Harmonic Analyzer Mechanical Fourier Computer

November 18, 2014 by 20 Comments

If you’re into mechanical devices or Fourier series (or both!), you’ve got some serious YouTubing to do.

[The Engineer Guy] has posted up a series of four videos (Introduction, Synthesis, Analysis, and Operation) that demonstrate the operation and theory behind a 100-year-old machine that does Fourier analysis and synthesis with gears, cams, rocker-arms, and springs.

In Synthesis, [The Engineer Guy] explains how the machine creates an arbitrary waveform from its twenty Fourier components. In retrospect, if you’re up on your Fourier synthesis, it’s pretty obvious. Gears turn at precise ratios to each other to create the relative frequencies, and circles turning trace out sine or cosine waves easily enough. But the mechanical spring-weighted summation mechanism blew our mind, and watching the machine do its thing is mesmerizing.

In Analysis everything runs in reverse. [The Engineer Guy] sets some sample points — a square wave — into the machine and it spits out the Fourier coefficients. If you don’t have a good intuitive feel for the duality implied by Fourier analysis and synthesis, go through the video from 1:50 to 2:20 again. For good measure, [The Engineer Guy] then puts the resulting coefficient estimates back into the machine, and you get to watch a bunch of gears and springs churn out a pretty good square wave. Truly amazing.

The fact that the machine was designed by [Albert Michelson], of Michelson-Morley experiment fame, adds some star power. [The Engineer Guy] is selling a book documenting the machine, and his video about the book is probably worth your time as well. And if you still haven’t gotten enough sine-wavey goodness, watch the bonus track where he runs the machine in slow-mo: pure mechano-mathematical hotness!

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Super Smash Bros On A Calculator

November 17, 2014 by 14 Comments

Move over, BlockDude! There’s a new calculator game in town. [Hayleia] and a few other programmers have been hard at work on a clone of Super Smash Bros for graphing calculators that is sure to keep you busy in your next calculus class.

The game, called Smash Bros Open, is based on the Nintendo fighting game and is written specifically for monochrome z80 calculators (the TI-83 and TI-84 being the most ubiquitous of these). The game runs in 6 MHz mode with a simple background, or it can run in 15 MHz mode with a more complicated background. The programmers intend for the game to be open source, so that anyone can add anything to the games that they want, with the hopes of making the game true to its namesake.

Anyone who is looking to download a copy of this should know that Smash Bros Open is currently a work-in-progress. Right now both players need to play on the same calculator (with different keys), and Fox is the only playable character. The programmers hope to resolve the two player issue by using a second calculator as a game pad, or by linking the two calculators using Global CalcNet. As for the other characters, those can be added by others based on the existing code which is available on the project’s forum post!

Thanks to [Chris] for the tip.

Because You Can’t Go To Germany Without Seeing Model Trains

November 17, 2014 by 18 Comments

As with all our extracurricular adventures, we needed to visit a few hackerspaces while in Munich. The first one was MCSM/Make Things Munich, formerly the Siemens Club for model engines. We’ve been to a few hackerspaces and have the passport stamps to prove it, and we can say without a doubt this space is unique.

MCSM was a hackerspace before the concept of hackerspaces existed. Originally, this was the Siemens Club for Model Engines, filled with engineers from the Siemens plant tinkering with model trains, model boats, and models of anything that moves. One of the members that guided us through the space, [Carlos Morra] told us when he joined, he alone dropped the average age of the space’s membership by a decade.

Inside the space, you’ll find the usual tools and equipment – lathes, CNC mills, an electronics workbench, and a bunch of old but still valuable equipment. Most of this equipment was salvaged from the Siemens plant. The organization for this space, though, cannot be compared to anything I’ve ever seen. There are floor to ceiling cabinets filled with everything you can imagine, all carefully indexed and sorted.

Of course, being formerly called the Model Engine club, there will be an immense train layout. I counted at least five gauges of track in two sprawling layouts, one of which was easily 15 square meters. It’s a true hackerspace built from a model train club, how can it get better than that?

Pictures below.

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Play Music On A High Voltage Keyboard

November 17, 2014 by 17 Comments

[Matt] works at a neon sign power supply company. When a vendor error left him with quite a few defective high voltage transformers, he couldn’t bring himself to toss them in the bin. [Matt] was able to fix the transformers well enough to work, and the idea for a high voltage keyboard began to brew. Unfortunately, the original transformers were not up to the task of creating a musical arc. At that point the project had taken on a life of its own. Matt grabbed some higher power transformers and started building.

The keyboard has 25  keys, each connected to an individual high voltage circuit with its own spark gap. The HV circuit is based upon a IR2153D self-oscillating half-bridge driver. (PDF link). The 2153D is modulated by a good old-fashioned 555 timer chip. No micros in this design, folks! The output of the IR2153D switches a pair of N-channel MOSFETS which drive the flyback transformers.

[Matt] created 25 copies of his circuit and built them up on individual PCBs. He assembled everything on a wooden board shaped roughly like a grand piano. The final project looks great – though [Matt] admittedly has no musical ability, so we can’t hear AC/DC flying out of those spark gaps just yet.

If you do want to hear sparks playing music, check out the OneTesla project we saw at MakerFaire NY 2013.

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Sand Cast Banana For Scale Is So Metal

November 17, 2014 by 23 Comments

If you’ve been on Reddit over the past year, you’ve likely encountered the “banana for scale” meme. [BFG121] felt that the size variation of bananas would not do – there needed to be a standard. He decided to make a metal banana out of re-purposed aluminum. He created his own furnace out of everyday objects including a hair dryer, metal bucket, cement, fire clay, and sand. [BFG121] used a typical banana as the reference for his sand casting mold. After melting the aluminum in his homemade furnace, he poured it into the empty mold, making sure there was an extra hole for the displaced air to escape. The end result is a perfect replica of a banana. [BFG121] made two aluminum bananas, and stamped each one with a serial number. One was given to Imgur headquarters while the other was auctioned on eBay. The winning bid (#39) was $67 USD, a very good ROI.

If you want to learn more about metal casting, check out myfordboy’s channel on YouTube.  You can also see an example of the “banana for scale” in this Hackaday article about a giant spirograph. Our only suggestion to [BFG121] is to send some to ASTM, NIST, and BIPM!

[via Reddit]

RasPiCommPlus, An Expansion Board For Expansion Boards

November 17, 2014 by 34 Comments

The easiest way to connect a GSM module to a Raspberry Pi would be to buy a breakout module, install some software, and connect to a mobile network with a Pi. Need GPS, too? That’s a whole other module, with different software. The guys behind RasPiCommPlus are working on a better solution – a breakout board for breakout boards that takes care of plugging a ton of modules into a Pi and sorts out the kernel drivers to make interfacing with these modules easy.

Right now, the team has a GPS and GSM module, digital in and out modules, an analog input module, and RS-232 and -485 modules. They’re working on some cool additions to the lineup, including a breakout for Sharp memory displays, a 9-axis IMU, a stepper motor driver, and a 1-wire breakout module.

Some of the RasPiCommPlus team showed up to the Hackaday Munich party and were kind enough to sit down for a demo video. You can check that out below.

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image of drfitwood on a beach

Ask Hackaday: Not Your Mother’s Feedback

November 17, 2014 by 33 Comments

Imagine you were walking down a beach, and you came across some driftwood resting against a pile of stones. You see it in the distance, and your brain has no trouble figuring out what you’re looking at. You see driftwood and rocks – you can clearly distinguish between the two objects without a second thought.

Think about the raw data entering the brain. The textures of the rocks and the driftwood are similar. The colors are similar. The irregular shapes are similar. Thus the raw data entering the brain’s V1 area for both objects must be similar as well. Now think about the borders that separate the pieces of driftwood from the edges of the rocks. From a raw data perspective, there is no border, and likewise no separation because the two objects are so similar.  But yet your brain can clearly see a rock and a piece of driftwood – two distinctly different objects. So how does the brain do this? How does it so easily differentiate between the two? If the raw data on either side of the border separating the wood and the rocks is the same, then there must be an outside influence determining where that border is. Jeff Hawkins believes this outside influence is a very special and most interesting type of feedback. Read on as we explain and attempt to implement this form of feedback in our hierarchical structure of invariant representations.

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