Pinewood Derby Cars Have Come A Long Way

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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Temperature Sensing Mug Means Never Burning Your Mouth Again

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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.

Continue reading “Temperature Sensing Mug Means Never Burning Your Mouth Again”

Sticky Sweet Animatronic Peep Show

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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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Third Time’s A Charm – 512 LED Cube Kicks It Up A Notch With RGB LEDs

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In the comments section of our 512-LED cube post from the other day, several people suggested that to take the project up a notch, building a similar cube using RGB LEDS was the next logical step. It seems that Hack-a-Day reader [vespine] was way ahead of the curve, as he sent us the build details of his 8x8x8 RGB cube shortly after the other story was published.

His cube, which was finished earlier this year, uses 512 10mm RGB LEDs, arranged on top of a simple elevated stand. The stand conceals all of the circuitry he uses to control the cube, the centerpiece of which is a PIC32 MCU. A dozen TLC5940 16-channel PWM drivers are used alongside the PIC in order to adjust the color output of the LEDs, each of which can be addressed and colored individually.

The end result is just about as amazing as you would imagine. He has created several quick demonstration animations, which you can view in the video below. Be sure to stop by his site to see all of his build details – there’s quite a lot there.

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Parts: 4×4 RGB Button Pad Controller SPI

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We covered SparkFun’s new RGB button pad controller a few weeks ago. This is a full-color clone of the monome interface; a 4×4 grid of buttons with tri-color LEDs underneath. Each LED has 24bits of color control, for more than 16million color combinations. Up to 10 panels can be chained together to create huge button grids, like SparkFun’s Tetris table. We previously used a smaller version in our RGB combination lock.

We asked SparkFun to send us the SPI version of the button controller to test. This is a new product developed in-house at SparkFun, with open source hardware and software. Read about our experience interfacing this board below.

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LED Life And Charlieplexing


Yesterday, we featured [Andrew]’s orientation aware camera. We want to highlight another one of his projects: LED Life. It’s a 6×5 LED matrix playing Conway’s Game of Life. He used the low power MSP430 like our e-paper clock. The best part of the writeup is his explanation of how Charlieplexing works. Microcontroller GPIO pins generally have three possible states: output high, output low, and input. This combined with the directional nature LEDs and some creative wiring means you can run a large matrix of individually addressable LEDs with just a few IO pins. Instead of just flipping the IO pins on and off you change their assigned state. Have a look at [Andrew]’s site for some great illustrations of how the system works. A video of his LED Life board is embedded below. Continue reading “LED Life And Charlieplexing”

Testing IR Camera Blocking

[youtube=http://www.youtube.com/watch?v=0u5hAfnq2-4&hl=en&fs=1&rel=0][randy] from F.A.T. tested the theory that infrared LEDs can actually hide you from the prying eyes of surveillance cameras. We’ve previously covered camouflage, IR, and other suggestions for eluding the cameras, but haven’t taken to sewing stuff onto our clothes yet. [randy] lined his hoodie with high-intensity infrared LEDs, hoping to create a halo effect that would hide his head, and tested his results. Unfortunately, his efforts were unsuccessful. He tested many many different combinations and we’re confident in his conclusion that it would be very hard to make this work.