We’ve all heard the “Do not stare into laser with remaining eye” joke. It’s funny because it’s true, as pretty much any laser a hobbyist can easily come by can cause permanent damage to eyes unless the proper precautions are taken. But a fiber laser with 200kW peak power is in another hazard class entirely.
Granted, outsized power ratings like this are a bit misleading, based as they are on femtosecond-long pulses. And to be sure, the fiber laser that [Marco Reps] tears down in the video below was as harmless as a kitten when he got it, thanks to its output optics having been unceremoniously shorn from the amplifier by its former owner. Reattaching the output and splicing the fiber would be necessary to get the laser lasing again, but [Marco] had other priorities in mind. He wanted to understand the operation of a fiber laser, but the tangle of fibers on two separate levels inside the chassis was somewhat inscrutable. The coils of fiber wrapped around the aluminum drums inside the chassis turned out to be the amplifier; fed by a semiconductor seed laser, the light pulse travels through the ytterbium-doped fiber of the two-stage amplifier, which is the active gain medium where stimulated emission, and therefore amplification, occurs.
With a little reverse engineering and the help of an online manual, he was able to understand the laser’s operation. A laser company helped him splice the optics back together – seeing the splicing rig in action is worth the price of admission alone – and the unit seems to be in more or less working order at this point. Normally the most powerful laser we see around here are the CO2 lasers in those cheap Chinese laser cutters, so we’re looking forward to learning more about fiber lasers.
In a recent study by a team of researchers at MIT, self driving cars are being programmed to identify the social personalities of other drivers in an effort to predict their future actions and drive safer on roads.
It’s already been made evident that autonomous vehicles lack social awareness. Drivers around a car are regarded as obstacles rather than human beings, which can hinder the automata’s ability to identify motivations and intentions, potential signifiers to future actions. Because of this, self-driving cars often cause bottlenecks at four-way stops and other intersections, perhaps explaining why the majority of traffic accidents involve them getting rear-ended by impatient drivers.
The research taps into social value orientation, a concept from social psychology that classifies a person from selfish (“egoistic”) to altruistic and cooperative (“prosocial”). The system uses this classification to create real-time driving trajectories for other cars based on a small snippet of their motion. For instance, cars that merge more often are deemed as more competitive than other cars.
When testing the algorithms on tasks involving merging lanes and making unprotected left turns, the behavioral predictions were shown to improve by a factor of 25%. In a left-turn simulation, the automata was able to wait until the approaching car had a more prosocial driver.
Even outside of self-driving cars, the research could help human drivers predict the actions of other drivers around them.
Recently [iot4c] stumbled upon this gorgeous Robotron Reiss plotter from 1989, brand-new and still in its original box. Built before the fall of the Berlin Wall in East Germany, it would be a crime to allow such a piece of computing history to go unused. But how to hook it up to a modern system? Bad enough that it uses some rather unusual connectors, but it’s about to be 2020, who wants to use wires anymore? What this piece of Cold War hardware needed was an infusion of Bluetooth.
While the physical ports on the back of the Robotron certainly look rather suspect, it turns out that electrically they’re just RS-232. In practice, this means converting it over was fairly straightforward. With a Bolutek BK3231 Bluetooth module and an RS-232 to UART converter, [iot4c] was able to create a wireless adapter that works transparently on the plotter by simply connecting it to the RX and TX pins.
A small DC buck converter was necessary to provide 3.3 V for the Bluetooth adapter, but even still, there was plenty of room inside the plotter’s case to fit everything in neatly. From the outside, you’d have no idea that the hardware had ever been modified at all.
But, like always, there was a catch. While Windows had no trouble connecting to the Bluetooth device and assigning it a COM port, the 512 byte buffer on the plotter would get overwhelmed when it started receiving commands. So [iot4c] wrote a little script in Node.js that breaks the commands down into more manageable chunks and sends them off to the plotter every 0.1 seconds. With this script in place the Robotron moved under its own power for the first time in ~30 years by parsing a HP-GL file generated by Inkscape.
Cooking a turkey right is serious business this time of year. With major holidays on the line, there’s no room for error – any mistake can leave guests disgruntled and starving. [Stephen Farnsworth] took a risk, though, and attempted to cook a turkey using AA batteries.
The allure of the AA for such a task is precisely because it’s such a poor choice. Designed for portability rather than high power output, it was never designed to be the energy source for a major cooking job. To get things over the line, [Steve] busted out the math to figure out how many batteries would be required. This involved computing cooking efficiencies, battery thermal performance, and the specific heat of the bird itself. With the numbers coming together a 300W slow cooker was put on duty, in order to avoid over-draining the batteries.
With 880 AAs loaded into a custom carrier, [Steve] hooked up the power meter and the cooker and kept a close eye on the temperatures. After a couple of hours, the battery pack started to heat up, so additional cooling was brought in to avoid fire. At just before the six hour mark, the turkey was cooked through and ready to eat. Estimates are that the batteries still had plenty of capacity to keep going for a few hours yet, too.
It’s not a fast or effective way to cook a turkey, but it’s certainly achievable. We fully expect [Steve] to submit the coin-cell turkey cook-off next year, too. Remember, a little engineering always helps, especially in the kitchen. Video after the break.
When you’re a nation state, secure communications are key to protecting your sovereignty and keeping your best laid plans under wraps. For the USA, this requirement led to the development of a series of secure telephony networks over the years. John McMaster found himself interested in investigating the workings of the STU-III secure telephone, and set out to replicate the secure keys used with this system.
[John] had a particular affinity for the STU-III for its method of encrypting phone calls. A physical device known as a Crypto Ignition Key had to be inserted into the telephone, and turned with a satisfying clunk to enable encryption. This physical key contains digital encryption keys that, in combination with those in the telephone, are used to encrypt the call. The tactile interface gives very clear feedback to the user about securing the communication channel. Wishing to learn more, John began to research the system further and attempted to source some hardware to tinker with.
As John explains in his Hackaday Superconference talk embeded below, he was able to source a civilian-model STU-III handset but the keys proved difficult to find. As carriers of encryption keys, it’s likely that most were destroyed as per security protocol when reaching their expiry date. However, after laying his hands on a broken key, he was able to create a CAD model and produce a mechanically compatible prototype that would fit in the slot and turn correctly.
The automobile is a wonderous invention, perhaps one of the most transformative of the 20th century. They’re machines that often inspire an all-consuming passion, capturing the heart with sights, sounds, and smells. However, for those who grew up isolated from car culture, it can be difficult to know how to approach cars as a hobby. If this sounds like you, fear not – this article is a crash course into getting your feet wet in the world of horsepower.
So You Like Cars, Eh?
The first step to becoming a true gearhead is identifying your specific passion. Car culture is a broad church, and what excites one enthusiast can be boring or even repulsive to another. Oftentimes, the interest can be spawned by a fond memory of a family member’s special ride, or a trip to a motor race during childhood.
Knowing what kind of cars you like is key to your journey. You might fall in love with classic American muscle and drag racing, or always fancied yourself in the seat of a tweaked-out tuner car a la The Fast And The Furious. Movies, posters, magazines, and your local car shows are a great way to figure out what excites you about cars. Once you’ve got an idea of what you like, it’s time to start thinking about picking out your first project car. Continue reading “How To Get Into Cars: Choosing Your First Project Car”→
For all the lip service the world’s governments pay to “space belonging to the people”, they did a pretty good job keeping access to it to themselves for the first 50 years of the Space Age. Oh sure, private-sector corporations could spend their investors’ money on lengthy approval processes and pay for a ride into space, but with a few exceptions, if you wanted your own satellite, you needed to have the resources of a nation-state.
All that began to change about 20 years ago when the CubeSat concept was born. Conceived as a way to get engineering students involved in the satellite industry, the 10 cm cube form factor that evolved has become the standard around which students, amateur radio operators, non-governmental organizations, and even private citizens have designed and flown satellites to do everything from relaying ham radio messages to monitoring the status of the environment.
But before any of that can happen, CubeSat builders need to know that their little chunk of hardware is going to do its job. That’s where Alan Johnston, a teaching professor in electrical and computer engineering at Villanova University, comes in. As a member of AMSAT, the Radio Amateur Satellite Corporation, he has built a CubeSat simulator. Built for about $300 using mostly off-the-shelf and 3D-printed parts, the simulator lets satellite builders work the bugs out of their designs before committing them to the Final Frontier.
Dr. Johnston will stop by the Hack Chat to discuss his CubeSat simulator and all things nanosatellite. Come along to learn what it takes to make sure a satellite is up to snuff, find out his motivations for getting involved in AMSAT and CubeSat testing, and what alternative uses people are finding the platform. Hint: think high-altitude ballooning.
Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.