Really, Really Geeky Wedding Invitations

January 30, 2013 by 53 Comments

invitation

Being real, ultimate geeks, [Bill] and [Mara] didn’t want to settle for plain, paper-based wedding invitations. No, they wanted something cooler, and came up with their own DIY electronic wedding invitations.

Since they would be making the invitations themselves, [Bill] and [Mara] needed a simple circuit that could be easily mass produced. They turned to the classic microcontroller-powered blinking LED circuit powered by an ATtiny13.

The first order of business was producing 50 printed circuit boards for each of the invitations. For this, [Bill] picked up an Xerox Phaser laser printer off of ebay and a few sheets of copper-clad kapton film. The etch resist was printed directly onto the kapton film and etched in a bath of ferric chloride, effectively making a flexible PCB.

These circuit boards were soldered up and laminated between the printed invitation and the card stock cutter with the help of a Silhouette Cameo paper cutter. After the cards were assembled, the battery was wired up and the cards shipped out.

The microcontroller inside the card was programmed to be asleep most of the time, waking up only every few seconds to check a light sensor to determine if the card was opened or not. If the microcontroller sensed the card was open, the lights began blinking, making it one of the most memorable wedding invitations [Bill] and [Mara]’s guests will ever receive.

You can check out a demo of the invitations after the break.

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Controlling A Raspberry Pi With Real Life Redstone

January 30, 2013 by 20 Comments

minepi

We’ve seen computers built in Minecraft out of redstone, the game’s version of electricity, circuits, and digital logic. We’ve even seen a few redstone contraptions controlling real-world devices. [Angus]’ build, though, takes things to a whole new level. He’s created a bridge between Minecraft circuits and their real life counterparts using a Raspberry Pi.

[Angus]’ build relies on a mod for Minecraft servers running as a Bukkit plugin. Blocks powered by redstone are labeled with an in-game sign, and messages regarding the state of a block are passed over the network using the MQTT protocol.

The hardware side of the build is a Raspberry Pi with a PiFace expansion board. With this setup, [Angus] can control LEDs on the PiFace by toggling Minecraft levers, or light up redstone lamps using the PiFace’s buttons.

If you’d like to try this out for yourself, you can grab the Bukkit plugin over on [Angus]’s git. Check out the video of the real life redstone in action after the break.

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Mr. Tea Is A Hot Plate And Magnetic Stirrer In The Same Enclosure

January 30, 2013 by 17 Comments

mr-tea-stir-and-hot-plate

Not being a coffee drinker [Hunter Scott] wanted a way to make tea while lurking in his workshop. Well it’s not exactly rocket science, as all you need is water at the right temperature and a vessel in which the tea can be steeped. But we do commend him on not only building a nice little hot plate enclosure, but rolling a magnetic stirrer into the other side of the box.

You heard us right, the stirrer is not combined with the plate, but resides on the underside of the same PSU enclosure. The plate itself is from a unit he bought at the store and cannibalized. The light switch dimmer lets him adjust the heat it puts out. When not hot, he can flip it over and use the stir plate. This consists of a hard drive magnet attached to a PC fan. For the stirrer itself he encased a neodymium magnet in some thermoplastic. The magnetic combination works well together with a demonstration which shows it stirring water through the base of a tea-cup.

Automated Doors For Theatre Effect

January 30, 2013 by 15 Comments

Door Actuator

For a theatre production, [Jason] needed a way to automatically open and close doors as a special effect. His solution, hosted on Github, lets him remotely control the doors, and put them into a ‘freak out’ mode for one scene in the play.

Two Victor 884 motor controllers are attached to an Arduino that controls the system. A custom controller lets [Jason] actuate the doors remotely, and LEDs are used to display the state of the system.

On the mechanical side, two wind shield wiper motors are used. These are connected to custom arms that were printed using a Lulzbot AO-100. The arms allow for the door to be automatically actuated, but also allow for actors to open the door manually.

The result is a neat special effect, and the 3D models that are included in the repository could be useful for other people looking to build automated doors. In the video after the break, [Jason] walks us through the system’s design and demonstrates it in action.

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Finding The Cheapest Board House

January 30, 2013 by 54 Comments

The prices for custom made circuit boards has never been cheaper, but surprisingly we’ve never seen a comparison of prices between the major board houses. [Brad] took the time to dig in to the price of 10 boards manufactured by Seeed Studios, OHS Park, and BatchPCB. He made some pretty graphs and also answered the question of where you can get your circuits made cheaply.

[Brad] got the prices for boards up to 20 cm x 20 cm from Seeed Studio’s Fusion PCB service, OSH Park, and BatchPCB. These results were graphed with Octave and showed some rather surprising results.

For boards over 20 cm2, the cheapest option is Seeed Studios. In fact, the price difference between Seeed and the other board houses for the maximum sized board is impressive; a 400 cm2 board from Seeed costs $150, while the same board from OSH Park is close to $1000.

Of course most boards are much smaller, so the bottom line is  for boards less than 20 cm2, your best bet is to go with OHS Park. If you don’t care when your boards arrive, or you need more than 10 or so, Seeed is the way to go. As far as the quality of the boards go, OSH Park is up there at the top as well.

Ask Hackaday: What’s An Easy Way To Build A Potentiometer For A Soldering Iron?

January 30, 2013 by 66 Comments

diy-potentiometer-2

[Lee] wrote in to share the work he’s done in building a controller for his soldering iron. The idea started when he was working with an ATX power supply. He figured if it works as a makeshift bench supply perhaps he could use it as the source for an adjustable iron. To get around the built-in short-circuit protection he needed a potentiometer to limit the current while allowing for adjustments. His first circuit used a resistor salvaged from an AT supply and a trimpot from some computer speakers. That melted rather quickly as the pot was not power rated.

This is a picture of his next attempt. He built his own potentiometer. It uses the center conductor from some coaxial cable wrapped around the plastic frame of an old cooling fan. Once the wire was in place he sanded down the insulation on top to expose the conductor. The sweeper is a piece of solid core wire which pivots to connect to the coil in different places. It works, and so far he’s managed to adjust a 5V rail between 5A and 20A.

How would you make this system more robust? Short of buying a trimpot with a higher power rating, do you think this is the easy way to build a soldering iron controller? Let us know by leaving your thoughts in the comments.

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MIT Media Lab’s Month In Shenzhen

January 30, 2013 by 8 Comments

When you’ve got a month worth of blog postings it’s pretty difficult to choose one photograph that sums it all up. This one shows the tour group from MIT Media Lab in ESD garb ready for their tour of Okano SMT and Speaker Factory. It was part of a tour of Shenzhen aimed at bringing graduate students up to speed on what it means to manufacture products in the city. Luckily, Freaklabs member [Akiba] was one of the staff members of the program and blogged extensively about the experience. At first glance his page full of post abstracts looks really boring, but click through because both his recount and the commented images associated with each day are fun and fascinating ways to tag along with the group.

If you’re really good with faces you can pick [Bunnie Huang] out of the lineup above (he’s the third from the right). He had the original idea for the program and brought aboard a few others to help make the thing a success. The group toured a wide range of factories and parts markets in the city. This included your traditional electronics manufacturing venues but there was even a side trip to a diaper and feminine napkin plant to see the non-electronic factories in operation. In addition to tours there were lectures by industry members like HAXLR8R, a group that specializes in helping start-ups navigate the manufacturing jungle.