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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Ceefax: The Original News On Demand

September 30, 2024 by Heidi Ulrich 21 Comments

Long before we had internet newsfeeds or Twitter, Ceefax delivered up-to-the-minute news right to your television screen. Launched by the BBC in 1974, Ceefax was the world’s first teletext service, offering millions of viewers a mix of news, sports, weather, and entertainment on demand. Fast forward 50 years, and the iconic service is being honored with a special exhibition at the Centre for Computing History in Cambridge.

At its peak, Ceefax reached over 22 million users. [Ian Morton-Smith], one of Ceefax’s original journalists, remembers the thrill of breaking stories directly to viewers, bypassing scheduled TV bulletins. The teletext interface, with its limited 80-word entries, taught him to be concise, a skill crucial to news writing even today.

We’ve talked about Ceefax in the past, including in 2022 when we explored a project bringing Ceefax back to life using a Raspberry Pi. Prior to that, we delved into its broader influence on early text-based information systems in a 2021 article.

But Ceefax wasn’t just news—it was a global movement toward interactive media, preceding the internet age. Services like Viditel and the French Minitel carried forward the idea of interactive text and graphics on screen.

Curing CRT Cataracts Freshens Up Retro Roundy TVs

September 29, 2024 by Dan Maloney 12 Comments

It’s been a long time since the family TV has had a CRT in it, and even longer since that it was using what was basically an overgrown oscilloscope tube. But “roundies” were once a thing, and even back in the early 80s you’d still find them in living rooms on TV repair calls, usually sporting a characteristic and unsightly bullseye discoloration.

Fast-forward a few decades, and roundy TVs have become collectible enough that curing their CRT cataracts is necessary for restorationists like [shango066], a skill he demonstrates in the video below. The defect comes from the composite construction of CRTs — a safety feature added by television manufacturers wisely concerned with the safety aspects of putting a particle accelerator with the twin hazards of high vacuum and high voltage in the family home. The phosphor-covered face of the tube was covered by a secondary glass cover, often tinted and frosted to improve the admittedly marginal viewing experience. This cover was often glued in place with an epoxy resin that eventually oxidized from the edges in, making the bullseye pattern.

The remedy for this problem? According to [shango066], it’s heat, and plenty of it. After liberating the tube from the remarkably clean TV chassis, he took advantage of a warm summer’s day and got the tube face cooking under a black plastic wrap. Once things were warmed up, more heat was added to really soften the glue; you can easily see the softening progress across the face of the tube in the video below. Once softened, gentle prying with wooden chopsticks completes the job of freeing the safety lens, also in remarkably good shape.

With the adhesive peeled off in an oddly satisfying manner, all that’s left is a thorough cleaning and gluing the lens back on with a little silicone sealant around the edges. We’d love to see the restored TV in operation, but that’s left to a promised future video. In the meantime, please enjoy a look at the retro necessities TV owners depended on in the good old days, which really weren’t all that good when you get down to it.

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Reverse Time Back To The Days Of RPN

September 26, 2024 by Bryan Cockfield 68 Comments

While Texas Instruments maintains dominance in the calculator market (especially graphing calculators), there was a time when this wasn’t the case. HP famously built the first portable scientific calculator, the HP-35, although its reverse-Polish notation (RPN) might be a bit of a head-scratcher to those of us who came up in the TI world of the last three or four decades. Part of the reason TI is so dominant now is because they were the first to popularize infix notation, making the math on the calculator look much more like the math written on the page, especially when compared to the RPN used by HP calculators. But if you want to step into a time machine and see what that world was like without having to find a working HP-35, take a look at [Jeroen]’s DIY RPN calculator.

Since the calculator is going to be RPN-based, it needs to have a classic feel. For that, mechanical keyboard keys are used for the calculator buttons with a custom case to hold it all together. It uses two rows of seven-segment displays to show the current operation and the results. Programming the Arduino Nano to work as an RPN calculator involved a few tricks, though. [Jeroen] wanted a backspace button, but this disrupts the way that the Arduino handles the input and shows it on the display but it turns out there’s an Arudino library which solves some of these common problems with RPN builds like this.

One of the main reasons that RPN exists at all is that it is much easier for the processor in the calculator to understand the operations, even if it makes it a little bit harder for the human. This is because early calculators made much more overt use of a stack for performing operations in a similar way to Assembly language. Rather than learning Assembly, an RPN build like this can be a great introduction to this concept. If you want to get into the weeds of Assembly programming this is a great place to go to get started.