Author: Al Williams

3907 Articles

VNAs And Crystals

December 6, 2024 by 7 Comments

Oscillators may use crystals as precise tuned circuits. If you have a vector network analyzer (VNA) — or even some basic test equipment — you can use it to learn the parameters of a crystal. [All Electronics Channel] has the details, and you can see how in the video below.

There was a time when a VNA was an exotic piece of gear, but these days they are relatively common. Crystal parameters are important because crystals have a series resonance and a parallel resonance and they are not at the same frequency. You also may need to know how much loading capacitance you have to supply to get the crystal at the right frequency.

Sometimes, you want to pull the crystal frequency, and the parameters will help you figure that out, too. It can also help if you have a crystal specified as series in a parallel-mode oscillator or vice versa.

If you don’t have a VNA, you can use a tracking signal generator, as [Grégory] shows towards the middle of the video. The quality of a tuned circuit depends on the Q factor, and crystals have a very high Q factor.

We did something similar in 2018. The other way to pull a crystal frequency is a bit extreme.

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How Corroded Can A Motherboard Be?

December 5, 2024 by 9 Comments

We will admit it. If we found a 386 motherboard as badly corroded as the one [Bits und Bolts] did, we would trash it—not him, though. In fact, we were surprised when he showed it and said he had already removed most of it in vinegar. You can check the board out in the video below.

There was still a lot of work to do on both the front and back of the board. The motherboard was a Biostar and while it isn’t as dense as a modern board, it still had plenty of surface mount parts jammed in.

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A Brief History Of Teleportation

December 5, 2024 by 81 Comments

OK, I know. We don’t have practical teleportation. But that hasn’t stopped generations of science fiction authors and movie makers from building stories around it. If you ask most ordinary people, they’d tell you the idea originated with the Star Trek transporter, but that’s far from the truth. So when did people start thinking about teleporting?

Ground Rules

Maybe it isn’t fair, but I will draw the line at magic or unexplained teleportation. So “The Tempest”, for example, doesn’t use technology but magic. To get to Barsoom, John Carter wished or slept to teleport to Mars. So, while technology might seem like magic, we’re focusing on stories where some kind of machine can send something — usually people — to somewhere else.

Of course, there’s a fine line between pure magic and pure technology where they overlap. For example, in the opera “Der Ring des Nibelungen”, a magic helmet gives people powers, including that of teleportation. While you could argue that Tarnhelm — the name of the magic helmet — was a technological artifact, it is still explained by magic, not science.

Some systems need a transmitter and a receiver. Sometimes, you only need the transmitter. Sometimes, you can only teleport within a limited range, but other make-believe systems can transport an entire starship across the galaxy.

Early Teleporters

The Man without a Body is a story from 1877 in which a scientist is able to transmit a cat via a telegraph wire. Encouraged, he attempts the same feat with himself, but the battery dies in the middle, leaving him with a disembodied head. The ending is decidedly devoid of science, but the story is possibly the earliest one with a machine sending matter across a distance.

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LongChat For Ham Radio

December 4, 2024 by 37 Comments

There was a time when ham radio operators were known for having long conversations over the radio — rag chewing, as they called it. A new program, LongChat, is a new entry into the ham radio software world that could bring chatting back to ham radio. [Tech Minds] has a video covering it (and using it), which you can see below.

While some people do talk using microphones or Morse code keys, there are a lot of digital modes now. Some, like RTTY or PSK31, can support conversations, but the more popular ones, like FT-8, are very stripped down. Your computer exchanges basic information with the other station’s computer, and that’s it.

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Fluke Meter Fails With A Simple Problem

December 4, 2024 by 19 Comments

[TheHWcave] found a Fluke 27 multimeter that looked like it had had quite a rough life. At first, the display flashed an overload indicator until he gave it a good smack—or, as he likes to call it, percussive maintenance. Even then, it would not give good readings, so it was time to open it up.

The display did work, so the obvious theory was something wrong with the analog board. Removing the shields showed what looked like a normal enough PCB. Or at least, the components looked fine. But on the solder side of the board, there was some corrosion on two contacts, so some careful cleaning and resoldering fixed the meter to be as good as new on at least some scales.

Tracing the pins, the corrosion put a resistor between two pins of an op-amp. The only remaining problem was the milliamp scale, but that was a simple blown fuse in the line. Since it was working, it was worth some time to clean up the ugly exterior, which is only cosmetic but still worth a little effort. He left the plastic case cracked and beaten, but he put a lot of effort into clearing up the display window.

You might wonder why you’d fix a meter when you can get one so cheap. However, these name-brand meters are high-quality and new, quite expensive. Even older ones can be worth the effort. While you usually don’t need an X-ray machine to fix something like this, it can’t hurt.

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A Month Without IPV4 Is Like A Month Without…

December 3, 2024 by 89 Comments

Recently, there was a Mastodon post from [nixCraft] challenging people to drop their NAT routers for the month of November and use only IPv6. What would it be like to experience “No NAT November?” [Alex Haydock] decided to find out.

What did he learn? You’d imagine he’d either wholeheartedly embrace IPv6 or stagger back in and warn everyone not to mess with their configuration. Instead, he recommends you go IPv6 mostly. He notes he is only talking about a home network, not necessarily networks for a big company or an Internet carrier. That’s a different topic.

IPv6 has been around since 1998, but it has been slow to catch on. However, OS support seems universal at this point. [Alex] was able to easily switch on IPv6 only using Windows, macOS, and several Linux flavors. He didn’t use any Android devices, but they should be OK. His iOS phones were fine.

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3D Printing Threaded Replacements

December 3, 2024 by 20 Comments

Printing an object with threads is nothing new. If you know the specifications on the other thread or you are in control of it, no problem. But [Shop Therapy] wanted to print parts that mate with an existing unknown thread. Out come the calipers.

The first measurement is the height. He rounded that up in the video but mentioned in the comments that it should really be a little smaller so that it seats properly.

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