Thinking Cap Is Also Party Hat

November 5, 2012 by Eric Evenchick 10 Comments

The Thinking Cap is a piece of wearable signage that lets you display what’s on your mind. The hat uses a Teensy 2.0 connected to a Bluetooth radio to allow the wearer to update the message on the fly, letting the room know what their thinking at that instant.

This hack is based off of LPD8806 controlled LED strips, which are becoming very popular for adding lots of LEDs to anything. There are five strips that need to be controlled over SPI, but the Teensy only has one SPI peripheral.

This lead to the use of multiplexer to allow for controlling each strip individually. The hat uses an interesting and low cost scheme to multiplex five channels using two 744052 dual 4 channel multiplexors and a 7400 inverter.

The Teensy can receive messages using the Bluetooth serial port protocol. The 5 x 7 pixel characters are stored in a framebuffer, and shifted around the hat to create the animation.

The result is a bright message circling around the user’s head, which can be updated with a smartphone over Bluetooth. Check out a video demo of the hat after the break.

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Hackaday Links: November 4, 2012

November 4, 2012 by Brian Benchoff 43 Comments

Wait, you’re using a Dremel to cut PCBs?

Cutting copper-clad board or – horrors – depanelizing PCBs is a pain if you don’t have the right tool. Over at Hub City Labs they’re using a small, cheap metal shear & break. Bonus: it can cut and bend sheet metal, so the Hub City folks can also make enclosures.

Color Codes? Yes, Color Codes.

[Joe] sent in a cool utility he whipped up called resisto.rs. Plug in a resistor value, and it’ll spit out the 4-band, 5-band, and surface mount labels for that resistor value. Pretty neat.

Parallel Ports

Parallel ports may be a dying breed, but that didn’t stop [Electroalek] from putting together a VU meter that connects to his LPT port. It’s an extremely simple design; just connect some LEDs and resistors to the pins of a parallel port, and you can easily control them via software on a computer. Playing around with an LPT port used to be common knowledge, so we’re glad to see [Electroalek]’s work here.

The power is out, but Radio Shack is still open

[Jason] is stuck in New Jersey without power and needed a way to charge his phone. He whipped up a cell phone charger using an RC car battery and an LM317 voltage regulator. It’s an easy circuit to piece together, and judging from [Jason]’s picture will hopefully keep his cell phone charged until the power comes back on.

Shooting 50 Nerf darts all at once

If [Rob]’s project log is to be believed, it looks like they’re having a lot of fun over in the Sparkfun warehouse. They decided to have a full-scale Nerf gun war for a summer intern’s last day. [Rob] came up with a DIY Nerf shotgun that shoots 50 darts across the room, just waiting to be found sometime in the next decade.

There’s a great video of [Rob] firing the single barrel (yeah, they made a trident-shaped one as well) gun at well prepared but unsuspecting coworkers. Be sure to check out the comments of this post to see Hackaday readers frothing at the mouth because PVC pipe isn’t a pressure vessel guys. You’ll all surely die.

Turning The Raspberry Pi Into A Cocktail MAME Coffee Table

November 4, 2012 by Brian Benchoff 35 Comments

Ah, the cocktail arcade cabinet. With the right design, its able to blend right in to any living room decor, much more than any traditional stand-up cabinet, at least. [graham] over on Instructables didn’t tear apart a 30-year-old arcade cabinet for his new coffee table. Instead, he built one from scratch, connected it to a Rasberry Pi, and brought hundreds of arcade classics right in front of his couch.

The build began by cutting up some wood to house the 24″ LCD screen, Raspi, and arcade controls. The LCD screen is supported with a rather clever system of cross braces screwed into the VESA mount, and of course a piece of perspex protects the screen from the inevitable spills and scratches.

The joystick two blue ‘player’ buttons and the player 1 and player two buttons are wired directly to the GPIO pins of the Raspberry Pi. The Raspi boots up into a selection of MAME games, but there’s also an option for opening up the window manager and browsing the web.

It’s a very neat build that’s a lot smaller (and easier to build) than a traditional cocktail cabinet. As [graham] is using it for a coffee table, it might get more use than a regular MAME build, to boot.

Hacked Farm Toy Plays Simon

November 4, 2012 by Caleb Kraft 10 Comments

My kids have a plastic farm toy. It moos, it oinks, it neighs, it
baas, and frankly, it grates. But since I tricked it out with an
attiny2313, at least it can play “Simon Says”.

This is what [Tom] said in his email to us. We love that when the toy annoyed [Tom], he improved it.

He started by inserting his own electronics. Using an ATTiny2313 for the brains, he proceeded to make it into an interesting game of “simon says”. Each stall is a button and has a nice bright LED in it to help you follow along. Interestingly, he preserved the original electronics as well and added a switch so he could change modes. Great job [Tom]!

Catch the video after the break.

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Capacitive Touch Business Card

November 4, 2012 by Caleb Kraft 15 Comments

[Jay Kickliter] sent in his latest electronic business card. This time, his goal was to make it much cheaper so he could actually afford to give it away. He did pretty well considering the two week timeline he mentions. This card is using an MSP430 with the capsense library to light up some LEDs any time the card is handled. While he states that it is much cheaper than his last, it is still around $8 a card, so he won’t be tossing these into everyone’s hands. He does point out though that it is always helpful to have hardware to show off at a hardware interview, and an electronic business card does that job very well.

As usual, you can read more details and download the files at his blog.

On Not Proving The Twin Prime Conjecture With AutoCAD

November 3, 2012 by Brian Benchoff 28 Comments

As an HVAC engineer by trade, [Carlos Paris] spends a lot of time in AutoCAD designing all those hidden pipes, tubes, and ducts hidden in a building’s rafters. One day, [Carlos] read of an open contest – the prize was over a million dollars – to generate a prime number with a billion digits. [Carlos] misheard this as, ‘a prime number greater than one billion’ and of course said this was a trivially easy task and opened up his favorite tool – AutoCAD – in an effort to discover the largest prime ever. [Carlos] never generated a remarkably large prime, but he did come up with a very, very cool visualization of prime numbers on a number line, as well as a great justification of the twin prime conjecture, a problem in mathematics that has remained unsolved for several generations.

[Carlos] started his investigations into the properties of prime numbers by drawing a series of circles on a number line in AutoCAD. These circles were of diameters of all the integers, and going down the number line, these circles started to have an interesting, chaotic pattern (see above picture). [Carlos] found that whenever two circles intersected, that position was a prime number. It’s really nothing more than a Sieve of Eratosthenes, but it’s a very cool-looking visualization nonetheless.

Looking deeper into his graph, [Carlos] discovered there were certain primes that had another prime number just two places down the number line. For example, the numbers 3 and 5, 29 and 31, and 41,and 43 are twin primes, as the difference between the primes is only 2. The idea there are infinitely many twin primes is a famous unsolved problem in mathematics – it’s obvious it must be true, but no mathematician has yet come up with a proof of this conjecture.

[Carlos] looked at his number line and simplified it to a generic prime number. By taking a generic number line and overlaying the multiples of other prime numbers on this graph, [Carlos] had a very, very clever way of understanding exactly how twin primes come into existence.

In the end, [Carlos] is no closer to proving the twin prime conjecture than anyone else. We’ve got to hand it to him, though, for nerding out with an engineer’s favorite tool – AutoCAD – and managing to derive some fairly obscure mathematics on his own.

After the break you can see [Carlos]’s videos describing the though process that went into his creation. Very, very cool work.

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The Smallest NES Controller Ever

November 3, 2012 by Brian Benchoff 24 Comments

A few months ago, [Ben] saw a video of the world’s largest NES controller. “I bet I could make the smallest,” he thought in a strange game of one-upmanship. Now [Ben] has the smallest fully functional NES compatible controller, a feat of engineering that can only end in very, very sore thumbs.

The old NES controller is a very simple device: eight buttons are connected directly to a 4021 shift register. Every time the NES is looking for a change in input, it reads out the data in the shift register and gets the status of all the buttons.

After finding the smallest footprint 4021 shift register he thought he could solder, [Ben] found some very small SMD push buttons and a very tiny resistor network for the pull ups. The result is tiny, and thanks to the sacrifices of a few NES controller extension cables he found on Amazon, 100% compatible with his old NES.

You can grab all the schematics over on [Ben]’s git. Tip ‘o the hat to [Troy] for sending this one in.