Megavallometer Camera Trigger

July 17, 2011 by Mike Nathan 4 Comments

megavallometer_camera_trigger

[Tobe] has an intervalometer for his camera, but he wanted a device that could trigger the shutter using several different methods, not just time. He calls his creation the Megavallometer, which can utilize any one of three distinct criteria.

He recently purchased an Arduino and a couple of shields, so he figured this would be a perfect project in which to use them. He hooked up a microphone and a photodiode to the Arduino, allowing him to use both sound and light to trigger his camera, depending on which mode he selects. Of course, the Megavallometer still incorporates the functionality of a standard intervalometer as well.

Once connected to his camera he selects one of the three trigger programs, and the Arduino handles the rest. If either the light or sound triggers are selected, the respective sensors measure the ambient levels upon selection, allowing for accurate results in any setting.

While the Megavallometer is a bit larger than other intervalometers we have seen, it looks incredibly useful and can likely be strapped to a tripod or similar if need be.

If you have a minute, be sure to check out the video on his site for a sneak peak if his Megavallometer in action.

Android Controlled T-shirt Cannon

July 16, 2011 by Brian Benchoff 33 Comments

Every year, Qualcomm hosts the “Battle of the Schools.” This year the goal was to build homemade contraptions that would be judged on how cool they are. [Doug DeCarme], [Shaver Deyerle], and [Zach Rattner] – three Qualcomm employees at Virginia Tech – built an Android controlled t-shirt cannon for this event and ended up tying with Michigan State for first place.

The cannon is built around an Arduino Uno and a BlueSMiRF Bluetooth modem. [Doug DeCarme], the Android developer of the group, put together an app that would fire each barrel independently. The valves for the cannon are just 150 PSI inline sprinkler valves, bought from the local Home Depot. From the project breakdown, the team spent less than $150 on entire project.

From the video, we see that they’re getting some pretty good distance firing t-shirts at 160 PSI. Although we question the wisdom of using PVC as a pressure vessel holding 160 PSI, changing the PVC to a proper air reservoir wouldn’t be that hard.

VGA Pong On A ChipKIT

July 16, 2011 by Mike Szczys 1 Comment

[Nathan] got his hands on a chipKIT Uno32 development board and wrote a Pong sketch that you can play with a VGA monitor. We love the hardware that makes this feel very much like the classic. It uses a collection of resistor-based digital to analog converters to generate the color signals for the VGA protocol. The score for each player is show on a 7-segment display instead of being printed on-screen. And the paddles are made up of a pair of potentiometers.

You’ll remember that the chipKIT Uno32 is an Arudino compatible 32-bit development board. This project shows how the hardware handles, and how easy it can be to generate VGA signals with it if you know what you’re doing.

For those interested in the game physics themselves, [Nathan] provided a nice explanation about ball movement at the bottom of his post. If you need even more details, dive into the code package that he links to.

Race Car POV LED Displays

July 15, 2011 by Mike Nathan 26 Comments

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Last year, when [Alex] was asked by his friend [Martin] to help him out with building some LED POV modules for a race car, his response was a enthusiastic “YES!”

[Martin’s] goal was to involve fans more deeply in the race, so he decided that the POV modules would carry messages from fans on-board, printing them in the night as the race cars screamed around the track. The pair started prototyping and testing a design, wrapping things up shortly before this year’s 24 hours of Nürburgring.

The modules consist of an Arduino-compatible AVR, a GPS module, a 16-LED light bar, and the circuitry for driving the LEDs. While most of the components are pretty standard fare, the we don’t often see a GPS sensor built into a POV display. [Alex] says that the sensor is used to calculate the speed of the cars, ensuring a uniform font size.

They took their LED displays to the 24 hours of Nürburgring, where they were invited by Audi to install the modules on a pair of R8 Le Mans race cars. As you can see by the pictures on his blog and Flickr set, the POV units worked out nicely without having to stretch the camera exposure times too far.

If you’ re interested to hear a bit more about how the displays were built, check out this entry in[Alex’s] blog, where he goes through some additional details.

Update:[Alex] pointed us to the videos!

Arduino Video Sampler

July 15, 2011 by Brian Benchoff 15 Comments

[gijs] sent in an Arduino video sampler he’s been working on. The sampler is able to capture, pause and play a short video forwards and backwards.

The video capture circuit is based on the Nootropic Design video experimenter. We’ve seen a few project use this video experimenter board, but never with such smooth video. The sampler samples frames at a resolution of 128×96 and stores everything in a 256Kbit SRAM. A back-of-the-envelope calculation tells us that the sampler can hold a little under a second of video, more than enough to do something cool.

[gijs] says there is a 1 bit version and a 1.5 bit version of his video sampler. While we’re busy wrapping our minds around what half a bit is, he’ll be upgrading the 1.5 bit version to 2 bits. He’s also ordered some PCBs and expects to have a kit out by October. Check out a demo after the break.

Continue reading “Arduino Video Sampler” →

Building A Single-button Combination Lock

July 14, 2011 by Mike Nathan 15 Comments

single_button_arduino_combination_lock

[John Boxall] of Little Bird Electronics was thinking about combination locks, and how one might improve or at least change the way these locks work. Traditional combo locks can be implemented in a variety of ways, most of which we are all familiar with. Standard rotary padlock and keypad-based electronic safes work just fine, but he was interested to see how one might implement a single button combination lock.

[John] determined that the best, if not only way, to build this sort of lock would require him to measure button press intervals. In his case he decided to monitor the intervals between his button presses instead, but the concept is the same. He first tested himself to see how accurately he could press and release the button, leaving a one-second space between presses. After looking at the results he determined that he would need to incorporate at least a 10% margin for error into his code in order to compensate for human error.

He then created an Arduino sketch to test his idea, defining a set of key press intervals that could be used to ‘unlock’ his imaginary vault. It worked quite well, as you can see in the video demo below.

Now we’re not suggesting that you lock up your mint condition My Little Pony collection or your illegal arms stash with this type of lock, but it could be useful as an extra failsafe for certain projects/gadgets that you want to keep all to yourself.

Continue reading “Building A Single-button Combination Lock” →

A Beginner’s Guide To Magnetometers

July 14, 2011 by Mike Nathan 9 Comments

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The folks over at LoveElectronics recently published an article that explains some of the ins and outs of magnetometers for those who are interested in trying one out, but might not understand how to use them.

A good part of the article focuses specifically on how to manipulate the HMC5883L magnetometer from Honeywell, but a lot of the information can be applied to other makes/brands of compass sensors. They start out discussing in very basic terms how the compass works, then delve into some specifics on how to interface the chip with an Arduino, courtesy of a breakout board that they sell. The breakout board is actually quite simple, so any number of custom iterations could be built for your own testing purposes.

They walk through the use of an HMC5883L-specific Arduino sketch they produced, making it easy for beginners to start getting useful data from the compass units. While a pre-made sketch might seem like a bit of a cop out, it at least gives the curious/motivated beginner a chance to look at some completed code in order to see how things work.

If you are interested in cutting your teeth on some additional beginner concepts, check out these other how-to articles and tutorials.