Calculating Pi To 10 Trillion Digits; The Last Number Is 5

November 28, 2011 by Brian Benchoff 44 Comments

In August, 2010, [Alexander Yee] and [Shigeru Kondo] won a respectable amount of praise for calculating pi to more digits than anyone else. They’re back again, this time doubling the number of digits to 10 Trillion.

The previous calculation of 5 Trillion digits of Pi took 90 days to calculate on a beast of a workstation. The calculations were performed on 2x Xeon processors running at 3.33 GHz, 96 Gigabytes of RAM, and 32 Terabytes worth of hard drives. The 10 Trillion digit attempt used the same hardware, but needed 48 Terabytes of disk to store everything.

Unfortunately, the time needed to calculate 10 Trillion digits didn’t scale linearly. [Alex] and [Shigeru] waited three hundred and seventy-one days for the computer to finish the calculations. The guys used y-cruncher, a multithreaded pi benchmarking tool written by [Alex]. y-cruncher calculates hexadecimal digits of pi; conveniently, it’s fairly easy to find the nth hex digit of pi for verification.

If you’re wondering if it would be faster to calculate pi on a top 500 supercomputer, you’d be right. Those boxes are a little busy predicting climate change, nuclear weapons yields, and curing cancer, though. Doing something nobody else has ever done is still an admirable goal, especially if it means building an awesome computer.

Rebuilding A Mac SE As A Server Again

November 26, 2011 by Brian Benchoff 12 Comments

Around this time last year, [Sprite_TM] took a 1980’s-era Macintosh SE and rebuilt it as a home file server. He used a Seagate Dockstar as the new motherboard, but over the past year he’s been annoyed with the fact that the Dockstar doesn’t have real SATA ports. Using USB to SATA converters on a server is a slow way of doing things, so [Sprite_TM] rebuilt his SE using an HP thin client. To do this, he had to break out the onboard SATA and PCIE; not an easy task, but that’s why [Sprite_TM] is around.

The first order of business was installing a pair of SATA ports. The stock thin client had two NAND-flash chips serving as the drive, both connected to a SATA controller. All [Sprite_tm] had to do was desolder the flash chips and wire up the new SATA connections. Easy enough.

Because the HP thin client only had 100Mbps Ethernet, [Sprite_tm] wasn’t looking forward to the order of magnitude difference between his expected rsync speeds and what he would get with a 1Gbps connection. The only problem is the thin client didn’t have a spare PCIE connection for an Ethernet card. That’s really no problem for [Sprite_tm], though: just desolder the GPU and run a few wires.

Just like last year’s work on his SE, [Sprite_tm] ended up with a functional and very cool home server. The old-school System 7 is still there, and of course he can still play Beyond Dark Castle. Awesome work, in our humble opinion.

Seeing With Another Person’s Eyes

November 23, 2011 by Brian Benchoff 9 Comments

We suppose they could just trade shoes, but that wouldn’t be a hack. [Timothy] wanted to design a team-building exercise at work, and he figured the best way to get some empathy would be to have people swap eyes. He calls his project eyeSwap and it is supposed to, “put the eye back in team.”

[Tim] found a few CRT viewfinders in a junk box attached small video cameras to each one. During the ‘training phase’ of his team-building exercises, both people playing the game complete a few hand-eye coordination tasks to get a feel for the rig. After the training phase, the inputs are swapped; Alice’s cameras are sent to Bob’s viewfinders and vice versa. The participants then complete the same tasks they did during the training phase.

The tasks aren’t that hard – putting balls into holes, for example – but it does require a huge amount of communication and coordination. eyeSwap reportedly builds trust and empathy towards others, and looks like a lot more fun than a ‘trust fall.’

Check out the video of two people playing eyeSwap after the break.

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Syneseizure Makes Objects Feel Loud

November 18, 2011 by Brian Benchoff 29 Comments

Synesthesia is a mix-up in the wiring of the brain where sensory inputs are perceived differently than what ‘normal people’ usually experience. People with synesthesia can have visual input mapped to aural perception in the mind, or driving along a highway where there’s a recent skunk roadkill can smell ‘loud.’ It’s an interesting way of perceiving the world that’s usually inaccessible to most of the population, but the Syneseizure tries to replicate this way of viewing the world.

There’s a bunch of types of synesthesia (Led Zeppelin feels purple, or apples smelling further away than grapes), but [Greg] and his team needed to choose one subtype to reduce the complexity of their project. They chose mapping visual input to touch sensation. This was accomplished by attaching a dozen speakers to the test subject’s face. A webcam recorded where the subject was looking at and with a Processing sketch, the webcam was reduced to a grayscale 4×3 pixel grid. The intensity of the each pixel corresponded to the strength of buzzing in each speaker. All that was left to do is put a mask over the subject and have them walk around.

The Syneseizure was built for Science Hack Day San Francisco and ended up winning the people’s choice award. There’s a bunch of pics and a great write-up on the project website, so be sure to check that out.

Polar Pen Plotter Draws Huge Images Very Slowly

November 17, 2011 by Brian Benchoff 7 Comments

[Euphy] just posted an Instructable of his Polargraph drawing machine that’s able to draw huge images slower than molasses in November. The plotter only uses two stepper motors to control the position of the pen and can be made nearly entirely from salvaged parts – [Euphy] built his for just about £150.

The Polargraph uses two stepper motor on the top corners of a large, flat surface. A weighted pen carriage is attached to both motors with beaded cord that’s often seen in window blinds. By controlling the distance from the carriage to each motor, the position of the pen can be precisely controlled. It’s not a very fast way of drawing an image (check out the real-time video), but it sure is interesting to watch.

There have been a few other rope-and-chain plotters, like Der Kritzler and Hektor. [Euphy]’s work is the is one of the best documented builds we’ve seen, and he’s also put up the code and a website.

We really could have used [Euphy]’s plotter when we wanted to draw some whiteboard art. While we’re out dumpster diving for some small stepper motors, check out the time-lapse video of the Polargraph after the break.

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Taking GPS Where No Man Has Gone Before

November 14, 2011 by Brian Benchoff 24 Comments

[Willem] has a friend that wanted to take a GPS datalogger up an unclimbed mountain the wilds of Kyrgyzstan. The GPS logger built for the expedition made it to the summit of Eggmendueluek, but it didn’t work the whole way up. Since the logger came back to London, [Willem] was able to do a complete teardown and failure analysis.

The data logger was built around a Jeenode with a GPS unit and MicroSD card reader added on. A few breakout boards were made and two of these bad boys were ensconced in water and dust proof enclosures. Powered by four AA batteries, the data loggers were able to handle the rigorous testing of being thrown down a staircase and also the harsh temperatures of London. Things changed in the wilds of Kyrgyzstan, though.

The data retrieved from the mountaineering expedition wasn’t the greatest – a few wires came loose after being thrown into the back of a Russian truck and jostled around. The AA batteries only powered the data loggers for three days, compared to the 12 day battery life in London. There are a few improvements needed for the next trip – some thermal insulation and not using solid core wire – but not that [Willem] has figured out the bugs he’s ready for his friend’s next expedition.

Controlling Shift Registers Via SPI

November 5, 2011 by Brian Benchoff 12 Comments

Hack a Day’s very own (and very prolific contributor) [Mike Szczys] put up a great tutorial on how to drive shift registers with an SPI interface.

[Mike]’s earlier tutorial of the 595 shift register goes through the functions of a shift register pin by pin. In a 595, bits for each position in the register are sent over one at a time. Most microprocessors have an Serial Peripheral Interface, and using an SPI bus means a lot less mucking about.

An ATmega168 was used for this build, although most Atmel chips can be made to work as an SPI master device. There are just three wires connecting the microcontroller to the shift register – SER, SRCLK, and RCLK. Like any other shift register setup, the build can be expanded by connecting the QH’ pin of the first 595 to the SER pin of the second.

[Mike] graciously made all the code for his build available. The video after the break is a 16-bit binary counter, a good stopping point before [Mike] rebuilds his Larson scanner/Cylon/Kitt, moving away from a PWM-based build to a register-based one.

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