Author: Jenny List

2979 Articles

So What’s All This HaLow Long-Range WiFi About Then?

May 26, 2024 by 18 Comments

We’re all used to wireless networking, but if there’s one thing the ubiquitous WiFi on 2.4 or 5 GHz lacks, it’s range. Inside buildings, it will be stopped in its tracks by anything more than a mediocre wall, and outside, it can be difficult to connect at any useful rate more than a few tens of metres away without resorting to directional antennas and hope. Technologies such as LoRa provide a much longer range at the expense of minuscule bandwidth, but beyond that, there has been little joy. As [Andreas Spiess] points out in a recent video though, this is about to change, as devices using the so-called HaLow or IEEE 802.11ah protocol are starting to edge into the realm of affordability.

Perhaps surprisingly, he finds the 5 GHz variant to be best over a 1km test with a far higher bandwidth. However, we’d say that his use of directional antennas is something of a cheat. Where it does come into its own in his tests, though, is through masonry, with far better penetration across floors of a building. We think that this will translate to better outdoor performance when the line of sight is obstructed.

There’s one more thing he brings to our attention, which seasoned users of LoRA may already be aware of. These lower frequency allocations are different between the USA and Europe, so should you order one for yourself, it would make sense to ensure you have the appropriate model for your continent. Otherwise, we look forward to more HaLow devices appearing and the price falling even further because we think this will lead to some good work in future projects.

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How Do You Fill The 1N34 Void?

May 26, 2024 by 31 Comments

The germanium point contact diode, and almost every semiconductor device using germanium, is now obsolete. There was a time when almost every television or radio would have contained one or two of them, but the world has moved on from both analogue broadcasting and discrete analogue electronics in its lower-frequency RF circuitry. [TSBrownie] is taking a look at alternatives to the venerable 1N34A point-contact diode in one of the few places a point-contact diode makes sense, the crystal radio.

In the video below the break, he settles on a slightly more plentiful Eastern European D9K as a substitute after trying a silicon rectifier (awful) and a Schottky diode (great in theory, not so good in practice). We’ve trodden this path in the past and settled on a DC bias to reduce the extra forward voltage needed for a 1N4148 silicon diode to conduct because, like him, we found a Schottky disappointing.

The 1N34 is an interesting component, and we profiled its inventor a few years ago. Meanwhile, it’s worth remembering that sometimes, we just have to let old parts go.

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How A DOS Format Blunder Revealed Some Priceless Source Code

May 25, 2024 by 14 Comments

As those of us who worked in the consumer software world back when physical media was king can attest, when a master disc has been sent for duplication and distribution there is no turning back from whatever code is in the hands of thousands of users. Usually such worries were confined to bugs or inadvertently sending out pre-release software versions, but [Lance Ewing] is here with the story of how Sierra On-Line once inadvertently released most of the source code for their game engine.

If you have some 720k floppy disk versions of the 1988 game Space Quest II, the first disk in the set appears to have nothing out of the ordinary, but a closer look reveals that the free space on the disk reported by DOS is greater than its used space. Diving in to the disk block contents with a hex editor reveals that many of the unused blocks in fact contain C code, and some further detective work allows the recovery of a not-quite complete set of source files for the company’s AGI, or adventure game interpreter. They had been left behind when the original master disk had been emptied by deleting them, rather than by formatting it afresh.

In commercial terms this would in 1988 have been something of a disaster for Sierra had it been discovered at the time, because it was the cornerstone of their success. As it was we’re told the code sat peacefully undetected until 2016, since when it has proved invaluable to those interested in computer game archaeology. Or did it? We’ll never know if a sharp-eyed competitor snagged it, and kept quiet.

Of course, these days, there are game engines that are open source. Some of them are very modern. Others… not so much.

Is This The World’s Smallest Multichannel Voltmeter?

May 22, 2024 by 8 Comments

The instrument which probably the greatest number of Hackaday readers own is likely to be the humble digital multimeter. They’re cheap and useful, but they’re single-channel, and difficult to incorporate into a breadboard project. If you’ve ever been vexed by these limitations then [Alun Morris] has just the project for you, in the world’s smallest auto-ranging multichannel voltmeter. It’s a meter on a tiny PCB with a little OLED display, and as its name suggests, it can keep an eye on several voltages for you.

At its heart is an ATtiny1614 microcontroller on a custom PCB, but for us the part we most like lies not in that but in the prototype version made on a piece of protoboard. There’s considerable soldering skill in bending surface mount components to your will on this material, and though these aren’t quite the smallest parts it’s still something that must have required some work under the magnifier.

All of the code and hardware details can be found in the GitHub repository, and for your viewing pleasure there’s a video showing it in action which we’ve placed below.

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Lost Foam Casting In Action

May 19, 2024 by 19 Comments

Even though not all of us will do it, many of us are interested in the art of casting metal. It remains a process that’s not out of reach, though, especially for metals such as aluminium whose melting points are reachable with a gas flame. The video below the break takes us through the aluminium casting process by showing us the lost-foam casting of a cylinder head for a BSA Bantam motorcycle.

The foam pattern is CNC milled to shape, and the leftover foam swarf is removed with a hot wire. The pattern is coated with a refractory coating of gypsum slurry, and the whole is set up in a tub packed with sand. We get the impression that the escaping gasses make this a tricky pour without an extra sprue, and indeed, they rate it as not perfect. The cooling fins on the final head are a little ragged, so it won’t be the part that goes on a bike, but we can see with a bit of refining, this process could deliver very good results.

For this pour, they use a gas furnace, but we’ve seen it done with a microwave oven. Usually, you are losing wax, not foam, but the idea is the same.

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A Tiny Tuner For The Low Power Ham

May 18, 2024 by 10 Comments

Something that all radio amateurs encounter sooner or later is the subject of impedance matching. If you’d like to make sure all that power is transferred from your transmitter into the antenna and not reflected back into your power amplifier, there’s a need for the impedance of the one to match that of the other. Most antennas aren’t quite the desired 50 ohms impedance, so part of the standard equipment becomes an antenna tuner — an impedance matching network. For high-power hams these are big boxes full of chunky variable capacitors and big air cored inductors, but that doesn’t exclude the low-power ham from the impedance matching party. [Barbaros Aşuroğlu WB2CBA] has designed the perfect device for them: the credit card ATU.

The circuit of an antenna tuner is simple enough, two capacitors and an inductor in a so-called Pi-network because of its superficial resemblance to the Greek letter Pi. The idea is to vary the capacitances and inductance to find the best match, and on this tiny model it’s done through a set of miniature rotary switches. There are a set of slide switches to vary the configuration or switch in a load, and there’s even a simple matching indicator circuit.

We like this project, in that it elegantly provides an extremely useful piece of equipment, all integrated into a tiny footprint. It’s certainly not the first ATU we’ve brought you.

Thanks [ftg] for the tip!

How Italians Got Their Power

May 18, 2024 by 28 Comments

We take for granted that electrical power standards are generally unified across countries and territories. Europe for instance has a standard at 230 volts AC, with a wide enough voltage acceptance band to accommodate places still running at 220 or 240 volts. Even the sockets maintain a level of compatibility across territories, with a few notable exceptions.

It was not always this way though, and to illustrate this we have [Sam], who’s provided us with a potted history of mains power in Italy. The complex twists and turns of power delivery in that country reflect the diversity of the power industry in the late 19th and early 20th century as the technology spread across the continent.

Starting with a table showing the impressive range of voltages found across the country from differing power countries, it delves into the taxation of power in Italy which led to two entirely different plug standards, and their 110/220 volt system. Nationalization may have ironed out some of the kinks and unified 220 volts across the country, but the two plugs remain.

Altogether it’s a fascinating read, and one which brings to mind that where this is being written you could still find a few years ago some houses with three sizes of the archaic British round-pin socket. Interested in the diversity of plugs? We have a link for that.