The Tri Rotor Drone: Why Has It Been Overlooked?

A DJI Phantom 3. Zimin.V.G. [CC BY-SA 4.0]
If you are a watcher of the world of drones, or multirotors, you may have a fixed idea of what one of these aircraft looks like in your mind. There will be a central pod containing batteries and avionics, with a set of arms radiating from it, each of which will have a motor and a propeller on its end. You are almost certainly picturing a four-rotor design, such as the extremely popular DJI Phantom series of craft.

Of course, four-rotor designs are just one of many possible configurations of a multirotor. You will commonly see octocopters, but sometimes we’ve brought you craft that really put the “multi” in “multirotor”. If the computer can physically control a given even number of motors, within reason, it can be flown.

There is one type of multirotor you don’t see very often though, the trirotor. Three propellers on a drone is a rare sight, and it’s something we find surprising because it’s a configuration that can have some surprising benefits. To think about why, it’s worth taking a look at some of the characteristics of a three-rotor machine’s flight.

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Coleco In Spat With ColecoVision Community

If you were a child of the late 1970s or early 1980s, the chances are that your number one desire was to own a games console. The one to have was the Atari 2600, notwithstanding that dreadful E.T. game.

Of course, there were other consoles during that era. One of these also-ran products came from Coleco, a company that had started in the leather business but by the mid 1970s had diversified into handheld single-game consoles. Their ColecoVision console of 1982 sold well initially, but suffered badly in the video game crash of 1983. By 1985 it was gone, and though Coleco went on to have further success, by the end of the decade they too had faded away.

The Coleco story was not over though, because in 2005 the brand was relaunched by a successor company. Initially it appeared on an all-in-one retro console, and then on an abortive attempt to crowdfund a new console, the Coleco Chameleon. This campaign came to a halt after the Chameleon prototypes were shown to be not quite what they seemed by eagle-eyed onlookers. Continue reading “Coleco In Spat With ColecoVision Community”

The Textile Bench

What’s on your bench? Mine’s mostly filled with electronic test equipment, soldering kit, and computers. I’m an electronic engineer by trade when I’m not writing for Hackaday, so that’s hardly surprising. Perhaps yours is like mine, or maybe you’ve added a 3D printer to the mix, a bunch of woodworking tools, or maybe power tools.

So that’s my bench. But is it my only bench? On the other side of the room from the electronics bench is a sturdy folding dining table that houses the tools and supplies of my other bench. I’m probably not alone in having more than one bench for different activities, indeed like many of you I also have a messy bench elsewhere for dismantling parts of 1960s cars, or making clay ovens.

My textile bench, with a selection of the equipment used on it.
My textile bench, with a selection of the equipment used on it.

The other bench in question though is not for messy work, in fact the diametric opposite. This is my textile bench, and it houses the various sewing machines and other equipment that allow me to tackle all sorts of projects involving fabric. On it I’ve made, modified, and repaired all sorts of clothing, I’ve made not-very-successful kites, passable sandals, and adventurous tent designs among countless other projects.

Some of you might wonder why my textile bench is Hackaday fodder, after all it’s probably safe to assume that few readers have ever considered fabricating their own taffeta ball gown. But to concentrate only on one aspect of textile work misses the point, because the potential is there for so much cross-over between these different threads of the maker world. So I’m going to take you through my textile bench and introduce you to its main tools. With luck this will demystify some of them, and maybe encourage you to have a go.

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Hardware Heroes: Tim Hunkin

If you were an engineering student around the end of the 1980s or the start of the 1990s, your destiny most likely lay in writing 8051 firmware for process controllers or becoming a small cog in a graduate training scheme at a large manufacturer. It was set out for you as a limited set of horizons by the university careers office, ready for you to discover as only a partial truth after graduation.

But the chances are that if you were a British engineering student around that time you didn’t fancy any of that stuff. Instead you harboured a secret dream to be [Tim Hunkin]’s apprentice. Of course, if you aren’t a Brit, and maybe you are from a different generation, you’ll have responded quizzically to that name. [Tim Hunkin]? Who?

[Tim Hunkin] is a British engineer, animator, artist and cartoonist who has produced a long series of very recognisable mechanical devices for public display, including clocks, arcade machines, public spectacles, exhibits and collecting boxes for museums, and much more. He came to my attention as an impressionable young engineer with his late 1980s to early 1990s British TV series  The Secret Life Of Machines, in which he took everyday household and office machines and appliances and explained and deconstructed them in an accessible manner for the public.

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The GNU GPL Is An Enforceable Contract At Last

It would be difficult to imagine the technological enhancements to the world we live in today without open-source software. You will find it somewhere in most of your consumer electronics, in the unseen data centres of the cloud, in machines, gadgets, and tools, in fact almost anywhere a microcomputer is used in a product. The willingness of software developers to share their work freely under licences that guarantee its continued free propagation has been as large a contributor to the success of our tech economy as any hardware innovation.

Though open-source licences have been with us for decades now, there have been relatively few moments in which they have been truly tested in a court. There have been frequent licence violations in which closed-source products have been found to contain open-source software, but they have more often resulted in out-of-court settlement than lengthy public legal fights. Sometimes the open-source community has gained previously closed-source projects, as their licence violations have involved software whose licence terms included a requirement for a whole project in which it is included to have the same licence. These terms are sometimes referred to as viral clauses by open-source detractors, and the most famous such licence is the GNU GPL, or General Public Licence. If you have ever installed OpenWRT on a router you will have been a beneficiary of this: the project has its roots in the closed-source firmware for a Linksys router that was found to contain GPL code.

Now we have news of an interesting milestone for the legal enforceability of open-source licences, a judge in California has ruled that the GPL is an enforceable contract. Previous case-law had only gone as far as treating GPL violations as a copyright matter, while this case extends its protection to another level.

The case in question involves a Korean developer of productivity software, Hancom Office, who were found to have incorporated the open-source Postscript and PDF encoder Ghostscript into their products without paying its developer a licence fee. Thus their use of Ghostscript falls under the GPL licencing of its open-source public version, and it was  on this basis that Artifex, the developer of Ghostscript, brought the action.

It’s important to understand that this is not a win for Artifex, it is merely a decision on how the game can be played. They must now go forth and fight the case, but that they can do so on the basis of a contract breach rather than a copyright violation should help them as well as all future GPL-licenced developers who find themselves in the same position.

We’re not lawyers here at Hackaday, but if we were to venture an opinion based on gut feeling it would be that we’d expect this case to end in the same way as so many others, with a quiet out-of-court settlement and a lucrative commercial licencing deal for Artifex. But whichever way it ends the important precedent will have been set, the GNU GPL is now an enforceable contract in the eyes of the law. And that can only be a good thing.

Via Hacker News.

GNU logo, CC-BY-SA 2.0.

A MIDI Harmonica

MIDI, or Musical Instrument Digital Interface, has been the standard for computer control of musical instruments since the 1980s. It is most often associated with electronic instruments such as synthesisers, drum machines, or samplers, but there is nothing to stop it being applied to almost any instrument when combined with the appropriate hardware.

[phearl3ss1] pushes this to the limit by adding MIDI to the most unlikely of instruments. A harmonica might seem to be the ultimate in analogue music, yet he’s created an ingenious Arduino-powered mechanism to play one under MIDI control.

The harmonica itself is mounted on a drawer slide coupled to a wheel taken from a pool sweeper and powered by a motor  that can move the instrument from side to side with a potentiometer providing positional feedback to form a simple servo. The air supply comes from a set of three bellows driven via a crank from another motor, and is delivered by what looks like a piece of PVC pipe to the business end of the harmonica.

The result is definitely a playable MIDI harmonica, though it doesn’t quite catch the essence of the human-played instrument. Judge for yourselves, he’s posted a build video which we’ve placed below the break.

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Hackaday Prize Entry: A PC-XT Clone Powered By AVR

There is a high probability that the device on which you are reading this comes somehow loosely under the broad definition of a PC. The familiar x86 architecture with peripheral standards has trounced all its competitors over the years, to the extent that it is only in the mobile and tablet space of personal computing that it has not become dominant.

The modern PC with its multi-core processor and 64-bit instruction set is a world away from its 16-bit ancestor from the early 1980s. Those early PCs were computers in the manner of the day, in which there were relatively few peripherals, and the microprocessor bus was exposed almost directly rather than through the abstractions and gatekeepers we’d expect to see today. The 8088 processor with an 8-bit external bus though is the primordial PC processor, and within reason you will find software written for DOS on those earliest IBM machines will often still run on your multiprocessor behemoth over a DOS-like layer on your present-day operating system. This 35-year-plus chain of mostly unbroken compatibility is both a remarkable feat of engineering and a millstone round the necks of modern PC hardware and OS developers.

Those early PCs have captured the attention of [esot.eric], who has come up with the interesting project of interfacing an AVR microcontroller to the 8088 system bus of one of those early PCs. Thus all those PC peripherals could be made to run under the control of something a little more up-to-date. When you consider that the 8088 ran at a modest 300KIPS and that the AVR is capable of running at a by comparison blisteringly fast 22MIPS, the idea was that it should be able to emulate an 8088 at the same speed as an original, if not faster. His progress makes for a long and fascinating read, so far he has accessed the PC’s 640KB of RAM reliably, talked to an ISA-bus parallel port, and made a CGA card produce colours and characters. Interestingly the AVR has the potential for speed enhancements not possible with an 8088, for example it can use its own internal UART with many fewer instructions than it would use to access the PC UART, and its internal Flash memory can contain the PC BIOS and read it a huge amount faster than a real BIOS ROM could be on real PC hardware.

In case you were wondering what use an 8088 PC could be put to, take a look at this impressive demo. Don’t have one yourself? Build one.