Get On 10 GHz For 3 Euros

December 22, 2016 by Jenny List 20 Comments

A frequent complaint you will hear about amateur radio is that it is a chequebook pursuit. Of course you can work the incredible DX if you spend $20k on a high-end radio, big antenna, and associated components. The reality is though that because it’s such a multi-faceted world there are many ways into it of which the operator with the shiny rig is taking only one.

On the commonly used HF and VHF bands at the lower end of the radio spectrum you will definitely find chequebook amateurs of the type described in the previous paragraph. But as you ascend into the microwave bands there are no shiny new radios on the market, so even the well-heeled licensee must plow their own furrow and build their own station.

You might think that this would remain a chequebook operation of a different type, as exotic microwave devices are not always cheap. But in fact these bands have a long history of extremely inexpensive construction, in which skilled design and construction as well as clever re-use of components from satellite TV systems and Doppler radar modules play a part. And it is a project following this path that is our subject today, for [Peter Knol, PA1SDB] has repurposed a modern Doppler radar module as a transmitter for the 10GHz or 3cm amateur band (Google Translate version of Dutch original). The best bit about [Peter]’s project is the price: these modules can be had for only three Euros.

Years ago a Doppler module would have used a Gunn diode in a waveguide cavity and small horn, usually with an adjacent mixer diode for receiving. Its modern equivalent uses a transistor oscillator on a PCB, with a dielectric resonator and a set of patch antennas. There is also a simple receiver on board, but since [Peter] is using a converted ten-Euro satellite LNB for that task, it is redundant.

He takes us through the process of adjusting the module’s frequency before showing us how to mount it at the prime focus of a parabolic antenna. FM modulation comes via a very old-fashioned transformer in the power feed. He then looks at fitting an SMA connector and using it for more advanced antenna set-ups, before experimenting with the attenuating properties of different substances. All in all this is a fascinating read if you are interested in simple microwave construction.

The result is not the most accomplished 10 GHz station in the world, but it performs adequately for its extremely low price given that he’s logged a 32 km contact with it.

Though we cover our fair share of amateur radio stories here at Hackaday it’s fair to say we haven’t seen many in the microwave bands. If however you think we’ve been remiss in this area, may we point you to our recent coverage of a microwave radio receiver made from diamond?

Via Southgate ARC.

Cheap Powerbank Logic And Teardown

December 21, 2016 by Jenny List 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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So Where’s My Low Voltage DC Wall Socket?

December 21, 2016 by Jenny List 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 Jenny List 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.

How Has Amazon Managed To Make Hackers Love Alexa?

December 19, 2016 by Jenny List 115 Comments

Our hackspace has acquired an Amazon Dot, courtesy of a member. It mostly seems to be used as a source of background music, but it has also spawned a seemingly never-ending new entertainment in which the hackspace denizens ceaselessly bait their new electronic companion with ever more complex and esoteric requests. From endless rephrasing and careful enunciation of obscure early reggae artists to try to settle a musical argument to hilarious mis-hearing on the part of our silicon friend, the fun never stops. “Alexa, **** off!” it seems results in “I’m sorry, I can’t find a device of that name on this network”.

That is just the experience of one hackspace, but it evidently does not end there. Every other day it seems that new projects using Alexa pass through the Hackaday timeline, so it looks as though Amazon’s online personal assistant has been something of a hit within our community.

Fair enough, you might say, we’re always early adopters of any new technology. But it’s a development over which I wonder; am I alone in finding it surprising? It’s worth taking a moment to look at the subject.

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LED Tetris Table

December 18, 2016 by Jenny List 7 Comments

No hackspace is complete without an arcade game project or two. Usually these projects are time-worn generic cabinets scarred by the frustrated kicks of a million teenagers, the decades-old Japanese CRT monitors inside of which are ready to shuffle off this mortal coil. You are lucky if you catch them on a rare moment of functioning, and their owners are always hovering ready to attend to any soon-to-expire electronics.

York Hackspace have done things a little differently though. Their member [John] has an arcade game project, but instead of an aged cabinet he’s produced his own tabletop game with an array of multicolour addressable LED strips powered by a Raspberry Pi. Each LED sits in its own foam cell under the translucent surface, so it forms a low resolution color block display.

It’s a Tetris game in its first incarnation, but there is also a copy of Snake underway for it. If it catches your attention you can write your own games, because all its resources are available in a GitHub repository.

This is one of many Tetris interfaces we’ve seen over the years. Largest was probably this skyscraper, but this oscilloscope version is particularly well-executed. One of our most recent forays into Tetris-land though is also one of the most technically interesting, a 446-byte implementation in a master boot record.

PIC Mesh, Accessible Distributed Networking

December 17, 2016 by Jenny List 6 Comments

Wireless networks have been reduced to a component, for most of us. We fit a device, maybe an ESP8266 module or similar, and as if by magic a network exists. The underlying technology has been abstracted into the firmware of the device, and we never encounter it directly. This is no bad thing, because using wireless communication without having to worry about its mechanics gives us the freedom to get on with the rest of our work.

It is however interesting once in a while to take a look at the operation of a real wireless network, and [Alex Wong], [Brian Clark], and [Raghava Kumar] have given us a project with the opportunity to do just that. Their PIC Mesh university project is a distributed wireless mesh network using 2.4GHz NRF24L01 transceiver modules and PIC32 microcontrollers. They have it configured for demonstration purposes with a home automation system at the application layer, however it could be applied to many other applications.

The real value in this project is in its comprehensive but easy to read write-up of the kind you’d expect from a university project. The front page linked above has an overview of how the mesh works, but there are also pages taking us through the hardware, the networking software layer, and the home automation application layer. If you have ever wanted to understand a simple mesh networking system, this is a good place to start.

We’ve covered quite a few mesh networks over the years, but sadly we can only link you to a few of them. We’ve had a mesh network using the Raspberry Pi, Project Byzantium’s “ad-hoc wireless mesh networking for the zombie apocalypse“, and a 1000-node Xbee network for testing purposes.