Tiny-TS: Just How Small Can A Playable Synethesiser Get?

December 11, 2016 by Jenny List 32 Comments

The early electronic synthesizers were huge machines, racks of electronic modules that filled entire rooms. Integration of electronics over time successively reduced them, first to the size of a large piece of furniture, then to tabletop consoles, to standalone keyboards, and to small MIDI black boxes taking their instructions from another instrument or a computer. The original mass of discrete electronics had been reduced to a pile of ICs, then chipsets, then finally single ICs and software implementations on microcomputers.

It’s thus possible to make a synthesizer these days that is pretty small. If you can fit a microcontroller in it, you can fit a synth into it. But how about a playable synthesizer? One with a keyboard, on which you can give a recital? How small can you make one of those? [Jan Ostman] has a contender for the smallest playable synthesizer prize with his Tiny-TS, a credit-card synthesiser with a one-octave capacitive keyboard and analog controls for synthesis parameters.

The heart of the synth is an ATMega328, for which he provides the software. The parameters adjustable by a series of pots are listed as DCO: Coarse pitch and Double, DCF: Filter peak and ENVmod, and ENV: Attack and Release affecting amplitude. You can build your own, or he tells us that he has the project up as a Kickstarter campaign if you fancy the chance of buying one ready-made.

In case you are wondering, it doesn’t sound too bad. Some minimalist synths sacrifice the breadth of sounds they can create, but not this one. He takes it through its paces in a YouTube video which we’ve put below the break.

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A Beautiful Morse Key From A Hard Drive Actuator

December 10, 2016 by Jenny List 19 Comments

Morse code, or CW, is a subject that divides the amateur radio community from top to bottom. For some it’s a faded anachronism, while for others it’s the purest form of the art. With it no longer in significant commercial or military use it is radio amateurs who keep it alive, and those for whom it is a passion devote considerable effort to its continuing use.

With well over a century of history behind it there are a huge array of morse keys available to the CW enthusiast. From vintage telegraph keys through WW2 surplus military keys to sideways “bug” keys and modern boutique handcrafted keys, many operators will amass a collection for the love of it, and regularly use them all.

Just one of the hand-drawn illustrations for this project.

Other operators create their own keys, either crafting them from raw materials or using whatever materials they have at hand. Keys have been made from every conceivable piece of junk that will conduct electricity, and made contacts to all parts of the world.

[H. P. Friedrichs, AC7ZL] has produced such a home-made key from surplus material, but it has nothing of the junkbox about it. He’s used the head actuator from a surplus hard drive as the arm of a straight key, and the result is an item of beauty. The actuator bearing is the pivot point, and the business end of the key replaces the hard drive’s heads. The spring is provided by the repulsive force between magnets, the connection at the rear is provided by a piece of guitar string, and the contacts themselves are taken from a surplus power relay. Even his write-up is a thing of beauty, a compelling read with hand-drawn illustrations. If you are not a Morse enthusiast it’s still an engaging project.

We’ve featured many keys here over the years, and this isn’t the first one using a hard drive actuator, as this mint tin paddle shows. Among others we’ve linked you to a collection of unorthodox keys, and of course shown you a vintage telegraph key with a Raspberry Pi decoder.

Amiga Zorro HDMI Graphics Card Hits The Market

December 10, 2016 by Jenny List 19 Comments

If you were a computer enthusiast in the late 1980s or early 1990s, the chances are that one of your objects of desire would have been a Commodore Amiga. These machines based on the 68000 line of processors and a series of specialized co-processors offered the best compromise between performance and affordability at the time, with multitasking, a GUI, and graphics capabilities that were streets ahead of their competition.

The Amiga story is littered with tales of what might have been, as dismal marketing and lacklustre product refreshes caused it to lurch from owner to owner and eventually fade away from the mainstream in the mid 1990s. But it’s been one of those products that never really died, as a band of enthusiasts have kept a small market for its software and hardware alive.

Workbench as you may not have seen it before.

Earlier this year we showed you a prototype of an unusual graphics card, a modern GPU implemented on an FPGA board that brought up-to-date HDMI monitor support to the Zorro expansion slots found in the big-box Amigas. It’s thus very interesting today to find that the board made it to market, and that you can buy one for your Amiga if you have a spare 189 Euros (now sold out but taking pre-orders for another production run). Producing any niche electronic product is a significant challenge, so it is always positive to see one that makes it.

As well as HDMI output the board features a micro SD card slot that is mountable as an Amiga volume, and an expansion header that is toured as “Hacker friendly”. Best of all though, the whole board is open-source with all resources on a GitHub repository, so as well as reading our coverage of the prototype you can immerse yourself in its internals if that is your thing.

It’s always good to see a new piece of hardware for an old computer see the light of day, though it’s fair to say this development won’t revive the Amiga platform in the way that the Raspberry Pi has for RiscOS. Still, the mere fact of an open-source Zorro FPGA implementation being released should mean that other cards become possible, so we await developments with interest.

[via forums.xilinx.com]

Thermoelectric Paint Opens Prospect Of Easier Energy Harvesting

December 9, 2016 by Jenny List 32 Comments

We will all be used to the thermoelectric effect in our electronic devices. The property of a junction of dissimilar conductors to either generate electricity from a difference in temperature (the Seebeck effect), or heating or cooling the junction (the Peltier effect). Every time we use a thermocouple or one of those mini beer fridges, we’re taking advantage of it.

Practical commercial thermoelectric arrays take the form of a grid of semiconductor junctions wired in series, with a cold side and a hot side. For a Peltier array the cold side drops in temperature and the hot side rises in response to applied electric current, while for a Seebeck array a current is generated in response to temperature difference between the two sides. They have several disadvantages though; they are not cheap, they are of a limited size, they can only be attached to flat surfaces, and they are only as good as their thermal bond can be made.

Researchers in Korea have produced an interesting development in this field that may offer significant improvements over the modules, they have published a paper describing a thermoelectric compound which can be painted on to a surface. The paint contains particles of bismuth telluride (Bi₂Te₃), and an energy density of up to 4mW per square centimetre is claimed.

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RainCube Spreads Its Umbrella

December 9, 2016 by Jenny List 15 Comments

There are times when a mechanism comes to your attention that you have to watch time and time again, to study its intricacies and marvel at the skill of its designer. Sometimes it can be a complex mechanism such as a musical automaton or a mechanical loom, but other times it can be a device whose apparent simplicity hides its underlying cleverness. Such a moment came for us today, and it’s one we have to share with you.

RainCube is a satellite, as its name suggests in the CubeSat form factor and carrying radar instruments to study Earthly precipitation. One of the demands of its radar system is a parabolic dish antenna, and even at its 37.5 GHz that antenna needs to be significantly larger than its 6U CubeSat chassis.

It is the JPL engineers’ solution to this problem that is the beautiful mechanism we want to show you. The parabola is folded within itself and tightly furled round the feedhorn within the body of the satellite. As the feedhorn emerges, first the inner sections unfurl and then the outer edge of the parabola springs out to form the dish antenna shape. Simultaneously a mechanism of simplicity, cleverness, and beauty, one we’d be very proud of if it were our creation.

There is nothing new in collapsible parabolas used in spacecraft antennas, petal and umbrella-like designs have been a feature of some of the most famous craft. But the way that this one has been fitted into such a small space (and so elegantly) makes it special, we hope you’ll agree.

[via space.com]

Diodes: The Switch You Never Knew You Had

December 9, 2016 by Jenny List 62 Comments

Vishay's take on the 1N4148 data sheet (PDF), describing it as a switching diode. — Vishay’s take on the 1N4148 data sheet (PDF), describing it as a switching diode.

When looking across the discrete components in your electronic armory, it is easy to overlook the humble diode. After all, one can be forgiven for the conclusion that the everyday version of this component doesn’t do much. They have none of the special skills you’d find in tunnel, Gunn, varicap, Zener, and avalanche diodes, or even LEDs, instead they are simply a one-way valve for electrical current. Connect them one way round and current flows, the other and it doesn’t. They rectify AC to DC, power supplies are full of them. Perhaps you’ve also used them to generate a stable voltage drop because they have a pretty constant voltage across them when current is flowing, but that’s it. Diodes: the shortest Hackaday article ever.

Not so fast with dismissing the diode though. There is another trick they have hiding up their sleeves, they can also act as a switch. It shouldn’t come as too much of a shock, after all a quick look at many datasheets for general purpose diodes should reveal their description as switching diodes.

So how does a diode switch work? The key lies in that one-way valve we mentioned earlier. When the diode is forward biased and conducting electricity it will pass through any variations in the voltage being put into them, but when it is reverse biased and not conducting any electricity it will not. Thus a signal can be switched on by passing it through a diode in forward bias, and then turned off by putting the diode into reverse bias.

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That NASA EM Drive Paper: An Expert Opinion

December 8, 2016 by Jenny List 167 Comments

A week or two ago we featured a research paper from NASA scientists that reported a tiny but measurable thrust from an electromagnetic drive mounted on a torsion balance in a vacuum chamber. This was interesting news because electromagnetic drives do not eject mass in the way that a traditional rocket engine does, so any thrust they may produce would violate Newton’s Third Law. Either the Laws Of Physics are not as inviolate as we have been led to believe, or some other factor has evaded the attempts of the team to exclude or explain everything that might otherwise produce a force.

As you might imagine, opinion has entrenched itself on both sides of this issue. Those who believe that EM drives have allowed us to stumble upon some hitherto undiscovered branch of physics seized upon the fact that the NASA paper was peer-reviewed to support their case, while those who believe the mechanism through which the force is generated will eventually be explained by conventional means stuck to their guns. The rest of us who sit on the fence await further developments from either side with interest.

Over at Phys.org they have an interview from the University of Connecticut with [Brice Cassenti], a propulsion expert, which brings his specialist knowledge to the issue. He believes that eventually the results will be explained by conventional means, but explains why the paper made it through peer review and addresses some of the speculation about the device being tested in space. If you are firmly in one of the opposing camps the interview may not persuade you to change your mind, but it nevertheless makes for an interesting read.

If EM drives are of interest, you might find our overview from last year to be an illuminating read. Meanwhile our coverage of the NASA paper should give you some background to this story, and we’ve even had one entered in the Hackaday Prize.