There’s been a lot of stories about arranging solar panels to mimic leaves on a tree, thereby boosting their efficiency. But before reading that story you might want to check out this blog post correcting some flaws in that breakthrough (page is down, here’s a cached version).

Before we go any further, we’d like to point out that the original work was done by a seventh grader. He looked at leaves on trees and postulated that the Fibonacci sequence can be found in the layout of leaves, and that by laying out solar cells in the same way you can capture more sunlight. Comments can get negative fast around here, so remember that trashing his work may discourage other kids from participating in science fair events.

Anyway, long story short: there were some issues with original assumptions, and about what was actually being measured during testing. The article linked at the top covers the fact that the cells were not measured under load, and that simple calculations can show why the tree-mimicking-cell-placement can be proven sub-optimal to 45 degree, south-facing solar farms.

[Thanks Jeffery and Steve for the original article and Brian for the follow-up article and cached link]

You know them, you love them, you take them for granted – they are single push button on/off switches. As [Dino] explains in the most recent episode of his Hack a Week series, they are typically implemented in the form of IC logic switches nowadays, but it wasn’t always that way. When they first came on to the scene in the 70’s, the single button soft switches were built using a set of transistors and a capacitor to get the job done, so [Dino] decided to research push on/push off transistor switches a bit and build his own.

After reading through a short tutorial, he was ready to go. As he explains in the video, the operation of the switch is fairly simple, though he did run into some odd issues when he prototyped the switch on a piece of breadboard. He’s looking for someone to explain why the unstable circuit suddenly performs better with the addition of a small capacitor between the battery’s positive lead and the circuit’s output, so if you have some insight, be sure to speak up in the comments.

In the meantime, check out [Dino’s] exploration of push on/push off switches below.

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Earlier today, [Jack] posted his latest video. He then promptly ran off to the secret Hackaday headquarters to begin work on the next one. Unfortunately there was a weird problem with Youtube which left the video un-viewable. We’ve fixed it now and wanted to let everyone know.

We’ve also been getting lots of questions about the videos, mainly about what future content we’ll cover.  Obviously, we’ve only done some very simple and goofy things so far.  We wanted to start simple to get the hang of everything. [Jack] has let us know that the upcoming videos are going to be a little bit more serious and deal with some different aspects of pcb design. We can’t wait to see what he comes up with.

[Pedro] had a busted laptop LCD screen on his hands, but rather than throw it out, he brainstormed what he could possibly do with what would typically be considered a worthless item. He decided to make a simple art installation using the scrapped part, so he gathered a few other supplies and got to work.

The first thing he did was pull the LCD screen from the laptop, separating the front panel from the backlight panel. He drained the liquid crystal fluid from the display, and set it inside a picture frame in place of the glass. He added spacers around the edge of the frame so that the backlight could be mounted several inches behind the LCD panel.

[Pedro] then found a few polystyrene and polycarbonate plastic items from around the house, and placed them inside the frame. As you can see in the picture above, the polarizing filter built into the LCD screen makes for some pretty cool effects.

While you could debate for hours over exactly what is art, there’s no denying that his PolFrame looks cool and is a great way to save electronics from the scrap heap. We just want to know what he did with the LC fluid he drained from the screen!

If you spent your weekend outside and away from the Internet, you might have missed the massive liquidation of HP TouchPads on Amazon, woot.com, WalMart, and the HP online store. Normally a $100 fully featured tablet is nothing to scoff at, but there is a catch: The HP TouchPad runs WebOS. WebOS is a fine operating system for a tablet, but it’s not Android. The folks at HacknMod.com posted a bounty for the first person to port Android to the HP TouchPad.

HacknMod is offering up $450 for a basic Android port and is looking for sponsors for the WiFi, Audio, Camera, and MultiTouch bounties. There’s a lot of discussion about the port on the XDA Developers and the RootsWiki forums if you’d like to get a bearing on how far along the project is. The TouchPad has already been rooted so there’s your starting point.

We’d like to throw our hat into the ring, but we missed out on the TouchPad fire sale. If anyone knows of an online shop where they’re still available, leave a message in the comments.

via HacknMod.com

[fpgaminer], [li_gangyi], and [newMeat1] have been working together for the last few months to build an FPGA bitcoin miner that blows GPU mining rigs out of the water in terms of power efficiency. The board requires only 6.8 watts for 100 Mhashes/second, but [li_gangyi]‘s blog says the team expects to hit 150-200 Mhashes with some improvements. That’s efficiency GPUs can’t touch.

Bitcoins are a digital currency that are ‘mined’ by calculating hashes that verify bitcoin transactions. While mining operations can be performed on a CPU, graphics cards and FPGAs beat CPUs by several orders of magnitude in terms of how many hashes can be performed per second.

The heart of the board is a Spartan-6 LX150 FPGA – a pricey bit of kit – and the team is selling each board for $440 USD. For that amount of money, you could buy two ATI 6770s at half the price and crunch four times as many hashes a second. At less than 7 watts, though, we wouldn’t worry too much about cooling the rig and the electricity costs will be very low.

Hackaday headquarters has recently been overrun by techno-groupies hanging around outside so we decided to take some measures to discourage that. A word of warning though, if last week’s video ruffled your feathers then you probably shouldn’t watch this one. In this video [Jack] shows you how to create a stun glove using a disposable camera and some leather spikes. To prove that it really works, he intentionally takes a jolt from it courtesy of Hackaday’s security chief [Vlad].

Check out the video after the break.
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[Roofus] had an older car, and unfortunately his stereo’s cassette player just wasn’t doing it for him. He always wanted to simply get into his car, pull out his cell phone, and have his music ready to play without any fuss. After messing around with all sorts of different tape adapters, he got fed up and decided to rig up an A2DP (Stereo Bluetooth Audio) adapter on his own.

He pulled the head unit out and started looking around to see how he could wire an adapter in. He figured the best course of action would be to remove the tape deck, and fool the stereo into thinking that a tape had been inserted. After spending some time tracing wires and studying how his old tape adapters worked, [Roofus] had an A2DP connection wired in and was ready to rock out.

Greeted with nothing but silence, he turned to his favorite hacking site (Hackaday, naturally) for assistance. Some friendly forum-goers helped him identify a ground loop issue, and he set off to his nearest RadioShack for a pair of isolation transformers that would fix his problem.

Once he knocked out the ground loop issues, his adapter worked like a charm. He put everything back together, and aside from a tiny switch he installed to toggle between audio sources, you would never know it was there.