TechyMagThings

Audiophiles all know everything sounds better fed through vacuum tubes, but did you know visualizers look better with them, too? That’s what we’re forced to conclude looking at the Tachyscope Laser, a 360-degree oscilloscope display that is [Daniel Ross]’s entry into the ongoing Frikkin Lasers contest.

The laser is a good old-fashioned helium–neon tube — something we see less and less of in this era of solid state lasers — and the wavelength gives the waveform display a retro charm. The actual display is unique in our experience, with the beam shining up through a hollow shaft to bounce off a galvanometer mirror on a spinning platform. Galvo sweeps the laser across a translucent target, which creates the waveform by persistence of vision as it spins at 100 RPM or so.

Does the fact that the audio signal feeds through a tube amp to drive the single galvanometer actually improve the visuals? Only in the sense that those tubes make the steampunk-style enclosure look really, really cool, as does the exposed laser tube. That all of the steampunk elements obviously have a point to them rather than just being a another “glue some gears on it” project is icing on the laser-flavored cake.

The contest runs until July 23rd, so there’s lots of time to get laserin’ — and remember that there are categories for DIY lasers and anything that isn’t a display, just in case you think this project puts the bar too high for a light show. We’ve actually featured one of [Daniel]’s tachyscope waveform visualizers before, but that one, madly enough, spun an actual CRT.

This week Jonathan chats with Florian Gilcher about Rust and Ferrous Systems! How have we gotten here, what’s coming next, and what’s new in the Rust world? Watch to find out!

• http://www.ferrous-systems.com
• http://www.ferrocene.dev
• http://www.oxidizeconf.com

Did you know you can watch the live recording of the show right on our YouTube Channel? Have someone you’d like us to interview? Let us know, or have the guest contact us! Take a look at the schedule here.

Direct Download in DRM-free MP3.

If you’d rather read along, here’s the transcript for this week’s episode.

Theme music: “Newer Wave” Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

If you’ve ever taken a close look at a vacuum tube, you’ll have seen the seals around the pins that keep everything air-tight while providing the the device’s electrical contacts. As [maurycyz] finds out, it’s not an easy process to get right.

The problem is one of both chemistry and thermal expansion, as while a good seal can be made between glass and red copper oxide, it remains very difficult indeed to stop the glass cracking on cooldown due to differing thermal expansion properties. We’re led through a variety of experiments including surface treatments and flattening the metal to a sheet, with varying pros and cons. The most successful seal on the page comes from very thin tungsten wire, though hardly the most practical conductor for a vacuum tube.

It’s a fascinating investigation for the casual reader, taking them into the properties of metal-glass bonds and the difficulties involved in making them. We have even more respect for the people who make their own tubes after reading it.

Let’s stop for a moment and pause to consider the smart bulb. Imagine going back 20 years and telling yourself that people will be putting computers capable of acting as web servers into light bulbs just so they can control them from their telephone instead of hitting the switch. The whole thing seems crazy — but its great, because it enables hacks like this one where [RickOOOOOO] takes a commercially-available ESP32 smart bulb, and hacks it into a local file server and digital library for banned books.

The word “banned” gets bandied about a lot — but assured, there’s nothing getting served up by [RickOOOOOO]’s bulb that’s going to help somebody will ill-intent build an improvised explosive device.  No, at least as conceived here, it appears to be full of easily-available e-books that were pulled from school libraries in the USA, which may-or-may not meet your personal definition of ‘banned’. Whatever you want to call them, we appreciate the idea that a student could hypothetically replace one of the bulbs at school with a hacked version serving up that sort of content. a bulb in such a school with a bulb hacked to host that sort of content–in minecraft, naturally.

In any case, the hardest part of the hack was carving the ESP32C3 in the bulb out of the IoToreo bulb enough to access it. Unfortunately having done so, [Rick] wasn’t able to get an SDcard interface soldered on, so he’s stuck with just 4MB for books and webserver. That means only a few epubs can fit on the bulb, but it’s better than those books being unavailable.

Like the solarpunk message board we featured recently, which also ran on an ESP32, the bulb broadcasts a public network that uses a captive portal to take you to the web interface of the library. From there, users can browse books– including learning from where they were banned and why–and admins can access a password-protected control panel. One neat work-in-progress feature on the control panel is that the bulb can still be used as a smart bulb, so you can try and match the light to its surroundings. In Minecraft, because of course we would never encourage kids to change light bulbs. Perish the thought!

Speaking of Minecraft, you can run a server on a lightbulb, too. Or DOOM, because of course even the light bulbs run DOOM now. What a time to be alive!

The basics of producing a stereophotograph of real life places were well-established by the time the View-Master arrived, but producing images of imaginary scenes was a bit more involved. [View Master Travels and Peter Dibble] took a look at how the fairy tale and media tie-in reels may have been made.

Staring with simple dioramas, View-Master eventually developed an entire team to work on fairy tales. One of the most influential members was sculptor [Florence Thomas]. She was instrumental in updating many of the original fairy tale reels from small scale miniatures to 1/6 scale dioramas for the scenes. Unfortunately, the department was eventually cut and all the original miniatures thrown away.

Before VCRs, View-Master was the primary way people could interact with their favorite TV shows and movies when they weren’t being broadcast. TV shows could be photographed while in production in Hollywood with a stereo camera giving great visual detail. Some cartoon and movie reels were less engaging, having been made from promotional images, giving more of a paper cutout appearance rather than “real” 3D. In either case, many of these visual techniques have been lost with little documentation on how they were achieved.

We previously covered [View Master Travels and Peter Dibble]’s History of the View-Master and how you can digitize the disks for posterity.

Slow-scan CRTs were never exactly common compared to their faster cousins, but given the popularity of Slow Scan TV (SSTV) amongst hams and NASA broadcasts, many of you are probably familiar with them. The slow scan rate of SSTV meant it required much less bandwidth, but in the early days you needed a CRT with a long-persistence phosphor to hold onto the image. [AJRussell]’s Glow Engine works much the same, with one key difference — instead of cathode rays, he’s using a frikkin laser beam.

In this case, the phosphor is Strontium Aluminate, the same stuff that gives most glow-in-the-dark toys and filament its kick. Energized by a 405 nm laser of questionable wattage, the phosphor will glow for several seconds, allowing the creation of an image. So while this is a laser projector, it works more like a CRT than most galvo projectors, which rely on Persistence of Vision to create an image. Here it’s persistence of fluorescence.

Because the phosphor is so slow, you don’t need the rapid scan rate you would with a laser projector, so [AJRussel] can skip the mirror drum and just mount the mirror on a gimbal motor. Field Oriented Control makes the precise sweeping of the gimbal possible, via a hall-effect sensor and the SimpleFOC library that we featured last year. The other axis just moves the laser and gimbal assembly on a big stepper. The whole thing is driven via an ESP32. The biggest downside is that the short focus range of the repurposed engraving laser means it’s smack dab in front of the screen.

This is a work in progress and still changing, so it’s not clear which — if any — of the various SSTV modes the Glow Engine can handle. Given the number of scanlines in the photos it looks like a good use case, and without trying it the timing might work, too:  [AJ] reports scanning left-to-right to generate a frame takes about eight seconds, depending on the resolution, and depending on the PWM power setting on the laser the image can last up to a minute.

Given the one-minute decay time with this particular phosphor, perhaps he can make a clock. If you have a longer-lasting glow powder, we’ve seen  uses for such a persistent display as well.

Every now and then a project comes into the Hackaday feed that has so many levels of wrong about it that you really shouldn’t do it at home, but is amusing enough to feature anyway with a warning. So it is with [ArcaEge]’s Capacitor Alarm Clock, which wakes up its unfortunate owner by blowing up electrolytic capacitors with reverse voltage. If you survive, you’ll certainly be awake!

It’s inspired unsurprisingly by an [ElectroBoom] video, and the premise is simple enough. An ESP32 serves as the clock, and triggers a relay for the alarm, which in turn overloads a suitably low-voltage electrolytic capacitor in a socket. The resulting explosion which appears in a video we’ve placed below the break, wakes the slumberer.

We don’t have to tell you that this is not the safest of hacks, and is presented here only for your entertainment. But it does provide a few points of interest, for example in identifying the difference between capacitors with a vent, and those without.

This isn’t the first time we’ve seen a project based around exploding capacitors, and that one maybe was a don’t-do-this-at-home too.