Rebuilding A $700k Refrigerator

February 21, 2024 by Bryan Cockfield 20 Comments

When cleaning out basements, garages, or storage units we often come across things long forgotten. Old clothes, toys, maybe a piece of exercise equipment, or even an old piece of furniture. [Ben] and [Hugh] were in a similar situation cleaning out an unused lab at the University of California Santa Barbara and happened upon an old refrigerator. This wasn’t just a mini fridge left over from a college dorm, though. This is a dilution refrigerator which is capable of cooling things down to near absolute zero, and these scientists are trying to get it to its former working state.

The pair are hoping to restore the equipment to perform dark matter experiments, but the refrigerator hasn’t been in use since about 2016 (and doesn’t have an instruction manual), which is a long time for a piece of specialty scientific equipment to be collecting dust. The first step is to remove wiring and clean it of all the grime it’s accumulated in the last decade. After that, the pair work to reassemble the layers of insulation around the main cooling plate and then hook up a vacuum pump to the device which also needed some repair work.

The critical step at this point is to evacuate the refrigerant lines so they can be filled with expensive Helium-3 and Helium-4. The problem is that there’s still some of this valuable gas in the lines that needs to be recovered, but the risk is that if any air gets into the cold section of the refrigerator it will freeze and clog the whole system. After chasing some other electrical and vacuum gremlins and discovering a manual from a similar refrigerator, they eventually get it up and running and ready for new scientific experiments. While most of us won’t discover a fridge like this cleaning out our attics, this refrigerator powered by rubber bands is a little more accessible to the rest of us.

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FLOSS Weekly Episode 770: 10% More Internet

February 14, 2024 by Jonathan Bennett 7 Comments

This week, Jonathan Bennett and Doc Searls talk with David Taht about the state of the Internet and, specifically, IPv4 exhaustion. We’re running out of IPv4 addresses! But we’ve been running out for something like ten years now. What gives? And why are nearly 20% of the world’s IPv4 addresses sitting unused? David has a hack that would give the world 10% more Internet, but Amazon might have something to say about it.

There’s even more, like Kessler Syndrome, some musing on what the Interplanetary Internet will look like, the worth of real paper books, and a long-term bet for some IPv4 addresses to come to fruition in 2038.

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EasyThreed K9: The Value In A €72 AliExpress FDM 3D Printer

February 12, 2024 by Maya Posch 28 Comments

The hot end of the EasyThreed K9 is actually pretty nifty. (Credit: [Thomas Sanladerer])

Recently, [Thomas Sanladerer] bought an EasyThreed K9 off AliExpress for a mere €72, netting him an FDM printer with a 10 x 10 x 10 cm build volume. The build plate is unheated, with optional upgrade, and there is no display to interact with the device: just a big multi-function ‘play’ button and five smaller buttons that direct the print head to preset locations above the build plate to allow for build plate leveling using the knobs on each corner. There’s also a ‘home’ button on the back for homing the print head, which pretty much completes the user interface. As the printer comes in a rather small box, the first step is to assemble the parts into something resembling a 3D printer.

What follows is both a mixture of wonder and horror, as the plastic build quality is everything but convincing, while at the same time, the self-contained nature of each of the three axes of the cantilevered design makes for very easy assembly. The print head has a nifty flip-up cover for easy access to the hot end, which makes the best of the anemic 24-watt power supply for the entire printer. A cooling fan with an air duct even provides part cooling, making this print head a contender for the ‘cheap but not terrible’ category. You can check out his full video review below.

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Recreating The Quadrophonic Sound Of The 70s

February 6, 2024 by Bryan Cockfield 23 Comments

For plenty of media center PCs, home theaters, and people with a simple TV and a decent audio system, the standard speaker setup now is 5.1 surround sound. Left and right speakers in the front and back, with a center speaker and a subwoofer. But the 5.1 setup wasn’t always the standard (and still isn’t the only standard); after stereo was adopted mid-century, audio engineers wanted more than just two channels and briefly attempted a four-channel system called quadrophonic sound. There’s still some media from the 70s that can be found that is built for this system, such as [Alan]’s collection of 8-track tapes. These tapes are getting along in years, so he built a quadrophonic 8-track replica to keep the experience alive.

The first thing needed for a replica system like this is digital quadrophonic audio files themselves. Since the format died in the late 70s, there’s not a lot available in modern times so [Alan] has a dedicated 8-track player connected to a four-channel audio-to-USB device to digitize his own collection of quadrophonic 8-track tapes. This process is destructive for the decades-old tapes so it is very much necessary.

With the audio files captured, he now needs something to play them back with. A Raspberry Pi is put to the task, but it needs a special sound card in order to play back the four channels simultaneously. To preserve the feel of an antique 8-track player he’s cannibalized parts from three broken players to keep the cassette loading mechanism and track indicator display along with four VU meters for each of the channels. A QR code reader inside the device reads a QR code on the replica 8-track cassettes when they are inserted which prompts the Pi to play the correct audio file, and a series of buttons along with a screen on the front can be used to fast forward, rewind and pause. A solenoid inside the device preserves the “clunk” sound typical of real 8-track players.

As a replica, this player goes to great lengths to preserve the essence of not only the 8-track era, but the brief quadrophonic frenzy of the early and mid 70s. There’s not a lot of activity around quadrophonic sound anymore, but 8-tracks are popular targets for builds and restorations, and a few that go beyond audio including this project that uses one for computer memory instead.

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Fixing A Malfunctioning Keithley Model 179 Digital Multimeter

February 2, 2024 by Maya Posch 7 Comments

Inspired by electronics repair videos on YouTube, [Steven Leibson] recently found himself hunting down something to fix on eBay. This ‘something’ ended up being a certified classic: a Keithley Model 179 digital multimeter from 1978. Listed as non-functional, the unit arrived at his door for less than $50. There weren’t any exciting pops or smoke when he powered it on, but the display seemed to be showing nothing but random nonsense.

The Keithley Model 179 multimeter has a convenient calibration sequence printed on its electrostatic shield cover and a deadly exposed ac line fuse in the upper left part of the photo. (Image credit: Steven Leibson) — The meter has a convenient calibration sequence printed on its electrostatic shield cover and a deadly exposed AC line fuse in the upper left part of the photo.

Ultimately reviving this little piece of history was quite simple, with the main issue turning out to be a dodgy inter-board connector between the main and display boards. After admiring an old repair attempt made on the component, he removed both the male and female connectors, replacing them with new ones.

This uncovered issues with the PCB, as the FR4 material and the traces on it had begun to delaminate, probably due to the old adhesive giving up due to age. With pretty low trace density this wasn’t anything that a bit of care couldn’t work around, fortunately.

Before finding this dodgy connector, [Steven] first tried to clean the front mechanical connectors, which took multiple sessions. This was followed up by oiling the mechanism. With the connector fixed and some cleaning, the meter’s display now read correctly. It still has some issues with starting up though, which [Steven] reckons are due to the old capacitors in the device.

Presumably some recapping will round off this fun device revival experience, but for the time being a Keithley Model 179 has been saved from e-waste, to inspire generations to come.

FLOSS Weekly Episode 768: Open Source Radio

January 31, 2024 by Jonathan Bennett 8 Comments

This week Jonathan Bennett and Doc Searls talk with Tony Zeoli about Netmix and the Radio Station WordPress plugin. The story starts with the Netmix startup, one of the first places doing Internet music in the 1990s. That business did well enough to get bought out just before the Dot Com bubble burst in 2000. Today, Tony runs the Radio Station plugin, which is all about putting a station’s show schedule on a WordPress site.

In the process, the trio covers Internet radio history, the licensing complications around radio and streaming, the state of local radio, and more. Is there a long term future for radio? Does Creative Commons solve the licensing mess? Is AI going to start eating radio, too? All this and more!

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