Retrotechtacular: Yamming CRT Yokes

February 19, 2025 by 28 Comments

Those of us who worked in TV repair shops, back when there was such a thing, will likely remember the cardinal rule of TV repair: Never touch the yoke if you can help it. The complex arrangement of copper wire coils and ferrite beads wrapped around a plastic cone attached to the neck of the CRT was critical to picture quality, and it took very little effort to completely screw things up. Fixing it would be a time-consuming and frustrating battle with the cams, screws, and spacers that kept the coils in the right orientation, both between themselves and relative to the picture tube. It was best to leave it the way the factory set it and to look elsewhere for solutions to picture problems.

But how exactly did the factory set up a deflection yoke? We had no idea at the time, only learning just recently about the wonders of automated deflection yoke yamming. The video below was made by Thomson Consumer Electronics, once a major supplier of CRTs to the television and computer monitor industry, and appears directed to its customers as a way of showing off their automated processes. They never really define yamming, but from the context of the video, it seems to be an industry term for the initial alignment of a deflection yoke during manufacturing. The manual process would require a skilled technician to manipulate the yoke while watching a series of test patterns on the CRT, slowly tweaking the coils to bring everything into perfect alignment.

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Be Careful What You Ask For: Voice Control

February 19, 2025 by 69 Comments

We get it. We also watched Star Trek and thought how cool it would be to talk to our computer. From Kirk setting a self-destruct sequence, to Scotty talking into a mouse, or Picard ordering Earl Grey, we intuitively know that talking to a computer is better than typing, right? Well, computers talking back and forth to us is no longer science fiction, and maybe we aren’t as happy about it as we thought we’d be.

We weren’t able to pinpoint the first talking computer in fiction. Asimov and van Vogt had talking computers in the 1940s. “I, Robot” by Eando Binder, and not the more famous Asimov story, had a fully speaking robot in 1939. You could argue that “The Machine” in E. M. Forster’s “The Machine Stops” was probably speaking — the text is a little vague — and that was in 1909. The robot from Metropolis (1927) spoke after transforming, but you could argue that doesn’t count.

Meanwhile, In Real Life

In real life, computers weren’t as quick to speak. Before the middle of the twentieth century, machine-generated speech was an oddity. In 1779, a mechanical contrivance by Wolfgang von Kempelen, famous for the mechanical Turk chess-playing automaton, could form simple words. By 1939, Bell Labs could do even better speech synthesis electronically but with a human operator. It didn’t sound very good, as you can see in the video below, but it was certainly expressive.

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In A World Without USB…

February 19, 2025 by 26 Comments

It is easy to forget that many technology juggernauts weren’t always the only game in town. Ethernet seems ubiquitous today, but it had to fight past several competing standards. VHS and Blu-ray beat out their respective competitors. But what about USB? Sure, it was off to a rocky start in the beginning, but what was the real competition at that time? SCSI? Firewire? While those had plusses and minuses, neither were really in a position to fill the gap that USB would inhabit. But [Ernie Smith] remembers ACCESS.bus (or, sometimes, A.b) — what you might be using today if USB hadn’t taken over the world.

Back in the mid-1980s, there were several competing serial bus systems including Apple Desktop Bus and some other brand-specific things from companies like Commodore (the IEC bus) and Atari (SIO). The problem is that all of these things belong to one company. If you wanted to make, say, keyboards, this was terrible. Your Apple keyboard didn’t fit your Atari or your IBM computer. But there was a very robust serial protocol already in use — one you’ve probably used yourself. IIC or I2C (depending on who you ask).

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MIT Demonstrates Fully 3D Printed, Active Electronic Components

February 19, 2025 by 26 Comments

One can 3D print with conductive filament, and therefore plausibly create passive components like resistors. But what about active components, which typically require semiconductors? Researchers at MIT demonstrate working concepts for a resettable fuse and logic gates, completely 3D printed and semiconductor-free.

Now just to be absolutely clear — these are still just proofs of concept. To say they are big and perform poorly compared to their semiconductor equivalents would be an understatement. But they do work, and they are 100% 3D printed active electronic components, using commercially-available filament.

How does one make a working resettable fuse and transistor out of such stuff? By harnessing thermal expansion, essentially.

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Belfry OpenSCAD Library (BOSL2) Brings Useful Parts And Tools Aplenty

February 18, 2025 by 16 Comments

OpenSCAD has a lot of fans around these parts — if you’re unaware, it’s essentially a code-based way of designing 3D models. Instead of drawing them up in a CAD program, one writes a script that defines the required geometry. All that is made a little easier with the Belfry OpenSCAD Library (BOSL2).

Designing a part like this is a cinch with BOSL2.

BOSL2 has an extensive library of base shapes, advanced functions for manipulating models, and some really nifty tools for creating attachment points on parts and aligning components with one another. If that sounds handy for designing useful objects, you’re in for even more of a treat when you see their functions for gears, hinges, screws, and more.

There’s even one that covers bottle necks and caps. (Those are all standardized by the way, so it’s never been easier to interface to existing bottles or caps in a project.)

OpenSCAD really is very versatile software. It powers useful tools like this screw, washer, and nut generator as well as having more unusual applications like a procedural terrain generator. It’s free, so if you’ve never looked into it, check it out!

Vacuum Forming With 3D Printed Moulds And Sheets

February 18, 2025 by 12 Comments

Vacuum forming is perhaps one of the less popular tools in the modern maker arsenal, something which surprises us a bit because it offers many possibilities. We’ve created our own vacuum forms on 3D printed moulds for ages, so it’s interesting to see [Pisces Printing] following the same path. But what you might not realize at first is that the vacuum forming sheets themselves are also 3D printed.

The full video is below the break, and in it he details making a mould from PETG, and in particular designing it for easy release. The part he’s making is a belt guard for a table top lathe, and the PETG sheet he’s forming it from is also 3D printed. He makes the point that it’s by no means perfect, for example he shows us a bit of layer separation, but it seems promising enough for further experimentation.  His vacuum forming setup seems particularly small, which looks as though it makes the job of making a sheet somewhat simpler.

The cost of a vacuum forming sheet of whichever polymer is hardly high, so we can’t see this technique making sense for everyday use. But as we’ve seen in previous experiments, the printed sheets so make it easy to add color and texture to the final product, which obviously adds some value to the technique.

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A Unique Linear Position Sensor Using Magnetostriction

February 18, 2025 by 16 Comments

To the extent that you’re familiar with magnetostriction, you probably know that it’s what makes big transformers hum, or that it’s what tips you off if you happen to walk out of a store without paying for something. But magnetostriction has other uses, too, such as in this clever linear position sensor.

Magnetostriction is just the tendency for magnetic materials to change size or shape slightly while undergoing magnetization, thanks to the tiny magnetic domains shifting within the material while they’re aligning. [Florian B.]’s sensor uses a side effect of magnetostriction known as the Wiedenmann effect, which causes a wire to experience a twisting force if a current pulse is applied to it in a magnetic field. When the current pulse is turned off, a mechanical wave travels along the wire to a coil, creating a signal. The difference in time between sending the pulse and receiving the reflection can be used to calculate the position of the magnet along the wire.

To turn that principle into a practical linear sensor, [Florian B.] used nickel wire stretched tightly down the middle of a PVC tube. At one end is a coil of copper magnet wire, while the other end has a damper to prevent reflections. Around the tube is a ring-shaped cursor magnet, which can move up and down the tube. An exciter circuit applies the current pulse to the wire, and an oscilloscope is used to receive the signal from the wire.

This project still appears to be in the prototype phase, as evidenced by the Fischertechnik test rig. [Florian] has been working on the exciter circuit most recently, but he’s done quite a bit of work on optimizing the cursor magnet and the coil configuration, as well as designs for the signal amplifier. It’s a pretty neat project, and we’re looking forward to updates.

If you need a deeper dive into magnetostriction, [Ben Krasnow] points the way.