Lighting LEDs with raindrops

lighting-leds-with-rain

[Steven] had one of those musical gift cards laying around, and thought he might as well reuse the piezo speaker inside it. Without a particular project in mind, he soldered an LED to the piezo and tapped on it, which caused the LED to illuminate as expected. He started to wonder what quantity of force would be required to light the LED, and if it could be done by a raindrop.

He first tested his theory in the shower, and as you can see in the video below it actually worked, though the light was dim and sporadic as you might imagine. He eventually discovered that for optimal lighting, the piezo worked best when struck by single droplets falling with pauses in between, from a minimum height of 4 feet. To achieve a water flow within those specifications, he built a rain funnel so that he can control the droplet frequency and intensity.

It seems to work pretty well from what we can see. Off the top of our heads we can’t seem to come up with any practical applications of the water powered LED, but it is an interesting set of experiments nonetheless.

Have an idea to use this setup that we totally missed? Let us know in the comments!

[Thanks, Rob]

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Turning LEDs into a camera

[Udo] figured out how to turn a bunch of LEDs into a very low resolution camera.

The build is based around [Udo]’s Blinkenlight shield he’s been developing over the past year. The camera operates under the idea that there’s really not much difference between a LED and a photodiode; LEDs can do light emission and detection. In actuality, the LED ‘camera’ isn’t all that different from a linear CCD array, the type of image sensor in flatbed scanners.

After connecting his Blinkenlight shield to his Arduino and computer, [Udo] wrote a sketch that would capture 17 values from his LED camera. These values are shot over the serial connection where high levels of light show up as smaller numbers and low light levels are understood as larger numbers.

[Udo] has been doing a lot of other cool stuff with his Blinkenlight shield, like a persistence of vision experiment and pretending to be [Michael Knight]. Check out the video after the break for a demo of [Udo]’s linear LED camera.

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Detailed tutorial shows how to unleash your inner [Michael Knight]

developing_a_larson_scanner

Our own [Mike Szczys] recently sat down and put together a great tutorial on building a Larson Scanner. The ubiquitous circuit is usually one of the first few projects on a budding hackers list of things to build, since they are just so darn fun.

Simple versions of the scanner sweep back and forth lighting the LEDs without any sort of transition between them. The configuration most familiar to us all as featured in Knight Rider and Battlestar Galactica are a bit more complex, and have a fading trail of light that follows behind the leading edge of the sweep. [Mike] notes that this fading is traditionally accomplished through the use of capacitors, which cause the light to gradually fade as the animation sweeps across the LED array. He decided to take a different route with his circuit, relying on PWM control of the LEDs instead.

Mike put together a simple circuit using an ATmega168, a handful of resistors, and of course, an array of LEDs. Utilizing interrupts and PWM, he was able to accurately recreate the iconic light sweep without the use of any capacitors. One big benefit to his design aside from the lower component count is the fact that he can easily adjust the speed of the sweep as well as the fading properties with a few small code tweaks.

Be sure to check out his blog at some point, where he shares his code, some circuit diagrams, and plenty more details on how his scanner was built. In the meantime, take a look at the video below to see the result of [Mike’s] work.

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Toy car fitted with lights and sirens is a children’s delight

police_car_lights_and_sirens

[Nathan], a member of the DangerousPrototypes forums, was looking for a project he could use to enter the 7400 logic competition they are holding. His kids had a small ride on police car, but the light bar on top contained no lights, and the car made no sounds when his children were in pursuit of baddies around the house. [Nathan] had all the inspiration he needed, and took to his workshop in order to fix this glaring oversight by the toys’ creators.

He designed a circuit based loosely around a Cylon-style light that he saw a while back at the Evil Mad Scientist Labs, which employed an oscillator and a 4107 decade counter to control the lights. His design uses a 74HC04 hex inverter as the oscillator, while the decade counter is used to modulate the siren’s frequency and control the rotating LED beacons.

The final result is great if you ask us. An “unnamed adult female” in the house was not nearly as impressed by the additions based upon how much time [Nathan] spent on the project, but his children were absolutely thrilled.

Continue reading to see a quick video of the revamped police car in action.

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Candied LEDs are a light, tasty treat

rock_candy_diffused_leds

[Emily Daniels] recently snagged a free iPad in the Instructables “Play with your food challenge” with an interesting way to work with LEDs. Growing up, most kids attempted to make, or at least have seen rock candy be produced. [Emily] thought it would be interesting to mix LEDs with the stuff to see what she could come up with, and her candied LEDs are the result.

The process is pretty straightforward, and involves mixing up a batch of supersaturated sugar syrup in which LEDs are suspended. The LEDs act as a nucleation point for the crystal formation, growing a nice solid coating of sugar after a couple weeks’ time. After some cleaning up, the LEDs can be connected to a coin cell battery or similar, as you would normally do. The sugar acts as a diffusing medium for the LEDs, giving them a nice soft beam pattern.

Obviously you likely wouldn’t want to use these for any long-term electronics project, but it’s a fun activity for the kids, and it could be a good way to incorporate electronics into baked goods.

Large scale Tetris game controlled with DDR pads

led_tetris_using_ddr_pads

Even though Tetris came to the US 25 long years ago, it never fails to entertain. Whatever it is that gives the game such lasting power is a mystery to us, but we’re always interested in seeing fresh takes on the classic game.

MIT students [Leah Alpert] and [Russell Cohen] tweaked Tetris a bit to get players off the couch and literally thinking on their feet. The game boards were constructed using RGB LEDs installed in laser-cut acrylic tubes, arranged in a pair of large 6 foot tall floor standing matrices.

Game play progresses as you would expect, with two players battling head to head to achieve the high score, while simultaneously sabotaging their opponent. Instead of controllers however, each player stands on a Dance Dance Revolution mat, manipulating their game pieces with their feet.

While the DDR pads aren’t exactly a Kinect controller, we have no doubt that playing Tetris this way is incredibly fun – we would certainly install a pair of these boards in our game room without a second thought.

Thanks to everyone who sent this in!

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Keeping simple children’s toys interesting with small modifications

souping_up_slot_cars

[Jaroslav] was racing slot cars with his son not too long ago, but like many of us discovered in our youth, driving cars around a small oval track can get dull after awhile. Rather than buy more track sections, he decided to fiddle with their cars a bit to make racing them a little more exciting.

After removing the top of his slot car, [Jaroslav] found that it cruised around corners with ease, giving him a distinct advantage over his son. He did the same with his son’s car to level the playing field, then he decided to add a few extra LEDs to make driving around the small track more lively.

Now, this obviously isn’t the most advanced of modifications, but it is a great example of extending the useful life of a toy by using cheap, easy to access components. We think that it would be reasonable to add even more features to the cars/track such as speed-dependent lighting or lap counters without changing the car dynamics all that much.

Any thoughts or suggestions to help [Jaroslav] soup up his kid’s race track even more? Share them with us in the comments.