That Elusive Valve Amp Sound, For Not A Lot! (There Has To Be A Catch)

September 1, 2020 by Jenny List 53 Comments

It was with considerable interest last month that I set out to track down where in the world there are still factories making tubes. My research found them in Slovakia, Russia, and China, and it’s fairly certain I didn’t find all the manufacturers by any means. There appeared to be a whole class of mundane tubes still in production that weren’t to be found on their glossy websites. A glance at any outlet through which Chinese modules can be bought will find this type of tube in small audio amplifier projects, and some of them can be astoundingly cheap. When faced with cheap electronics of course I’m tempted to buy some, so I parted with about £10 ($12.50) and bought myself a kit for a two-tube device described as a stereo preamplifier and headphone amplifier.

An Unusual Tube Choice For Audio

What I received for my tenner was a press-seal bag with a PCB and a pile of components, and not much else. No instructions, which would have been worrisome were the board not clearly marked with the value of each component. The circuit was on the vendor’s website and is so commonly used for these sort of kits that it can be found all over the web — a very conventional twin common-cathode amplifier using a pair of 6J1 miniature pentodes, and powered through a +25 V and -25 V supply derived from a 12 VAC input via a voltage multiplier and regulator circuit. It has a volume potentiometer, two sets of phono sockets for input and output, and the slightly naff addition of a blue LED beneath each tube socket to impart a blue glow. I think I’ll pass on that component.

The 6J1 seems to be ubiquitous throughout the Chinese kits, which is surprising when you understand that it’s not an audio tube at all. Instead it’s a small-signal VHF amplifier, a rough equivalent of the European EF95, and would be much more at home in an FM radio receiver or turret TV tuner from the 1950s. I can only assume that somewhere in China there’s a tube factory tooled up for radio tube production that is targeting this market, because another tube you will see in audio power amplifier kits is the FU32 or QQV03-20 in European parlance, a large power beam tetrode that might have been found in a 1950s military radio transmitter. Still just as if you were to use an RF transistor in an audio circuit it would give good account of itself, so it is with an RF tube. There is no reason a 6J1 won’t do an acceptable job in a circuit such as this one.

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Start Me Up: What Has The Windows 95 Desktop Given Us 25 Years Later?

August 31, 2020 by Jenny List 104 Comments

We’ve had something of an anniversary of late, and it’s one that will no doubt elicit a variety of reactions from our community. It’s now 25 years ago that Windows 95 was launched, the operating system that gave the majority of 1990s PC users their first taste of a desktop-based GUI and a 32-bit operating system.

To the strains of the Rolling Stones’ Start me up, Microsoft execs including Bill Gates himself jubilantly danced on stage at the launch of what was probably to become the company’s defining product, perhaps oblivious to the line “You make a grown man cry” which maybe unwittingly strayed close to the user experience when faced with some of the software’s shortcomings.

Its security may seem laughable by the standards of today and the uneasy marriage of 16-bit DOS underpinning a 32-bit Windows operating system was clunky even in its heyday, but perhaps now is the best time to evaluate it unclouded by technical prejudice. What can we see of Windows 95 in the operating systems we use today, and thus from that can we ask the question: What did Windows 95 get right? Continue reading “Start Me Up: What Has The Windows 95 Desktop Given Us 25 Years Later?” →

Hackaday Links: August 30, 2020

August 30, 2020 by Dan Maloney 12 Comments

Tech history is rife with examples of bizarre product demos, but we’ve got to think that Elon Musk’s Neuralink demo this week will have to rank up there with the weirdest of them. Elon’s job here was to sell the proposition that having a quarter-sized plug removed from your skull by a surgical robot and having it plunge 1,024 tiny wires into your gray matter will be totally normal and something that all the cool kids will be doing someday. We watched the 14-minute supercut of the demo, which went on for considerably longer than that due to the realities of pig wrangling, and we remain unsold on the technology. Elon selling it as “a Fitbit in your skull, with tiny wires” probably didn’t help, nor did the somewhat terrifying appearance of the surgical robot needed to do the job. On the other hand, Gertrude the Bionic Pig seemed none the worse for her implant, which was reportedly wired to her snout and sending data wirelessly. The demonstration of reading joint positions directly from the brain was honestly pretty neat. If you want to dive deeper into Neuralink, check out Maya’s great article that separates fact from science fiction.

Jerry Carr, NASA astronaut and commander of the third and final crewed Skylab mission, passed away this week at the age of 88. Carr’s Skylab 4 mission was record-breaking in 1974, with the three astronauts living and working in the orbiting workshop for 84 days. The mission contributed a vast amount of information on space medicine and the human factors of long-duration spaceflight. Carr retired from NASA in 1977 and had a long career as an engineer and entrepreneur. It’s sad to lose yet another of the dwindling number of heroes remaining from NASA’s manned-flight heyday.

Speaking of spaceflight, the closest most of us DIYers can get to space is likely courtesy of a helium-filled balloon. If you’ve ever considered sending something — or someone — aloft, you’ll find this helium balloon calculator an invaluable tool. Just plug in the weight of your payload, select from a few common balloon sizes, and the calculator will tell you how many you need and how much gas it will take to fill them. It’s got a second section that tells you how many more balloons it’ll take to get to a certain altitude, should merely getting off the ground not be enough for you.

If 2020 has proven anything, it’s that time is, at best, a negotiable concept. Improbably, September is only a day away, after an August that somehow took forever to go by in the blink of an eye. With that in mind, October is OSHWA’s Open Hardware Month, with this year’s theme being “Label and Certify”. We’re a little bit in love with the Open Hardware Facts generator, which takes your open-source hardware, software, and documentation license and generates a USDA “Nutrition Facts”-style label for your product. They’ve also added tools to make it easier to get OSHWA certification for your project.

And finally, what would it be like to pilot a giant exoskeleton? Like, a 9,000 pound (4,100 kg), quadrupedal all-terrain beast of a mech? Turns out you can (theoretically) find out for yourself courtesy of Furrion Exo-Bionics and their monster mech, dubbed Prosthesis. The machine has been in development for a long time, with the vision of turning mech racing into the next big thing in sports entertainment. Their Alpha Mech Pilot Training Program will allow mere mortals to learn how to pilot Prosthesis at the company’s proving ground in British Columbia. Details are sparse, so caveat emptor, but it sure looks like fun.

Impossibilities And 3D Printing

August 29, 2020 by Elliot Williams 43 Comments

This week our own [Donald Papp] wrote a thought-provoking piece on buying and selling 3D-printer models. His basic point: if you don’t know what you’re getting until you’ve purchased it, and there’s no refund policy, how can you tell if your money is being well spent? It’s a serious problem for these nascent markets, because when customers aren’t satisfied they won’t come back.

It got me thinking about my own experience, albeit with all of the free 3D models out there. They are a supremely mixed bag, and even though you’re not paying for the model, you’re paying in printing time, filament, and effort. It pays to be choosy, and all of [Donald]’s suggestions hold in the “free” market as well.

Only download models that have been printed at least once, have decent documentation about things like layer height, filament type, and support, and to the best of your abilities, be critical about the ability to fabricate the part at all. Fused-deposition printers can only print on top of previous layers, and have a distinct grain, so you need to watch out for overhangs and print orientation. With resin printers, you need to be careful about trapped volumes of uncured resin. You want to be sure that the modeler at least took these considerations into account.

But when your parts have strength requirements, fits, and tolerances, it gets even worse. There’s almost no way a designer can know if you’re overextruding on your first layers or not. Different slicers handle corners differently, making inner surfaces shrink to varying degrees. How can the designer work around your particular situation?

My personal answer is open-source. Whenever possible, I prefer models in OpenSCAD. If you download an STL with ten M8 bolt holes, you could widen them all in a modeling program, but if you’ve got the source code, it’s as easy as changing a single variable. Using the source plays to the customizability of 3D printing, which is perhaps its strongest suit, in my mind. Nobody knows exactly how thick your desk is but you, after all. Making a headphone hook that’s customizable is key.

So even if the markets for 3D prints can solve the reliability problems, through customer reviews or requirements of extensive documentation, they’ll never be able to solve the one-size-fits-nobody issue. Open source fixes this easily. Sell me the source, not the STL!

Hackaday Podcast 082: DJ CNC, NFC Black Box, Sound Of Keys, And Payin’ For 3D Prints

August 28, 2020 by Mike Szczys 2 Comments

Hackaday editors Elliot Williams and Mike Szczys check in on the best hacks from the past week. All the buzz is the algorithm that can reverse engineer your house keys from the way they sound going into the lock. Cardboard construction goes extreme with an RC car build that’s beyond wizard-level. Speaking of junk builds, there’s a CNC mill tipped on its side grinding out results worlds better than you expect from something made with salvaged CD-ROM drives. And a starburst character display is a clever combination of laser cutting and alternative using UV-cured resin as a diffuser.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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This Week In Security: XCode Infections, Freepik, And Crypto Fails

August 28, 2020 by Jonathan Bennett 8 Comments

There is a scenario that keep security gurus up at night: Malware that can detect software compilation and insert itself into the resulting binary. A new Mac malware, XCSSET (PDF), does just that, running whenever Xcode is used to build an application. Not only is there the danger of compiled apps being malicious, the malware also collects data from the developer’s machine. It seems that the malware spreads through infected Xcode projects.

WordPress Plugins

WordPress has a complicated security track record. The core project has had very few serious vulnerabilities over the years. On the other hand, WordPress sites are routinely compromised. How? Generally through vulnerable plugins. Case in point? Advanced Access Manager. It’s a third party WordPress plugin with an estimate 100,000 installations. The problem is that this plugin requires user levels, a deprecated and removed WordPress feature. The missing feature had some unexpected results, like allowing any user to request administrator privileges.

The issue has been fixed in 6.6.2 of the plugin, so if you happen to run the Advanced Access Manager plugin, make sure to get it updated. Beyond that, maybe it’s time to do an audit on your WordPress site. Uninstall unused plugins, and make sure the rest are up to date, along with the WordPress installation itself. Continue reading “This Week In Security: XCode Infections, Freepik, And Crypto Fails” →

VR Technology Helps Bring A Galaxy Far, Far Away To Our TV

August 27, 2020 by Roger Cheng 18 Comments

Virtual reality is usually an isolated individual experience very different from the shared group experience of a movie screen or even a living room TV. But those worlds of entertainment are more closely intertwined than most audiences are aware. Video game engines have been taking a growing role in film and television production behind the scenes, and now they’re stepping out in front of the camera in a big way for making The Mandalorian TV series.

Big in this case is a three-quarters cylindrical LED array 75 ft (23 m) in diameter and 20 ft (6 m) high. But the LEDs covering its walls and ceiling aren’t pointing outwards like some installation for Times Square. This setup, called the Volume, points inward to display background images for camera and crew working within. It’s an immersive LED backdrop and stage environment.

Incorporating projected imagery on stage is a technique going at least as far back as 1933’s King Kong, but it is very limited. Lighting and camera motion has to be very constrained in order to avoid breaking the fragile illusion. More recently, productions have favored green screens replaced with computer imagery in post production. It removed most camera motion and lighting constraints, but costs a lot of money and time. It is also more difficult for actors to perform their roles convincingly against big blank slabs of green. The Volume solves all of those problems by putting computer-generated imagery on set, rendered in real time via video game engine Unreal.

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