Build A Spinning POV In A Day

April 19, 2011 by Mike Szczys 10 Comments

We love spinning POV displays but have yet to build one to call our very own. This project might be the one that we end up building. It’s looks good and it’s the only persistence of vision display that comes to mind which can be built in twelve hours.

The spinning is taken care of by a PC fan. This actually helps with some of the calculations as this fan spins at a know RPM. That information, along with a bit of geometry, can be used to calculate the timer interrupts for syncing the display. A reference point for this device is provided by an IR receiver/emitter pair which is easy to wire up since you already need a voltage source for the fan itself. The rest of the hardware is pretty common: a battery holder is centered on the axis for proper weight distribution and protoboard houses the components such as a PIC 18F252, 74LS373 data latches, and the LEDs themselves. The circuit is wire-wrapped, and works like a charm as evidenced in the clip after the break.

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Guitar Teaches You To Play Using LEDs

April 19, 2011 by Mike Nathan 38 Comments

guitarduino

[Andrew] is an electrical engineering student at UIC, and decided that he would build a MIDI guitar for his senior design project. After tinkering for awhile, things were not looking good, and the MIDI guitar idea was scrapped. With his deadline creeping up, he came up with a new idea, the Guitarduino. His new project is a guitar that teaches you how to play chords and scales by showing you the proper notes to play via LEDs embedded in the guitar’s neck.

He removed the neck, and carefully drilled the holes that would eventually house his 130+ LEDs. The LEDs were wired to his Arduino via some multiplexing circuitry that resides on the back of the guitar’s body. The Arduino was mounted on the front of the guitar along with a shield used for communicating with his LED array. He built another shield that serves as the LCD display as well as the input board for his guitar.

The final result of all his work is fantastic. The user simply needs to dial in the chord or scale that he wants to learn, and the guitar lights up, showing the proper finger positions on the fretboard. We could see this coming in quite handy for anyone just starting to learn how to play.

Check out the video below to see a demonstration and walkthrough [Andrew] put together highlighting his guitar’s features.

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Pinewood Derby Cars Have Come A Long Way

April 16, 2011 by Jesse Congdon 20 Comments

Get your graphite and hike a wheel, [Aron Hoekstra] writes in to completely embarrass us with some excellent pinewood derby cars. In the pursuit of that extra something [Aron] consulted with his sons who came up with some cool ideas for cars, one Tron themed and the other basically a Wiimote with wheels! The official Pinewood derby rules say nothing about electronics, so as long as nothing helps the block-o-wood travel down the track faster, anything goes. This means you are free to load up whatever cool lights you want, but will have to earn your robotics merit badge some other way.

[Aron] Starts the builds by carving out the shape of the cars, each feature a hollowed out cavity underneath to accommodate the batteries and electronics. For the Tron Light Runner car, one continuous EL strip weaves in and out of the derby car’s body, and a single AAA battery runs the driver. [Aron] notes that it took around five feet of EL wire to cover the little car, which is two more than the driver is rated for. Fortunately the extra little bit of additional wire had little effect on its brightness.

The Wiimote car has detailed 3d buttons, a breadboard with a linear regulator, and PIC 16F628 driving blue LEDs. For the majority of the time the PIC simply runs a chase routine for the four LEDs, but [Aron] went through the trouble to program in the Wiimote’s start-up sequence!

Shown above the [Hokestra]’s work is my older brother’s pinewood derby car (top left) and my… potato rocket… thing… (top right) from many many years ago. I now seriously regret not considering LEDs! Although I think all that existed then was red, green and IR.

Check out videos of the [Hoekstra] bros’ cars after the jump!

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LED Build Monitor Helps Keep An Eye On Your Servers

April 12, 2011 by Mike Nathan 7 Comments

In his line of work, Hackaday reader [Pedantite] often has to monitor the build status of several continuous integration servers throughout the day. One afternoon, he got the idea to install a set of stop lights in the office in order to monitor the status of the servers, but filed it away as a “wouldn’t it be cool if…” project.

After some time had passed, he was bitten by the idea bug again and decided he would build a physical device to display the status of his build processes. This time around, he brainstormed on a smaller scale and the result is the “Indictron” you see above.

He built a simple LED board made up of four rows of four LEDs to display the build processes. Different LEDs are lit depending on the project’s current build status as well as the results of the previous build. The board uses an ATmega88, and interfaces with a compiler watchdog application using a virtual USB package made specifically for AVR micro controllers.

The end result is a simple, yet useful status board that “just works”. He does not seem to have code or schematics posted on his site at the moment, but we’re pretty sure he would share them upon request.

If you’re interested in a bit more of [Pedantite’s] work, check out his “Good Times” parental timer we featured last week.

Temperature Sensing Mug Means Never Burning Your Mouth Again

April 12, 2011 by Mike Nathan 14 Comments

temp_sensing_mug

Some people tend to get awfully attached to their favorite mug. Like an old friend, the mug holds a special place in their hearts, and there’s a weird sadness when it finally gives up the ghost. Through the winter months [Ben’s] girlfriend is never without hers, and when it broke, he decided to give her a new one with some added functionality.

He built her a temperature sensing mug that uses a rather novel way of determining how hot or cold the contents are. Instead of using a thermistor to determine the drink’s temperature, he opted to use a simple diode since it is well known that a diode’s forward voltage varies with temperature. After determining the diode’s voltage range using hot and cold beverages, he hooked it up to the ADC of a PIC12F615 micro controller. The temperature is displayed via 10 LEDs, which are driven through a pair of 8-bit shift registers and buffers since his PIC did not have enough pins to control them on its own.

He had some PCBs made, and after a handful of setbacks got everything put together. He says the mug works pretty well, though the display changes a bit more slowly than he would like. He also mentions that if he builds a second version, he will be sure to select a different PIC that has enough I/O pins to do the job, as well as use a thermistor instead of a simple diode for sensing the temperature.

Continue reading to see a brief demo video [Ben] put together.

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Webcam Images Processed And Played Back On LED Display

April 10, 2011 by Mike Szczys 13 Comments

[Mathieu] has bee working to refine the code running on an LED matrix, and added some neat display tricks along the way. He wanted to make the display directly addressable from a computer. The 96×64 bi-color LED display is powered by an Atmel FPSLIC and already used double-buffering. Enabling a PC to write directly to one of the buffers was not too hard, requiring just a bit of optimization to get the timing right. From the look of the video after the break, he nailed it.

The video feed is generated from a webcam stream using Matlab to process each image. Just 50 lines of code captures a frame, sizes it appropriately, converts the result to black and white for edge detection, then finishes the job by compressing image data for transmission to the embedded processor. We’d like to say it’s easier that it sounds but we’re pretty impressed with this work. The display manages about 42 Hz with the current setup.

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Sticky Sweet Animatronic Peep Show

April 7, 2011 by Mike Nathan 14 Comments

peeps_peep_show

With Easter quickly approaching, [Kyle] decided to finally build a project that is as tasty as it is wrong.

Behold, the Animatronic “Peep” show! Using nearly a dozen marshmallow Peeps, he constructed a stage for his “performers” and a seating area for their “clients”. The structure was built mostly from balsa wood and foamboard, featuring a retractable curtain, stage lighting, and music.

Once triggered, the embedded Arduino gets to work animating the stage lights and blaring “Cherry Pie” while the sugar-coated onlookers await their entertainment. The curtain is drawn back and a trio of winged dancers emerge one by one, ready to entertain the crowd. The onlookers even offer up dollar bills to the dancers via a servo-mounted arm.

The project uses a total of 10 servos driven by the Arduino, along with an audio decoder chip to provide the proper ambiance for the marshmallow debauchery. [Kyle] says that he put together about 650 lines of code to get the whole thing running, but there doesn’t seem to be any way to download it at the moment – hopefully we’ll see something posted soon.

It might not be high-brow, but it sure beats blowing up old, stale Peeps in the microwave!

Stick around for a trio of videos demonstrating the Peep show as well as revealing some of the stage’s inner workings.

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