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ESP32 Boards With Displays: An Overview

พฤ, 05/24/2018 - 12:00

The ESP8266 has become practically the 555 chip of WiFi connected microcontrollers. Traditionally, you’d buy one on a little breakout board with some pins and a few connectors, and then wire up anything else you need. The ESP8266’s big brother, the ESP32, hasn’t quite taken over from the ESP8266, but it has a lot more power and many more options. [Andreas] has a new video that shows seven new ESP32 boards that have integral displays. These boards can simplify a lot of applications where you need both WiFi and a user interface.

Of the boards examined, six of them have OLED displays, but one has an E-paper display. To summarize results, [Andreas] summarized his findings on these seven along with others in an online spreadsheet.

The boards include:

  • TTGO with 2.9 E-paper display
  • TTGO TS V1.2
  • TTGO T4
  • TTGO Pro V2
  • TTGO LoRa V2
  • Wemos
  • Wifi Kit32

There are two pieces of software to do testing and those are available on GitHub if you want to test new boards or do your own testing.

The review is very practical, examining power consumption, available pins, and how easy it is to use on a breadboard. Since [Andreas] comes tot his with a voice of experience he also looks at things like battery switches, and whether the device crashes if you disconnect the USB power. Spoiler alert: He was not happy with the E-paper display board.

These display-bearing devices are much easier than using a separate ESP32 for each pair of digits. If you need a much bigger display, there’s always this.

Using TensorFlow To Recognize Your Own Objects

พฤ, 05/24/2018 - 09:00

When the time comes to add an object recognizer to your hack, all you need do is choose from many of the available ones and retrain it for your particular objects of interest. To help with that, [Edje Electronics] has put together a step-by-step guide to using TensorFlow to retrain Google’s Inception object recognizer. He does it for Windows 10 since there’s already plenty of documentation out there for Linux OSes.

You’re not limited to just Inception though. Inception is one of a few which are very accurate but it can take a few seconds to process each image and so is more suited to a fast laptop or desktop machine. MobileNet is an example of one which is less accurate but recognizes faster and so is better for a Raspberry Pi or mobile phone.

You’ll need a few hundred images of your objects. These can either be scraped from an online source like Google’s images or you get take your own photos. If you use the latter approach, make sure to shoot from various angles, rotations, and with different lighting conditions. Fill your background with various other things and even have some things partially obscuring your objects. This may sound like a long, tedious task, but it can be done efficiently. [Edje Electronics] is working on recognizing playing cards so he first sprinkled them around his living room, added some clutter, and walked around, taking pictures using his phone. Once uploaded, some easy-to-use software helped him to label them all in around an hour. Note that he trained on 24 different objects, which are the number of different cards you get in a pinochle deck.

You’ll need to install a lot of software and do some configuration, but he walks you through that too. Ideally, you’d use a computer with a GPU but that’s optional, the difference being between three or twenty-four hours of training. Be sure to both watch his video below and follow the steps on his Github page. The Github page is kept most up-to-date but his video does a more thorough job of walking you through using the software, such as how to use the image labeling program.

Why is he training an object recognizer on playing cards? This is just one more step in making a blackjack playing robot. Previously he’d done an impressive job using OpenCV, even though the algorithm handled non-overlapping cards only. Google’s Inception, however, recognizes partially obscured cards. This is a very interesting project, one which we’ll be keeping an eye on. If you have any ideas for him, leave them in the comments below.

Retro Rebuild Recreates SGI Workstation Demos On The Go

พฤ, 05/24/2018 - 06:00

When [Lawrence] showed us the Alice4 after Maker Faire Bay Area last weekend it wasn’t apparent how special the system was. The case is clean and white, adorned only with a big red button below a 7″ screen with a power switch around the back. When the switch is flicked the system boots to display a familiar animation and drops you at a menu. Poking around from here elicits a variety of self-contained graphics demos, some interactive. So this is a Raspberry Pi in a box playing videos, right? Not even close.

Often retro computing focuses on personal computer systems. When they were new the 8-bit graphics or intricate 2D sprites were state of the art, but now their appeal tends towards learning opportunities and the thrill of nostalgia. This may still be true of Alice4, the system [Brad, Lawrence, Mike, and Chris] put together to run Silicon Graphics (SGI) demos from the mid 1980’s but it’s not the whole story. [Lawrence] and [Brad] had both worked at SGI during its heyday and had fond memories of the graphics demos that shipped with those mammoth workstation. So they built Alice4 from the FPGA up to run those very same demos in real-time.

Thanks to Moore’s law, today’s embedded systems put yesterday’s powerhouses within reach. [Lawrence] and [Brad] found the old demo code in a ratty FTP server, and tailor-made Alice4’s software and hardware to run them natively. [Brad] wrote a libgl which implements the subset of the IrisGL API needed to support their selected set of demos. The libgl emits sets of triangles to the SDRAM where [Lawrence’s] HDL running on the onboard FPGA fetches them to interpolate color and depth and draw the result on-screen. Together they allow the $99 Altera Cyclone V development board at Alice4’s heart to run these state of the art demos in the palm of your hand.

Alice4 is open source and extensively documented. Peruse the archeology of reverse engineering the graphics API or the discussion of FIFO design in the FPGA. If those don’t sate your appetite check out a video of Alice4 in action after the break.

Grawler: Painless Cleaning For Glass Roofs

พฤ, 05/24/2018 - 03:00

Part of [Gelstronic]’s house has a glass roof. While he enjoys the natural light and warmth, he doesn’t like getting up on a ladder to clean it every time a bird makes a deposit or the rainwater stains build up. He’s tried to make a cleaning robot in the past, but the 25% slope of the roof complicates things a bit. Now, with the addition of stepper motors and grippy tank treads, [Gelstronic] can tell this version of GRawler exactly how far to go, or to stay in one place to clean a spot that’s extra dirty.

GRawler is designed to clean on its way up the roof, and squeegee on the way back down. It’s driven by an Arduino Pro Micro and built from lightweight aluminium and many parts printed in PLA. GRawler also uses commonly-available things, which is always a bonus: the brush is the kind used to clean behind appliances, and the squeegee blade is from a truck-sized wiper. [Gelstronic] can control GRawler’s motors, the brush’s spin, and raise/lower the wiper blade over Bluetooth using an app called Joystick BT Commander. Squeak past the break to see it in action.

As far as we can tell, [Gelstronic] will still have to break out the ladder to place GRawler and move him between panels. Maybe the next version could be tethered, like Scrobby the solar panel-cleaning robot.

Open Source Underwater Distributed Sensor Network

พฤ, 05/24/2018 - 01:30

One way to design an underwater monitoring device is to take inspiration from nature and emulate an underwater creature. [Michael Barton-Sweeney] is making devices in the shape of, and functioning somewhat like, clams for his open source underwater distributed sensor network.

The clams contain the electronics, sensors, and means of descending and ascending within their shells. A bunch of them are dropped overboard on the surface. Their shells open, allowing the gas within to escape and they sink. As they descend they sample the water. When they reach the bottom, gas fills a bladder and they ascend back to the surface with their data where they’re collected in a net.

Thus far he’s made a few clams using acrylic for the shells which he’s blown himself. He soldered the electronics together free-form and gave them a conformal coating of epoxy. He’s also used a thermistor as a stand-in for other sensors and is already working on a saturometer, used for measuring the total dissolved gas (TDG) in the water. Knowing the TDG is useful for understanding and mitigating supersaturation of water which can lead to fish kills.

He’s also given a lot of thought into the materials used since some clams may not make it back up and would have to degrade or be benign where they rest. For example, he’s been using a lithium battery for now but would like to use copper on one shell and zinc on another to make a salt water battery, if he can make it produce enough power. He’s also considering using 3D printing since PLA is biodegradable. However, straight PLA could be subject to fouling by underwater organisms and would require cleaning, which would be time-consuming. PLA becomes soft when heated in a dishwasher and so he’s been looking into a PLA and calcium carbonate filament instead.

Check out his hackaday.io page where he talks about all these and more issues and feel free to make any suggestions.

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Mechanisms: Solenoids

พฤ, 05/24/2018 - 00:01

Since humans first starting playing with electricity, we’ve proven ourselves pretty clever at finding ways to harness that power and turn it into motion. Electric motors of every type move the world, but they are far from the only way to put electricity into motion. When you want continuous rotation, a motor is the way to go. But for simpler on and off applications, where fine control of position is not critical, a solenoid is more like what you need. These electromagnetic devices are found everywhere and they’re next in our series on useful mechanisms.

A Coil and a Plunger

A physicist will tell you a solenoid simply a coil of wire through which current can be passed. That’s it. Other than in the physics lab, though, such a simple device is not of much mechanical use, so what we tend to think of as a solenoid is slightly more complicated. A practical solenoid has a coil, but it’s also going to have several mechanical parts to make it work as an actuator.

Plunger-type solenoid. Source: UniqueMachines

A plunger solenoid is a good example of the basics. The air core of the solenoid’s coil is partially occupied by an iron or mild steel plunger, held in place by a return spring. When current is applied to the coil, a magnetic field forms, and the plunger is pulled forcefully into the solenoid’s core. When current stops flowing, the magnetic field collapses, and the return spring forces the plunger back to the resting state. This is characteristic of most solenoids — they’re either actuated or they’re not. This makes them great for jobs that require something to be positioned in either one position or another over a short distance, like valves that stop the flow of liquid through a pipe or tubing.

Plunger solenoids range in size from the very tiny to the ludicrously large. On the small side, plunger solenoids see service as actuators for microfluidics valves in scientific and medical applications, and in the drive head for the impact style of dot-matrix printers (yes, each one of those dots is the plunger of a solenoid).

You likely interact with medium-sized solenoids on a daily basis. The click at the beginning and end of your refrigerator’s ice maker is what switches the water on and off to refill the tray. You’ll hear a similar click in fountain soda machines. And those pinball wizards among us will attest that the forces throwing that silver ball around the playfield are generated by solenoids.

Stepping up the scale, there’s a fairly large solenoid inside the starter motor of almost every car and truck on the road, at least those with internal combustion engines. The solenoid sits atop the starter motor and is responsible for connecting and disconnecting the starter from the system. The solenoid’s plunger is attached to the motor drive shaft via a lever. When the ignition key is turned, the solenoid coil is energized, pulling the plunger in and moving the lever out along the now-spinning motor shaft. This drives a pinion gear out to engage with the engine flywheel to crank the engine until it starts.

Solenoid Styles One type of rotary solenoid. Source: UniqueMachines

Other styles of solenoid are available, including rotary solenoids. These are exactly what they sound like: actuators that can rotate between two positions. Designs vary, but the most common types have a permanent magnet rotor on a shaft inside the solenoid’s core. When the coil is energized, the rotor experiences a torque due to the magnetic field, much like the rotor of a permanent magnet motor. The rotor only moves to a physical stop, though, and is returned to the resting position by a spring when the coil is de-energized. If the polarity of the coil is reversed, then the rotor and shaft can swing the other way, making this style of rotary solenoid bistable. Other rotary solenoids use a metal disc with ramped grooves and ball bearings; when the plunger is sucked into the core, the ball bearings force the disc and shaft to rotate along the grooves.

AC, DC, and Snubbing

As electrically simple devices, solenoids can run on either AC or DC. A DC solenoid tends to be quieter because the magnetic field is constant while the coil is energized. An AC solenoid tends to chatter as the magnetic field varies and the force of the return spring overcomes it at the instant the current changes direction in the coil. This tendency can be mitigated by the use of a shading ring to alter the magnetic circuit of AC solenoids. A shading ring is just a small copper ring that sits inside the core of the solenoid so it contacts the plunger when it’s fully retracted. The magnetic field of the energized coil induces a current inside the ring, which in turn creates its own magnetic field that lags the phase of the solenoid’s field by 90°. When the solenoid’s field falls to zero as the AC waveform passes the zero point, the magnetic flux from the shading ring keeps the solenoid retracted, eliminating the bothersome chatter.

While any solenoid will run on AC or DC, care needs to be taken to observe the coil’s specs. Solenoids represent an inductive load, and so their impedance is much higher in AC applications. So if a solenoid rated for 24 VAC were powered by 24 VDC, it would probably burn out quickly as the current through it would exceed the design specs. This could be avoided with a current limiting resistor or by lowering the DC supply voltage.

Like their cousin the relay, solenoids have the potential to damage whatever circuit is controlling them. When the current flowing through a solenoid or relay coil is removed, the voltage spikes as the magnetic field collapses. If that spike gets into sensitive components, like a transistor driving the coil, the device could be destroyed. The classic remedy for this with DC coils is the snubber diode, connected in parallel across the coil with the anode on the negative side. The snubber gives the induced current somewhere to go when the power is removed from the coil to prevent it from inducing the high voltage spike. Snubber diodes won’t work on AC coils, so an RC snubber, with a small resistance and capacitance in series with each other placed in parallel across the coil, serves the same purpose.

This is only a brief look at what solenoids are and do, and how to incorporate these mechanisms into your designs.

Friday Hack Chat: Making Programming Easier

พุธ, 05/23/2018 - 23:00

There is a long history of graphical programming languages. Some people don’t like to code, and for them, graphical programming languages replace semicolons and brackets with easy-to-understand boxes and wires.

This Friday, we’re going to be talking about graphical programming languages with [Boian Mitov]. He’s a software developer, founder of Mitov Software, and the creator of Visuino, a graphical programming language for the embedded domain. He specialized in video, audio, DSP, DAQ, industrial automation, communications, computer vision, artificial intelligence, as well as parallel and distributed computing. [Boian] is the author of the OpenWire open source technology, the IGDI+ open source library, the VideoLab, SignalLab, AudioLab, PlotLab, InstrumentLab, VisionLab, IntelligenceLab, AnimationLab, LogicLab, CommunicationLab, and ControlLab libraries, OpenWire Studio, Visuino, and author of the “VCL for Visual C++” technology.

For this Hack Chat, we’re going to be talking about ways to make programming microcontrollers easier. The focus of this discussion is Visuino, a graphical programming environment. Visuino allows anyone to program an Arduino, Teensy, or an ESP simply by connecting wires and choosing some logic. Think of it as a step above the programming environment that came with the Lego Mindstorms, Scratch, or whatever else MIT was coming out with in the early ‘aughts.

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Hack Chat Event Page and we’ll put that in the queue for the Hack Chat discussion.

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week is just like any other, and we’ll be gathering ’round our video terminals at noon, Pacific, on Friday, May 25th.  Here’s a clock counting down the time until the Hack Chat starts.

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 Friday; join whenever you want and you can see what the community is talking about.

Plant Biology is a Gateway

พุธ, 05/23/2018 - 22:00

Too many college students have been subject to teachers’ aids who think they are too clever to be stuck teaching mere underclassmen. For that reason, [The Thought Emporium] is important because he approaches learning with gusto and is always ready to learn something new himself and teach anyone who wants to learn. When he released a video about staining and observing plant samples, he avoided the biggest pitfalls often seen in college or high school labs. Instead of calling out the steps by rote, he walks us through them with useful camera angles and close-ups. Rather than just pointing at a bottle and saying, “the blue one,” he tells us what is inside and why it is essential. Instead of telling us precisely what we need to see to get a passing grade, he lets our minds wonder about what we might see and shows us examples that make the experiment seem exciting. The video can also be seen below the break.

The process of staining can be found in a biology textbook, and some people learn best by reading, but we haven’t read a manual that makes a rudimentary lab seem like the wardrobe to Narnia, so he gets credit for that. Admittedly, you have to handle a wicked sharp razor, and the chance of failure is never zero. In fact, he will tell you, the opportunities to fail are everywhere. The road to science isn’t freshly paved, it needs pavers.

If a biology lab isn’t in your personal budget, a hackerspace may have one or need one. If you are wondering where you’ve heard [The Thought Emporium]’s voice before, it is because he is fighting lactose intolerance like a hacker.

SpaceX’s Next Giant Leap: Second Stage Recovery

พุธ, 05/23/2018 - 21:01

With the successful launch of the Bangabandhu-1 satellite on May 11th, the final version of the Falcon 9 rocket has finally become operational. Referred to as the “Block 5”, this version of the rocket is geared specifically towards reuse. The lessons learned from the recovery and reflight of earlier builds of the F9 have culminated into rocket that SpaceX hopes can go from recovery to its next flight in as few as 24 hours. If any rocket will make good on the dream of spaceflight becoming as routine as air travel, it’s going to be the Falcon 9 Block 5.

While there might still be minor tweaks and improvements made to Block 5 over the coming years, it’s safe to say that first stage recovery of the Falcon 9 has been all but perfected. What was once the fodder of campy science fiction, rockets propulsively lowering themselves down from the sky and coming to rest on spindly landing legs that popped out of the sides, is now a reality. More importantly, not only is SpaceX able to bring the towering first stage back from space reliably, they’re able to refuel it, inspect it, and send it back up without having to build a new one for each mission.

But as incredible a technical accomplishment as this is, SpaceX still isn’t recovering the entire Falcon 9 rocket. At best, they have accomplished the same type of partial reusability that the Space Shuttle demonstrated on its first flight all the way back in 1981. Granted they are doing it much faster and cheaper than it was done on the Shuttle, but it still goes against the classic airplane analogy: if you had to replace a huge chunk of the airliner every time it landed, commercial air travel would be completely impractical.

SpaceX has already started experimenting with recovering and reusing the payload fairings of the Falcon 9, and while they haven’t pulled it off yet, they’ll probably get there. That leaves only one piece of the Falcon 9 unaccounted for: the second stage. Bringing the second stage back to Earth in one piece might well be the most challenging aspect of developing the Falcon 9. But if SpaceX can do it, then they’ll have truly developed humanity’s first fully reusable rocket, capable of delivering payloads to space for little more than the cost of fuel.

Different Stages, Different Challenges

While the first stage is there to get the payload up, it could be said that the second stage is responsible for moving the payload sideways. The second stage absolutely pours on the speed: on the most recent launch it accelerated the payload from 8,019 km/h at stage separation to the 26,967 km/h required to maintain low Earth orbit in just a few minutes. Once the payload separates and continues on with its mission, the second stage is for all intents and purposes its own spacecraft moving at orbital speed and altitude.

Bringing it down to a gentle landing on Earth therefore has all the same challenges of landing any other spacecraft, except for the fact that the second stage has none of the hardware that would traditionally be necessary to pull off such a feat. It’s a bit like trying to land an airplane without landing gear. Or wings.

In early concept videos from SpaceX, the second stage was shown outfitted with a heat shield, landing legs, and even a retractable engine nozzle. All of these features would have worked together to make the stage capable of the same autonomous propulsive landings the first stage performs. But the problem with this “super” second stage is weight.

Every kilogram of recovery gear added to the second stage is one less kilogram of payload delivered to space. For a commercial launch provider like SpaceX, that is a problem. Fortunately, the Falcon 9 tends to be underutilized by most payloads, so there’s some wiggle room to play with. For example, the Bangabandhu-1 satellite weighed approximately 3,700 kg, which is less than half the Falcon’s capability for that particular launch profile: geostationary transfer orbit. So if the recovery hardware can be limited to less than 1,000 kg or so, it shouldn’t have an impact on the kinds of payloads the Falcon is likely to encounter.

An Unexpected Solution

Weight really adds up when building spacecraft. Consider that the landing legs on the Falcon 9 first stage weigh around 2,000 kg on their own. Any attempt at recovering the second stage needs to be done with the absolute minimum of additional hardware. A full heat shield like the Dragon capsule has would likely eat up too much of that mass budget, same with the “grid fins” used to stabilize the first stage as it falls back down to Earth.

So how do get the second stage through the atmosphere and stabilize it? The first hint at the answer comes from a recent Tweet by Elon Musk:

Party balloons and a bouncy house? If anyone else said something like that, we’d just assume it was kind of joke. But we thought it was a joke when he Tweeted about sending his Tesla Roadster to space, and we all know how that turned out. So what does it all mean?

Meet the Ballute

The idea of using an inflatable balloon to slow down high altitude supersonic vehicles was pioneered in 1958 by Goodyear. NASA demonstrated that the so-called ballute (as it’s both a balloon and parachute) concept could be used for spacecraft reentry when a small one was used to safely decelerate a test article from Mach 4.2 in 1968. Unfortunately tests with larger ballutes failed, and ultimately the concept was never used for the space program.

From Elon’s Tweets, it looks like SpaceX is looking to revisit the ballute concept, using it to ease the Falcon 9’s second stage journey through the atmosphere. After performing a de-orbit burn, the second stage could deploy a ballute to help slow and stabilize it as it comes back down from space. But that’s only half the problem. You still have to get it on the ground without damaging it.

Catch a Falling Star Stage

With the second stage at a low enough altitude and speed thanks to the ballute, it could then deploy either a traditional parachute of parafoil to make the final approach towards the recovery point. As the second stage would likely not have any landing gear or legs due to weight constraints, the landing area would apparently be an inflatable structure of some type that can catch the stage without damaging it. In principle this is very similar to the work currently being done to catch the Falcon 9’s fairings with a large ship-mounted net.

Again, this would borrow heavily from earlier NASA research. In 1963, experiments were performed to determine if the first stage of the Saturn rocket could be recovered using an inflatable wing structure.

Iterative Design

At the risk of trivializing the accomplishments of SpaceX, it’s fair to say that very little of their technology is actually new. Rather, they combine Silicon Valley style R&D and modern construction techniques with technology pioneered during the Space Race of the 1960’s to rapidly produce evolutionary improvements. This allowed them to get to orbit in a fraction of the time it would have taken had they started completely from scratch, and now it seems they’ll be turning their attention towards iterating through NASA recovery concepts from the Gemini and Apollo programs to help turn Falcon 9 into the world’s first truly reusable rocket.

That said, it wouldn’t be the first time SpaceX abruptly changed their approach. The final method for second stage recovery could be vastly different from what Elon has been hinting at. It’s also possible that they abandon it entirely. Even with only partial reuse of the Falcon 9, they’re by far the cheapest game in town.

The bottom line is, we just don’t know yet. It’s interesting to theorize like this, but until we watch a live YouTube stream of a Falcon 9 second stage riding down from space under a balloon, anything’s possible. One thing’s for sure though, no matter what their plans are, they’ve got the world’s attention.

Blowing Rings With Cannons, Fogs, And Lasers

พุธ, 05/23/2018 - 18:00

In today’s healthy lifestyle oriented world, blowing smoke rings won’t impress too many people anymore. Unless of course you are [NightHawkInLight] and blow them with a vortex cannon and add lasers for visual effects. Although, his initial motivation was to build a device that could shoot lost frisbees out off the trees in his backyard disc golf course, and as avid enthusiast of shooting things through the air using a propane torch, he opted for a vortex cannon to avoid the risk of injuries shooting a projectile may cause.

With safety in mind from the beginning, [NightHawkInLight] chose to build the cannon in ways that won’t expose him or people following his footsteps to any toxic fumes. The barrel is formed by securing a roll of terrace board and simply pulling it into a cone. A series of PVC pipes and adapters build the combustion chamber that fits the terrace board barrel on its one end, and the propane torch nozzle on its other end. For easier aim and stability, he also adds a tripod mount.

Since air vortices are, well, air, and therefore not visible by themselves, they don’t offer the most visual excitement. [NightHawkInLight] solved this with a fog machine attached to the barrel, and a laser line module, which you can see for yourself in his build video after the break. In a previous vortex cannon project we could also see a more outdoorsy approach to add visibility to it.

Automatic I2C Address Allocation For Daisy-Chained Sensors

พุธ, 05/23/2018 - 15:00

Many readers will be familiar with interfacing I2C peripherals. A serial line joins a string of individual I2C devices, and each of the devices has its own address on that line. In most cases when connecting a single device or multiple different ones there is no problem in ensuring that they have different addresses.

What happens though when multiple identical devices share an I2C bus? This was the problem facing [Sam Evans] at Mindtribe, and his solution is both elegant and simple. The temperature sensors he was using across multiple identical boards have three pins upon which can be set a binary address, and his challenge was to differentiate between them without the manufacturing overhead of a set of DIP switches, jumpers, or individual pull-up resistors. Through a clever combination of sense lines between the boards he was able to create a system in which the address would be set depending upon whether the board had a neighbour on one side, the other, or both. A particularly clever hack allows two side-by-side boards that have two neighbours to alternate their least significant bit, allowing four identical boards each with two sensors to be daisy-chained for a total of eight sensors with automatic address allocation.

We aren’t told what the product was in this case, however it’s irrelevant. This is a hardware hack in its purest sense, one of those which readers will take note of and remember when it is their turn to deal with a well-populated I2C bus. Of course, if this method doesn’t appeal, you can always try an LTC4316.

This Computer Is As Quiet As The Mouse

พุธ, 05/23/2018 - 12:00

[Tim aka tp69] built a completely silent desktop computer. It can’t be heard – at all. The average desktop will have several fans whirring inside – cooling the CPU, GPU, SMPS, and probably one more for enclosure circulation – all of which end up making quite a racket, decibel wise. Liquid cooling might help make it quieter, but the pump would still be a source of noise. To completely eliminate noise, you have to get rid of all the rotating / moving parts and use passive cooling.

[Tim]’s computer is built from standard, off-the-shelf parts but what’s interesting for us is the detailed build log. Knowing what goes inside such a build, the decisions required while choosing the parts and the various gotchas that you need to be aware of, all make it an engaging read.

It all starts with a cubic aluminum chassis designed to hold a mini-ITX motherboard. The top and side walls are essentially huge extruded heat sinks designed to efficiently carry heat away from inside the case. The heat is extracted and channeled away to the side panels via heat sinks embedded with sealed copper tubing filled with coolant fluid. Every part, from the motherboard onwards, needs to be selected to fit within the mechanical and thermal constraints of the enclosure. Using an upgrade kit available as an enclosure accessory allows [Tim] to use CPUs rated for a power dissipation of almost 100 W. This not only lets him narrow down his choice of motherboards, but also provides enough overhead for future upgrades. The GPU gets a similar heat extractor kit in exchange for the fan cooling assembly. A fanless power supply, selected for its power capacity as well as high-efficiency even under low loads, keeps the computer humming quietly, figuratively.

Once the computer was up and running, he spent some time analysing the thermal profile of his system to check if it was really worth all the effort. The numbers and charts look very promising. At 100% load, the AMD Ryzen 5 1600 CPU levelled off at 60 ºC (40 ºC above ambient) without any performance effect. And the outer enclosure temperature was 42 ºC — warm, but not dangerous. Of course, performance hinges around “ambient temperature”, so you have to start getting careful when that goes up.

Getting such silence comes at a price – some may consider it quite steep. [Tim] spent about A$3000 building this whole system, thanks in part due to high GPU prices because of demand from bitcoin mining. But cost is a relative measure. He’s spent less on this system compared to several of his earlier projects and it let’s him enjoy the sounds of nature instead of whiny cooling fans. Some would suggest a pair of ear buds would have been a super cheap solution, but he wanted a quiet computer, not something to cancel out every other sound in his surroundings.

Machine Learning Crash Course From Google

พุธ, 05/23/2018 - 09:00

We’ve been talking a lot about machine learning lately. People are using it for speech generation and recognition, computer vision, and even classifying radio signals. If you’ve yet to climb the learning curve, you might be interested in a new free class from Google using TensorFlow.

Of course, we’ve covered tutorials for TensorFlow before, but this is structured as a 15 hour class with 25 lessons and 40 exercises. Of course, it is also from the horse’s mouth, so to speak. Google says the class will answer questions like:

  • How does machine learning differ from traditional programming?
  • What is loss, and how do I measure it?
  • How does gradient descent work?
  • How do I determine whether my model is effective?
  • How do I represent my data so that a program can learn from it?
  • How do I build a deep neural network?

Google says you should be adept at intro level algebra and that higher math could be helpful, although not essential. You should also know something about programming with some familiarity in Python. The exercises run in your browser, so you don’t need any exotic set up. There are also a few tools that have suggested tutorials if you aren’t up to speed on them already. For example, the pandas library and bash are included in that list.

If you get really serious, Google have a lot of educational resources that will take you further. If you learn better by example, you might try getting naked. If you want an even longer class, try this one.

Spared No Expense: Cloning The Jurassic Park Explorer

พุธ, 05/23/2018 - 06:00

While you’d be hard pressed to find any serious figures on such things, we’d wager there’s never been a vehicle from a TV show or movie that has been duplicated by fans more than the Staff Jeeps from Jurassic Park. Which is no great surprise: not only do they look cool, but it’s a relatively easy build. A decent paint job and some stickers will turn a stock Wrangler into a “JP Jeep” that John Hammond himself would be proud of.

While no less iconic, there are far fewer DIY builds of the highly customized Ford Explorer “Tour Vehicles”. As a rather large stretch of the film takes place within them, the interiors were much more detailed and bears little resemblance to the stock Explorer. Building a truly screen accurate Jurassic Park Tour Vehicle was considered so difficult that nobody has pulled it off since the movie came out in 1993. That is until [Brock Afentul] of PropCulture decided to take on the challenge.

In an epic journey spanning five years, [Brock] has created what he believes is the most accurate Jurassic Park Tour Vehicle ever produced; and looking at the side by side shots he’s done comparing his Explorer to the ones from the movie, it’s hard to disagree. A massive amount of work went into the interior, leaving essentially nothing untouched. While previous builds have tried to modify the stock dashboard to look like the one from the movie, he built a completely new dash from MDF and foam and coated it in fiberglass. The center console featuring the large display was also faithfully reproduced from the movie, and runs screen accurate animations, maps, and tour information. The seats also had to be replaced, multiple times in fact, as he had a considerable amount of trouble getting somebody to upholster them to his standards.

But perhaps the most difficult component of all was the clear acrylic roof bubble. These were critical to filming the movie, as they not only let the viewer see down into the Tour Vehicles but also let the characters see out during the iconic tyrannosaurus attack. But because the roof bubble was created only for the movie and never existed as a real aftermarket product, it usually gets ignored in Tour Vehicle builds. It’s simply too difficult to produce for most people. The omission of the bubble was always considered a case of artistic license; in the same way nobody expects a replica DeLorean from Back to the Future to actually fly or travel through time.

But [Brock] wanted to take his Tour Vehicle all the way, so he partnered up with a local glass shop that let him rent time in their oven so he could heat up acrylic sheets. Once heated to the appropriate temperature, they could be removed and wrapped around a mold to make the bubble. The process took weeks to perfect, but in the end he and a few friends got the hang of it and were able to produce a gorgeous roof bubble that they fitted to the already very impressive Explorer.

While previous Jurassic Park Tour Vehicle replicas were unquestionably awesome, this build really does take it to the next level. Short of equipping the garage with a movie-accurate super computer, it’s hard to see how the bar can get any higher.

Restoring A 1930s Oscilloscope – Without Supplying Power

พุธ, 05/23/2018 - 03:00

We’ve all done it: after happening across a vintage piece of equipment and bounding to the test bench, eager to see if it works, it gets plugged in, the power switch flipped, but… nothing. [Mr Carlson] explains why this is such a bad idea, and accompanies it with more key knowledge for a successful restoration – this time revitalising a tiny oscilloscope from the 1930s.

Resisting the temptation to immediately power on old equipment is often essential to any hope of seeing it work again. [Mr Carlson] explains why you should ensure any degraded components are fixed or replaced before flipping the switch, knowing that a shorted/leaking capacitor is more than likely to damage other components if power is applied.

The oscilloscope he is restoring is a beautiful find. Originally used by radio operators to monitor the audio they were transmitting, it features a one inch CRT and tube rectification, in a tight form factor.

[Mr Carlson] uses his capacitor leakage tester to determine if the main filter capacitor needs replacing – it does, no surprises there – as well as confirming the presence of capacitors potted into the power transformer itself. These have the potential to not only derail the restoration, but also cause a safety hazard through leakage to the chassis.

After replacing and rewiring everything that’s relevant, the scope is hooked up to an isolation transformer, and it works first time – showing the value of a full investigation before power-up. [Mr Carlson] quips, “It really doesn’t have a choice; when it’s on this bench, it’s going to work again”, a quote which will no doubt resonate with Hackaday readers.

[Mr Carlson] promises to integrate the scope into a new piece of test equipment in the near future, but in the meantime you can read about his soldering station VFD mod, or his walk-in AM radio transmitter.

Smiling Robot Moves Without Wires

พุธ, 05/23/2018 - 01:30

What could be cuter than a little robot that scuttles around its playpen and smiles all day? For the 2018 Hackaday prize [bobricius] is sharing his 2D Actuator for Micro Magnetic Robot. The name is not so cute, but it boasts a bill of materials under ten USD, so it should be perfect for educational use, which is why it is being created.

The double-layer circuit board hides six poles. Three poles run vertically, and three of them run horizontally. Each pole is analogous to a winding in a stepper motor. As the poles turn on, the magnetic shuttle moves to the nearest active pole. When the perpendicular windings activate, it becomes possible to lock that shuttle in place. As the windings activate in sequence, it becomes possible to move left/right and forward/back. The second video demonstrates this perfectly.

[bobricius] found inspiration from a scarier source, but wants us to know this is his creation, not a patent infringement. We are not lawyers.

Here is a way to visualize just what is happening with those FETs. Watch as a power lead is brushed across the terminals in order. With this kind of basic kit, students could learn the value of motor acceleration, deceleration, or launching little magnets at their classmates.

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Robert Hall and the Solid-State Laser

พุธ, 05/23/2018 - 00:00

The debt we all owe must be paid someday, and for inventor Robert N. Hall, that debt came due in 2016 at the ripe age of 96. Robert Hall’s passing went all but unnoticed by everyone but his family and a few close colleagues at General Electric’s Schenectady, New York research lab, where Hall spent his remarkable career.

That someone who lives for 96% of a century would outlive most of the people he had ever known is not surprising, but what’s more surprising is that more notice of his life and legacy wasn’t taken. Without his efforts, so many of the tools of modern life that we take for granted would not have come to pass, or would have been delayed. His main contribution started with a simple but seemingly outrageous idea — making a solid-state laser. But he ended up making so many more contributions that it’s worth a look at what he accomplished over his long career.

Merry Christmas Robert N. Hall in his lab. Source: General Electric

Robert Hall, given the middle name Noel in honor of his arrival on Christmas Day in 1919, was an inquisitive lad from the start. It seemed that inventing ran in the family, with his uncle Sydney being an aircraft engine designer and self-described career inventor. At a young age, his uncle took him to a sort of industrial fair in his hometown of New Haven, Connecticut, where Robert got to see all sorts of demonstrations and displays of the latest electrical innovations. His uncle explained how everything worked, which inspired young Robert to read and study as much as he could.

By the time high school rolled around, he was experimenting in a lab he built in his bedroom. He also discovered astronomy and build his own telescopes from scratch. An obviously promising student, Robert was recruited by Caltech and won a scholarship just before the start of World War II. When his funds ran out, he worked at Lockheed Aircraft, gaining valuable experience in industry and making contacts that would serve him well later.

He finally finished his physics degree in 1942 and was recruited by General Electric for their Schenectady Research Lab. As a test engineer in an industrial R&D facility during a time of war and complete national mobilization, Hall had a chance to make an impact, which he took full advantage of. Working with a team focused on using magnetrons to jam German radar, Hall’s team designed and built the first continuous-wave (CW) magnetrons. These devices would be employed during the war, but would also go on to become the heart of every microwave oven in use today. It’s even said that the possibly apocryphal story of the Raytheon engineer who was inspired to build the first microwave oven by a melting chocolate bar had his pocket zapped by one of Hall’s CW magnetrons.

Hall was encouraged to leave GE and seek his Ph.D. in physics, again from Caltech. He returned to Schenectady in 1948, ready to head up a lab of his own in the relatively new field of semiconductors. In a perfect lesson in exquisite timing, Bell Labs announced the transistor shortly after he arrived, and the whole semiconductor field exploded. GE being GE, they were mainly interested in the uses of semiconductors in power electronics, so Hall worked on high-power transistors and germanium power rectifiers. He contributed greatly to the field with innovations in purifying germanium by fractional crystallization, achieving purities that no other group was capable of. He also worked on silicon transistors, inventing two ways to dope the silicon: alloying and impurity diffusion. Pretty much every transistor ever made can trace its lineage back to those two methods.

Challenge Accepted

Hall’s innovations made GE a leader in silicon transistors by the early 1960s, and secured Hall’s place as the leading expert on semiconductors. Word came to the physics world of the invention of the laser in May of 1960, and Hall and his team devoured all the information they could get on the new field that showed so much promise. But the early lasers were complicated and fussy devices, and the need for a simpler laser was clear.

Good-natured and well-liked by his peers, Hall was teased that since he had already invented so many things, he should take a stab at a solid-state laser. Even though he thought it would be impossible, he accepted the challenge and hit the books. He knew that gallium arsenide diodes could emit enormous amounts of infrared light, so he crunched the numbers and found that he might be able to make a laser from the stuff. He put together a small team and got to work, and within just a few days, they had built a working device from a crystal only 1/3 of a millimeter on a side. It needed liquid nitrogen cooling and only worked in pulse mode, but the world finally had a laser that didn’t need pumping by an outside source of energy. The solid-state laser had arrived.

US Patent 3,245,002, for a “Stimulated Emission Semiconductor”

The GE team wrote up their results quickly and submitted a paper to the Physical Review Letters. Sadly, some chicanery resulted when the paper was sent out for peer review. Two of the reviewers were from two different competing corporate labs working on solid-state lasers, and when they read of Hall’s success, they short-circuited the process and held a press conference to announce that they had “invented” the solid-state laser. Luckily, Hall’s patent was granted along with the others; in any event, his team was the first to publish, so there’s little doubt as to the fatherhood of the solid-state laser.

Hall continued working at GE until his retirement, racking up 43 patents and 81 publications. His other work impacted the fields of nuclear physics, where his high-purity semiconductors are used for sensitive gamma-ray detectors. And while GE never developed Hall’s laser into a commercial product — the work of building a continuous-wave room-temperature solid-state laser was left to others — every single point-of-sale barcode scanner, CD player, laser pointer, and perhaps most importantly, every fiber optic connection that would eventually stitch together the backbone of the Internet, all trace back to that tiny crystal on Robert Hall’s lab bench in 1962.

Hacking a Cheap Laser Rangefinder

อังคาร, 05/22/2018 - 22:30

When a new piece of technology comes out, the price is generally so high that it keeps away everyone but the die hard early adopters. But with time the prices inch down enough that more people are willing to buy, which then drives the prices down even more, until eventually the economies of scale really kick in and the thing is so cheap that it’s almost an impulse buy. Linux SBCs, Blu-ray lasers, 3D printers; you name it and the hacker community has probably benefited from the fact that it’s not just the hacker community that’s interested anymore.

Which is exactly what’s started to happen with laser rangefinders. Once almost exclusively a military technology, you can now pick a basic “laser tape measure” for less than $40 USD from the normal overseas suppliers. Unfortunately, as [iliasam] found, they aren’t particularly well suited other tasks. For one there’s no official way of getting the data out of the thing, but the other problem is that the sample rate is less than one per second. Believing the hardware itself was promising enough, he set out to reverse engineer and replace the firmware running on one of these cheap laser rangefinders (Google Translate from Russian).

His blog post is an absolute wealth of information on how these devices operate, and a must read for anyone interested in reverse engineering. But the short version is that he figured out a way to reprogram the STM32F100C8T6 microcontroller used in the device, and develop his own firmware that addresses the usability concerns of this otherwise very promising gadget.

With some minor hoop jumping, the laser tape measure PCB can be hooked up to an ST-Link programmer, and the firmware provided by [iliasam] can be used to enable an easy to use serial interface. Perfect for pairing with an Arduino or Raspberry Pi to get fast and accurate range data without breaking the bank.

It probably won’t surprise you to see this isn’t the first time [iliasam] has gotten down and dirty with a laser rangefinder. This extremely impressive build from last year allowed for incredibly accurate 3D scans of his room, and before that he created his own rangefinder from scratch.

Hands-On: Flying Drones with Scratch

อังคาร, 05/22/2018 - 21:01

I’ll admit it. I have a lot of drones. Sitting at my desk I can count no fewer than ten in various states of flight readiness. There are probably another half dozen in the garage. Some of them cost almost nothing. Some cost the better part of a thousand bucks. But I recently bought a drone for $100 that is both technically interesting and has great potential for motivating kids to learn about programming. The Tello is a small drone from a company you’ve never heard of (Ryze Tech), but it has DJI flight technology onboard and you can program it via an API. What’s more exciting for someone learning to program than using it to fly a quadcopter?

For $100, the Tello drone is a great little flyer. I’d go as far as saying it is the best $100 drone I’ve ever seen. Normally I don’t suggest getting a drone with no GPS since the price on those has come down. But the Tello optical sensor does a great job of keeping the craft stable as long as there is enough light for it to see. In addition, the optical sensor works indoors unlike GPS.

But if that was all there was to it, it probably wouldn’t warrant a Hackaday post. What piqued my interest was that you can program the thing using a PC. In particular, they use Scratch — the language built at MIT for young students. However, the API is usable from other languages with some work.

Information about the programming environment is rather sparse, so I dug in to find out how it all worked.

Programming Setup

As with a lot of hardware programming tasks, setting up the toolchain is the most frustrating part. You need to use the offline version of Scratch which requires Adobe Air. I had trouble getting this to work on a Linux system so I  finally gave up and installed it on a Windows laptop.

Scratch, though, is just part of it. You also need to install nodejs and a few files from Ryze Tech (PDF). The Ryze files are installed via a hidden menu command accessed by holding shift while clicking “File”. You are then greeted with the “Import Experimental HTTP Extension,” option. Once this is complete you’ll wind up with some blocks in the “More Blocks” category shown here. Tello acts as a WiFi access point and control is established when you connect to it with your computer and run the nodejs server from the command prompt.

There is API documentation (PDF) available if you’d like to look under the hood. From reading the API documentation, I learned the move units are in centimeters and some have minimums as well as maximums. The blocks will let you set any value you want, though. It just won’t have the desired effect.

A Simple Program

I put together a quick little Scratch program. It just runs a simple pattern and adds some sound effects (from the PC, not the drone). I immediately discovered a gotcha.

The blocks simply issue commands, but there is no feedback. For example, if you send a fly forward command followed by a rotate command, the rotate command will fall on deaf ears. You must give the drone time to execute each command. From Scratch, I didn’t see a way to wait for the response, so you simply have to guess how long something is going to take.

You can probably puzzle most of this out. The top block tells the program to start when you press the Go flag (part of the Scratch environment). The purple launch and landing sounds are just recordings located on the computer. The gold boxes are all for control.

Talking through this program: the drone takes off, moves forward in 3 spurts, rotates 180 degrees, then moves forward in 4 spurts. Then it backs up the last spurt and lands.

Fly blocks have a minimum distance of 20 cm. In my program, I set a “fly up” block to 10 to test this. The drone won’t respond to this block unless you change that to at least 20. If you find your commands are not being executed, it may be worth reading the API documentation I mentioned before to see if you are within the minimum and maximum ranges for each block.

How’s it Work?

It works. This drone uses an optical sensor for position awareness. This is not GPS, it’s more like how an optical mouse sensor works. You can see the optical sensors on the underside of the Tello as the drone files over the New York skyline (sort of) in the picture to the left.

If you don’t have a lot of light for the optical sensors, all bets are off. But if you do, it works pretty well. The rotation seems spot on. There was a little drifting around, so the takeoff and landing were not always exactly in the same spot, but it was close.

So it did work. I’m not sure it would be ideal for a beginner since the set up is frustrating and the lack of feedback can be confusing. For exciting kids about programming, you’d be better served with Lego Mindstorms or some similar offering.

For those that do have experience with coding, you may want to investigate the non-Scratch bindings. There are other bindings to the API, like programming Tello using Go which we covered last month. And there’s also the secret API the official applications use, which has been decoded by a community effort.

For $100, even if you don’t care about programming them these drones are great little fliers. Add a $30 Bluetooth controller and they get better (the Bluetooth connects to your phone, not the drone). When they start getting discounted for half the price they’ll be no-brainers.

Raspberry Pi Keeps Cool

อังคาร, 05/22/2018 - 18:00

In general, heat is the enemy of electronics. [Christopher Barnatt] is serious about defeating that enemy and did some experiments with different cooling solutions for the Raspberry Pi 3. You can see the results in the video below.

A simple test script generated seven temperature readings for each configuration. [Barnatt] used a bare Pi, a cheap stick-on heatsink, and then two different fans over the heatsink. He also rigged up a large heatsink using a copper spacer and combined it with the larger of the two fans.

We aren’t sure if we would have used his methodology for these tests. The script executes quickly and it wasn’t clear that the temperature rise was leveling off. We weren’t sure just how much this was loading the CPU either. However, the results matched up with what you’d expect, so the script and data generation methods were probably fine.

The really interesting part to this wasn’t so much the results. We expected a bigger fan to do better and bigger fan and heat sink to do best of all. However, it was interesting watching the way the different cooling systems were mounted on the Pi and powered. The final solution — which was overkill anyway — was not mounted in a way that would lend itself to deployment. But the rest of the fan and heatsink combinations could easily be adapted for real projects.

If you really want to get serious, you can always plunge the Pi in oil. Or mount a thermoelectric heat pump and dump the excess heat into a bucket of water. But for most of us, just about any of the fan solutions here will be more than enough.