Author: Jenny List

3543 Articles

Ask Hackaday: Earth’s Magnetic Field Shifting Rapidly, But Who Will Notice?

March 6, 2019 by 92 Comments

Just when you though it was safe to venture out, the National Oceanic and Atmospheric Administration released an unexpected update. Magnetic North is on the move — faster than expected. That’s right, we know magnetic north moves around, but now it’s happened at a surprising rate. Instead of waiting for the normal five year interval before an update on its position, NOAA have given us a fresh one a bit earlier.

There are some things that we can safely consider immutable, reliable, they’ll always be the same. You might think that direction would be one of them. North, south, east, and west, the points of the compass. But while the True North of the Earth’s rotation has remained unchanged, the same can not be said of our customary method of measuring direction.

Earth’s magnetic field is generated by a 2,000 km thick outer core of liquid iron and nickel that surrounds the planet’s solid inner core. The axis of the earth’s internal magnet shifts around the rotational axis at the whim of the currents within that liquid interior, and with it changes the readings returned by magnetic compasses worldwide.

The question that emerged at Hackaday as we digested news of the early update was this: as navigation moves inexorably towards the use of GPS and other systems that do not depend upon the Earth’s magnetic field, where is this still relevant beyond the realm of science?

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The Primordial Sinclair ZX Spectrum Emerges From The Cupboard

March 4, 2019 by 12 Comments

The Centre for Computing History in Cambridge, UK, receive many donations from which they can enrich their collection and museum displays. Many are interesting but mundane, but the subject of their latest video is far from that. The wire-wrapped prototype board they reveal with a flourish from beneath a folded antistatic mat is no ordinary computer, because it is the prototype Sinclair ZX Spectrum.

It came to the museum from Nine Tiles, a local consultancy firm that had been contracted by Sinclair Research in the early 1980s to produce the BASIC ROM that would run on the replacement for their popular ZX81 home microcomputer. The write-up and the video we’ve placed below the break give some detail on the history of the ROM project, the pressures from Sinclair’s legendary cost-cutting, and the decision to ship with an unfinished ROM version meaning that later peripherals had to carry shadow ROMs with updated routines.

The board itself is a standard wire-wrap protoboard with all the major Spectrum components there in some form.  This is a 16k model, there is no expansion connector, and the layout is back-to-front to that of the final machine. The ULA chip is a pre-production item in a ceramic package, and the keyboard is attached through a D connector. Decent quality key switches make a stark contrast to the rubber keys and membrane that Spectrum owners would later mash to pieces playing Daley Thompson’s Decathlon.

This machine is a remarkable artifact, and we should all be indebted to Nine Tiles for ensuring that it is preserved for those with an interest in computing to study and enjoy. It may not look like much, but that protoboard had a hand in launching a huge number of people’s careers in technology, and we suspect that some of those people will be Hackaday readers. We’ll certainly be dropping in to see it next time we’re in Cambridge.

If you haven’t been to the Centre for Computing History yet, we suggest you take a look at our review from a couple of years ago. And if prototype home computers are your thing, this certainly isn’t the first to grace these pages.

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The Cat, The Aircraft, And The Tiny Computer

March 4, 2019 by 29 Comments

Sharing your life with a cat is a wonderful and fulfilling experience. Sharing your life with an awake, alert, and bored cat in the early hours when you are trying to sleep, is not. [Simon Aubury] has just this problem, as his cat [Snowy] is woken each morning by a jet passing over. In an attempt to identify the offending aircraft, he’s taken a Raspberry Pi and a software-defined radio, and attempted to isolate it by spotting its ADS-B beacon.

The SDR was the ubiquitous RTL chipset model, and it provided a continuous stream of aircraft data. To process this data he used an Apache Kafka stream processing server into which he also retrieved aircraft identifying data from an online service. Kafka’s SQL interface for interrogating multiple streams allowed him to untangle the mess of ADS-B returns and generate a meaningful feed of aircraft. This in turn was piped into an elasticsearch search engine database, upon which he built a Kibana visualisation.

The result was that any aircraft could be identified at a glance, and potential noise hotspots forecast. Whether all this heavy lifting was worth the end result is for you to decide, however it does provide an interesting introduction to the technologies and software involved. It is however possible to monitor ADS-B traffic considerably more simply.

Thanks [Oleg Anashkin] for the tip.

Talk To Your ‘Scope, And It Will Obey

March 3, 2019 by 3 Comments

An oscilloscope is a device that many of us use, and which we often have to use while our hands are occupied with test probes or other tools. [James Wilson] has solved the problem of how to control his ‘scope no-handed, by connecting it to a Raspberry Pi 3 running the snips.ai voice assistant. This is an interesting piece of software that runs natively upon the device in contrast to the cloud service provided by the likes of Alexa or Google Assistant.

The ‘scope in question is a Keysight 1000-X that can be seen in the video below the break, but looking at the Python code we could imagine the same technique being brought to other instruments such as the Rigol 1054z we looked at controlling via USB a year or two ago. The use of the snips.ai software provides a pointer to how voice-controlled projects in our community might evolve beyond the cloud services, interestingly though they do not make a big thing of it their software appears to be open-source.

Oscilloscopes do not have to be remotely controlled by voice alone. It seems to be a common desire to take measurements no-handed — one project we’ve featured in the past did the job with a foot switch.

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This Vintage Op-Amp Opens A Fascinating Window Into Semiconductor History

March 2, 2019 by 6 Comments

We have covered enough of the work of [Ken Shirriff] on these pages to know that when he publishes something, it will be a fascinating read and work of the highest quality. And so it is with his latest, a very unusual op-amp on which he performs his usual reverse engineering. Not only does it lead us directly to some of the seminal figures in the early years of the semiconductor industry, it turns out to have been a component manufactured to a NASA specification and of which there is an example on the Moon.

The metal can revealed a hybrid circuit when the lid was removed, one in which individual transistors were wired together with a single block containing a group of thin-film resistors. At the start of the 1960s the height of consumer electronics would have been your domestic TV which would have been an all-tube affair, so while it sounds archaic this would truly have been a space-age piece of technology. The designer is revealed as the legendary [Bob Pease], and the transistors take us back to the semiconductor physicist [Jean Hoerni], inventor of the planar transistor and one of the famous eight defectors from Shockley Semiconductor in the 1950s who kick-started the semiconductor boom.

The op-amp itself is a relatively simple design without the compensation capacitor you might expect in a modern device, but what makes it unusual for its time is the use of [Hoerni]’s planar JFETs at its input. [Ken]’s analysis is as usual extremely thorough, and the bit of Silicon Valley history it gives us is the icing on the cake.

If you have a thirst for ancient op-amps, you might like our look at the first commercially available fully-integrated design, the Fairchild μA702.

The FAA Mandates External Registration Markings For Drones

February 26, 2019 by 68 Comments

Drone fliers in the USA must soon display their registration markings on the exterior of their craft, rather than as was previously acceptable, in accessible interior compartments. This important but relatively minor regulation change has been announced by the FAA in response to concerns that malicious operators could booby-trap a craft to catch investigators as they opened it in search of a registration. The new ruling is effective from February 25th, though they are inviting public comment on it.

As airspace regulators and fliers across the world traverse the tricky process of establishing a safe and effective framework for multirotors and similar craft we’ve seen a variety of approaches to their regulation, and while sometimes they haven’t made complete sense and have even been struck down in the courts, the FAA’s reaction has been more carefully considered than that in some other jurisdictions. Rule changes such as this one will always have their detractors, but as an extension of a pre-existing set of regulations it is not an unreasonable one.

It seems inevitable that regulation of multirotor flight will be a continuing process, but solace can be taken at the lower end of the range. A common theme across the world seems to be a weight limit of 250 g for otherwise unrestricted and unregistered craft, and the prospects for development in this weight category in response to regulation are exciting. If a smaller craft can do everything our 2 kg machines used to do but without the burden of regulation, we’ll take that.

An ATtiny Metal Detector

February 26, 2019 by 18 Comments

A metal detector used to be an entirely analogue instrument, an oscillator whose frequency changed with the inductance of its sense coil when a piece of metal approached. [Łukasz Podkalicki] shows us a more sophisticated machine, but with judicious use of an ATtiny 13 it is not a complex one.

A pulsed induction metal detector induces a current spike in its search coil, and times the decay of the resulting oscillation. The coil is part of a resonant circuit with a capacitor, and any metal in its field will change its resonant frequency. In [Łukasz]’s design the ATtiny13 fires a pulse at his coil using a MOSFET, and the voltages at the coil are sensed by an analogue pin through an appropriate clamp circuit. His software does the timing, and sounds a buzzer upon metal detection. It’s a deliciously simple implementation, and while as he shows us in the video below the break its relatively small coil is more suited to detecting coins or wires behind the drywall than locating lost hoards, there is probably ample scope for further experimentation.

This isn’t the first project from [Łukasz] that has found its way into these pages, his history with the ATtiny13 goes back a few years.

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