A Turntable For Model Railroads

January 11, 2019 by 17 Comments

Way back when, before diesel-electric locomotives were a thing, trains weren’t really able to go backwards too well. Also it’s sometimes necessary to turn carriages around in a small space. For that, the railway turntable was invented. If you want to implement one on a model layout, this project from DIY & Digital Railworld is for you.

The project is at an early stage – thus far, laying out how to set up an Arduino Uno using a potentiometer to control the speed of a stepper motor, which rotates the turntable. The turntable itself is a 3D printed part sourced from Thingiverse, designed to suit the specific stepper motor used.

This has the easy part sorted – rotating a piece of track through 360 degrees to orient a train properly. However, there’s significant work ahead. Power needs to be hooked up to the rails, and a system for accurately aligning the turntable with outgoing tracks needs to be devised. This is particularly relevant for N-gauge setups, where tolerances are everything.

We’d love to know how you’d tackle the various issues to build a working model turntable in the comments. We’ve seen some serious model railroad builds before around these parts. Video after the break.

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ESP8266 AC Controller Shows Whats Possible

January 11, 2019 by 13 Comments

People often get the impression that home built hardware is destined to have a certain amateurish look or feel to it. It’s as though just because you didn’t buy it in a store, it will look cheap or thrown together. While it’s true a hacked together device could look like it was built from the parts bin (and to be fair, sometimes it is), there are plenty of examples of DIY hardware that could give commercial offerings a run for their money.

A case in point is this fantastic ESP8266 air conditioner controller created by [Sitinut Waisara] (Google Translate). Between the simple yet elegant 3D printed enclosure to the very slick user interface on its OLED screen, this project could easily pass as a commercial device. In fact, we’ve seen commercial offerings that didn’t look half this good, let alone offer the same features for what this cost in components and printer filament. It’s a perfect example of what the modern hacker or maker is capable of with the wide array of tools and components currently available to us.

What’s perhaps the most impressive about this project, especially given how good it looks on the outside, is how little there really is on the inside. Beyond the NodeMCU board and SSD1332 OLED display, the only components inside the device are the three tactile buttons, a photoresistor so it can dim the display’s brightness based on ambient light level, an IR LED so it can send commands to the AC unit, and a handful of passives. The hardware side of this design is so simple that [Sitinut] was able to put the whole thing together on a scrap of perfboard. Not that you’d be able to tell when it gets installed into the 3D printed wall-mount enclosure, complete with printed button caps.

While the hardware side of the project might be rather light, the software is anything but. [Sitinut] really went all-in writing his code for the ESP, adding in the little features like the automatic screen dimming and pulling the current time from NTP that often get overlooked in our rush to get a project out the door. He even included a whole collection of icons to display on the OLED screen, which goes a long way towards selling that professional look. But his effort wasn’t limited to cosmetics or clever features, there was also plenty of work put into decoding the IR signals used to control the AC unit and getting all the features and functions plugged into MQTT.

We’ve seen a number of projects that aimed at dragging an existing HVAC system kicking and screaming onto the “Internet of Things”, some considerably less complex than others. But few have had the level of polish that [Sitinut] has put into his controller, so we take our hats off to him.

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No Moving Parts: Phased Array Antennas Move While Standing Still

January 11, 2019 by 15 Comments

If you watch old science fiction or military movies — or if you were alive back in the 1960s — you probably know the cliche for a radar antenna is a spinning dish. Although the very first radar antennas were made from wire, as radar sets moved higher in frequency, antennas got smaller and rotating them meant you could “look” in different directions. When most people got their TV with an antenna, rotating those were pretty common, too. But these days you don’t see many moving antennas. Why? Because antennas these days move electrically rather than physically using multiple antennas in a phased array. These electronically scanned phased array antennas are the subject of Hunter Scott’s talk at 2018’s Supercon. Didn’t make it? No problem,  you can watch the video below.

While this seems like new technology, it actually dates back to 1905. Karl Braun fed the output of a transmitter to three monopoles set up as a triangle. One antenna had a 90 degree phase shift. The two in-phase antennas caused a stronger signal in one direction, while the out-of-phase antenna canceled most of the signal and the resulting aggregate was a unidirectional beam. By changing the antenna fed with the delay, the beam could rotate in three 120 degree steps.

Today phased arrays are in all sorts of radio equipment from broadcast radio transmitters to WiFi routers and 5G phones. The technique even has uses in optics and acoustics.

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Low Tech High Safety And The NYC Subway System

January 11, 2019 by 29 Comments

The year is 1894. You are designing a train system for a large city. Your boss informs you that the mayor’s office wants assurances that trains can’t have wrecks. The system will start small, but it is going to get big and complex over time with tracks crossing and switching. Remember, it is 1894, so computing and wireless tech are barely science fiction at this point. The answer — at least for the New York City subway system — is a clever system of signals and interlocks that make great use of the technology of the day. Bernard S. Greenberg does a great job of describing the system in great detail.

The subway began operation in 1904, well over 30 years since the above-ground trains began running. A clever system of signals and the tracks themselves worked together with some mechanical devices to make the subway very safe. Even if you tried to run two trains together, the safety systems would prevent it.

On the face of it, the system is very simple. There are lights that show red, yellow, and green. If you drive, you know what these mean. But what’s really interesting is the scheme used at the time to make them light.

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Hackaday Podcast 001: Seriously, We Know What We’re Doing

January 11, 2019 by 12 Comments

First podcast of the new year! Editors Elliot Williams and Mike Szczys look back on the most interesting hacks and can’t-miss articles from the past week (or so). Highlights include abusing IPv6 addresses, underclocking WiFi, taking Wii out of the livingroom, scratch built microphones, computer prophecy coming true, and the end of an automotive era. Full show notes below.

This week, Hackaday Contributor Bob Baddeley came on the show to discuss developments in facial recognition technology and its use in the wild.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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Robot Arm Is A Fast Learner

January 11, 2019 by 3 Comments

Not long ago, machines grew their skills when programmers put their noses to the grindstone and mercilessly attacked those 104 keys. Machine learning is turning some of that around by replacing the typing with humans demonstrating the actions they want the robot to perform. Suddenly, a factory line-worker can be a robot trainer. This is not new, but a robot needs thousands of examples before it is ready to make an attempt. A new paper from researchers at the University of California, Berkeley, are adding the ability to infer so robots can perform after witnessing a task just one time.

A robotic arm with no learning capability can only be told to go to (X,Y,Z), pick up a thing, and drop it off at (X2, Y2, Z2). Many readers have probably done precisely this in school or with a homemade arm. A learning robot generates those coordinates by observing repeated trials and then copies the trainer and saves the keystrokes. This new method can infer that when the trainer picks up a piece of fruit, and drops it in the red bowl, that the robot should make sure the fruit ends up in the red bowl, not just the location where the red bowl was before.

The ability to infer is built from many smaller lessons, like moving to a location, grasping, and releasing and those are trained with regular machine learning, but the inference is the glue that holds it all together. If this sounds like how we teach children or train workers, then you are probably thinking in the right direction.

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Ask Hackaday: Help Me Pick A CAD Package

January 11, 2019 by 143 Comments

Of all the skills that I have picked up over the years as an engineer, there is one that has stayed with me and been a constant over the last three decades. It has helped me work on electronic projects, on furniture, on car parts, robots, and even garments, and it is likely that I will continue using it periodically for the rest of my career. You see, I am a trained PAD expert.

Don't build this, it's fundamentally flawed! Sometimes the front of an envelope is as effective as its back.
Don’t build this, it’s fundamentally flawed! Sometimes the front of an envelope is as effective as its back.

PAD, you ask? OK, it’s an acronym of my own coinage, it stands for Pencil Aided Design, and it refers to the first-year undergraduate course I sat many years ago in which I learned technical drawing to the old British standard BS308. If I’m making something then by far the quickest way for me to visualise its design is to draw it, first a freehand sketch to get a feel of how everything will sit, then a series of isometric component drawings on graph paper with careful attention to dimensions and angles. Well, maybe I lied a little there, the graph paper only comes in when I’m doing something very fancy; the back of an envelope is fine as long as the dimensions on the diagram are correct.

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