Month: July 2011

Building A Solar Power Heliostat

July 13, 2011 by 16 Comments

[Frits] has been working on an solar panel heliostat (in Dutch, check out the translated page here).

The heliostat uses a small PICAXE to control the motor, along with an DS1307 real-time clock to make sure the motors start at dawn. Instead of using optical encoders or magnetic sensors, the angle of the heliostat is measure with a pot attached to the drive shaft. [Frits] did a lot of data collection to figure out that this method is accurate to about 1 degree – just fine for something that doesn’t need to be exact.

According to [Frits] this heliostat will put out 12 to 50 percent more electricity than a fixed panel. Although the build does seem a little bulky, putting it on a  house with a roof pitch of 23.5° would greatly reduce the horizontal profile.

A video of a solar panel rotating at 15 degrees/hour isn’t that interesting, so [Frits] posted a clip of 6 mirrors slewing around fairly fast to demonstrate his system. Check it out after the break.

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Automotive Battery Voltage Monitor

July 13, 2011 by 32 Comments

car_battery_voltage_monitor

[Rajendra’s] car had just about all the bells, whistles, and gauges he could dream of, but he thought it was missing one important item. In an age where cars are heavily reliant on intricate electrical systems, he felt that he should have some way of monitoring the car’s battery and charging system.

To keep tabs on his car’s electrical system, he built a simple device that allows him to monitor the battery’s instantaneous voltage when the car is powered off, as well as the charging voltage across the battery when the car is running. A PIC16F1827 runs the show, using a simple voltage divider network to step the input voltage down to an acceptable level for use with the PIC’s A/D conversion channel. The resultant measurements are output to a four digit 7 segment display, mounted on the front of the device.

He says that the voltage monitor works quite well, and we’re sure he feels a lot better about the health of his car’s charging system. For anyone interested in keeping closer tabs on their car, he has a circuit diagram as well as code available on his site.

Faux LED Scroller Using Phosphorescence

July 13, 2011 by 38 Comments

poor_mans_phosphorescent_led_scroller

Hackaday reader [BGR] wrote in to share a video he put together showing off a cool “poor man’s LED scroller” that he built. Rather than build a huge array of LEDs, spending tons of time time wiring and programming, he decided to use only a handful of LEDs on a moving display instead.

The scroller is built upon a PIC16F887 microcontroller which resides on an EasyPIC6 dev board he borrowed for the project. The PIC controls a strip of eight bright white LEDs, which are used to write text on a long strip of phosphorescent paper that can be found at many printing supply outfits. The paper’s dispensing mechanism was cobbled together with parts from several sources, including  a laser printer and VCR.

When he wants to display a message, he inputs text into a flash application he wrote. The app sends the LED byte values to his scroller via a separate serial proxy that talks to the pic over his computer’s COM port.

The effect is pretty slick, looking similar to a slow-moving diffused LED scroller. The messages disappear after about 5 minutes in a pitch black room, which is perfect, since he originally intended to use the device for displaying Twitter updates. He is already considering a second revision of the project, which he wants to mount on the wall – sounds great to us!

Be sure to swing by YouTube to see the video, or continue reading to watch it here.

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Xbox 360 DVD Changer Is The Ultimate In Gaming Laziness

July 12, 2011 by 33 Comments

ben_heck_xbox_360_disc_changer

Let’s face it – gamers have a reputation for being pretty lazy. In the most recent episode of his web series, [Ben Heck] takes on the stereotypical gamer role and cranks the laziness factor to 11, lamenting the fact that he needs to get up off the couch to swap discs in his Xbox 360 console. Never allowing laziness get in the way of his hacking, he springs into action, hauling off to his shop in order to construct an Xbox DVD changer system.

He grabbed a pair of CD changers and popped them open to see how they operated. After choosing the best candidate based on its CD loading method, he got to work disassembling the changer. The old CD player and its guts were removed, which he replaced with DVD drive components ripped from his Xbox. Quite a bit of trimming and tweaking was required to swap out the components, but it seems that [Ben] got things working just fine.

With the mechanical portion of the project out of the way, he dug into the electronics. The CD changer had no way of knowing how to interface with the Xbox and vice versa, so [Ben] had to devise a way for the two devices to communicate. He used an Arduino Uno to control the systems, triggering the CD carousel only when the Xbox thought it had its drive slot opened.

While the system looks a bit unpolished, and the controller quite bulky, we love this thing!  No matter if you are lazy or not, jamming these two devices together is exactly what hacking is all about.

Shoulder Surfing With OpenCV

July 12, 2011 by 14 Comments

shoulder_surfing_with_shoulder_pad

While it seems that many people are wise to shoulder surfing, keeping a lookout for anyone spying on their passwords, [Haroon] wrote in to remind us that the threat is just as real today as it ever was.

The subjects of his research are touch screen phones and tablets, which utilize on-screen keyboards for data entry. He says that while nearly all password entry boxes on these devices are obscured with the traditional line of asterisks, the keyboards themselves are quite an interesting vulnerability.

Since touch screen technology can be finicky at times, most vendors ship their devices with some sort of key press verification system. On the iPhone and iPad, for instance, each key is highlighted in blue following a button press. This functionality makes it quite easy for shoulder surfers to casually steal your password if you’re not paying attention.

But what if you are well aware of your surroundings? [Haroon] has developed a piece of software he calls shoulderPad, which is based on openCV that does the surfing for him. The application can monitor a video stream, live or recorded, extracting the user’s password from the highlighted button presses. His demonstrations show the recording taking place at a relatively close distance, but he says that it would be quite easy to use surveillance footage or zoom lenses to capture key presses from afar.

He does say that the button highlighting can be easily disabled in the iPhone’s options pane, which should negate this sort of attack for the most part.

Continue reading to see a quick video of shoulderPad in action.

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Character LCD Screen Add-on For Android Devices

July 12, 2011 by 10 Comments

Here’s an Android accessory project that adds a secondary LCD display. It utilizes the Android Open Accessory Development Kit standard to connect the 16×2 character LCD as a USB device. It pairs an app on the phone which runs transparently with firmware for the ATmega2560-based Arduino compatible board you see to the left. The app launches as soon as the auxiliary hardware is connected and is responsible for determining which lines of text are pushed out to the LCD. The example code displays the current time on the top line, and scrolls incoming text messages as they are received.

This is a good way to get your feet wet with the ADK hardware. We’ve already seen it used for larger displays like this LED marquee, but this smaller test project doesn’t require much hardware setup. Chances are you either already have an Arduino and character LCD on hand, or can easily borrow which makes this an easy weekend project.

One note on that Arduino compatible board; it’s called a Freakduino ADK but we couldn’t figure out if it’s a Freak Labs product or not. If you have some insight about that, please leave a comment.

FPGA Generated SPDIF Output

July 12, 2011 by 13 Comments

[Mike Field] just finished implementing SPDIF generation on an FPGA. SPDIF is an industry standard for transmitting digital audio signals; the acronym stands for Sony/Philips Digital Interconnect Format. It’s been around for more than a decade and since it’s found on most home-audio equipment, building an SPDIF output into your projects may be quite a desirable feature. [Mike] mentions several ideas for this functionality like building high-end test equipment, or providing a high-quality output for electronic instruments.

He first jumped into analyzing the specification in order to determine the hardware requirements. Due to some issues with jitter, he found it necessary to use a 100 MHz clock signal. This pushes the jitter down to +/- 5ns of jitter, which he concedes may raise the hackles of audio purists, but does satisfy the published standard. Output requires just one pin of the FPGA and the five components seen above. A hex inverter (74HC04) voltage divider, capacitor, and RCA connector transmit the 0.5V signal to your audio-receiver of choice. Of course, since TOSLINK fiber optic connectors use the same protocol, you could redesign the output and make this an optical connection.