How Does A Circuit Breaker Break?

January 26, 2021 by 32 Comments

Even if you aren’t an electronics person, you probably have a working knowledge of circuit breakers. When the lights go out, you find the circuit breaker and flip it back to the on position. Most people understand, too, that the breaker will trip if you overload the circuit with too many things plugged in or with an accidental short circuit. But how does this common device actually work? Keep in mind, circuit breakers need to be super reliable and have been around long enough that you can imagine they are pretty low tech. [Learn Engineering] has a very clear video about what goes on inside a circuit breaker that’s worth the eight minutes to watch. You can see the video below.

The handle is a mechanical engineering marvel, using two springs and a special design so that even a tiny force will cause it to snap to the off position. That takes care of a human tripping it. However, you have two other cases where you want to turn it off: overload and short circuit.

Continue reading “How Does A Circuit Breaker Break?” →

Cable Mechanism Maths: Designing Against The Capstan Equation

January 26, 2021 by 20 Comments

I fell in love with cable driven mechanisms a few years ago and put together some of my first mechanical tentacles to celebrate. But only after playing with them did I start to understand the principles that made them work. Today I want to share one of the most important equations to keep in mind when designing any device that involves cables, the capstan equation. Let some caffeine kick in and stick with me over the next few minutes to get a sense of how it works, how it affects the overall friction in your system, and how you can put it to work for you in special cases.

A Quick Refresher: Push-Pull Cable Driven Mechanisms

But first: just what exactly are cable driven mechanisms? It turns out that this term refers to a huge class of mechanisms, so we’ll limit our scope just to push-pull cable actuation systems.

These are devices where cables are used as actuators. By sending these cables through a flexible conduit, they serve a similar function to the tendons in our body that actuate our fingers. When designing these, we generally assume that the cables are both flexible and do not stretch when put in tension. Continue reading “Cable Mechanism Maths: Designing Against The Capstan Equation” →

Linear Pong Loses A Dimension But Remains Challenging

January 26, 2021 by 15 Comments

When Pong hit the scene in the early 70s, there was something about the simplicity of the 2D monochrome tennis game that made it engaging enough that enthusiastic proto-gamers shorted-out machines by stuffing their coin boxes to overflowing.  But even with the simplicity of Pong’s 2D gameplay, the question becomes: could it by made simpler and still be playable?

Surprisingly, if this one-dimensional Pong game is any indication, it actually seems like it can. Where the original Pong made you line up your paddle with the incoming ball, with the main variable being the angle of the carom from your opponent, [mircemk]’s version, limited to a linear game field, makes the ball’s speed the variable. Players take control of the game with a pair of buttons at the far ends of a 60-LED strip of WS2812s. The ball travels back and forth along the strip, bouncing off a player’s paddle only if they push their button at the exact moment the ball arrives. Each reflection back to the opponent occurs at a random speed, making it hard to get into a rhythm. To add some variety, each player has a “Boost” button to put a little spice on their shot, and score is kept by LEDs in the center of the play field. Video of the game play plus build info is below the break.

With just a Neopixel strip, an Arduino Nano, and a small handful of common parts, it should be easy enough to whip up your own copy of this surprisingly engaging game. But if the 2D-version is still more your speed, maybe you should check out the story of its inventor, [Ted Dabney]. Or, perhaps building a clock that plays Pong with itself to idle the days away is more your speed.

Continue reading “Linear Pong Loses A Dimension But Remains Challenging” →

What’s The Deal With Chromium On Linux? Google At Odds With Package Maintainers

January 26, 2021 by 152 Comments

Linux users are more likely than most to be familiar with Chromium, Google’s the free and open source web project that serves as the basis for their wildly popular Chrome. Since the project’s inception over a decade ago, users have been able to compile the BSD licensed code into a browser that’s almost the same as the closed-source Chrome. As such, most distributions offer their own package for the browser and some even include it in the base install. Unfortunately, that may be changing soon.

A post made earlier this month to the official Chromium Blog explained that an audit had determined “third-party Chromium based browsers” were using APIs that were intended only for Google’s internal use. In response, any browser attempting to access features such as Chrome Sync with an unofficial API key would be prevented from doing so after March 15th.

To the average Chromium user, this doesn’t sound like much of a problem. In fact, you might even assume it doesn’t apply to you. The language used in the post makes it sound like Google is referring to browsers which are spun off of the Chromium codebase, and at least in part, they are. But the search giant is also using this opportunity to codify their belief that the only official Chromium builds are the ones that they provide themselves. With that simple change, anyone using a distribution-specific build of Chromium just became persona non grata.

Unhappy with the idea of giving users a semi-functional browser, the Chromium maintainers for several distributions such as Arch Linux and Fedora have said they’re considering pulling the package from their respective repositories altogether. With a Google representative confirming the change is coming regardless of community feedback, it seems likely more distributions will follow suit.

Continue reading “What’s The Deal With Chromium On Linux? Google At Odds With Package Maintainers” →

3D Printed Box Gets Bigger

January 26, 2021 by 10 Comments

If you ever watched Dr. Who, you probably know that the TARDIS looked like a police call box on the outside, but was very large on the inside. When asked, the Doctor had some explanation of how something can look small when it is far away and large when it is close up, which never made much sense. However, [iQLess] has been 3D printing boxes in a small area, that fold out to be much larger boxes. (Video, embedded below.) The design comes from someone called [Cisco] who has a lot of interesting print in place designs.

You can find the design on the Prusa site or Thingiverse. The boxes do take a while to print, according to the video below. What was interesting to us, though, is that you should be able to print a design like this to create a box larger than your printer.

Continue reading “3D Printed Box Gets Bigger” →

Custom Bite Sensor Replaces Keyboard Expression Pedal

January 26, 2021 by 2 Comments

Sometimes, standard hardware won’t do when it comes to the differently abled. [Ben Krasnow] found himself recently working on a project for a musician who doesn’t have the use of his legs, and thus needed to create a new interface to replace a standard expression pedal.

[Ben] is a big fan of the build first method of working, and demonstrates why it works well. In this case, the first attempt involved a pneumatic design, where the user would bite down on an air bladder that actuated a remotely-located potentiometer via a tube and bellows. However, while this design worked, the tactile feedback was poor. This led to experimentation with mechanical designs, with an initial attempt involving a 3D printed mechanism and a rotary pot. This was better, but still had problems with damage from teeth and poor feel .The final design is essentially an analog button, built with fabric-impregnated silicone for wear resistance and using a linear pot for smooth feedback.

The final design is impressively tidy, and [Ben] notes that while it looks simple, it was only arrived at by trying plenty of worse solutions first. We’ve seen other work done in the gaming world too; recently, modular controllers have come into vogue to serve a wide variety of needs. Video after the break.

Continue reading “Custom Bite Sensor Replaces Keyboard Expression Pedal” →

Steam Engine Replica From LEGO

January 25, 2021 by 25 Comments

If engineering choices a hundred years ago had been only slightly different, we could have ended up in a world full of steam engines rather than internal combustion engines. For now, though, steam engines are limited to a few niche applications and, of course, models built by enthusiasts. This one for example is built entirely in LEGO as a scale replica of a steam engine originally produced in 1907.

The model is based on a 2500 horsepower triple-expansion four-cylinder engine that was actually in use during the first half of the 20th century. Since the model is built using nothing but LEGO (and a few rubber bands) it operates using a vacuum rather than with working steam, but the principle is essentially the same. It also includes Corliss valves, a technology from c.1850 that used rotating valves and improved steam engine efficiency dramatically for the time.

This build is an impressive recreation of the original machine, and can even run at extremely slow speeds thanks to a working valve on the top,  allowing its operation to be viewed in detail. Maximum speed is about 80 rpm, very close to the original machine’s 68 rpm operational speed. If you’d prefer your steam engines to have real-world applications, though, make sure to check out this steam-powered lawnmower.

Thanks to [Hari] for the tip!

Continue reading “Steam Engine Replica From LEGO” →