Wonder Woman And The Real Lasso Of Truth

December 18, 2019 by Al Williams 33 Comments

You might think it is strange that a story about technology would start off talking about Wonder Woman. When you realize the technology in question is a lie detector, you might think, “Oh, that’s right. Wonder Woman had the lasso of truth, so this is just a lame association.” You might think that, but you’d be wrong. Turns out, Wonder Woman and real life polygraphs have a much deeper connection; both the polygraph and Wonder Woman share a common creator.

It makes a good story to say that William Marston — an internationally famous psychologist — created the polygraph, but as you might expect it wasn’t the result of a single person’s effort. However, Marston played a key role and also was behind promoting the technology. So, too, even though he is credited as Wonder Woman’s sole creator, the truth is probably a bit more complex.

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Linux Fu: Stupid SSH Tricks

December 17, 2019 by Al Williams 52 Comments

If you connect to remote computers over the Internet, it is a pretty good chance you use some form of SSH or secure shell. On Linux or Unix you’ll use the ssh command. Same goes for Linux-like environments on Windows like Cygwin or WSL. For native Windows, you might be using Putty. In its simplest form, ssh is just a terminal program that talks to a server using an encrypted connection. We think it is very hard to eavesdrop on anyone communicating with a remote computer via ssh.

There are several tricks for using ssh — some are pretty straightforward and some are things you might not think of as being in the domain of a terminal program. You probably know that ssh can copy files securely, and there are easy and hard ways to set up logging in with no password.

However, you can also mount a remote filesystem via ssh (actually, there are several ways to do that). You can use ssh to securely browse the web in your favorite browser, or even use it to tunnel specific traffic by port or even use it as a makeshift VPN. In fact, there’s so much ground to cover that this won’t be the last Linux Fu to talk about ssh. But enough setup, let’s get to the tricks.

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Prusa Dares You To Break Their Latest Printer

December 16, 2019 by Tom Nardi 158 Comments

Two months after its surprise reveal at the 2019 East Coast RepRap Festival, the Prusa Mini has started shipping out to the first wave of early adopters. True to form, with the hardware now officially released to the public, the company has begun the process of releasing the design as open source. In their GitHub repository, owners can already find the KiCad files for the new “Buddy” control board and STLs for the machine’s printable parts.

But even so, not everyone feels that Prusa Research has made the Mini as “open” as its predecessors. Some concerned owners have pointed out that according to the documentation for the Buddy board, they’ll need to physically snap off a section of the PCB so they can flash custom firmware images via Device Firmware Upgrade (DFU) mode. Once this piece of the board has been broken off, which the documentation refers to as the Appendix, Prusa Research will no longer honor any warranty claims for the electronic components of the printer.

For the hardcore tinkerers out there, this news may come as something of a shock. Previous Prusa printers have enjoyed a fairly active firmware development community, and indeed, features that started out as user-developed modifications eventually made their way into the official upstream firmware. What’s more, certain hardware modifications require firmware tweaks to complete.

Prusa Research explains their stance by saying that there’s no way the company can verify the safety of community developed firmware builds. If thermal runaway protections have been disabled or otherwise compromised, the results could be disastrous. We’ve already seen it happen with other printers, so it’s hard to fault them for being cautious here. The company is also quick to point out that the installation of an unofficial firmware has always invalidated the printer’s warranty; physically breaking the board on the Mini is simply meant as a way to ensure the user understands they’re about to leave the beaten path.

How much support is a manufacturer obligated to provide to a user who’s modified their hardware? It’s of course an issue we’ve covered many times before. But here the situation is rather unique, as the user is being told they have to literally break a piece off of their device to unlock certain advanced functionality. If Prusa wanted to prevent users from running alternate firmware entirely they could have done so (or at least tried to), but instead they’ve created a scenario that forces the prospective tinkerer to either back down or fully commit.

So how did Prusa integrate this unusual feature into their brand new 32-bit control board? Perhaps more importantly, how is this going to impact those who want to hack their printers? Let’s find out.

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The Hornsdale Power Reserve And What It Means For Grid Battery Storage

December 16, 2019 by Zoe Skyforest 130 Comments

Renewable energy has long been touted as a major requirement in the fight to stave off the world’s growing climate emergency. Governments have been slow to act, but prices continue to come down and the case for renewables grows stronger by the day.

However, renewables have always struggled around the issue of availability. Solar power only works when the sun is shining, and wind generators only when the wind is blowing. The obvious solution is to create some kind of large, grid-connected battery to store excess energy in off-peak periods, and use it to prop up the grid when renewable outputs are low. These days, that’s actually a viable idea, as South Australia proved in 2017.

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Reflection On A Decade Of Hackerspace Expansion

December 13, 2019 by Jenny List 44 Comments

A few days ago I was invited to a party. Party invites are always good, and if I can make it to this one I’ll definitely go. It’s from a continental European hackerspace, and it’s for their tenth birthday party. As I spent a while checking ferries and flights it struck me, a lot of the spaces in my sphere are about a decade old. I went to London Hackspace’s 10th earlier in the year, and a host of other British hackerspaces aren’t far behind. Something tells me I’ll be knocking back the Club Mate and listening to EDM of some form at more than one such party in the coming year.

For most of the decade since I found the then-recently-established mailing list of my local hackerspace I’ve spent a lot of my time involved in more than one space. I’ve been a hackerspace director, a member, and many roles in between and I’ve seen them in both good times and bad ones. Perhaps it’s time to sit back and take stock of that decade and ask a few questions about hackerspaces. How have they fared, what state are they in now, and where are they going?

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WWII Aircraft Radio Roars To Life: What It Takes To Restore A Piece Of History

December 12, 2019 by Gregory L. Charvat 59 Comments

I’ve been told all my life about old-timey Army/Navy surplus stores where you could buy buckets of FT-243 crystals, radio gear, gas masks, and even a Jeep boxed-up in a big wooden crate. Sadly this is no longer the case. Today surplus stores only have contemporary Chinese-made boots, camping gear, and flashlights. They are bitterly disappointing except for one surplus store that I found while on vacation in the Adirondacks: Patriot of Lake George.

There I found a unicorn of historical significance; an un-modified-since-WW2 surplus CBY-46104 receiver with dynamotor. The date of manufacture was early-war, February 1942. This thing was preserved as good as the day it was removed from its F4F Hellcat. No ham has ever laid a soldering iron or a drill bit to it. Could this unit have seen some action in the south Pacific? Imagine the stories it could tell!

My unconventional restoration of this radio followed strict rules so as to minimize the evidence of repair both inside and out yet make this radio perform again as though it came fresh off the assembly line. Let’s see how I did.

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Linux Fu: Debugging Bash Scripts

December 11, 2019 by Al Williams 23 Comments

A recent post about debugging constructs surprised me. There were quite a few comments about how you didn’t need a debugger, as long as you had printf. For that matter, we’ve all debugged systems where you had nothing but an LED to flash or otherwise turn on to communicate with the user. However, it is hard to deny that a debugger can help with complex code.

To say you only need printf would be like saying you only need machine language. Technically accurate — you can do anything in machine language. But it sure makes things easier to have an assembler or some language to help you work out your problem. If you write a simple bash script, you can use the equivalent to printf — maybe that’s the echo command, although there is usually a printf command on a typical system, if you want to use it. However, there are other things you can do with bash including a pretty cool debugger if you know how to find it.

I assume you already know how to use echo and printf, but let’s dig into how to use trace execution line by line without the need for echo statements on every other line. Along the way, you’ll learn how to get started with the bash debugger.

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