Using Motors As Encoders

September 13, 2018 by 8 Comments

If you have a brushless motor, you have some magnets, a bunch of coils arranged in a circle, and theoretically, all the parts you need to build a rotary encoder. A lot of people have used brushless or stepper motors as rotary encoders, but they all seem to do it by using the motor as a generator and looking at the phases and voltages. For their Hackaday Prize project, [besenyeim] is doing it differently: they’re using motors as coupled inductors, and it looks like this is a viable way to turn a motor into an encoder.

The experimental setup for this project is a Blue Pill microcontroller based on the STM32F103. This, combined with a set of half-bridges used to drive the motor, are really the only thing needed to both spin the motor and detect where the motor is. The circuit works by using six digital outputs to drive the high and low sided of the half-bridges, and three analog inputs used as feedback. The resulting waveform graph looks like three weird stairsteps that are out of phase with each other, and with the right processing, that’s enough to detect the position of the motor.

Right now, the project is aiming to send a command over serial to a microcontroller and have the motor spin to a specific position. No, it’s not a completely closed-loop control scheme for turning a motor, but it’s actually not that bad. Future work is going to turn these motors into haptic feedback controllers, although we’re sure there are a few Raspberry Pi robots out there that would love odometry in the motor. You can check out a video of this setup in action below.

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My Career As A Spammer, And Other Stories From The Sneakernet

September 13, 2018 by 12 Comments

A large hacker camp is in microcosm a city, it has all the services you might expect to find in a larger settlement in the wider world. There is a telecommunication system, shops, bars, a health centre, waste disposal services, a power grid, and at some camps, a postal system. At Electromagnetic Field, the postal system was provided by the Sneakernet, a select group of volunteers including your Hackaday scribe under the direction of the postmaster Julius ter Pelkwijk. I even had the fun of delivering some chopped pork and ham. (More on that later.) Continue reading “My Career As A Spammer, And Other Stories From The Sneakernet” →

Packing 10 Into 1: A Square Inch Dekatron Replacement

September 13, 2018 by 11 Comments

One of the things that always attracts our eye in old movies is how many kinds of displays you see on old gear both real and imaginary. Really old stuff usually had meters or circular recorders. But slightly newer movies often had some kind of exotic digital display with Nixes or Numitron tubes. One of the really exotic display devices was a Dekatron. While these are pretty rare, you can make a stand-in using modern LEDs and [Dave] did just that in an entry into our square inch competition.

These were gas-filled tubes with ten positions. You had to reset the tube and then the tube would visibly count pulses providing a visual indicator from zero to nine. Depending on the tube configuration, you could use them to count or to act as a divider. Those with neon fill looked sort of orange, although there were argon-based ones that had a purple glow. You can see what an older version of the board looks like in the video below or skip to the second video if you want to see the real ones in action.

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The DIN Rail And How It Got That Way

September 13, 2018 by 56 Comments

Unless you’ve spent some time in the industrial electrical field, you might be surprised at the degree of integration involved in the various control panels needed to run factories and the like. Look inside any cabinet almost anywhere in the world, and you’ll be greeted by rows of neat plastic terminal blocks, circuit breakers, signal conditioners, and all manner of computing hardware from programmable logic controllers right on to Raspberry Pis and Arduinos.

A well-crafted industrial control panel can truly be a thing of beauty. But behind all the electrical bits in the cabinet, underneath all the neatly routed and clearly labeled wires, there’s a humble strip of metal that stitches it all together: the DIN rail. How did it come to be, and why is it so ubiquitous?

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Researcher uses antenna to clone Tesla key fob

Tesla Opens With Precomputed Key Fob Attack

September 13, 2018 by 43 Comments

This clever precomputation attack was developed by a group of researchers at KU Leuven in Belgium. Unlike previous key fob attacks that we’ve covered in the past which have been essentially relay attacks, this hack precomputes a ton of data, looks for a collision in the dataset, and opens the door. Here’s how it works.

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Wood Shines In This SCARA Robotic Arm Project

September 13, 2018 by 9 Comments

[igarrido] has shared a project that’s been in the works for a long time now; a wooden desktop robotic arm, named Virk I. The wood is Australian Blackwood and looks gorgeous. [igarrido] is clear that it is a side project, but has decided to try producing a small run of eight units to try to gauge interest in the design. He has been busy cutting the parts and assembling in his spare time.

Besides the beautifully finished wood, some of the interesting elements include hollow rotary joints, which mean less cable clutter and a much tidier assembly. 3D printer drivers are a common go-to for CNC designs, and the Virk I is no different. The prototype is driven by a RAMPS 1.4 board, but [igarrido] explains that while this does the job for moving the joints, it’s not ideal. To be truly useful, a driver would need to have SCARA kinematic support, which he says that to his knowledge is something no open source 3D printer driver offers. Without such a driver, the software has no concept of how the joints physically relate to one another, which is needed to make unified and coherent movements. As a result, users must control motors and joints individually, instead of being able to direct the arm as a whole to move to specific coordinates. Still, Virk I might be what’s needed to get that development going. A video of some test movements is embedded below, showing how everything works so far.

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TI(ny) Is A New Take On The TI-99/4A

September 12, 2018 by 23 Comments

Way back in the 1980s, in the heyday of the personal computer revolution, Texas Instruments were one of the major players. The TI-99/4A was one of their more popular machines, selling 2.8 million units after an epic price war with the Commodore VIC-20. However once it had been discontinued, fans were left wanting more from the platform. Years later, that led [Fabrice] to produce the TI(ny), his take on an upgraded, more integrated TI-99/4A (Google Translate link).

Having spent many years working on these machines, [Fabrice] was very familiar with the official TI schematics – regarding both their proper use and their errors, omissions and inaccuracies. With a strong underlying knowledge of what makes a TI-99/4A tick, he set out to pen his own take on an extended model. [Fabrice] rolls in such features as Atari-compatible joystick ports, slot connectors for PeBOX expansion cards, and an RGB video output. It’s then all wrapped up in a very tidy looking case of somewhat unclear construction; it appears to be modified from an existing small computer case, and then refinished to look almost stock.

The best detail, though? It’s all made with components available in 1983! We see a lot of retro builds that are the equivalent of throwing a modern fuel-injected V8 into a vintage muscle car, and they are fantastic – but this is a project that shows us what was possible way back when.

Overall it’s a tidy build that shows what the TI-99/4A could have been if it was given a special edition model at the end of its life. If you’re looking to relive the glory days of the machine yourself, what better way then firing up the best demo on the platform? As the saying goes – Don’t Mess With Texas.

[Thanks to g_alen_e for the tip!]