Microcontroller communications using flashing lights


[Scott] was driving in the pouring rain behind a car with its blinkers on when inspiration struck. He had previously created a simple communications system using his sound card that allowed him to send data to a microcontroller from his PC, but he thought that doing the same thing with light would be an interesting exercise.

He decided that the best way to go about building such a system would be to use a phototransistor along with his computer monitor to send data to his microcontroller. While he couldn’t really think of any practical application for the project, that didn’t stop him from putting it together just for grins.

[Scott] says the circuit is dead-simple, and includes a pair of phototransistors along with their required resistors. The receiver was tied into the ADC of his microcontroller, where he was easily able to pick up some simple light patterns. His ultimate goal is to put together a javascript application that sends data to his microcontroller, though he’s looking for a bit of assistance on the programming side of things – any takers?

While [Scott] couldn’t come up with any applications off the top of his head, we know of at least one. Anyone familiar with the Bloomberg financial application will likely have come across their “B-Unit”. This piece of hardware is about the size of a credit card, but thicker. Armed with a fingerprint scanner and a photodiode, it reads a series of flashing lights from your computer screen in order to ‘synchronize’ the unit for each login session that is not initiated with an official Bloomberg keyboard. So there’s one for you!

Continue reading to see a video of the system in action.

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Security Bot 2

[William] Had originally built a little Security Bot to roam the halls of his house while he was not at home. He wanted a little bit more and started Security Bot 2 to include a good pile of sensors and add pan and tilt control to the onboard camera. Thanks to ordering pieces from a “who’s who” list of robotic and electronic hobby shops, the bits and pieces quickly arrived making assembly less tedious.

Packed on board of the 4WD platform are IR switches, IR distanace sensors, line sensors, Ultrasonic sensor, an Xbee (soon to be replaced with a WiFi Shield), pan/tilt brackets/servo, SpeakJet/TTS/Speakers, LCD, battery, serial motor controller, ICSP pocket programmer, Arduino Mega 2560, DSS Circuits Fuel Gauges, plus motors, batteries, camera, leds and a wiimote connection. (whew, that’s a mouth full)

All put together with some perfboards, breakout boards and a lot of jumper wire Security Bot2 is ready to patrol your premises!

Making and selling Star Wars costumes ruled to be legal


[Andrew Ainsworth] has been making and selling costumes based on Star Wars character (some original, and some of his own creation) for several years. Lucasfilm sued him for $20 million back in 2004 claiming infringement of intellectual property rights. He stopped selling them in the US (as it was a US copyright) but now the UK Supreme Court has ruled in his favor, siding with his claim that the costumes are functional items and not works of art.

Good for him, but copyright issues aren’t what interests us here. The BBC clip showing him using a vacuum former to make the Stormtrooper helmet really caught our attention. A bit of further searching led us to find the thirteen minute video after the break showing the entire process, from sculpting the mold by hand, to forming the components, and the final assembly seen above. It’s a fascinating process that makes use want to build our own vacuum former (preferably on a larger scale than this one). It would come in handy whether it’s Star Wars, Daft Punk, or any number of other projects you’ve got in mind.

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SMD Soldering with Gas

[desimon] had a wanted to use some accelerometer chips, but their 3x3mm 16-VFQFN packages made it pretty darn hard to solder by hand. While there are endless ways to approach this, we found this one peculiarity interesting from his use of a gas torch, though it is pretty much hot air reflow.

A PCB for the tiny devices is etched and tinned, the pads have a healthy but not overdone amount of solder applied to them. A liberal coat of flux, rough alignment of the chip and a few gentle passes from the torch and the hobby grade solder melts while the surface tension pulls everything into final alignment.

Having personally used a hot air gun a number of times (and also burning my hand about the same number of times) the localized heat of the torch does make more sense, and there is virtually no heat up time for it either, though it appears just as easy to scorch the board. It is a live flame so be careful!

3D printed singularity drive platform

[Silas] is a student at Olin College and came up with a platform using the singularity drive system in his spare time.

We covered a LEGO build of a singularity drive earlier this month. Instead of wheels, treads or legs, this drive system has a hemisphere spinning along its vertical axis. Interestingly, the robot does not change the speed or direction of its drive motor at all. IEEE is now calling this drive system a “singularity drive,” because math.

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