Subchannel Stations: The Radio Broadcasts You Didn’t Know Were There

December 20, 2024 by 31 Comments

Analog radio broadcasts are pretty simple, right? Tune into a given frequency on the AM or FM bands, and what you hear is what you get. Or at least, that used to be the way, before smart engineers started figuring out all kinds of sneaky ways for extra signals to hop on to mainstream broadcasts.

Subcarrier radio once felt like the secret backchannel of the airwaves. Long before Wi-Fi, streaming, and digital multiplexing, these hidden signals beamed anything from elevator music and stock tickers to specialized content for medical professionals. Tuning into your favorite FM stations, you’d never notice them—unless you had the right hardware and a bit of know-how.

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Multimeter Gets Socket Upgrade To Use Nicer Probes

December 20, 2024 by 11 Comments

[Piffpaffpoltrie] had a problem. They found the InLine VA40R to be a perfectly usable multimeter, except for a couple of flaws. Most glaring among these were the tiny sockets for the test probes. These proved incompatible with the probes they preferred to use, so naturally, something had to be done. 

The desire was to see the multimeter work with [Piffpaffpoltrie]’s connector of choice: the 4 mm Multi Contact banana plug from Stäubli. Swiss-made, gold-plated, and highly reliable, nothing else would do. The original sockets on the multimeter were simply too small to properly accept these, so to make them work, they were machined down, drilled, tapped, and then fitted with a short M3 screw which was then soldered in place. This short length of thread then allowed the new sockets to bolt right into the PCB in place of the original sockets.

Ultimately, many would just buy a new multimeter. This hack is a fiddly and time-consuming one, but it’s kind of neat to see someone go to such lengths to customize their tools to their own satisfaction.

We don’t see a lot of multimeter hacks, because these tools usually get all the necessary features from the manufacturer. Still, the handful we’ve featured have proven most interesting. If you’re tinkering away at customizing your own test gear, don’t hesitate to drop us a line!

Watch A 3D Scan Become A Car Body Model

December 20, 2024 by 1 Comment

Not all 3D scanning is alike, and the right workflow can depend on the object involved. [Ding Dong Drift] demonstrates this in his 3D scan of a project car. His goal is to design custom attachments, and designing parts gets a lot easier with an accurate 3D model of the surface you want to stick them on. But it’s not as simple as just scanning the whole vehicle. His advice? Don’t try to use or edit the 3D scan directly as a model. Use it as a reference instead.

Rather than manipulate the 3D scan directly, a better approach is sometimes to use it as a modeling reference to fine-tune dimensions.

To do this, [Ding Dong Drift] scans the car’s back end and uses it as a reference for further CAD work. The 3D scan is essentially a big point cloud and the resulting model has a very high number of polygons. While it is dimensionally accurate, it’s also fragmented (the scanner only captures what it can see, after all) and not easy to work with in terms of part design.

In [Ding Dong Drift]’s case, he already has a 3D model of this particular car. He uses the 3D scan to fine-tune the model so that he can ensure it matches his actual car where it counts. That way, he’s confident that any parts he designs will fit perfectly.

3D scanning has a lot of value when parts have to fit other parts closely and there isn’t a flat surface or a right angle to be found. We saw how useful it was when photogrammetry was used to scan the interior of a van to help convert it to an off-grid camper. Things have gotten better since then, and handheld scanners that make dimensionally accurate scans are even more useful.

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Old BBC Micro Gets Some Disk Help From A Raspberry Pi

December 19, 2024 by 15 Comments

[Peter Mount] had a simple problem. He’d treated himself to a retro purchase in the form of a BBC Master 128—a faster sequel to the BBC Micro Model B. The only problem was he needed a way to get software on to it. Cue a creative hack using a Raspberry Pi Zero W.

When [Peter] received the machine, it already had a GoTek floppy emulator, which pulled disk images off a USB drive. However, he wanted an easier and quicker way to get disk images to and from the machine for development purposes. Swapping the USB drive to and from another machine seemed too tedious.

Instead, he decided to swap in a Pi Zero W for this purpose, setting it up to emulate a flash drive by following instructions from MagPi Magazine. This would allow him to use the SCP tool to copy disk images over to the Pi Zero W via its WiFi connection. Basically, the Pi Zero W was acting as a wirelessly-updated storage device hooked up to the GoTek floppy emulator.

It’s a nifty way of doing things. [Peter] could have set about creating his own floppy emulator from scratch with wireless capability included. However, there was no need. He just needed a wirelessly-accessible USB drive, and the Pi Zero W was more than happy to act in that role.

The BBC Micro is a beloved machine of many in the British Isles, and it had rather an extended family. If you’ve pulled off your own nifty hack on this classic machine, be sure to hit us up on the tipsline!

Getting Dial-Up To Work Over VOIP Isn’t Always Easy

December 19, 2024 by 26 Comments

Dial-up modems used to be the default way of accessing the Internet, but times have moved on. They’re now largely esoteric relics from a time gone by. With regular old phone lines rather hard to come by these days, [Peter Mount] decided to try getting a pair of dial-up modems working over VoIP instead.

The build started with a pair of Linksys PAP2T VoIP phone adapters, which were originally designed for hooking regular phones up to VoIP systems. He paired each US Robotics modem with a PAP2T, and then hooked both into a VoIP Private Branch Exchange which he set up using 3cx on a Raspberry Pi 3B+. The Pi also acted as a server for the modems to connect to. It took a lot of fiddly configuration steps, but he found success in the end. On YouTube, he demonstrates the setup—with that glorious modem sound—communicating successfully at a rate of 9600 baud.

It’s nice to see this vintage hardware communicating in a what is effectively a simulated world created entirely within modern hardware. We’ve seen similar projects before, like this attempt to get dial-up going over Discord. If you’re doing your own odd-ball screechy communications experiments, don’t hesitate to drop us a line!

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Fixing 1986 Sinclair Spectrum+2 With A High-Score Of Issues

December 19, 2024 by 6 Comments

The Sinclair ZX Spectrum+2 was the first home computer released by Amstrad after buying up Sinclair. It’s basically a Sinclair ZX Spectrum 128, but with a proper keyboard and a built-in tape drive. The one that [Mark] of the Mend it Mark YouTube channel got in for repair is however very much dead. Upon first inspection of the PCB, it was obvious that someone had been in there before, replacing the 7805 voltage regulator and some work on other parts as well, which was promising. After what seemed like an easy fix with a broken joint on the 9 VDC input jack, the video output was however garbled, leading to the real fault analysis.

Fortunately these systems have full schematics available, allowing for easy probing on the address and data lines. Based on this the Z80 CPU was swapped out to eliminate a range of possibilities, but this changed nothing with the symptoms, and a diagnostic ROM cartridge didn’t even boot. Replacing a DS74LS157 multiplexer and trying different RAM chips also made no difference. This still left an array of options on what could be wrong.

Tracking down one short with an IC seemed to be a break, but the video output remained garbled, leaving the exciting possibility of multiple faults remaining. This pattern continues for most of the rest of the video, as through a slow process of elimination the bugs are all hunted down and eliminated, leaving a revived Spectrum+2 (and working tape drive) in its wake, as well as the realization that even with all through-hole parts and full schematics, troubleshooting can still be a royal pain.

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Fibonacci Clock Looks Like Beautiful Modern Art

December 19, 2024 by 11 Comments

Don’t ask us why, but hackers and makers just love building clocks. Especially in the latter case, many  like to specialize in builds that don’t even look like traditional timepieces, and are difficult to read unless you know the trick behind them. [NerdCave] has brought us a pleasing example of such a thing, in the form of this gorgeous Fibonacci clock.

The build was inspired by an earlier Fibonacci clock that later became a Kickstarter project. Where that build used an Atmega328P, though, [NerdCage] landed on using a Raspberry Pi Pico W instead. The build throws the microcontroller board on a custom PCB, and sticks in inside an attractive 3D-printed enclosure. Black filmanet was used for the body, while white filament was used for the face of each square to act as a diffuser. Addressable RGB LEDs are used to illuminate the five square segments of the clock.

Obviously, you’re wondering how to read the clock. All you need to know is this. The first five numbers in the Fibonacci sequence are 1, 1, 2, 3, and 5. Each square on the clock represents one of these numbers—the side lengths of each square match these numbers. Red and green are used to represent hours and minutes, respectively, while a blue square is representing both. Basically, to get the hour, add up the values of red and blue squares, and to get the minutes, do the same with green and blue squares, but then multiply by 5. In the header image, the clock is displaying 8:55 PM… we think.

We’ve featured Fibonacci-themed clocks before, albeit ones with entirely different visual themes. Video after the break.

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