Author: Jenny List

3399 Articles

934 MHz: When The Government Really Doesn’t Want You To Have CB

April 7, 2026 by 39 Comments

In the mid 1970s there were a spate of movies depicting the romance and lifestyle of truck drivers in the southern half of the United States. Over on the other side of the Atlantic these were naturally received not as works of drama but as documentaries, and thus began a craze for British drivers to do up their Ford Capri so in the right light and with your eyes nearly closed, it almost looked like Burt Reynolds’ Pontiac Trans Am from Smokey and the Bandit.

Such a fine automobile was of course incomplete without a CB radio, highly illegal at the time, which led to an underground CB craze and its eventual legalization in 1981. [Ringway Manchester] is here with a tale from that era, of 934 MHz CB, an odd and underused allocation that was eventually phased out for commercial services.

When UK CB was eventually legalized by the government, it was very obvious that they really didn’t want to. Brits got 27 MHz as FM only with meager power and a weird set of frequencies that nobody else had, and a second band way up in the UHF range, at 934 MHz. We remember they originally tried to make a UHF band the only allocation on purpose because it was nearly useless for mobile operation, and Brits only got 27 MHz by fighting back in the political lobbying space.

The video below tells the story of the band, with relatively scarce and expensive equipment leading to it being an exclusive band more similar to the amateur bands, with little resemblance to its raucous 27 MHz counterpart. How much activity there was depended very much on where in the country you were, which of course wasn’t where your Hackaday scribe was as a teenager even if it had been affordable. Eventually the government saw the little flashing pound signs and grabbed it back for a mobile radio service that never materialized, and now the frequencies are part of the mobile phone spectrum.

Have a watch for an odd bit of UK radio nostalgia and some 2020s illegal CB’ers, and if you want more it’s a subject we’ve touched on before.

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Cleaning An IBM 5150, And The Perfect Period PCB Soldermask

April 5, 2026 by 12 Comments

Now that early PCs have moved firmly from the realm of e-waste into being collector’s items, it’s worth putting in some effort to restore them if you find one. [Epictronics] has an early IBM 5150, the ancestor of all today’s PCs, and is bringing it back to life. Along the way, he’s building a replica AdLib sound card, making a useful discovery about how to make new parts look authentic.

The video below the break is a gentle journey through an early PC teardown, followed by the construction of the replica sound card. Here’s the interesting nugget of information: these new cards are careful recreations of the originals, but they just don’t look right. It seems modern soldermask is too shiny, and as luck would have it, there’s another option that is much more period-authentic. We hadn’t noticed matte green was available, but it certainly captures the look of those days much better.

As you might expect, such an old machine has a range of dead capacitors and a few chips. There’s a lucky escape with a Varta battery on an expansion card, having very little leakage, and part of one of the floppy drives needs some surgery. It’s gentle hacking that’s engaging to watch, and of course, at the end, we’re rewarded with the thing booting properly.

You might think reproducing a sound card is unusual, but we’ve seen it a number of times.

Continue reading “Cleaning An IBM 5150, And The Perfect Period PCB Soldermask” →

Scrap Vintage Camera Goes Digital With Scanner Parts

April 4, 2026 by 3 Comments

Every collector ends up with items that are worthless, usually because they are broken or incomplete. When [Graindead] found a 1920s glass-plate reflex camera for pennies with plenty of missing parts, it was obvious that what he had was a piece of junk. Throw it away? No, he turned it digital with the aid of a small document scanner.

A reflex camera like this one is the ancestor of the 35mm single-lens reflex cameras we may still be familiar with today, in that is has a flip-up mirror inside to bounce the light onto a ground glass screen. The photographer can see what the lens sees to set up the shot, before flipping the mirror out of the way and exposing the glass plate film by pulling out a dark slide. This one was missing the ground glass and the lens, so he has to grind a replacement, and bodge in a similar-age Carl Zeiss Tessar lens.

In the video below you can see the build, and a range of pictures including some trichrome colour shots. It gives an imperfect result even compared to the same camera with its period film, but the point here is the art rather than the clarity. We’d take this one out with us, if it were ours.

For more vintage digital fun, have a look at a similar adaptation that shoots video.

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The Rapper, The Canadian Academics, And The Secret Behind The Earworm

April 4, 2026 by 13 Comments

There are many events so far in 2026 that could reasonably have been predicted, but perhaps one which couldn’t is a Hackaday scribe in Europe unexpectedly finding herself with a constant earworm from Afroman. The rapper, who most of us know only from his year 2000 hit single about getting high, made the news after an inept police raid on his house, and in turn a court case over his musical denunciations of the authorities.

It’s fair to say they picked on the wrong guy, but in thinking about why, the answer is in the earworm. He has the unique skill of making a song irritatingly catchy, which led us to the question of how a catchy song works. As luck would have it a team from the University of Waterloo have recently released a paper in which they explain  it all in terms of maths, giving the rest of us a formula where the likes of Afroman are presumably born with it.

We won’t pretend that Hackaday’s mathematical expertise stretches beyond that needed for engineering, but for the more advanced numberphiles among us the university’s write-up goes into some detail about their use of group theory to study the patterns and symmetry in a given piece of music. It’s a new approach that joins other more famous guides to musical success, so perhaps if you couple it with the stuff your music teacher failed to tell you in school, you could be on your way to the top of the charts. Meanwhile here at Hackaday we’ll stick to more conventional inspiration.

Header: Chris Gilmore, CC BY-SA 2.0.

Making A Vintage Allen Scythe Electric

April 3, 2026 by 7 Comments

The Allen Scythe is one of those fantastic pieces of vintage agricultural machinery which would never be allowed to be manufactured today for health and safety reasons. It’s a two-wheel walk-behind device with a frightening reciprocating cutter bar which makes short work of almost anything. It’s the perfect tool for the roughest of brush clearance, but it demands respect. [Way Out West Workshop Stuff] has one, and is replacing the vintage Villiers two-stroke engine with an electric motor.

The conversion is straightforward enough, the Villiers crankshaft being replaced with a straight-through axle that can be driven by the motor. We particularly like the use of a cable tie as a splash lubricator. The shaft is turned to accept the Villiers’ bearings, the gear to drive the Allen, and a chain sprocket where the cord start would go on the engine. A mounting plate puts the motor above, a chain is fitted, and it’s ready to go once a hefty battery pack has been installed.

There are two videos below the break, showing construction, and finally the machine in action. The electric Allen is every bit as useful as the original, without the noise and vibration. Villiers motors can be temperamental, so we’d view it as an upgrade worth having.

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For Such A Small Program, ZX81 1K Chess Sure Packs A Lot In

April 3, 2026 by 12 Comments

The Sinclair ZX81 was hardly the most accomplished of 1980s 8-bit microcomputers, but its ultra-low-budget hardware was certainly pressed into service for some impressive work. Perhaps the most legendary piece of commercial software in this vein was 1K Chess, which packed an entire chess engine into the user-available bytes in the unexpanded 1K ZX’s memory map. [MarquisdeGeek] has taken this vintage piece of code in 2026 and subjected it to a thorough analysis, finding all the tricks along the way.

Though hackers have since found ways to trick the ’81 into displaying bitmap graphics, using it as intended is text-only with some limited block graphics. The chess board then is text-only, and its illusion of “thinking” about moves comes courtesy of the on-screen board doubling as the play area memory. In the GitHub repository you can find decompiled and annotated versions as well as the original ZX binary, with as a bonus a screen capture of the game as it appears as BASIC with the ZX’s odd means of storing Z80 code in REM statements.

If that wasn’t enough, in his note giving us the tip he reveals that much of the work was done in a ZX emulator running in a Dragon emulator, and gives us a fun glimpse of the game running in an emulator on a Cheap Yellow Display inside 1K Chess cassette box. We like it, a lot!

If you need a greater ZX81 fix, take a look at how this machine chased the beam to make TV graphics on the cheap.

DC In The Data Center For A More Efficient Future

April 3, 2026 by 51 Comments

If you own a computer that’s not mobile, it’s almost certain that it will receive its power in some form from a mains wall outlet. Whether it’s 230 V at 50 Hz or 120 V at 60 Hz, where once there might have been a transformer and a rectifier there’s now a switch-mode power supply that delivers low voltage DC to your machine. It’s a system that’s efficient and works well on the desktop, but in the data center even its efficiency is starting to be insufficient. IEEE Spectrum has a look at newer data centers that are moving towards DC power distribution, raising some interesting points which bear a closer look.

A traditional data center has many computers which in power terms aren’t much different from your machine at home. They get their mains power at distribution voltage — probably 33 KV AC where this is being written — they bring it down to a more normal mains voltage with a transformer just like the one on your street, and then they feed a battery-backed uninterruptible Power Supply (UPS) that converts from AC to DC, and then back again to AC. The AC then snakes around the data center from rack to rack, and inside each computer there’s another rectifier and switch-mode power supply to make the low voltage DC the computer uses.

The increasing demands of data centers full of GPUs for AI processing have raised power consumption to the extent that all these conversion steps now cost a significant amount of wasted power. The new idea is to convert once to DC (at a rather scary 800 volts) and distribute it direct to the cabinet where the computer uses a more efficient switch mode converter to reach the voltages it needs.

It’s an attractive idea not just for the data center. We’ve mused on similar ideas in the past and even celebrated a solution at the local level. But given the potential ecological impact of these data centers, it’s a little hard to get excited about the idea in this context. The fourth of our rules for the responsible use of a new technology comes in to play. Fortunately we think that both an inevitable cooling of the current AI hype and a Moore’s Law driven move towards locally-run LLMs may go some way towards solving that problem on its own.

header image: Christopher Bowns, CC BY-SA 2.0.