Linux Fu: A Little Help For Bash

February 2, 2018 by Al Williams 23 Comments

It isn’t uncommon these days for a programmer’s editor to offer you help about what you are typing, ranging from a pop up with choices to a full-blown code template. If you have written a million lines of code in the language, this might even annoy you. However, if you use it only occasionally, these can be very helpful. I’ve used Unix and Linux for many years, but I realize that there are people who don’t use it every day. With the Raspberry Pi, Linux servers, and Windows 10 having a bash shell, there are more people using a shell “every once in a while” than ever before. Could you use a little help? If so, you might try bashelp: a little something I put together while writing about bash completion.

There’s good news and bad news. The good news is that Unix has a built-in help command — man — and has for some time. The bad news is that you need to stop what you are typing and enter a man command to use it. Man, by the way, is short for manual.

There are GUI front-ends to man (like yelp, on the left) and you can even use a web browser locally or remotely. However, none of these are connected to what you are typing. You have to move to another window, enter your search term, then go back to your typing. That got me to thinking about how to get a sort of context-sensitive inline help for bash.

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Start Your Apollo Collection With An Open Source DSKY

February 2, 2018 by Dan Maloney 20 Comments

Given that there have been only six manned moon landings, and that almost all of the hardware that started on the launch pad was discarded along the way, getting your hands on flown hardware is not generally the business of mere mortals. Such artifacts are mostly in museums or in the hands of very rich private collectors. Enthusiasts have to settle for replicas like this open source Apollo Guidance Computer DSKY.

The DSKY, or Display and Keyboard, was the user interface for the Apollo Guidance Computer, that marvel of 1960s computer engineering that was purpose-built to control the guidance and navigation of the Command and Lunar Excursion modules. [ST-Geotronics] has made a decent replica of the DSKY using 3D-printed parts for the housing and bezel. There’s a custom PCB inside that houses a matrix of Neopixels for the indicator light panel and seven-segment LEDs for the numeric displays. Sadly but understandably, the original electroluminescent display could not be reproduced, but luckily [Fran Blanche] is working on just that project these days. The three-segment displays for the plus and minus signs in the numeric displays proved impossible to source commercially, so the team had to roll their own for that authentic look. With laser cut and engraved overlays for the displays and keycaps, the look is very realistic, and the software even implements a few AGC-like functions.

We like this a lot, although we could do without the sound clips, inspirational though Kennedy’s speech was. Everything is open source so you can roll your own, or you can buy parts or even a complete kit too.

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What Are Those Hieroglyphics On Your Laptop Charger?

February 2, 2018 by Bob Baddeley 93 Comments

Look on the back of your laptop charger and you’ll find a mess of symbols and numbers. We’d bet you’ve looked at them before and gleaned little or no understanding from what they’re telling you.

These symbols are as complicated as the label on the tag of your shirt that have never taught you anything about doing laundry. They’re the marks of standardization and bureaucracy, and dozens of countries basking in the glow of money made from issuing certificates.

The switching power supply is the foundation of many household electronics — obviously not just laptops — and thus they’re a necessity worldwide. If you can make a power supply that’s certified in most countries, your market is enormous and you only have to make a single device, possibly with an interchangeable AC cord for different plug types. And of course, symbols that have meaning in just about any jurisdiction.

In short, these symbols tell you everything important about your power supply. Here’s what they mean.

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Flexiphone Rises From The Ashes Of Broken Instruments

February 2, 2018 by Adam Fabio 7 Comments

The mechanics of an old Rhodes Piano, and a set of chromatic saucer bells rescued from a reed organ. What do these two things have to do with each other? If you’re [Measured Workshop], they are the makings of a new instrument. The Flexiphone is a transposable instrument with a piano keyboard and interchangeable sound source.

The Rhodes is a great stage instrument. Unlike a piano with strings, it uses tines mounted above the key mechanism. It is also relatively compact for an analog instrument. This made it perfect as a donor for the Flexiphone’s keyboard. [Measured Workshop] cut they mechanism down to 30 keys, just under 2 octaves. The key mechanism was also cleaned up and restored with new felt.

The sounding portion of the Flexiphone is a set of chromatic saucer bells. The bells are mounted on a felt covered threaded rod, which itself sits in a wood frame. The bell frame sits on top of the base in one of three slots. Each slot is a halftone transposed from the last. Simply moving the bells allows the player to transpose the entire instrument. The bells and their rod frame can also be completely removed and replaced with any other sound source.

The Flexiphone sounds great — sometimes. As [Measured Workshop] says, bells contain many harmonics. playing single or double notes sounds rather sweet, but chords can sometimes become a shrill assault on the ears. Still, it’s an awesome hack with plenty of potential for future mods.

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Keeping Magnetized Marbles From Stopping The Music

February 2, 2018 by Dan Maloney 18 Comments

Take a couple of thousand steel balls, add a large wooden gear with neodymium magnets embedded in it, and what do you get? Either the beginnings of a wonderful kinetic music machine, or a mess of balls all stuck together and clogging up the works.

The latter was the case for [Martin], and he needed to find a way to demagnetize steel balls in a continuous process if his “Marble Machine X” were to see the light of day. You may recall [Martin] as a member of the band Wintergatan and the inventor of the original Marble Machine, a remarkable one-man band that makes music by dropping steel balls on various instruments. As fabulous a contraption as the original Marble Machine was, it was strictly a studio instrument, too fragile for touring.

Marble Machine X is a complete reimagining of the original, intended to be robust enough to go on a world tour. [Martin] completely redesigned the lift mechanism, using magnets to grip the balls from the return bin and feed them up to a complicated divider. But during the lift, the balls became magnetized enough to stick together and no longer roll into the divider. The video below shows [Martin]’s solution: a degausser using magnets of alternating polarity spinning slowly under the sticky marbles. As a side note, it’s interesting and entertaining to watch a musician procrastinate while debugging a mechanical problem.

We can’t wait to see Marble Machine X in action, but until it’s done we’ll just settle for [Martin]’s other musical hacks, like his paper-tape programmed music box or this mashup of a synthesizer and a violin.

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A Grandfather Clock BarBot

February 1, 2018 by James Hobson 10 Comments

As the saying goes, it’s five o’clock somewhere; when the clock finally strikes the hour, that same clock can pour you a drink thanks to redditor [Diggedypomme].

This bar-clock can dispense beverages with up to four different spirits and four mixers, and takes orders over voice, keyboard, or web-controls. A belt-driven drink loading platform pushes out through a spring-loaded door and once the vessel is in place and the order received, peristaltic pumps dispense the spirits while servos open taps for the mixers — a far easier method to administer the often carbonated liquids. A Raspberry Pi acts as this old-timer’s brain, an Arduino controls the lights, and a HAT to controls the servos. Here’s a more in-depth tour of what’s going on behind the bar, but check out the video after the break for a full run through of a few drink orders!

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Three Wires = One Motor

February 1, 2018 by James Hobson 24 Comments

Here’s a quick build to show off fundamentals of electric current to new makers — or a cool party trick that might earn you a buck. [Jay] from the [Plasma Channel] shows off how you can make a simple motor with only three pieces of enameled wire in under five minutes.

Start with a roll of 26-guage — or thicker — magnet wire, and a pair of scissors or knife. For the base, wrap fifteen to twenty turns of wire around any spherical object about one and a half inches in diameter, leaving a few inches extra on both ends. Wrap those ends around your coil a few tines to secure it and straighten out the excess length — one will act as a support and the other will connect to your power source. Another piece of wire — similarly wrapped around the base coil — acts as the other support and the other terminal. Scrape off the wire coating from one side on both support wires and curl them into small loops. Halfway done!

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