Graphing The Efficiencies Of LED Light Strips

October 23, 2012 by 35 Comments

After adding a few LED light strips above his desk, [Bogdan] was impressed with the results. They’re bright, look awesome, and exude a hacker aesthetic. Wanting to expand his LED strip installation, [Bogdan] decided to see if these inexpensive LED strips were actually less expensive in the long run than regular incandescent bulbs. The results were surprising, and we’ve got to give [Bogdan] a hand for his testing methodology.

[Bogdan]’s test rig consists of a 15 cm piece of the LED strip left over from his previous installation. A Taos TSL2550 ambient light sensor is installed in a light-proof box along with the LED strip, and an AVR microcontroller writes the light level from the sensor and an ADC count (to get the current draw) of the rig every 6 hours.

After 700 hours, [Bogdan]’s testing rig shows some surprising results. The light level has decreased about 12%, meaning the efficiency of his LED strip is decreasing. As for projecting when his LEDs will reach the end of their useful life, [Bogdan] predicts after 2200 hours (about 3 months), the LED strip will have dropped to 70% of their original brightness.

Comparing his LED strip against traditional incandescent bulbs – including the price paid for the LED strip, the cost of powering both the bulb and the strip, the cost of the power supply, and the time involved in changing out a LED strip, [Bogdan] calculates it will take 2800 hours before cheap LEDs are a cost-effective replacement for bulbs. With a useful life 600 hours less than that, [Bogdan] figures replacing your workshop lighting with LED strips – inexpensive though they are – isn’t an efficient way to spend money.

Of course with any study in the efficiency of new technology there are bound to be some conflating factors. We’re thinking [Bogdan] did a pretty good job at gauging the efficiency of LED strips here, but we would like to see some data from some more expensive and hopefully more efficient LED strips.

Controlling A Cockroach Leg With Your Mind

October 23, 2012 by 11 Comments

If one hack that controls amputated cockroach legs this week wasn’t enough for you, we’ve got another.

Earlier this week we saw two neuroscientists at Backyard Brains put on a show at a TED talk by connecting an amputated cockroach leg (don’t worry, they grow back) to a $100 electronic device called the SpikerBox. The SpikerBox allows students to explore the world of axons and action potentials by listening in on the electronic signals generated by the hair on the legs of a cockroach. For the finale for their TED talk, the SpikerBox guys attached an MP3 player to the cockroach leg, causing the now dead appendage to dance a little jig.

This new build – the Salt Shaker from Thinker Thing again allows students to amputate cockroach legs, pin them down with electrodes, and cause muscle contractions with the sound of science. Thinker Thing took this one step further than the neuroscientists at Backyard Brains; now you can control a cockroach leg with your mind.

The folks at Thinker Thing are using an off the shelf EEG system from Emotiv to capture the alpha, beta, and delta brainwaves of their new human test subjects. By interpreting these brain signals, they can convert these small variations in cerebral electrical activity to sound files. From there, it’s simply a matter of plugging in the Salt Shaker and moving a cockroach leg with your mind.

In the video after the break you can check out the folks at Thinker Thing playing around with their Salt Shaker and controlling a cockroach leg with a team member’s mind.

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Exploring The Mandelbrot Set In Real Time

October 23, 2012 by 33 Comments

The Mandelbrot set – the fractal ‘snowman turned on its side’ seen above – has graced the covers of magazines, journals, and has even been exhibited in art galleries. An impressive feat for what is nothing more than a mathematical function, and has become something of an obsession for [Chiaki Nakajima].

Even on modern computers, generating an image of a portion of the Mandelbrot set takes a good bit of time. When [Chiaki] discovered this fractal in the mid-1980s, the computers of the day took hours to generate a single, low-resolution image. Real-time zooming and scrolling was impossible but [Chiaki] made the best of what he had on hand and built Pyxis, a Mandelbrot set generator made entirely out of TTL logic chips (Google Translate here).

The original Pyxis connected to a desktop computer via a breakout box. while a special program toggled the bits and registers inside the Pyxis to generate pictures of the Mandelbrot set a thousand times faster than the CPUs of the day could muster.

Time marches on, and the original logic chip Pyxis is can be easily surpassed by even the slowest netbooks. There is, however, another way to build a hardware Mandelbrot set generator: FPGAs.

A few years ago, [Chiaki] began work on the Pyxis2010 (translation), an FPGA-based Mandelbrot set generator able to dynamically zoom and pan around the world’s most popular fractal. Built around an Altera Cyclone III FPGA he picked up from Digikey for $600 (no, not a dev board, just a bare chip), [Chiaki] began deadbugging his circuit directly onto the pins of the hugely expensive FPGA. A man with a steady hand and no fear if there ever was one.

Instead of connecting his Mandelbrot generator to a computer and using it as a co-processor, [Chiaki] decided he wanted something more portable. He found an old Sony PSP, removed the LCD screen, and integrated it into his circuit. After a careful bit of dremeling and fabrication, [Chiaki] had a hand-held Mandelbrot generator that is able to display images of the world’s most famous fractal faster than any desktop computer.

It goes without saying this build is incredible. The technical skill to build an insanely fast Mandelbrot generator on an FPGA is astonishing, but basing it off a logic-chip based build reaches into the realm of godliness. You can check out a video of this amazing build after the break.

Props to [Ian Finder] for sending this one in.

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Traffic Camera Countermeasure

October 23, 2012 by 212 Comments

Don’t get us wrong, we drive very carefully as it’s the most dangerous thing we do on a regular basis. But even a careful driver can get caught by bad traffic and a red light camera. These are devices that monitor intersections. If you get caught in the middle when the light goes red they take a picture and you get a ticket in the mail. Well, that’s the way it used to be. This traffic camera countermeasure puts it to an end. As you can see, the noPhoto uses a flash of its own to overexpose traffic camera images.

The image above shows the prototype. The foil is reflecting a flash on either side onto the license plate using a flash sensor which acts as the trigger. According to the demo video after the break, the system can even defeat the pre-flash, and dual-photo types of cameras.

There are pretty tight restrictions on using lights on your vehicles (colors, placement, etc.). We wonder if this passes muster?

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A TTL Timer Project Of Yore

October 22, 2012 by 6 Comments

[Viktor] just pulled out another one of his decades-old projects. This time around it’s a timer he built using 7400 logic chips. It was a great way for him to learn about electronics, and ended up serving as his alarm clock every morning.

Two pieces of copper clad board were cut to the same size. One of them was etched to act as the circuit board. The other was outfitted as a face plate. The same type of transfer sheets used to mask the traces of the circuit were also used to apply labels to the face plate. It was then coated with acrylic spray to protect it and stave off corrosion. The clock keeps time based on a half-wave rectified signal. The source is from a transformer which steps mains voltage down to a safe level for the 7805 regulator that supplies the clock’s power bus.

We’re glad [Viktor] has been showing off these old projects. We’ve also enjoyed seeing a TV sleep timer he built. If you’ve got something neat for yester-year why not dust it off, post the details, and send us a tip about it?

TinyMatrix Derivative Uses PIC Instead Of AVR

October 22, 2012 by 25 Comments

[Stu] has a teenage niece whose birthday is coming up and he wanted to give her something unique as a gift. He’s working on an LED matrix pendant that can display pixel graphics, play animations, and scroll messages.

He began the work after drawing inspiration from the TinyMatrix project. That clever design uses a DIP AVR chip soldered directly to the legs of a 5×7 LED matrix. It was powered by a coin cell with the power and ground wires acting as the necklace for the pendant. [Stu] is more comfortable developing using PIC chips, so he based his project on a 16F88. It will not run from a 3V source so he’s got a few issued to work out before the final design is finished.

One thing that’s quite interesting is his side project. After growing weary of hand coding the arrays for each frame of an animation he wrote a GUI in C# that let him design the image and output the code with a few clicks of the mouse.

Battling Most Useless Machine Gets An Expressive Upgrade

October 22, 2012 by 21 Comments

We suppose the only thing more useless than a most useless machine is giving it an emoticon face. But that’s exactly what has happened with this project. But you’ll want to seen the whole thing, as the presentation involves much more than an angry box that can shut itself off.

This is the second iteration of the angry box. As we saw about 18 months ago, it will eventually get fed up with you turning the switch on and freak out by driving itself all over the desk. This version starts off with a rather pleasant face drawn on the red LED matrix which takes up the front side of the enclosure. It will nonchalantly flip the switch to the off position after first being activated. But if you insist on turning it back on things get angry rather quickly. This is shown in the video after the break. But if you can get past the horrible machine translation there are some build details to be had in this post.

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