Wireless Arduino message board


[uhclem] was looking for a novel yet easy way to remind his kids to do their chores, and instead of using a series of post-it notes, he constructed a nice wireless Arduino-powered message board.  The message board is powered by an Arduino Pro, and communicates with his computer via a pair of series 1 Xbee radios which relay a series of canned messages to an attached VFD.  He installed all of the components in an old cigar box, and mounted it on the wall, making for a nice overall presentation.

Programming of the messages does not require any special software as the user interface is handled by the Arduino and accessed via a standard terminal session. [uhclem] mentions that the his code consumes nearly all of the device’s RAM when running, so he keeps a handful of canned messages stored in the Arduino’s flash memory, recalling them when needed.  The optional EEPROM is used to allow for streaming messages to the device as well.

Grinding down your computer to just 8.5 watts

What can you do to make sure your system is running as efficiently as possible? Take a page out of [Mux’s] book, who went to great lengths to measure and adjust his system for ultimate efficiency (translated). What he ended up with is 8.5 Watts of consumption at idle and about 50 Watts under load. Luckily he posted a six-part series with all of the details.

Some of the changes he made were in software, like reducing voltage to certain hardware by adjusting BIOS settings, and installing display drivers that put the screen into the proper sleep mode. Others were hardware changes like swapping out the power supply with a hacked PicoPSU and removing unnecessary parts from the motherboard like the MAX232 com-port chip. Looks like we need to audit our always-on MythTV box and see if we can apply any of these power-saving techniques.

[Thanks Gijs]

555 Timer circuit simulation software


[FightCube] wrote in recommending a very helpful piece of circuit simulation software for those of you still constructing entries for the 555 design contest.   LTSpiceIV, available from Linear Technology, allows you to construct moderately complex 555 driven circuits including common components such as capacitors, resistors, diodes, FETs, and more.  Once you have constructed your circuit, you can view the results in an easy to use visualization window, without ever having to touch your soldering iron or a breadboard.  According to [FightCube], the software is fairly easy to use, and best of all, it’s free.

He has shared one basic circuit he built as a demonstration of the software’s capabilities, and promises to share more in order to motivate others to enter the contest.

Update: Open source pick-and-place

[Tim’s] been busy moving his pick-and-place build toward completion. We looked in on the first version of the vacuum head back in October. Since then he’s ditched the camera enclosure which allows for more light and better mounting. The tip has been replaced by one from a pair of vacuum tweezers, and the whole thing is now mounted on a diy CNC machine. The video after the break shows it picking up that IC and moving it around the table. Looks like the part rotation feature is very accurate.

He mentions that the CNC he’s using is quite slow. We hope he checks out this printable Delta robot; hardware that is often used with pick and place machines.

Continue reading “Update: Open source pick-and-place”

Mixed I/O testing module

Needing to test the display interface for a multitude of different sensors [Fileark] built himself this analog and digital input/output simulator. Along the bottom is a double row of trimpots that adjust analog voltages. Each voltage is measured by the Arduino inside and its value is displayed on the graphic LCD screen to confirm that the hardware you’re testing is making correct measurements. There’s also digital I/O in two different forms. To the upper left are momentary push buttons but the DIP switch bank below that allows the same connections to be toggled on and off. It’s not an automated test bed, but if you’ve got a lot of I/O, or a lot of hardware to test this will save you some real time.

Don’t miss the demonstration video after the break.

Continue reading “Mixed I/O testing module”

Theremin midi board is like using autotune

[Steve Hobley] built a Theremin interface board that tracks pitch and volume. Using this setup he’s able to pass data over a midi interface which effectively converts the instrument into a non-contact midi controller. As we joked in the headline, this does allow for the use of autotune, by snapping notes that are sharp or flat to the center of the nearest pitch. But you should watch the video after the break to see [Steve] show off the other features as well. A keyboard can be used to seed a starting pitch, with arpeggios of several different tonalities built on top of it based on the input from the Theremin.

Want the details? Unfortunately you’ll have to pay for the schematics. But the concept is still just as interesting to read about, even if you don’t know what went into the system. Continue reading “Theremin midi board is like using autotune”

FareBot – Android NFC Proof of Concept


Upon learning that the Nexus S smartphone was equipped with a Near Field Communications NFC) radio, [Eric Butler] decided he would put the newly released Gingerbread SDK to good use.  Focusing initially on ORCA fare cards used by several Washington state transit systems, he built an open-source application he calls FareBot, which can read data from any MIFARE DESFire branded cards.  Utilizing the NFC radio in the Nexus S, he was able to dump all of the unprotected information from the fare cards, including  the remaining card balance and the last 10 locations where the card was used.

The author hopes that his proof of concept application encourages other developers to expand on his project and to explore the data stored on transit cards around the world. While it is in its early stages, [Eric] would ultimately like to see this project expanded to allow the use of NFC-enabled smartphones as transit cards themselves via downloadable apps.  He suggests that helping people understand the amount of data which can be freely obtained from these cards will eventually force the manufacturers to better inform consumers of the existing system’s shortcomings, which in turn might spur on smartphone-based transit initiatives.