Author: Elliot Williams

1449 Articles

One SMT Breakout To Rule Them All

April 16, 2016 by 33 Comments

You need to use surface-mount technology (SMT) parts in your design. But you also need to prototype. How to fit those little buggers into your breadboard?

[Simon] came up with a general-purpose SMT-to-breadboard solution. Now, there are already myriad adapter boards for the many-pin devices: SSOP-to-DIP adapters and so on. But what do you do when you just need to work that tiny SOT223 voltage regulator into a breadboarded circuit?

[Simon]’s solution fills that gap with one breadboardable design to handle all of your small-pin-count part needs. It accommodates SOT223, SOT323, and SOT23 three-pin parts like transistors or voltage regulators, and also has pads for all of the common two-terminal parts like resistors and capacitors from 0402 on up to 1206. You could build up a full voltage regulator circuit on one of these things. He’s even included some whitespace on the back for your notes.

SMT parts aren’t even the future any more. And with the right procedure, they’re not hard to hand-assemble. So the next time you have some extra space in a PCB order, toss in a couple of [Simon]’s breakouts and you’ll be ready for your next breadboarding session.

Bela: Real-Time BeagleBone Audio/Analog Cape

April 13, 2016 by 16 Comments

Bela is a cape for the BeagleBone Black that’s aimed at artists and musicians. Actually, the cape is much less than half of the story — the rest is in some clever software and a real-time Linux distribution. But we’re getting ahead of ourselves. Let’s talk hardware first.

First off, the cape has stereo input and output as well as two amplified speaker outs. It can do all of your audio stuff. It also has two banks of analogue inputs and outputs, each capable of handling eight signals. In our opinion, this is where the Bela is cool. In particular, the analog outputs are not Arduino-style “analog outputs” where it’s actually a digital output on which you can do PWM to fake an analog signal. These are eight 16-bit outputs from an AD5668 DAC which means that you can use the voltages directly, without filtering.

Then there’s the real trick. All of these input and output peripherals are hooked up to the BeagleBone’s Programmable Realtime Units (PRUs) — a hardware subsystem that’s independent of the CPU but can work along with it. The PRU is interfaced with the real-time Linux core to give you sub-microsecond response in your application. This is a big deal because a lot of other audio-processing systems have latencies that get into the tens of milliseconds or worse, where it starts to be perceptible as a slight lag by humans.

The downside of this custom analog and audio I/O is that it’s not yet supported by kernel drivers, and you’ll need to use their “Heavy Audio Tools” which compiles Pd programs into C code, which can then drive the PRUs. Of course, you can write directly for the PRUs yourself as well. If you just want to play MP3s, get something you have a bunch of simpler, better options. If you need to do responsive real-time audio installations, Bela is a way to go.

The project is open-source, but we had to do a bunch of digging to find what we were looking for. The hardware is in zip files here, and you’ll find the software here. The demo projects look/sound pretty cool and their Kickstarter is long over-funded, so we’re interested to see what folks make with these.

Stealing 3D Prints By Sound

April 12, 2016 by 48 Comments

In the open hardware world, we like to share 3D design files so that our friends and (global) neighbors can use and improve them. But we’ve all printed things from time to time that we’d like to keep secret. At least this is the premise behind this article in Science which proposes a novel method of 3D-printer-based industrial espionage: by recording the sound of the stepper motors and re-creating the toolpath.

Unfortunately, the article is behind a paywall so we’re short on the details, but everyone who’s played the Imperial March on their steppers has probably got the basic outline in their mind. Detecting the audio peak corresponding to a step pulse should be fairly easy. Disentangling the motions of two axes would be a bit harder, but presumably can be done based on different room-acoustic filtering of the two motors. Direction is the biggest question mark for us, but a stepper probably has a slightly audible glitch when reversing. Keeping track of these reversals could do the trick.

What do you think? Anyone know how they did it? Does someone with access to the full article want to write us up a summary in the comments?

[Thanks LVfire via Ars Technica]

[Edit: We were sent a copy of the full article (thanks [PersonUnknown]!) and it doesn’t explain any technical details at all. Save yourself the effort, and have fun speculating, because reading the article won’t help.]

Dump Your (Old) Computer’s ROM Using Audacity

April 12, 2016 by 32 Comments

If you’ve got an old calculator, Commodore 64, or any other device that used a tape recorder to store and retrieve data, you’ve probably also got a bunch of cassettes lying around, right? Well, you can get rid of them now (or sell them to nostalgic collectors for outrageous prices) because you can just as easily dump them to Audacity, decode them and archive them on a more sane medium.

In [Kai]’s case, the computer was a Sharp Pocket Computer system, and in his post there’s a lot of detail that’s specific to that particular system. If that’s applicable to you, go read up. In particular, you’ll be glad to find that the Pocket-Tools is a software suite that will encode and decode files between the Sharp binary formats and audio. Along the way, we found similar tools for Casio pocket computers too.

For a more general-purpose approach, like if you’re trying to dump and load data from a more standard computer that uses 1200/2400 Hz FSK encoding, this Python library may be useful, or you can implement the Goerzel algorithm yourself on your platform of choice. If you’ve got a particular binary format in mind, though, you’ll have to do the grunt work yourself.

Anyone out there still using these audio data encodings? We know that ham radio’s APRS system runs on two tones. What else? Why and when would you ever transfer data this way these days?

via the Adafruit blog!

Audio Out Over UART

April 11, 2016 by 40 Comments

There’s a reason that the bog-standard serial port will never die. It’s just so robust and simple. When you need a console that will absolutely work with minimal software and hardware, UART is the way to go. Because of this, UART hacks abound. Here’s a new one to us, and a challenge to our readers.

[Tiziano Bacocco] decided to use UART signals as a type of PWM to create audio. That’s right, he’s plugging the serial TX line straight into a speaker. This gives you eight possible PWM output voltage levels. The trick is using some Python code (using the awesome pyserial module) to down-quantize the audio data to fit these eight possible values and then push them out at the correct sampling rate. ffmpeg is used to pre-process the files.

Continue reading “Audio Out Over UART” →

“World’s Brightest” Flashlight

April 10, 2016 by 46 Comments

With the crazy extremes of light flux density that are possible these days, we’re putting quotation marks around “world’s brightest”, but it’s abundantly clear that this flashlight build is very much too bright. No, really. Why would you want a flashlight so bright that you have to wear sunglasses to look at anything that’s within a twenty foot radius?

Because you can. [Mads Nielsen] combined 18, one hundred Watt LED units with some giant machined heatsinks, fans to cool those heatsinks, lenses, and other hardware to make a device that turns electrons into photons at an alarming rate. Each chip-on-board LED package requires 32 Volts, and they’re pairwise in series so it’s a 64 V system. A boot converter pushes up the twelve LiPo battery packs up to the required voltage.

Even with the relatively high voltage, this thing sucks in 27 A, so the power supply is distributed among four of these boost converters. All of this means thick cables and a rather hefty power switch. When you’re designing something ridiculous, all of these little details come out of the woodwork. We’ve included part one of the four-part build video here, because they’re full of great detail. [Mads] has a lot more interesting LED-related info on his YouTube channel. You can watch the showing-off video on your own time.

Continue reading ““World’s Brightest” Flashlight” →

Listen To Meteors Live

April 9, 2016 by 15 Comments

When the big annual meteor showers come around, you can often find us driving up to a mountaintop to escape light pollution and watching the skies for a while. But what to do when it’s cloudy? Or when you’re just too lazy to leave your computer monitor? One solution is to listen to meteors online! (Yeah, it’s not the same.)

Meteors leave a trail of ionized gas in their wake. That’s what you see when you’re watching the “shooting stars”. Besides glowing, this gas also reflects radio waves, so you could in principle listen for reflections of terrestrial broadcasts that bounce off of the meteors’ tails. This is the basis of the meteor burst communication mode.

[Ciprian Sufitchi, N2YO] set up his system using nothing more than a cheap RTL-SDR dongle and a Yagi antenna, which he describes in his writeup (PDF) on meteor echoes. The trick is to find a strong signal broadcast from the earth that’s in the 40-70 MHz region where the atmosphere is most transparent so that you get a good signal.

This used to be easy, because analog TV stations would put out hundreds of kilowatts in these bands. Now, with the transition to digital TV, things are a lot quieter. But there are still a few hold-outs. If you’re in the eastern half of the USA, for instance, there’s a transmitter in Ontario, Canada that’s still broadcasting analog on channel 2. Simply point your antenna at Ontario, aim it up into the ionosphere, and you’re all set.

We’re interested in anyone in Europe knows of similar powerful emitters in these bands.

As you’d expect, we’ve covered meteor burst before, but the ease of installation provided by the SDR + Yagi solution is ridiculous. And speaking of ridiculous, how about communicating by bouncing signals off of passing airplanes? What will those ham radio folks think of next?