post a few photos of the process.

I really like the idea of the Boarduino, because I found I was doing almost all of my prototyping on a breadboard, and it seemed like I was always trying to figure out new and different ways to anchor the big Arduino down.

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Inspired by Armadillo Aerospace and their laptop-controlled Pixel rocket, I decided to figure out how to use an Arduino module to achieve wireless remote control of a flight vehicle.

Along the path to development, an achievable intermediate goal would be something like a wireless RC rover with a video camera, monitored and controlled with a laptop and joystick on a WiFi network.

Step one in the process is simple joystick control of a servo over a USB connection. This project builds upon the process documented in “Arduino Serial Servo Control.” I welcome any comments or suggestions for improving or adapting this code.

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The digital pins on the Arduino board can be set (with code) to output either HIGH (5V) or LOW (0V) — essentially ON or OFF. This is great for applications like blinking LEDs or activating relays.

But what if we wanted an output voltage somewhere in between 0V and 5V? This might be useful in applications like controlling the speed of a DC motor, or “dimming” an LED.

Well, the digital pins cannot directly produce an analog voltage; as we’ve said, they’re either HIGH or LOW. But it turns out we can simulate these “in-between” voltages using a technique called Pulse Width Modulation, or PWM.

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Building a liquid-propellant rocket engine is pretty much the pinnacle of amateur engineering projects.

The 1967 book How to Design, Build and Test Small Liquid-Fuel Rocket Engines can be read online, or you can download the entire file in zip format.

From the introduction:

The purpose of this publication is to provide the serious amateur builder with design information, fabrication procedures, test equipment requirements, and safe operating procedures for small liquid-fuel rocket engines.

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MAKE Blog pointed me to this extremely cool project called a Wave Bubble. Essentially, this device is a portable, battery-powered radio frequency jammer, that will effectively disable cellphone and other RF communication (RFID, GPS, WiFi) within about a 2-meter radius of the user.

The design of the Wave Bubble comes from an MIT EE/CS masters thesis entitled “Social Defense Mechanisms: Tools for Reclaiming our Personal Space,” in which the author describes the tradition of designing and using electronic devices as social commentary, known as “Design Noir.”

In addition to providing a detailed description and circuit diagrams for builing the Wave Bubble, the thesis is also rife with intelligent commentary on the psycho-social implications of using electronic products and is quite an enjoyable read.

From the thesis:

Manufacture and use of Wave Bubble is not exempt from FCC regulations. Anyone who decides to build and use it is performing an act of civil disobedience.

I love it! More information and some great photos are available at ladyada.net.

The simplest model rocket launch controller is the Estes Electron Beam, which is powered by four AA batteries and comes with 17 feet of launch wire and micro clips for attaching an Estes igniter. This system is adequate for launching small models with a single black powder motor. However, for firing a cluster of motors, or for igniting composites, a battery with more amps is required. In addition, spectators of high-power launches will need to be farther away from the launch pad than 17 feet. Unfortunately, electrical resistance in a long launch wire negates some of the advantages of using a larger battery. This problem can be solved by using a relay switch located near the launch pad, allowing the main battery to sit as close to the motor igniters as possible, while the launch controller remains at a safe distance.

The LC-3 Electronic Relay

The LC-3 is the third iteration of Principia’s electronic Launch Control system. It is based on a similar design by Eric Ohmit, but differs primarily in that the controller is powered independently of the main battery. The full system (pictured below, left) consists of a Control Box, a Relay Box, a pair of connector cables to the battery and the igniters, clip whips for multiple igniters, and 100 feet of RJ-11 (telephone) cord to connect the control box with the relay. [Click any photo to enlarge.]

The Control Box (pictured above, right) incorporates a key-operated arm/safe switch, which ensures that only the designated range safety officer (RSO) can initiate a launch. In addition, the control box provides a green LED continuity indication, which tells the operator that the circuit is complete and that the battery and igniters have been properly connected. Continuity is confirmed by flipping the red “Continuity” switch to the ‘on’ position and noting the illumination of the green LED. The LC-3 is then armed with the key switch, which causes the red “Arm” LED to light, and a high-pitched piezo buzzer will sound, indicating to all spectators that the rocket is ready to fire. When both the green “Continuity” LED and the red “Arm” LED are illuminated, the red “Launch” button will become active and also illuminate, and the relay can then be engaged by depressing the button. If all goes well, the motor will light and the rocket will launch.

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The Rocket-Mounted Video Camera Project came to an abrupt end as the V-2 model rocket Prima Donna suffered a catastrophic failure (CATO) on its first launch attempt. Although tragic, the CATO was captured on video from multiple angles, and represents a classic case of a rare Estes engine failure. [Scroll down for videos.]

An examination of the video and debris is currently underway, but the consensus is that the extreme cold (-15°C) caused the propellant grain to separate from the interior wall of the rocket motor case.

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The Rocket-Mounted Video Camera project is nearing completion. Prior to the flight test phase, however, prudence demands that we run a few simulations to ensure that the rocket will have a safe and stable flight.

Initial Evaluation

Before beginning construction, we made a few ballpark calculations using (a free trial version of) RockSim, a Windows-based model rocket design tool, to verify that the addition of the camera wouldn’t adversely affect the model’s flight characteristics. To increase performance, we also swapped the specified D12 engine for a higher-impulse E9.

The images below show the results of this evaluation. You can see from the flight profile graph on the left that the predicted maximum altitude with the E9 motor is nearly 1000 feet. The stability diagram on the right shows the center of gravity (CG) position with the E9 engine, but without the addition of the video camera in the nose.

Although the CG was a little further aft than is desirable, we determined that the addition of the video camera and battery pack to the nose of the rocket would only improve stability, and that the E9 motor would help compensate for the loss of performance that the camera’s weight would create. Based on this preliminary analysis, we decided to go ahead with rocket construction, using an Estes E9-8 engine, the video PCB and a 2AAA battery pack.

Now that the build is complete and the camera is installed, we need to revisit these calculations with the actual mass measurements, to assure that we have an accurate picture of the flight profile before the first test flight.

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It’s hard to believe how rewarding it can be making something this pointless! This is my version of “Hello World” on the Arduino. Instead of just flashing an LED on and off, this variation flashes a three-letter Morse code navaid identifier (something familiar to aviators).

The Arduino is a wonderful new open-source physical computing platform and programming environment. It is based on the Atmel ATmega8 microcontroller, and is cheap and easy to learn. Microcontrollers can be used in everything from automation and robotics to interactive art projects. Get the skinny at http://arduino.cc/.

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The idea comes from MAKE Magazine, Vol. 7: Hack a $30, “single-use” camcorder and fly it on a model rocket. The project involves disassembly of the plastic camera housing, soldering a stripped USB cable onto the camera’s circuit board, hacking the board’s embedded software to make it reusable, then mounting it in the nosecone of an Estes rocket kit. With persistence, the project can be completed in a long weekend, and the results are spectacular.

The CVS “Single-Use” Camcorder

The Pure Digital One-Time Use Video Camcorder is marketed by CVS and Rite-Aid pharmacies as an inexpensive and user-friendly device for capturing family memories, vacation outings and the like. With only three buttons, it is simple enough for anyone to use. A 1.5-inch color LCD serves as a viewfinder, and allows you to watch a playback of the most recent clip. The camera’s firmware and data are stored on a Samsung 128MB non-volatile flash memory chip which holds roughly 20 minutes of digital video.

The palm-sized camera costs less than thirty bucks, but there’s a catch. When your 20 minutes are up, you take the camera back to CVS, where they charge you a $13 processing fee to download the video data and burn it onto a DVD for you. The camera’s memory is then cleared, but you don’t get to keep it; it gets sent back to the manufacturer for repackaging and resale. Well, with a little tinkering and some steady-handed soldering, we’ll make our own camera interface, turning this product into a compact, reliable and — best of all — reusable digital video platform.

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