Ben Franklin’s Weak Motor And Other Forgotten Locomotion

October 3, 2017 by 11 Comments

Most of the electric motors we see these days are of the electromagnetic variety, and for good reason: they’re powerful. But there’s a type of motor that was invented before the electromagnetic one, and of which there are many variations. Those are motors that run on high voltage, and the attraction and repulsion of charge, commonly known as electrostatic motors.

Ben Franklin — whose electric experiments are most frequently associated with flying a kite in a thunderstorm — built and tested one such high-voltage motor. It wasn’t very powerful, but was good enough for him to envision using it as a rotisserie hack. Food is a powerful motivator.

What follows is a walk through the development of various types of these motors, from the earliest ion propelled ones to the induction motors which most have never heard of before, even an HV hacker such as yours truly.

Continue reading “Ben Franklin’s Weak Motor And Other Forgotten Locomotion” →

Becdot Teaches With Touch

October 3, 2017 by 5 Comments

Braille is a tactile system of communication, used the world over by those with vision impairment. Like any form of language or writing, it can be difficult to teach and learn. To help solve this, [memoriesforbecca] has developed Becdot as a teaching tool to help children learn Braille.

The device is built around four Braille cells, which were custom-designed for the project. The key was to create a device which could recreate tactile Braille characters at low cost, to enable the device to be cheap enough to be used a children’s toy. The Braille cells are combined with an NFC tag reader. Small objects are given NFC tags which are programmed into the Becdot. When the object is placed onto the reader, the Braille cells spell out the name of the object. Objects can be tagged and the system programmed with a smartphone, so new objects can be added by the end user.

It’s a great way to teach Braille, and an impressive build that keeps costs down low. Details are a little thin on the ground, and we’d love to see more detail on how the actuators on the Braille cells work. We’ve seen similar projects before, like this Hackaday prize entry. Share your theories in the comments below.

A Vintage Morse Key Turned Into USB Keyboard

October 3, 2017 by 23 Comments

Time was when only the cool kids had new-fangled 102-key keyboards with a number pad, arrow keys, and function keys. They were such an improvement over the lame old 86-key layout that nobody would dream of going back. But going all the way back to a one-key keyboard is pretty cool, in the case of this Morse keyer to USB keyboard adapter.

To revive her dad’s old straight key, a sturdy mid-20th century beast from either a military or commercial setup, [Nomblr] started with a proper teardown and cleaning of the brass and Bakelite pounder. A Teensy was chosen for the job of converting Morse to keyboard strokes; careful consideration to the timing of dits and dahs and allowances for contact debouncing were critical to getting the job done. A new wooden base not only provides stability for the key but hides the Teensy and makes for a new presentation. The video below shows it in action; our only complaint is the lack of sidetone to hear the Morse as you pound out that next great novel one click at a time.

Lovingly restored telegraph gear is a bit of a thing around here; we featured this vintage telegraph sounder revived with a Morse code sender not too long ago.

https://www.youtube.com/watch?v=qh_apYcr4xI

[via r/DIY]

Thanks to [Liz] for the tip

Accidental Satellite Hijacks Can Rebroadcast Cell Towers

October 2, 2017 by 21 Comments

A lot of us will use satellite communications without thinking much about the satellite itself. It’s tempting to imagine that up there in orbit is a communications hub and distribution node of breathtaking complexity and ingenuity, but it might come as a surprise to some people that most communications satellites are simple transponders. They listen on one frequency band, and shift what they hear to another upon which they rebroadcast it.

This simplicity is not without weakness, for example the phenomenon of satellite hijacking has a history stretching back decades. In the 1980s for example there were stories abroad of illicit trans-atlantic serial links nestling as unobtrusive single carriers among the broad swathe of a broadcast satellite TX carrier.

Just sometimes, this phenomenon happens unintentionally. Our attention was drawn to a piece by [Harald Welte] on the unintended rebroadcast of GSM base station traffic over a satellite transponder, and of particular interest is the presentation from a conference in 2012 that it links to. The engineers show how they identified their interference as GSM by its timing frames, and then how they narrowed down its source to Nigeria. This didn’t give them the uplink in question though, for that they had to make a downconverter from an LNB, the output of which they coupled to an aged Nokia mobile phone with a wire antenna placed into an RF connector. The Nokia was able to decode the cell tower identification data, allowing them to home in on the culprit.

There was no fault on the part of the GSM operator, instead an unterminated port on the uplink equipment was enough to pick up the GSM signal and introduce it into the transponder as a parasitic signal for the whole of Europe and Africa to hear. Meanwhile the tale of how the engineers identified it contains enough detective work and outright hardware hacking that we’re sure the Hackaday readership will find it of interest.

If satellite hacks interest you, how about reading our thread of posts on the recapture of ISEE-3, or maybe you’d like to listen for a lost satellite from the 1960s.

Thanks [Kia] for the tip.

Understanding Floating Point Numbers

October 2, 2017 by 67 Comments

People learn in different ways, but sometimes the establishment fixates on explaining a concept in one way. If that’s not your way you might be out of luck. If you have trouble internalizing floating point number representations, the Internet is your friend. [Fabian Sanglard] (author of Game Engine Black Book: Wolfenstein 3D) didn’t like the traditional presentation of floating point numbers, so he decided to explain them a different way.

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Friction Differential Drive Is A Laser-Cut Triumph

October 2, 2017 by 6 Comments

Here on Hackaday, too often do we turn our heads and gaze at the novelty of 3D printing functional devices. It’s easy to forget that other techniques for assembling functional prototypes exist. Here, [Reuben] nails the aspect of functional prototyping with the laser cutter with a real-world application: a roll-pitch friction differential drive built from just off-the shelf and laser-cut parts!

The centerpiece is held together with friction, where both the order of assembly and the slight wedged edge made from the laser cutter kerf keeps the components from falling apart. Pulleys transfer motion from the would-be motor mounts, where the belts are actually tensioned with a roller bearing mechanism that’s pushed into position. Finally, the friction drive itself is made from roller-blade wheels, where the torque transferred to the plate is driven by just how tightly the top screw is tightened onto the wheels. We’d say that [Reuben] is pushing boundaries with this build–but that’s not true. Rather, he’s using a series of repeatable motifs together to assemble a both beautiful and complex working mechanism.

This design is an old-school wonder from 2012 uncovered from a former Stanford course. The legendary CS235 aimed to teach “unmechanically-minded” roboticists how to build a host of mechanisms in the same spirit as MIT’s How-to-make-almost-Anything class. While CS235 doesn’t exist anymore, don’t fret. [Reuben] kindly posted his best lectures online for the world to enjoy.

Continue reading “Friction Differential Drive Is A Laser-Cut Triumph” →

A Bit Of Mainstream Coverage For The Right To Repair

October 2, 2017 by 80 Comments

Here at Hackaday, we write for a community of readers who are inquisitive about the technology surrounding them. You wouldn’t be here if you had never taken a screwdriver to a piece of equipment to see what makes it work. We know that as well as delving inside and modifying devices being core to the hardware hacker mindset, so is repairing. If something we own breaks, we try to work out why it broke, and what we can do to fix it.

Unfortunately, we live in an age in which fixing the things we own is becoming ever harder. Manufacturers either want to sell us now hardware rather than see us repair what breaks, or wish to exercise total control over the maintenance of their products. They make them physically impossible to repair, for example by gluing together a cellphone, or they lock down easy-to-repair items with restrictive software, for example tractors upon which every replacement part must be logged on a central computer.

This has been a huge issue in our community for a long time now, but to the Man In The Street it barely matters. To the people who matter, those who could change or influence the situation, it’s not even on the radar. Which makes a piece in the British high-end weekly newspaper The Economist particularly interesting. Entitled “A ‘right to repair’ movement tools up“, it lays out the issues and introduces the Repair Association, a political lobby group that campaigns for “Right to repair” laws in the individual states of the USA.

You might now be asking why this is important, why are we telling you something you already know? The answer lies in the publication in which it appears. The Economist is aimed at politicians and influencers worldwide. In other words, when we here at Hackaday talk about the right to repair, we’re preaching to the choir. When they do it at the Economist, they’re preaching to the crowd who can make a difference. And that’s important.

You may recognise the tractors mentioned earlier as the iconic green-and-yellow John Deere. We’ve written about their DRM before.

Neon sign, All Electronics Service, Portland, Visitor7 [CC BY-SA 3.0].