Rain Activated Light Show In An Umbrella

May 20, 2012 by Caleb Kraft 6 Comments

In a decision we completely agree with, these industrious young women decided that playing in the rain would only be more fun if it included an interactive light show. They wanted the rain itself to cause LEDs in their umbrella to light up. To achieve this, they put piezo sensors on each of the 8 panels of the umbrella. When that panel gets hit, its LEDs light up. You can see in the video after the break that it was quite effective.

Their next step should be to somehow increase the resolution to be similar to this one, while maintaining interactivity with the rain. How would you sense rain drops with more definition though?

[via Adafruit]

Building A Color Sensor Using Luminosity

May 19, 2012 by Caleb Kraft 13 Comments

[Richard Osgood] is back again with an interesting project. This time he has constructed a color sensor. His initial design was to use three LEDs and a photoresistor. He would shine a red, then green, then blue LED on a surface and record the reflected light with the photoresistor allowing him to determine how much reflected light there was of each color. Unfortunately, he found it to be completely unreliable. An attempt at using a light frequency sensor didn’t work either. What did finally work, was a luminosity sensor shown above.

Finally, his prototype worked. Unfortunately only the red LED gives readings that he considers to be adequate with the blue and green being “not all quite right”. With this type of circuit, he could build a clone of the magic chameleon lamp.

Motion Sensitive RGB Lamp Can Standby For 3 Years

May 16, 2012 by Mike Szczys 4 Comments

Ooooh, nice enclosure! This is a little motion sensing lamp which [Krazatchu] built a few years back as a Mother’s Day gift. The PIR sensor is easy enough to see as the white dome on the front of the case. But look closely below that and you’ll see the LDR which it uses to keep the thing asleep during the day. This is intended to save on batteries but the original version still ate through them like crazy. This year he gutted it and worked out a much more power-friendly design.

He moved to a TLC1079 OpAmp which greatly reduced power consumption when reading from the PIR sensor. The microcontroller was also upgraded from an ATtiny13 to an ATmega328, making the new version Arduino compatible. It puts itself to sleep and keeps the lights out during the day, drawing just 0.08 mA. When driving the RGB LED the lamp pulls about 50 mA. That should still last a while on three AA batteries but we’d still recommend using rechargeables.

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Helicopter Light Painting Continues To Snuff Out Physics Lesson On Your Brain

May 14, 2012 by Mike Szczys 8 Comments

Cool picture, huh? Wait until you see the video footage of this LED-adorned RC helicopter flying on a dark night. But this isn’t an art project. Analyzing the long-exposure photography turns out to be a great way of clearing up some of the physics of flight which otherwise are not at all intuitive. The helicopter used here has different colored lights on the nose and tail, as well as lights on the rotors.

Depending on how the aircraft is moving, different 3D spirography is captured by the camera. When you zoom in on part of the flight path it becomes clear that there are wider arcs on one side of the fuselage than there are on the other. This has to do with the forward progress of the aircraft and the rotation of the blades. The phenomenon is well known by helicopter enthusiasts, and accounted for in the design. But what we didn’t realize is that it actually translates to a theoretical speed limit for the aircraft. Our childhood love of Airwolf — the TV helicopter that could outrun jets — has been deflated.

You should remember the helicopter physics videos featured here last month. This is the latest offering and we’re still wanting more!

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Recycle Lithium Cells By Building Custom Flashlights

May 14, 2012 by Mike Szczys 30 Comments

This isn’t a brightest flashlight in the world type of hack (but it does manage to push about 1000 lumens). [Stephen Webb] is finding a use for leftover parts by building his own simple LED flashlights. As you can see, he uses PVC parts available at any hardware or home store. These are a good choice; they’re cheap, light weight, resilient, designed to be water tight, they easily thread together and have connectors that reduce the diameter of the fittings.

The electronics use standard size cylindrical Lithium cells. These are found in many types of Laptop and Power Tool batteries. Often when one of those battery packs bites the dust it’s an issue of one or more bad cells. [Stephen] desolders the cells, and reuses the good ones in this project.

We didn’t see any mention of a recharging technique. Does anyone have any advice on how to top these cells off if they’re not in their original power pack form?

Extremely Detailed Light Painting Bar

May 10, 2012 by Caleb Kraft 6 Comments

[Matt Pandina] has been documenting his build of a very nice light painting bar on his G+ page. His light painting bar has 64 RGB LEDs being driven by an ATmega328P and four TLC5940 chips. He wrote his own libraries to talk to the TLC5940 as well as his own libraries to pull images off of a MicroSD card. He also wrote a cross-platform program that automatically converts a directory of pngs to something the TLC5940s expect. He says the secret to getting his24-bit color correction looking right is gamma correction. It seems that when the LEDs were run too bright, he couldn’t get the colors quite right. In case you’re curious, those images are 15 inches tall!

You can follow along through his posts as he starts with just a few LEDs and slowly updates and grows it to the impressive state it is at currently.

Building A Bigger Bar Graph

May 10, 2012 by Mike Szczys 5 Comments

Take a gander at the Giant LED bar graph which [Chunky Hampton] recently completed (from this image we don’t think the nick name suits him). It’s simple both mechanically and electrically, but we love the look and think it would be a nice addition to your home, hackerspace, or as a children’s museum exhibit (we’re looking at you [Mr. Porter]).

The enclosure is a hunk of PVC electrical conduit. It’s got to be one of the largest sizes, but still should be found at most home stores. The base mounts easily and the cover snaps into place. [Chunky] used a hole saw to create the openings for the LED modules. They’re circular boards with multiple single-color LEDs on them. A common power bus feeds the high side of each bit, while a couple of transistor ICs controlled by 595 shift registers address them on the low side. From there just use any controller you wish, but in this case it’s an Arduino.

[Chunky] uses the meter to display power output from his stationary bicycle generator. But he also put together a little Larson Scanner demo which you can see after the break.

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