Edge-lit Musical Birthday Card

[Monirul Pathan] decided to make the card as unique as this gift when getting ready for a birthday. He designed and built his own musical card with LED edge-lit acrylic to display the message.

The electronic design seeks to keep things as flat as possible. The card-shaped acrylic panel has a void to fit the PCB exactly, and the components are relatively flat. One thing we found quite interesting is that the ATtiny85 which drives the device is surface mounted, but it is not a surface mount component. The layout includes though-hole pads, but instead of drilling holes [Monirul] clipped off the excess of the DIP legs and soldered the remainder directly to the copper. We suppose this isn’t going to get a lot of use so it just needs to hold together for one day.

As you can see in the video after the break, the speaker plays ‘Happy Birthday’ followed by ‘Under the Sea’. At the same time, four blue LEDs pulse to the music, lighting up the words that are engraved in the plastic.

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Hackaday Links: October 17, 2010

Cards you should crank

These greeting cards must be the product of a mechanical engineer run amok. They come with a crank and are designed to entertain with their simple, yet elegant movements. [Thanks Phil]

Magnetic card stripe reader

[JP] built an Arduino based magnetic card reader. It uses off-the-shelf parts but if you don’t mind buying the components this will get you up and running in no time. If you want more info there’s also this Teensy based version.

Homemade Airsoft sentry gun

This sentry gun has an amazingly fast firing rate that can continue for quite a while, thanks to the big flashlight housing that is holds a lot of ammo. [Thanks David]

Scanner easter egg

The engineers over at HP had a little fun building an easter egg into this scanner. If you know what you’re doing you can get it to play the Ode to Joy. It needs to join the old-hardware band from our Links post earlier in the month. [Thanks Googfan]

Face-slapping Security Gaff In Stored-value Cards

The laundry machines at [Hans Viksler’s] apartment were converted over from coin operation to stored value cards. We’ve all dealt with these cards before and [Hans] thought it would be fun to do a little sniffing around at how this particular company implements them. We’ve covered how to read these cards and there have been several stories regarding how to bypass the security that they use.

But [Hans] wasn’t interested in stealing value, just in seeing how things work. So he stuck the card in his reader and after looking around a bit he figured out that they use the Atmel AT88SC0404C chip. He downloaded the datasheet and started combing through the features and commands. The cards have a four-wrong-password lockout policy. He calculated that it would take an average of over two million cards to brute force the chip’s stored password. But further study showed that this is a moot point. He fed the default password from the datasheet to his card and it worked.

We know it takes quite a bit of knowledge for the average [Joe] to manipulate these cards at home, but changing the default password is literally the very least the company could have done to protect their system.

Card Shuffling Machine Failure


Breaking from his usually routine of winning at everything, [Glacial Wanderer] has posted one of his projects that didn’t actually work. It’s a Rube Goldberg style card shuffling machine. He wanted something that was visually interesting while still randomizing the cards. A blower would be mounted to the top to mix the cards similar to a lottery ball machine. The cards would then drop into a chute that would make sure all of the cards were oriented correctly before being presented to the user. After building the first prototype, several problems were apparent. The first of which was the fan not being strong enough. His interest was waning and it looked like the time he’d have to invest in fixes was growing quickly, so he decided to cut his loses. He still posted about the prototype in hopes that it could help someone else exploring this sort of machine. A video of the mechanism can be found below.

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Magnetic Stripe Card Spoofer

After building a USB magnetic stripe reader, [David Cranor] has found a way to fool a magnetic stripe reader using a hand-wound electromagnet and an iPod. The data on a card is read and stored on a computer, then encoded as a WAV file using a C++ program. The iPod plays the WAV file with the data through a single-stage opamp amplifier connected to the headphone jack. The amplifier is used to drive the electromagnet. Video embedded after the jump.

By no means is this a new idea. There have been a lot of mangetic stripe projects and software. This project in particular references the 1992 Phrack article “A Day in the Life of a Flux reversal” by [Count Zero].

Don’t get your hopes up just yet on strolling through high security installations using this little device. It can only replay the data from a card that has been recorded. If you don’t have a known working card, it won’t get you very far.

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