Scott Swaaley On High Voltage

December 14, 2018 by Jenny List 29 Comments

If you were to invent a time machine and transport a typical hardware hacker of the 1970s into 2018 and sit them at a bench alongside their modern counterpart, you’d expect them to be faced with a pile of new things, novel experiences, and exciting possibilities. The Internet for all, desktop computing fulfilling its potential, cheap single-board computers, even ubiquitous surface-mount components.

What you might not expect though is that the 2018 hacker might discover a whole field of equivalent unfamiliarity while being very relevant from their grizzled guest. It’s something Scott Swaaley touches upon in his Superconference talk: “Lessons Learned in Designing High Power Line Voltage Circuits” in which he describes his quest for an electronic motor brake, and how his experiences had left him with a gap in his knowledge when it came to working with AC mains voltage.

When Did You Last Handle AC Line voltages?

If you think about it, the AC supply has become something we rarely encounter for several reasons. Our 1970s hacker would have been used to wiring in mains transformers, to repairing tube-driven equipment or CRT televisions with live chassis’, and to working with lighting that was almost exclusively provided by mains-driven incandescent bulbs. A common project of the day would have been a lighting dimmer with a triac, by contrast we work in a world of microcontroller-PWM-driven LEDs and off-the-shelf switch-mode power supplies in which we have no need to see the high voltages. It may be no bad thing that we are rarely exposed to high-voltage risk, but along the way we may have lost a part of our collective skillset.

Scott’s path to gaining his mains voltage experience started in a school workshop, with a bandsaw. Inertia in the saw kept the blade moving after the power had been withdrawn, and while that might be something many of us are used to it was inappropriate in that setting as kids are better remaining attached to their fingers. He looked at brakes and electrical loads as the solution to stopping the motor, but finally settled on something far simpler. An induction motor can be stopped very quickly indeed by applying a DC voltage to it, and his quest to achieve this led along the path of working with the AC supply. Eventually he had a working prototype, which he further developed to become the MakeSafe power tool brake.

Get Your AC Switching Right First Time

The full talk is embedded below the break, and gives a very good introduction to the topic of switching AC power. If you’ve never encountered a thryristor, a triac, or even a diac, these once-ubiquitous components make an entrance. We learn about relays and contactors, and how back EMF can destroy them, and about the different strategies to protect them. Our 1970s hacker would recognise some of these, but even here there are components that have reached the market since their time that they would probably give anything to have. We see the genesis of the MakeSafe brake as a panel with a bunch of relays and an electronic fan controller with a rectifier to produce the DC, and we hear about adequate safety precautions. This is music to our ears, as it’s a subject we’ve touched on before both in terms of handling mains on your bench and inside live equipment.

So if you’ve never dealt with AC line voltages, give this talk a look. The days of wiring up transformers to power projects might be largely behind us, but the skills and principles contained within it are still valid.

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How To Stay Grounded When You Have Zero Potential

December 12, 2018 by Brian Benchoff 100 Comments

Ground is an interesting topic when it comes to engineering. Either it’s the reference level for a digital circuit (not necessarily at zero volts, either), or it’s the return path for current, or it’s the metal chassis, which shouldn’t be the return path for current or else something’s terribly broken. Erika Earl’s talk at this year’s Hackaday Superconference is all about ground.

The first type of ground to talk about is the ground in your outlets and walls. The AC safety ground is the third pin on your plug that should be attached to the chassis of your washer/dryer on one end, and somehow connected to the neutral wire somewhere near your breaker box. The theory of this being if a conductor touches the chassis of a lamp or appliance, all the current will go along that ground bus saving you from electrocution. It should also trip the circuit breaker.

But really we’re rarely dealing with mains power around here. When it comes to electronic design, we’re mostly dealing with analog grounds and digital grounds in circuits. Sometimes these are the same, sometimes they’re not, but they’re both usually referenced to 0 Volts, Add in some considerations for EMC, and ground loops, and you have an astonishing amount of knowledge wrapped up in having zero potential.

If you want to know about what ground actually is, this isn’t a talk to miss. Erika has tons of experience chasing down grounds as an audio engineer, and her career highlights including the director of hardware engineering at Slate Digital and the Senior Technical Engineer at LA’s legendary Village Recording Studios. There’s a lot of experience here, and if you want to where to find your ground, Erika is the person to ask.

Warnings On Steroids – Static Code Analysis Tools

December 12, 2018 by Sven Gregori 11 Comments

A little while back, we were talking about utilizing compiler warnings as first step to make our C code less error-prone and increase its general stability and quality. We know now that the C compiler itself can help us here, but we also saw that there’s a limit to it. While it warns us about the most obvious mistakes and suspicious code constructs, it will leave us hanging when things get a bit more complex.

But once again, that doesn’t mean compiler warnings are useless, we simply need to see them for what they are: a first step. So today we are going to take the next step, and have a look at some other common static code analysis tools that can give us more insight about our code.

You may think that voluntarily choosing C as primary language in this day and age might seem nostalgic or anachronistic, but preach and oxidate all you want: C won’t be going anywhere. So let’s make use of the tools we have available that help us write better code, and to defy the pitfalls C is infamous for. And the general concept of static code analysis is universal. After all, many times a bug or other issue isn’t necessarily caused by the language, but rather some general flaw in the code’s logic.

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Julius Lilienfeld And The First Transistor

December 11, 2018 by Dan Maloney 31 Comments

Here’s a fun exercise: take a list of the 20th century’s inventions and innovations in electronics, communications, and computing. Make sure you include everything, especially the stuff we take for granted. Now, cross off everything that can’t trace its roots back to the AT&T Corporation’s research arm, the Bell Laboratories. We’d wager heavily that the list would still contain almost everything that built the electronics age: microwave communications, data networks, cellular telephone, solar cells, Unix, and, of course, the transistor.

But is that last one really true? We all know the story of Bardeen, Brattain, and Shockley, the brilliant team laboring through a blizzard in 1947 to breathe life into a scrap of germanium and wires, finally unleashing the transistor upon the world for Christmas, a gift to usher us into the age of solid state electronics. It’s not so simple, though. The quest for a replacement for the vacuum tube for switching and amplification goes back to the lab of Julius Lilienfeld, the man who conceived the first field-effect transistor in the mid-1920s.

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ABS: Three Plastics In One

December 11, 2018 by Dan Maloney 31 Comments

It would be really hard to go through a typical day in the developed world without running across something made from ABS plastic. It’s literally all over the place, from toothbrush handles to refrigerator interiors to car dashboards to computer keyboards. Many houses are plumbed with pipes extruded from ABS, and it lives in rolls next to millions of 3D-printers, loved and hated by those who use and misuse it. And in the form of LEGO bricks, it lurks on carpets in the dark rooms of children around the world, ready to puncture the bare feet of their parents.

ABS is so ubiquitous that it makes sense to take a look at this material in terms of its chemistry and its properties. As we’ll see, ABS isn’t just a single plastic, but a mixture that takes the best properties of its components to create one of the most versatile plastics in the world.

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The Space Station Has A Supercomputer Stowaway

December 10, 2018 by Tom Nardi 59 Comments

The failed launch of Soyuz MS-10 on October 11th, 2018 was a notable event for a number of reasons: it was the first serious incident on a manned Soyuz rocket in 35 years, it was the first time that particular high-altitude abort had ever been attempted, and most importantly it ended with the rescue of both crew members. To say it was a historic event is something of an understatement. As a counterpoint to the Challenger disaster it will be looked back on for decades as proof that robust launch abort systems and rigorous training for all contingencies can save lives.

But even though the loss of MS-10 went as well as possibly could be expected, there’s still far reaching consequences for a missed flight to the International Space Station. The coming and going of visiting vehicles to the Station is a carefully orchestrated ballet, designed to fully utilize the up and down mass that each flight offers. Not only did the failure of MS-10 deprive the Station of two crew members and the experiments and supplies they were bringing with them, but also of a return trip which was to have brought various materials and hardware back to Earth.

But there’s been at least one positive side effect of the return cargo schedule being pushed back. The “Spaceborne Computer”, developed by Hewlett Packard Enterprise (HPE) and NASA to test high-performance computing hardware in space, is getting an unexpected extension to its time on the Station. Launched in 2017, the diminutive 32 core supercomputer was only meant to perform self-tests and be brought back down for a full examination. But now that its ticket back home has been delayed for the foreseeable future, NASA is opening up the machine for other researchers to utilize, proving there’s no such thing as a free ride on the International Space Station.

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The Evolution Of Wireless Game Controllers

December 10, 2018 by Drew Littrell 14 Comments

The story goes that Atari was developing a premium model of their popular home video game console, the Atari 2600, for the 1981 fiscal year. Internally known as the Stella RC, this model revision promised touch sensitive game selection toggles, LED indicators, and onboard storage for the controllers. The focus of the project, however, was the “RC” in Stella RC which stood for remote control. Atari engineers wanted to free players from the constraints of the wires that fettered them to their televisions.

Problem with the prototypes was that the RF transmitters in the controllers were powerful enough to send a signal over a 1000 ft. radius, and they interfered with a number of the remote garage door openers on the market. Not to mention that if there were another Stella RC console on the same channel in an apartment building, or simply across the street, you could be playing somebody else’s Pitfall run. The mounting tower of challenges to making a product that the FCC would stamp their approval on were too great. So Atari decided to abandon the pioneering Stella RC project. Physical proof of the first wireless game controllers would have been eliminated at that point if it were created by any other company… but prototypes mysteriously left the office in some peculiar ways.

“Atari had abandoned the project at the time…[an Atari engineer] thought it would be a great idea to give his girlfriend’s son a videogame system to play with…I can’t [comment] about the relationship itself or what happened after 1981, but that’s how this system left Atari…and why it still exists today.”

– Joe Cody, Atari2600.com

Atari did eventually get around to releasing some wireless RF 2600 joysticks that the FCC would approve. A couple years after abandoning the Stella RC project they released the Atari 2600 Remote Control Joysticks at a $69.95 MSRP (roughly $180 adjusted for inflation). The gigantic price tag mixed with the video game market “dropping off the cliff” in 1983 saw few ever getting to know the bliss of wire-free video game action. It was obvious that RF game controllers were simply ahead of their time, but there had to be cheaper alternatives on the horizon.

Out of Sight, Out of Control with IR Schemes

Nintendo AVS 1985 Display — Nintendo AVS console deck and IR controller on display.

Video games were a dirty word in America in 1985. While games themselves were still happening on the microcomputer platforms, the home console business was virtually non-existent. Over in Japan, Nintendo was raking in money hand over fist selling video games on their Famicom console. They sought to replicate that success in North America by introducing a revised model of the Famicom, but it had to impress the tech journos that would be attending its reveal at the Consumer Electronics Show (CES).

The prototype system was called the Nintendo Advanced Video System (AVS). It would feature a keyboard, a cassette tape drive, and most importantly two wireless controllers. The controllers used infrared (IR) communication and the receiver was built-into the console deck itself. Each controller featured a square metallic directional pad and four action buttons that gave the impression of brushed aluminum. The advancement in video game controller technology was too good to be true though, because the entire system received a makeover before releasing as the Nintendo Entertainment System (NES) that Christmas. The NES lacked the keyboard, the tape drive, and the IR controllers and its change in materials hardly captured the high-end flash of the AVS. The removal of IR meant the device was cheaper to manufacture. A decision that ultimately helped the NES to become a breakout success that in turn brought back dedicated video game consoles single-handedly.

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