Want To Learn Artificial Intelligence? Good.

September 5, 2011 by Brian Benchoff 39 Comments

In a little more than a month, tens of thousands of people around the world will attend a class on Artificial Intelligence at Stanford. Registration for this class is still open for both class ‘tracks’. The “basic” track is simply watching lectures and answering quizzes, or a slightly more advanced version of MIT OpenCourseware or Khan Academy. The “advanced” track is the full class, requires homework and exams, and aspires to Stanford difficulty.

With thousands of people taking this class, there’s bound to be a few study groups popping up around the web. The largest ones we’ve seen are /r/aiclass on Reddit and the stack overflow style aiqus. The most common reply to ‘what language should I learn from this class?’ is Python, although there’s an online code repo that has the text’s working code in Lisp, Java, C++ and C#.

If AI doesn’t float your boat, there are two more classes being taught from Stanford this fall: machine learning and introduction to databases. Any way you look at it, you’re getting to take a class from one of the preeminent instructors in the field for free. Do yourself a favor and sign up.

Thanks to everyone who sent this in. You can stop now.

Freakin’ Huge CNC Router

September 4, 2011 by Brian Benchoff 22 Comments

[Tom] sent in a gigantic 3-axis router that he pieced together during a 2 week-long work experience placement. Looking at this picture showing a 12-inch ruler on the work area, we realized that this may be the largest CNC router we’ve seen on Hack A Day.

[Tom]’s employer gave him some obsolete axes, so piecing the mechanical components together was very easy. The only real problem was interfacing the CNC controller to a computer. This meant [Tom] had to convert G Code to the code used by the antiquated NSK axes. Where G Code defines arcs with a start point, end point, and radius, the NSK code defines arcs with a start point, end point, and another point along the arc. It’s a tricky bit of math, but [Tom] built some software that did this in Visual Basic.

Right now, [Tom] only has a pen tool attached to the router; you can check that in action after the break. We’re trying to imagine what we would do with a 4 m² work area; this could easily be used to make a giant reprap or other 3D printer.

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Highway Based Soundtrack Recordings

September 1, 2011 by Brian Benchoff 21 Comments

[Urpo Lankinen] has a father who is a huge movie buff, and once you care deeply about something it begins appearing everywhere you look. While driving on a back-country road one day, [Urpo]’s dad noticed that the shadows of the trees on the road looked like an optical film soundtrack, so it was up to the son to make it happen.

Early sound-on-film technologies like the RCA Photophone, and Movietone recorded audio onto the film stock with a variable area exposure. This exposure corresponds to the waveform of the audio signal. [Urpo] figured that his small digital video camera served the same purpose as the audio sensors inside the projector, so he put a piece of tissue paper over the lens and wound up with a video that was just frames of gray.

[Urpo] built an app in Processing that averages the pixels in each frame of the video. Of course, recording at 30 frames/second won’t produce any audio this way, so he modulated a triangle wave with this data in Audacity. In the end it really doesn’t sound like much, but it’s great to see such a geeky build.

We’d love to post the video after a break but [Urpo] doesn’t believe in YouTube embeds. We’ll honor his wishes, so you can check out the video here.

Zigbee Home Automation Gives Us Another Reason Not To Get Up

August 24, 2011 by Brian Benchoff 27 Comments

[Russell] sent in a neat home automation project he’s been working on. Even though the project only has two devices so far, we can already see the potential of his project.

Instead of the X10 standard that has been a staple of home automation for more than 30 years, [Russell] went with ZigBee modules. Aside from being much faster and more flexible than X10 home automation modules, ZigBees also open up a bunch of projects that would be impossible if he went with X10. With some well-placed IR transmitters hidden in his living room, it would be possible to have a TV and cable box controlled via the Internet.

So far, [Russell] built an network-controlled RGB ‘mood lamp’ and an infrared remote for his central air. Everything is controlled through a web app, and [Russell] says that additional modules can be easily added to the code.

Check out [Russell]’s demo of his project after the break.

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Ohm Sense Makes Sense Of Resistor Color Bands

August 6, 2011 by Brian Benchoff 59 Comments

[Alex Busman]’s first foray in iOS programming looks like a pretty useful tool. He came up with Ohm Sense, an iPhone app that will take a picture of a resistor and calculate the value based on the color bands. It’s a great tool that we wish we had when we were starting out. At 99 cents, the app is also much cheaper than the emotional cost of our relationship with Violet.

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Building A One-instruction Computer

July 27, 2011 by Brian Benchoff 23 Comments

[Hasith] sent in this project where he goes through the process of designing a one instruction CPU in Verilog. It may not win a contest for the coolest build on Hack A Day, but we really do appreciate the “applied nerd” aspect of this build.

With only one instruction, an OISC is a lot simpler than the mess we have to deal with today. There are a few instructions that by themselves are Turing-complete (like Subtract and branch if negative, and Move). Designing an OISC with one of these instructions means it can also emulate a Turing machine.

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A Study In AVR Power Saving Techniques

July 26, 2011 by Mike Nathan 88 Comments

amtel_avr

[Scott] found the iCufflinks from Adafruit Industries pretty interesting, but he thought that the stated run time of 24 hours was a bit short. He figured he could improve the product’s power consumption at least a little bit, to improve the overall battery life.

From their schematics, he placed an order for parts and built two identical iCufflink mock-ups side by side – one running their code and one running his. He took baseline current draw measurements, then got busy slimming down the cufflinks’ software. It had been 20 years since he touched assembly, and he has never written it for an AVR, but judging by his work he’s not rusty in the least.

He slowed the ATtiny’s clock down and tweaked a few other settings for a savings of 53μA, but the real improvements came via a fairly simple fix. The original code called for the processor to institute a counting loop to sleep, which he found to be very wasteful. Instead, he chose to put the processor in an idle state, using the chip’s watchdog timer to wake it when it was time to pulse the LED. The power savings from this change alone was a whopping 261μA!

When he was said and done, the changes save about 315μA of current draw, and should allow the cufflinks to run for up to 38 hours without swapping batteries. In [Scott’s] opinion, a nearly 60% improvement in battery life is pretty good for a day’s work, and we’re inclined to agree.