Hands On With A Giant Nixie Tube

October 24, 2024 by Dave Rowntree 9 Comments

[Sam Battle] is no stranger to these pages, nor is his Museum is not Obsolete. The museum was recently gifted an enormous Nixie tube created by Dalibor Farný, a B-grade (well, faulty) unit that could not be used in any of their commissioned works but was perfectly fine for displaying in the museum’s retro display display. This thing is likely the largest Nixie tube still being manufactured; although we read that it’s probably not the largest ever made, it’s still awesome.

Every hacker should have their own museum.

It is fairly simple to use, like all Nixie tubes, provided you’re comfortable with relatively high DC voltages, albeit at a low current. They need a DC voltage because if you drive the thing with AC, both the selected cathode digit plate and the anode grid will glow, which is not what you need.

Anyway, [Sam] did what he does best, clamped the delicate tube in some 3D printed mounts and hooked up a driver made from stuff he scraped out of a bin in the workshop. Obviously, for someone deeply invested in ancient electromagnetic telephone equipment, a GPO (British General Post Office, now BT) uniselector was selected, manually advanced with an arcade-style push button via a relay. This relay also supplies the ~140 V for the common anode connection on the Nixie tube. The individual digit cathodes are grounded via the uniselector contacts. A typically ancient GPO-branded snubber capacitor prevents the relay contacts from arcing over and ruining the display unit. There isn’t much more to it, so if you’re in the Ramsgate, UK, area anytime soon, you can pop in and play with it for yourself.

Nixies are cool, we’ve covered Nixie projects for years, like this DIY project from ages ago. Bringing such things into the modern area is the current specialty of Dalibor Farný, with this nice video showing some of the workmanship involved. By the way — the eagle-eyed will have noticed that we covered this particular Nixie tube before, shown in the format of a large art installation. But it doesn’t hurt to get close up and play with it on the bench.\

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Keeping Tabs On An Undergraduate Projects Lab’s Door Status

October 24, 2024 by Maya Posch 18 Comments

Over at the University of Wisconsin’s Undergraduate Projects Lab (UPL) there’s been a way to check whether this room is open for general use by CS undergraduates and others practically for most of the decades that it has existed. Most recently [Andrew Moses] gave improving on the then latest, machine vision-based iteration a shot. Starting off with a historical retrospective, the 1990s version saw a $15 camera combined with a Mac IIcx running a video grabber, an FTP server and an HP workstation that’d try to fetch the latest FTP image.

As the accuracy of this system means the difference between standing all forlorn in front of a closed UPL door and happily waddling into the room to work on some projects, it’s obvious that any new system had to be as robust as possible. The machine vision based version that got installed previously seemed fancy: it used a Logitech C920 webcam, a YOLOv7 MV model to count humanoids and a tie into Discord to report the results. The problem here was that this would sometimes count items like chairs as people, and there was the slight issue that people in the room didn’t equate an open door, as the room may be used for a meeting.

Thus the solution was changed to keeping track of whether the door was open, using a sensor on the two doors into the room. Sadly, the captive-portal-and-login-based WiFi made the straightforward approach with a reed sensor, a magnet and an ESP32 too much of a liability. Instead the sensor would have to communicate with a device in the room that’d be easier to be updated, ergo a Zigbee-using door sensor, Raspberry Pi with Zigbee dongle and Home Assistant (HA) was used.

One last wrinkle was the need to use a Cloudflare-based tunnel add-on to expose the HA API from the outside, but now at long last the UPL door status can be checked with absolute certainty that it is correct. Probably.

Featured image: The machine vision-based room occupancy system at UoW’s UPL. (Credit: UPL, University of Wisconsin)

Seven New Street Fighter 2 Arcade Rom Hacks

October 23, 2024 by Dave Rowntree 2 Comments

[Sebastian Mihai] is a prolific programmer and hacker with a particular focus on retrocomputing and period games, and this latest hack, adding new gameplay elements to Capcom’s Street Fighter II – Champion Edition, is another great one. [Sebastian] was careful to resist changing the game physics, as that’s part of what makes this game ‘feel’ the way it does, but added some fun extra elements, such as the ability to catch birds, lob barrels at the other player, and dodge fire.

The title screen was updated for each of the different versions, so there is no doubt about which was being played. This work was based on their previous hacks to Knights of the Round. Since both games shared the same Capcom CPS-1 hardware, the existing 68000 toolchain could be reused, reducing the overhead for this new series of hacks. Continue reading “Seven New Street Fighter 2 Arcade Rom Hacks” →

75-In-One Music

October 23, 2024 by Jenny List 18 Comments

It’s likely that many Hackaday readers will have had their interest in electronics as a child honed by exposure to an electronics kit. The type of toy that featured a console covered in electronic components with spring terminals, and on which a variety of projects could be built by wiring up circuits. [Matthew North Music] has a couple of these, and he’s made a video investigating whether they can be used to make music.

The kits he’s found are a Radio Shack one from we’re guessing the 1970s, and a “Cambridge University Recording Studio” kit that looks to be 1990s-vintage. The former is all discrete components and passive, while the latter sports that digital audio record/playback chip that was the thing to have in a novelty item three decades ago. With them both he can create a variety of oscillator and filter circuits, though for the video he settles for a fairly simple tone whose pitch is controlled by an light-dependent resistor, and a metronome as a drum beat.

The result is a little avant garde, but certainly shows promise. The beauty of these kits is they can now be had for a song, and as grown-ups we don’t have to follow the rules set out in the book, so we can see there’s a lot of fun to be had. We look forward to some brave soul using them in a life performance at a hacker camp. Continue reading “75-In-One Music” →

Symbolic Nixie Tubes Become Useful For Artistic Purposes

October 10, 2024 by Lewin Day 2 Comments

When it comes to Nixie tubes, the most common usage these days seems to be in clocks. That has people hunting for the numerical version of the tubes, which are usually paired with a couple of LEDs to make the colon in the middle of the clock. However, other Nixie tubes exist, like the IN-7, which has a whole bunch of neat symbols on it instead. [Joshua] decided to take these plentiful yet less-popular tubes and whip them up into a little art piece.

The IN-7 is a tube normally paired with the numerical IN-4 tube in instrumentation, where it displays unit symbols relevant to the number being displayed. It can display omega, +, M, pi, m, A, -, V, K, and ~.

[Joshua]’s build is simple enough. It spells the word “MAKE” in Nixie tubes as a neat sign for a makerspace. It uses “M” for Mega, “A” for Amps, “K” for Kilo for the first three letters. The fourth letter, “e”, is achieved by turning the tube 90 degrees, so the “m” for milli approximates that character. Two rows spelling “MAKE” (or “MAKe”) are assembled, powered via a small circuit which [Joshua] assembled on a custom-etched board using the toner transfer process. The electronics are all wrapped up in a neat laser-cut acrylic enclosure which was designed in Inkscape.

It’s a neat little project which makes good use of a Nixie tube that is, by and large, unloved. It also recalls us of a misspent youth, writing silly words on scientific calculators using only the available Greek characters. Meanwhile, if you’re working on your own Nixie builds, we’ve featured some neat drivers that you might just find valuable.

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Braun TS2 Radio Turns 68, Gets Makeover

October 9, 2024 by Al Williams 7 Comments

The Braun TS2 radio was a state-of-the art tube set in 1956. Today it still looks great, but unsurprisingly, the one that [Manuel Caldeier] has needed a little tender loving care. The table radio had a distinct style for its day and push-buttons. However, the dial glass and the speaker grill needed replacement. Even more interesting, the radio has a troublesome selenium rectifier, giving him the perfect chance to try out his new selenium rectifier solid-state replacement.

The radio is as good-looking inside as it is outside. You can tell that this isn’t his first restoration, as he has several tricks to test things at different stages of the project.

While the radio looked good, it smelled of smoke, which required a big effort to clean. The dial glass was intact enough for him to duplicate it in a graphic program and print it on a transparent adhesive sticker. With a deep breath, he removed the original markings from the glass so he could add the sticker to it. That didn’t work because the label needed cutouts. So now he is waiting for a piece of acrylic that will have the art UV printed on it.

We want to see the next part as we imagine the radio sounds as good as it looks when it is working. If you want to know more about the rectifier replacement, we covered that earlier. Even years later, Braun would have a clean aesthetic.

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What Happened To Duracell PowerCheck?

October 9, 2024 by Al Williams 83 Comments

Remember Duracell’s PowerCheck? The idea was that a strip built into the battery would show if the battery was good or not. Sure, you could always get a meter or a dedicated battery tester — but PowerCheck put the tester right in the battery. [Technology Connections] has an interesting video on how these worked and why you don’t see them today. You can see it below.

Duracell didn’t invent the technology. The patent belonged to Kodak, and there were some patent issues, too, but the ones on the Duracell batteries used the Kodak system. In practice, you pushed two dots on the battery, and you could see a color strip that showed how much capacity the battery had left. It did this by measuring the voltage and assuming that the cell’s voltage would track its health. It also assumed — as is clearly printed on the battery — that you were testing at 70 degrees F.

The temperature was important because the secret to the PowerCheck is a liquid crystal that turns color as it gets hot. When you press the dots, the label connects a little resistor, causing the crystals to get warm. The video shows the label taken apart so you can see what’s inside of it. The resistor isn’t linear so that’s how it changes only part of the bar to change color when the battery is weak but not dead.

It is a genius design that is simple enough to print on a label for an extremely low cost and has virtually no components. PowerCheck vanished from batteries almost as suddenly as it appeared. Some of it was due to patent disputes. But the video purports that normal people don’t really test batteries.

Watch out for old batteries in gear. Of course, if you want to really test batteries, you are going to need more equipment.

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