An Eye-Catching Raspberry Pi Smart Speaker

December 21, 2016 by 15 Comments

[curcuz]’s BoomBeastic mini is a Raspberry Pi based smart connected speaker. But don’t dis it as just another media center kind of project. His blog post is more of a How-To guide on setting up container software, enabling OTA updates and such, and can be a good learning project for some. Besides, the design is quite elegant and nice.

boombeastic_02The hardware is simple. There’s the Raspberry-Pi — he’s got instructions on making it work with the Pi2, Pi2+, Pi3 or the Pi0. Since the Pi’s have limited audio capabilities, he’s using a DAC, the Adafruit I2S 3W Class D Amplifier Breakout for the MAX98357A, to drive the Speaker. The I2S used by that part is Inter-IC Sound — a 3 wire peer to peer audio bus — and not to be confused with I2C. For some basic visual feedback, he’s added an 8×8 LED matrix with I2C interface. A Speaker rounds out the BoM. The enclosure is inspired by the Pimoroni PiBow which is a stack of laser cut MDF sheets. The case design went through four iterations, but the final result looks very polished.

On the software side, the project uses Mopidy — a Python application that runs in a terminal or in the background on devices that have network connectivity and audio output. Out of the box, it is an MPD and HTTP server. Additional front-ends for controlling Mopidy can be installed from extensions, enabling Spotify, Soundcloud and Google Music support, for example. To allow over-the-air programming, [curcuz] is using resin.io which helps streamline management of devices that are hard to reach physically. The whole thing is containerized using Docker. Additional instructions on setting up all of the software and libraries are posted on his blog post, and the code is hosted on GitHub.

There’s a couple of “To-Do’s” on his list which would make this even more interesting. Synced audio being one: in a multi-device environment, have the possibility to sync them and reproduce the same audio. The other would be to add an Emoji and Equalizer display mode for the LED matrix. Let [curcuz] know if you have any suggestions.

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Cheap Powerbank Logic And Teardown

December 21, 2016 by 43 Comments

A fixture on many British high streets are pound shops. You may have an equivalent wherever in the world you are reading this; shops in which everything on sale has the same low price. They may be called dollar stores, one-Euro stores, or similar. In this case a pound, wich translates today to a shade under $1.24.

Amid the slightly random selection of groceries and household products are a small range of electronic goods. FM radios, USB cables and hubs, headphones, and mobile phone accessories. It was one of these that caught [Julian Ilett]’s eye, a USB power bank. (Video embedded below.)

You don’t get much for a quid, and it shows in this product. A USB cable that gets warm at the slightest current, a claimed 800 mA of output at 5V from a claimed 1200 mAh capacity, and all from an 18650 Li-ion cell of indeterminate origin. The active component is an FM9833E SOIC-8 switching regulator and charger (220K PDF data sheet, in Chinese).

A straightforward teardown of a piece of near-junk consumer electronics would not normally be seen as something we’d tempt you with, but [Julian] goes on to have some rather pointless but entertaining fun with these devices. If you daisy-chain them, they can be shown to have the properties of rudimentary digital logic, and in the video we’ve put below the break it is this that he proceeds to demonstrate. We see a bistable latch, a set-reset latch, a very slow astable multivibrator, and finally he pulls out a load more power banks for a ring oscillator.

If only [MacGyver] had found himself trapped in a container of power banks somewhere from which only solving a complex mathematical conundrum could release him, perhaps he could have fashioned an entire computer! The best conclusion is the one given at the end of the video by [Julian] himself, in which he suggests (and we’re paraphrasing here) that if you feel the idea to be unworthy of merit, you can tell him so in the comments.

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Alan Yates: Why Valve’s Lighthouse Can’t Work

December 21, 2016 by 51 Comments

[Alan Yates] is a hacker’s engineer. His job at Valve has been to help them figure out the hardware that makes virtual reality (VR) a real reality. And he invented a device that’s clever enough that it really should work, but difficult enough that it wasn’t straightforward how to make it work.

In his presentation at the Hackaday Supercon 2016, he walked us through all of the design and engineering challenges that were eventually conquered in getting the Lighthouse to market. We’re still a bit overwhelmed by the conceptual elegance of the device, so it’s nice to have the behind-the-scenes details as well.

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I Think I Failed. Yes, I Failed.

December 21, 2016 by 16 Comments

Down the rabbit hole you go.

In my particular case I am testing a new output matching transformer design for an audio preamplifier and using one of my go to driver circuit designs. Very stable, and very reliable. Wack it together and off you go to test and measurement land without a care in the world. This particular transformer is designed to be driven with a  class A amplifier operating at 48 volts in a pro audio setting where you turn the knobs with your pinky in the air sort of thing. Extra points if you can find some sort of long out of production parts to throw in there for audiophile cred, and I want some of that.

img_2857-2Lets use some cool retro transistors! I merrily go along for hours designing away. Carefully balancing the current of the long tailed pair input. Picking just the right collector power resistor and capacitor value to drive the transformer. Calculating the negative feedback circuit for proper low frequency cutoff and high frequency stability, and into the breadboard the parts go — jumper clips, meter probes, and test leads abound — a truly joyful event.

All of the voltages check out, frequency response is what you would expect, and a slight tweak to the feedback look brought everything right into happiness. Time to fire up the trusty old HP 334A Distortion Analyzer. Those old machines require you to calibrate the input circuit and the volt meter, tune a filter to the fundamental frequency you are applying to the device under test and step down to lower and lower orders of distortion levels until the meter happily sits somewhere in the middle of a range.

Most modern circuits in even cheap products just go right down to sub .1% total harmonic distortion levels without even a thought and I expected this to be much the same. The look of horror must have been pronounced on my face when the distortion level of my precious circuit was something more akin to a clock radio! A frantic search began. Was it a bad jumper, or a dirty lead in the breadboard, or an unseated component? Was my function generator in some state of disrepair? Is the Stephen King story Maximum Overdrive coming true and my bench is going to eat me alive? All distinct possibilities in this state of panic.

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A Menorah For The 21st Century

December 21, 2016 by 4 Comments

For those new and experienced, this time of year is a great chance for enterprising makers to apply their skills to create unique gifts and decorations for family and friends. [Mike Diamond] of What I Made Today built a phone controlled, light-up menorah. It’s a charming way to display some home automation know-how during the holidays.

Expanding on his previous project — a pocket-sized menorah — a Raspberry Pi Zero with a WiFi dongle, some LEDs, wire, and tea lights suffice for the materials, while setting-up Blynk on the Raspberry Pi and a phone to control the lights ties it together after mounting it in an old monitor housing.

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So Where’s My Low Voltage DC Wall Socket?

December 21, 2016 by 185 Comments

What are the evocative sounds and smells of your childhood? The sensations that you didn’t notice at the time but which take you back immediately? For me one of them is the slight smell of phenolic resin from an older piece of consumer electronics that has warmed up; it immediately has me sitting cross-legged on our living room carpet, circa 1975.

"Get ready for a life that smells of hot plastic, son!" John Atherton [CC BY-SA 2.0], via Wikimedia Commons.
“Get ready for a life that smells of hot plastic, son!” John Atherton [CC BY-SA 2.0], via Wikimedia Commons.
That phenolic smell has gone from our modern electronics, not only because modern enclosures are made from ABS and other more modern plastics, but because the electronics they contain no longer get so hot. Our LCD TV for instance nowadays uses only 50 watts, while its 1970s CRT predecessor would have used several hundred. Before the 1970s you would not find many household appliances that used less than 100 watts, but if you take stock of modern electrical appliances, few use more than that. Outside the white goods in your kitchen and any electric heaters or hair dryers you may own, your appliances today are low-powered. Even your lighting is rapidly being taken over by LEDs, which are at their heart low-voltage devices.

There are many small technological advancements that have contributed to this change over the decades. Switch-mode power supplies, LCD displays, large-scale integration, class D audio and of course the demise of the thermionic tube, to name but a few. The result is often that the appliance itself runs from a low voltage. Where once you would have had a pile of mains plugs competing for your sockets, now you will have an equivalent pile of wall-wart power supplies. Even those appliances with a mains cord will probably still contain a switch-mode power supply inside.

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UK Government To Hold Drone Licensing Consultation

December 21, 2016 by 47 Comments

All over your TV and radio this morning if you live in the UK is the news that the British government is to hold a consultation over the licensing of multirotors, or drones as they are popularly known. It is being reported that users will have to sit a test to acquire a licence before they can operate any machine that weighs above 250 g, and there is the usual fog of sloppy reporting that surrounds any drone story.

This story concerns us on several fronts. First, because many within our community are multirotor enthusiasts and thus we recognise its importance to our readership. And then because it takes as its basis of fact a series of reported near misses with aircraft that look very serious if taken at face value, but whose reported facts simply don’t match the capabilities of real multirotors. We’ve covered this issue in the past with an incident-by-incident analysis, and raised the concern that incident investigators behave irresponsibly in saying “It must have been a drone!” on the basis of no provable evidence. Indeed the only proven British collision was found to have been with a plastic bag.

Of course irresponsible multirotor fliers who threaten public safety should be brought to book. Lock them up, throw away the key, whatever is appropriate. But before that can be done, any debate must be conducted on a level playing field. Our final concern is that this is an issue which is being framed almost entirely on the basis of one side’s interest groups and hysteria on the part of the uninformed about a new technology, rather than a balanced examination of the issues involved. It’s the old “People are having fun. This must be stopped!” idea that infects so much lawmaking, and it’s not very pretty.

Fortunately while it is being reported in some quarters as a done deal as in “Drone fliers must sit a test”, in fact this story is “The Government will ask people what they think about drone fliers sitting a test”. It’s a consultation, which means a Parliamentary committee will sit down and hear evidence before deciding on any legislation. The good news about consultations is that they are open to submissions from the general public, so if you are a British multirotor flier you can submit your own arguments. We will keep you posted with any news about the consultation as we have it.

Header image: 최광모 [CC BY-SA 4.0], via Wikimedia Commons.