Make Your Own Magnetic Ink

July 17, 2012 by 12 Comments

Here [Catarina Mota] is showing off a ring of magnetic ink printed on a piece of paper. It’s strong enough to hold a disc magnet in place when the paper is raised vertically. This strength comes from mixing your own batch of ink.

Magnetic ink has been around a long time and is most often used in banking. The account number and routing number on the bottom left of paper checks are printed in magnetic ink to allow for automated recognition. Iron oxide is charged by the reader as it passes through. In this case, magnetite is used as the doping agent as it has very strong ferromagnetic properties. By mixing it with acrylic medium in a vortex mixer you end up with a homogeneous ink.

There’s a quick demo after the break that shows how well this printed ring holds the magnet. What are some things for which you would use this ink? Leave a comment to let us know.

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Optical Fiber Twin-flash Adapter

July 17, 2012 by 7 Comments

[Marcell] has always been turned off by the price tag of commercially available double flash adapters. He decided to see what kind of performance he could get out of a flash adapter which he built himself.

The raw materials used should seem quite familiar. The optical fibers act as a conduit to redirect the light from the flash, but he needed a way to hold them in place. He chose to use locline. It’s a product we often see in CNC mill builds to blow debris away from the cutter head. It’s hollow, and holds its position. This is perfect because it allows for easy adjustment and provides a channel through which the fibers can be routed. The Y adapters used here run to a hard board base which connects to the mounting lug on the bottom of the camera. [Marcell] suggests using a T-piece if available because the Y fitting made it a bit more difficult to push the fibers through.

Store Your RFID Transit Card Inside Your Cellphone

July 17, 2012 by 54 Comments

Check it out, this is a Boston transit pass — or at least the parts of it that matters. [Becky Stern] got rid of the rest in a bid to embed the RFID tag inside her cellphone.

The transit pass, called a CharlieCard, started out as a normal credit card shaped tag which you might use for access in the workplace. She unsheathed the chip and its antennae by giving it a generous soak in acetone. In about thirty minutes the plastic card looks more like paper pulp, and you can gently fish out the electronics. These are now small enough to fit in the back cover of a cellphone much like those inductive charging hacks.

[Becky] put hers in an iPhone. But the idea comes from [Dhani Sutanto] who used the same technique to extract the coil from a London transit pass. He then embedded the hardware in a resin cast ring.

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Retrotechtacular: The Birth Of Satellite Communications

July 17, 2012 by 4 Comments

Last week was the fifty year anniversary of the launching of Telstar 1, the first communications satellite. Take a look back at the marvel of the early technology as shown in this newsreel footage about the first broadcast. The first formal use was a speech by President Kennedy allowing most of Europe to “witness democracy at work”. You’ve got to love that cold war era propaganda.

In addition to this electronics-filled marvel there were other experiments going on at the time that used passive devices as satellites. Project Echo sought to put reflective balloons at an altitude where they could be used to bounce signals around the curvature of the earth. This came almost exactly two years before the advent of Telstar 1.

There was a lot of media coverage of this anniversary, but the most interesting for us was an NPR interview with [Walter Brown], one of the engineers who helped build the device. Apparently nuclear weapons testing in space the day before the launch caused the initial tests to fail.

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Lightweight Web Server Using The MSP430

July 17, 2012 by 17 Comments

Need a tiny web server? [Rob] over on the 43oh forums made an Ethernet booster pack for the very popular TI MSP430 microcontroller. If that’s not enough, [Rob] also put together an all-in-one solution with a MSP430 and Ethernet controller that can be powered by a battery. Along with the web server that fits in just 5k of flash, we’re going to say [Rob] has a very good solution for remote sensing and data logging.

For his Ethernet-enabled 430, [Rob] chose to use the WIZnet W5200 Ethernet controller. This chip communicates with the 430 via and SPI interface and has a hardware TCP/IP stack that supports TCP, UDP, and PPPoE, offloading all the low-level stuff off of the 430 and onto the Ethernet controller.

After the break there are a pair of videos of [Rob] showing off his tiny web server. A few neat features include a full memory dump of the 430, as well as a reading the states of all the pins via an HTML page. If you’re looking for a way to collect data over Ethernet, we don’t think you could do better than [Rob]’s tiny 430-based web server. Also, if you’d like to control a few devices over the Internet, [Rob] included a few optoisolators  for lights or appliances.

The code is available on the 43oh forum page, but [Rob] says he’ll clean that up and put it in a Git.

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Finger Recognition On The Kinect

July 17, 2012 by 9 Comments

The Kinect is awesome, but if you want to do anything at a higher resolution detecting a person’s limbs, you’re out of luck. [Chris McCormick] over at CogniMem has a great solution to this problem: use a neural network on a chip to recognize fingers with hardware already connected to your XBox.

The build uses the very cool CogniMem CM1K neural network on a chip trained to tell the difference between counting from one to four on a single hand, as well as an ‘a-okay’ sign, Vulcan greeting (shown above), and rocking out at a [Dio] concert. As [Chris] shows us in the video, these finger gestures can be used to draw on a screen and move objects using only an open palm and closed fist; not too far off from the Minority Report and Iron Man UIs.

If you’d like to duplicate this build, we found the CM1K neural network chip available here for a bit more than we’d be willing to pay. A neural net on a chip is an exceedingly cool device, but it looks like this build will have to wait for the Kinect 2 to make it down to the consumer and hobbyist arena.

You can check out the videos of Kinect finger recognition in action after the break with World of Goo and Google Maps.

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Make A Game For A Retro Console, Win Prizes

July 17, 2012 by 2 Comments

For all you old-school console hackers out there, there’s a homebrew coding competition being held by NeoTeam for all the retro (and not so retro) consoles of yesteryear. If you’ve ever programmed for the NES, GBA, PC Engine, N64, or even the Dreamcast, now’s your chance to write a game or app and hopefully win a small prize and a great deal of street cred.

Last year, the Neo Coding Competition saw some very cool entries such as [smealum]’s amazing work in bringing Minecraft to the Nintendo DS ([smealum]’s non-forum DScraft page is here). DScraft won [smealum] a cool $500 USD, but the bragging rights for bringing Minecraft to the DS are far more valuable than any monetary reward.

There are two categories for the competition, an app division and a game division. All the retro platforms are open for development in this contest, so if you want to write something for your Master System, NES, 32X, or Saturn, you better get started: the contest ends August 20th.