Author: Elliot Williams

1450 Articles

3D Printed Surfboard

January 26, 2015 by 25 Comments

You whippersnappers these days with your 3D printers! Back in our day, we had to labor over a blank for hours, getting all sweaty and covered in foam dust. And it still wouldn’t come out symmetric. Shaping a surfboard used to be an art, and now you’re just downloading software and slinging STLs.

Joking aside, [Jody] made an incredible surfboard (yes, actual human-sized surfboard) out of just over 1 kilometer of ABS filament, clocking 164 hours of printing time along the way. That’s a serious stress test, and of course, his 3D printer broke down along the way. Then all the segments had to be glued together.

But the printing was the easy part; there’s also fiberglassing and sanding. And even though he made multiple mock-ups, nothing ever goes the same on opening night as it did in the dress rehearsal. But [Jody] persevered and wrote up his trials and tribulations, and you should give it a look if you’re thinking of doing anything large or in combination with fiberglass.

Even the fins are 3D printed and the results look amazing! We can’t wait for the ride report.

Shaka.

When Adding Noise Helps

January 25, 2015 by 20 Comments

It’s a counterintuitive result that you might need to add noise to an input signal to get the full benefits from oversampling in analog to digital conversion. [Paul Allen] steps us through a simple demonstration (dead link, try Internet Archive) of why this works on his blog. If you’re curious about oversampling, it’s a good read.

Oversampling helps to reduce quantization noise, which is the sampling equivalent of rounding error. In [Paul’s] one-bit ADC example, the two available output values are zero volts and one volt. Any analog signal between these two values is rounded off to either zero or one, and the resulting difference is the quantization error.

In oversampling, instead of taking the bare minimum number of samples you need you take extra samples and average them together. But as [Paul] demonstrates, this only works if you’ve got enough noise in the system already. If you don’t, you can actually make your output more accurate by adding noise on the input. That’s the counterintuitive bit.

We like the way he’s reduced the example to the absolute minimum. Instead of demonstrating how 16x oversampling can add two bits of resolution to your 10-bit ADC, it’s a lot clearer with the one-bit example.

[Paul’s] demo is great because it makes a strange idea obvious. But it got us just far enough to ask ourselves how much noise is required in the system for oversampling to help in reducing quantization noise. And just how much oversampling is necessary to improve the result by a given number of bits? (The answers are: at least one bit’s worth of noise and 22B, respectively, but we’d love to see this covered intuitively.) We’re waiting for the next installment, or maybe you can try your luck in the comment section.

The Original Seven (Eight?) Segment Display

January 9, 2015 by 36 Comments

The seven-segment LED display is ubiquitous. But how old do you think the fundamental idea behind it is? You nixie tube fans will be thinking of the vacuum-tube era, but a reader sent us this patent filed in 1908 where [Frank W. Wood] builds a numeric display with plain-vanilla light bulbs, slots cut in wood, and lots of wires.

The OCR on the patent is poorly done — you’re going to want to download the PDF and read it locally. But as it states in the patent, “Referring again to Fig. 1, the novel arrangement of the lamp compartments will be readily understood.”

Technically it’s not a seven-segment display at all. [F.W. Wood] designed these really nice-looking “4”s with the diagonal heads, and so he needed eight segments per digit. But the basic idea shines through, if you pardon the pun.

The other figures demonstrate the machine that’s used to send the signals to light up the lights. It’s a rotating drum with the right contacts on the bottom side to make connections and turn on the right lights at the other end. Low tech, but it’s what was available at the time.

We’re stoked that we’re not responsible for wiring this thing up, and we’re a bit awed by how old the spirit behind one of our most ubiquitous technologies is.

Thanks to [mario59] for the nostalgic tip!

Global Space Balloon Challenge

January 7, 2015 by 20 Comments

Looking for a reason to put up a balloon and payload into near-space? Not that one’s necessary, but the Global Space Balloon Challenge has got a variety of good reasons for you to do so, in the form of prizes and swag from their sponsors. Go for highest altitude, best photograph, longest ground track, best on-board science payload, or a bunch more. Have a look through the gallery to check out last year’s winners, including teams that dropped a 3ft paper airplane or floated an R2D2 replica.

Basically all you need to do is register on their website and then go fly a high-altitude balloon between April 10th and 27th. Last year 60 teams took part, and this year they’ve already got 90 teams from 31 countries.

And if you’re just getting into the (hobby? sport?) of high-altitude ballooning, be sure to check out their tutorials and forum. Of course Hackaday has been covering folks’ near-space balloon efforts for a while now too, so you’ve got plenty of reading.

So what are you waiting for? Helium’s not getting any cheaper and spring is on its way. Start planning your balloon launch now.

Pendulum Music For Oscilloscope And Photodiodes

December 28, 2014 by 9 Comments

Two turntables and a microphone? Try two oscilloscopes and a couple of photodiodes. [dfiction] reinterpreted Steve Reich’s classic feedback piece for more modern electronics. The video is embedded after the break.

The original Pendulum Music is a conceptual musical composition from the heady year of 1968. Basically, you set a bunch of microphones swinging across speakers, making feedback as they pass by. The resulting rhythmic and tonal oscillations change over time as the swinging damps down. It’s either mesmerizing or entirely boring, depending on your mindset.

In the [dfiction] version, the feedback is produced by passing a “light microphone” over an oscilloscope. And since he’s got a pair of these setups, the one microphone also feeds the other ‘scope. The resulting sound is this chaotic and gritty noise-rumble. We dig it.

If slowly evolving “process music” pushes the boundaries of your attention span (or if it’s just not your thing) you can totally skip around in the video. Try around 1:40 and 3:45 into the piece just to get an idea of what’s going on. But once you’re there, you might as well let it run its course.

Continue reading “Pendulum Music For Oscilloscope And Photodiodes” →

31st Chaos Communications Congress

December 27, 2014 by 10 Comments

The 31st annual Chaos Communications Congress (31C3) kicked off today and you’ve already missed some great talks. If you’re not in Hamburg, Germany right now, you can watch the talks as they happen on the live stream. So stop reading this blog post right now, and check out the list of presentations. (But don’t fret if you’ve already missed something that you’d like to see. All the talks are also available after the fact.)

For those of you whose worldview is centered firmly on the You Ess of Ay, you’ll be surprised to learn that the Congresses are essentially the great-grandaddy of the US hacker conventions. If you’re one of the many (old?) US hackers who misses the early days of yore before DEFCON got too slick and professional, you’ll definitely like the CCC. Perhaps it’s the German mindset — there’s more emphasis on the community, communication, and the DIY aesthetic than on “the industry”. It’s more HOPE than DEFCON.

This is not to say that there won’t be some great hacking showcased at 31C3. It is the annual centerpiece of the European hacker scene, after all. Hardware, firmware, or software; it’s all exploited here.

Some of the talks are in German, naturally, but most are in English. If you haven’t attended before, you at least owe it to yourself to check out the live stream. Better yet, if you’re a member of an American hackerspace, you can at least set up local remote viewing for next year. Or maybe you’ll find yourself visiting Germany next Christmas.

[Image: Wikipedia / Tobias Klenze / CC-BY-SA 3.0]

Towards The Perfect Coin Flip: The NIST Randomness Beacon

December 19, 2014 by 75 Comments

Since early evening on September 5th, 2013 the US National Institute of Standards and Technology (NIST) has been publishing a 512-bit, full-entropy random number every minute of every day. What’s more, each number is cryptographically signed so that you can easily verify that it was generated by the NIST. A date stamp is included in the process, so that you can tell when the random values were created. And finally, all of the values are linked to the previous value in a chain so that you can detect if any of the past numbers in the series have been altered after the next number is published. This is quite an extensive list of features for a list of random values, and we’ll get into the rationale, methods, and uses behind this scheme in the next section, so stick around.

Continue reading “Towards The Perfect Coin Flip: The NIST Randomness Beacon” →