DIY Microcontroller-switched Power Strip

June 23, 2012 by Mike Nathan 22 Comments

switched-power-strip

[Teknynja] was looking for a way to control several discrete AC-powered devices using a microcontroller, and while he did consider the Powerswitch tail 2 from Adafruit, handling 5 devices would get pretty expensive. Rather than buying a complete off the shelf solution, he decided to build his own 5-way switched outlet.

He picked up a sturdy metal power strip from a local hardware store along with some Sharp S201S06V relays he ordered online. After test fitting his relays inside the power strip’s chassis, he wired up 5 of the 6 outlets through them to allow for switching via a microcontroller. He configured the 6th outlet to be live at all times, providing a power source for the control system he planned on using to switch the other receptacles.

[Teknynja] pulled the connector from an old PS/2 mouse for use as a control wire, connecting one wire to each of the relays. He says that the strip is working quite well, and after a few months of use it is holding up nicely.

Musical Light Show Is Far Less Complex Than You Might Think

June 21, 2012 by Mike Nathan 15 Comments

color-changing-light-tube

[Matt and Jason Tardy], who make up the musical performance duo known as AudioBody, were recently featured on Make: explaining how they put on one of their trademark segments. The most popular portion of their show features color changing tubes of light which the pair spin and fling around not unlike a higher-tech version of the Blue Man Group. While the visuals are pretty slick, the technique behind it is far simpler than most people initially imagine.

As you can see in video below, the tubes look to be nothing more than simple white lights. As the brothers work through their performance however, the tubes switch from white to blue and back again with a liquid-like transition between the colors.

The [Tardys] say that most people peg a microcontroller or other complex electronics as the source of their light wizardry, but the real answer is much simpler. Embedded in the end of each tube is a bright LED flashlight. A sliding blue filter positioned inside the tube provides the silky smooth transition between colors – no fancy electronics required.

If you would like to see how they were built, be sure to swing by the AudioBody web site for a how-to presentation by the [Tardys] themselves.

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Machining Cartridge Connectors From PCI Sockets

June 20, 2012 by Mike Szczys 7 Comments

[Ed] needed a bunch of edge connectors for video game cartridges. He was unable to source parts for Neo Geo Pocket games and ended up building his own from PCI sockets. But it sounds like this technique would work with other console cartridges as well.

From the picture you can see that this is a bit more involved than just slapping a cartridge into a socket. Because there are multiple steps, and many connectors were needed, [Ed’s] dad lent a hand and built a few jigs to help with the cutting. The first step was to cut off the key and the narrow end of the socket. These NGP cartridges are one-sided, so the socket was cut in half using a board with a dado cut in it as a jig. From there the plastic bits can be cleaned up before pulling out two center pins and cutting a groove to receive the cartridge key. There are also two shoulder cuts that need to be made after trimming the piece to length. The video after the break will walk you through this whole process.

These PCI sockets are versatile. One of our other favorite hacks used them to make SOIC programming clips.

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Building Your Own Atari Cartridges

June 16, 2012 by Caleb Kraft 9 Comments

Have you ever wanted to create your own atari games from scratch? Thanks to the Grand Idea Studio, you can download the files to make your own cartridge PCBs. There isn’t a ton of information here, as this is an old project that isn’t being supported anymore. However, you can download the instructions, schematics, and gerber files for carts that work in the 3 main models of the atari 2600. As [Tyler] over at Adafruit points out, you could easily 3d print your own shell as well.

Detecting Cosmic Rays With 18 Geiger Tubes

June 16, 2012 by Brian Benchoff 21 Comments

What do you do if you have 18 Geiger tubes lying around? [Robert] had an interesting idea to build a cosmic ray detector and hodoscope to observe the path cosmic rays take while flying through his lab.

[Robert]’s cosmic ray detector works by detecting the output 9 Geiger tubes on the y-axis and 9 Geiger tubes on the x-axis with a coincidence circuit. When a cosmic ray flies through the detector, it should trigger two tubes simultaneously. By graphing which of the two tubes were triggered on an array of 81 LEDs, [Robert] not only knows when a cosmic ray is detected, but where the cosmic ray was.

The detectors do pick up a little background radiation, but thanks to [Robert]’s coincidence circuit, he can be fairly certain that what he’s recording are actually high-energy cosmic rays.

Before building the 9×9 hodoscope, [Robert] built a similar drift hodoscope that simply plots the path a cosmic ray takes through an array of Geiger tubes. You can check out videos of both these cosmic ray detectors after the break.

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Penny Auction Hacking; Put On Your Statistician’s Hat

June 14, 2012 by Mike Szczys 11 Comments

Penny auctions are where you must pay a fee each time you bid. Certainly this alters the behavior of the bidders, but there doesn’t seem to be a lot of info about exactly how. In preparation for an analytics degree, [Jay] decided to study penny auctions and see if he can win a contest based on his findings. Now he’s not necessarily looking to make a living by gaming the auction system. But we were interested to see how he went about getting information, and what he has to say about the results.

Since there really isn’t a large body of data available, he scraped it himself. You’ll want to page through his posts on the topic, but basically he’s using Python on a fast machine. This is made quite a bit easier through the use of Selenium RC, but it also means he’s got a lot of instances of Firefox running to track multiple auctions. Scraped data is stored in CSV files, and posted to his front page daily.

From what he’s captured so far [Jay] suggests that time of day, type of auction, and several other factors dictate when you should bid to attain the best deals.

MITx 6.002x Wraps Up; Here’s A Review From One Of The Students

June 14, 2012 by Mike Szczys 28 Comments

[Jorge] just finished MITx 6.002x with the fine score of 99.1%. Congratulations! We just finished reading through this review of his experience (translate) with the 14-week class and it sounds like the program is extremely well executed. For those that don’t remember, this is an intro to circuits and electronics course offered at the Massachusetts Institute of Technology. Except 6.002x is free to all as an online course (but if you actually want a certificate a fee may be involved).

Above is one of the many screenshots which [Jorge] took of the student web interface. It looks great, and offers pretty much everything you need to complete the class. The textbook, which runs at least $65 for a paper copy, is available through the web interface as part of the course. The labs even include web demos you can use to simulate circuits and probe and measure the resulting signals and wave forms. If you have questions there is access to the teachers, but also a set of forums where you can work with other students.

Perhaps most interesting is [Jorge’s] assessment of the time you will spend working on the class. He thinks that if you’re already familiar with electronics the work can be complete in about one afternoon per week. Scheduling is flexible — tests are available for one week, but once you start taking one it must be completed in 24 hours.

He believes this will be offered again in the fall so keep a look out for registration to begin.

[Thanks Pan]