Civil Defense Disco Ball Rocks Ground Zero

Old Civil Defense survey meters like the V-715 are interesting conversation starters, but of very little practical use today. These devices were intended to be a sort of litmus test that survivors of a nuclear blast could use to determine when it was safe to venture out of their radiation shelter: if the needle on the meter moves, even when it’s on the most sensitive setting, you should probably go back inside. Since [Hamilton Karl] would (hopefully) never need such an indicator, he decided to have a little fun with this Cold War holdover and turn it into a Disco Containment Unit.

Technical details are a little sparse on this one, but we can infer most of it just from the pictures. In place of the original meter [Hamilton] has mounted a tiny mirrored ball inside of a protective cage, which is spun by a geared motor that’s occupying the space that used to be taken up by the ion chamber.

A handful of Adafruit NeoPixel RGB LEDs, an Arduino Nano, and a few switches to control it all round out the functional aspects of the build, and a new disco-themed trefoil replaces the original Civil Defense logo on the side. The project page mentions there’s a piezo buzzer onboard that performs a stirring rendition of “Stayin’ Alive” by the Bee Gees, but alas there’s no video that shows it in action.

Thanks to the rugged construction and built-in handle of these old survey meters, [Hamilton] can now take the party with him wherever he goes. Not that he can really go anywhere with this whole global pandemic hanging over our heads, but at least he’ll be ready when things start trending towards normal. In a way the device’s functionality has now been reversed from how it originally worked, since the meter going wild will now be an indicator that its safe to come out.

While the V-715 isn’t of much use outside of a post-apocalyptic hellscape, the V-700 is actually a proper Geiger counter that’s still useful for surveying or research. An important distinction to remember if you ever get a chance to snap one of them up at a swap meet or flea market. Whenever we can start having those again, anyway.

This Week In Security: Ubiquiti, Nissan, Zyxel, And Dovecot

You may have been one of the many of us who received an email from Ubiquiti this week, recommending a password change. The email stated that there was an unauthorized access of Ubiquiti systems, and while there wasn’t evidence of user data being accessed, there was also not enough evidence to say emphatically that user data was not accessed. Ubiquiti has mentioned that the database that may have been accessed contains a user’s name, email address, hashed password, and optionally the mailing address and phone number.

Depending on how the Ubiquiti authentication system is designed, that hashed password may be enough to log in to someone’s account. In any case, updating your password would invalidate the potentially compromised hash. This event underscores a complaint voiced by Ubiquiti users: Ubiquiti has been making it difficult to administrate hardware without a cloud-enabled account. Continue reading “This Week In Security: Ubiquiti, Nissan, Zyxel, And Dovecot”

Programmable Filament For Multicolor Printing

A recent research paper shows a way to create multicolor 3D prints using a single extruder if you are too lazy to babysit the machine and switch filament. The concept: print your own “programmable” filament that has the right colors in the right place. This is the same idea as manually splicing filament but presumably is more efficient since the process works with one color at a time and doesn’t repeat. In other words, to print the 64 squares of a chessboard you’d swap filament at least 64 times on each layer. Using programmable filament, you’d load one spool, print half of the filament, load another spool, print the other half, and then finally load the newly created filament and print the chessboard. Notice that the first two operations aren’t printing the chessboard. They are printing the spool of filament you feed through on the third pass.

There are machines made to do this, of course, although they generally just splice lengths of filament together for you automatically. Using one filament solves the problems of keeping multiple heads in alignment as well as the added cost and complexity. However, you now have different problems such as the transition between materials and knowing exactly how much material will be at each point in the print.

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A 136 Euro Pulse Jet For Some No-Firework Lockdown Fun

With the aim of reducing virus transmission due to gatherings during the pandemic, the Dutch government have banned fireworks. The people of the Netherlands like their noisy things so we’re told that the ban has been widely flouted, but [Build Comics] are a law-abiding group of workshop tool heroes. For their lockdown noise, they created an entirely-legal pulsejet. The interesting part is that it was made entirely using fairly basic tools on a minimalist budget, with TIG and MIG eschewed in favour of a mundane stick welder.

The form of the pulse jet will probably be familiar as it has been taken from other published designs. A long tube is bent back upon itself with a combustion chamber placed in one of its arms such that the jet forms a resonant chamber that produces continuous pulses of exhaust gas. This one is made from stainless steel tube, and the exhaustive documentation should be worth a look for anyone tempted to make their own. Welding thin sheet with a stick welder requires quite a bit of skill, and in a few places they manage to burn a hole or two. One requires a patch, but the time-honoured technique of running a bead around the edge manages to successfully close another.

Their first attempt to fire it up using a leaf blower with a 3D-printed adapter fails, but following the construction of a more resilient part and a more efficient gas injector the engine starts. It’s then taken out on a farm for some serious noise without too many angry neighbours, as you can see in the video below the break.

The hero tools of Build Comics have appeared here before, most recently with an analogue meter clock.

Continue reading “A 136 Euro Pulse Jet For Some No-Firework Lockdown Fun”