When Nearly Flat Isn’t Really Flat

December 6, 2023 by Jenny List 83 Comments

An aerial photo of the UK city of Milton Keynes — Is Mk really flat? Thomas Nugent, CC BY-SA 2.0.

From where I am sitting, the earth is flat. The floor that runs the length of the unit my hackerspace sits in is flat, the concrete apron behind it on which we test our Hacky Racers is flat, and a few undulations in terrain notwithstanding, it remains flat as I walk up the road towards Stony Stratford.

Of course, Hackaday hasn’t lost its mind and joined the conspiracy theorists, the earth is definitely spherical as has been known and proved multiple times since antiquity. But my trivial observation made in a damp part of Buckinghamshire still holds; that for a given value of flat which disregards a few lumps and bumps in the ground, my corner of the English city of Milton Keynes is pretty flat. Which leads from a philosophical discussion to an engineering one, if I can reasonably describe a city-sized area on an Earth-sized sphere as flat, how flat does a surface have to be to be considered flat? And from that stems a fascinating story of the evolution of precision machining. Continue reading “When Nearly Flat Isn’t Really Flat” →

Operate Your Own Nuclear Reactor, Virtually

December 6, 2023 by Al Williams 31 Comments

If you’ve ever wanted to operate your own nuclear reactor, you probably aren’t going to get one in your backyard shop. However, thanks to the University of Manchester, you can get a simulated one in your browser. The pressurized water reactor looks realistic and gives you controls that — we are fairly sure — are greatly simplified compared to the real thing.

We suggest you start with the tour before you start unless, you know, you’ve operated a reactor before. You have to balance the control rods, the coolant pumping, and the steam output to produce as much power as possible without melting the core.

If the reactor were real, the pressure vessel would weigh as much as two 747 jets! Despite the high-tech, the business end is a conventional steam generator. The only difference is that the steam is made by the heat of the nuclear reaction instead of by burning coal or gas.

To operate the reactor, you’ll turn on the coolant pumps and wait for the high-pressure liquid to reach 290 C. In real life, this takes about 8 hours, but lucky for us, the simulation is sped up. Once you reach the right temperature, you can lift the control rods to start generating heat. This will let you adjust the steam output to try to match the demand at any given time. But if you go out of bounds, the reactor will helpfully shut down. Of course, that doesn’t help your score.

We don’t know how realistic it is, but we do know Homer Simpson probably has fewer shutdowns than we do. There are different types of reactors, of course. Operating them may be difficult, but creating fuel for them is no simple task, either. Just maybe put out your candles before you start playing.

Ask Hackaday: Could Rating Airlines Stop Flights From Spreading Diseases?

December 6, 2023 by Lewin Day 82 Comments

A few weeks ago, I found myself the victim of flights from hell. My first flight was cancelled, leaving me driving home late at night, only to wake again for a red-eye the next morning. That was cancelled as well, with the second replacement delayed by a further hour. All in all I ended up spending a good ten hours extra in the airport surrounded by tired, sick, and coughing individuals, and ended up a full 16 hours late to my destination. On the return, I’d again tangle with delays, and by the weekend’s close, I’d contracted a nasty flu for my trouble.

All this had me riled up and looking for revenge. I had lost hours of my life to these frustrations, and the respiratory havoc claimed a further week of my working life. It had me realizing that we could surely improve the performance and hygiene of our airliners with a simple idea: a website called Flights From Hell.

Continue reading “Ask Hackaday: Could Rating Airlines Stop Flights From Spreading Diseases?” →

The Deere Disease Spreads To Trains

December 6, 2023 by Jenny List 37 Comments

If the right-to-repair movement has a famous story, it’s the familiar green and yellow John Deere tractor. Farmers and mechanics have done their own repairs as long as there have been tractors, but more recent Deeres have been locked down such that only Deere-authorised agents can fix them. It’s a trend that has hurt the value of a second-had Deere, but despite that it appears to be spreading within the machinery world. Now there’s a parallel on Polish railways, as Polish-made Newag electric passenger trains have been found to give errors when serviced by non-Newag workshops.

At the heart of the problem are the PLCs which control all aspects of a modern rail traction system, which thanks to a trio of Poland and Germany based researchers have been found to play a range of nasty tricks. They’ll return bogus error codes after a set date which would presumably be reset by the official service, if the train has been laid up for a while, or even if they are detected via GPS to have visited a third-party workshop. Their work will be the subject of a talk at 37C3 which should be worth watching out for.

It will be especially interesting to juxtapose the reaction to this revelation with cases such as the Deere tractors, because of course Poland is part of the European Union. We’re not specialist EU competition lawyers, but we know enough to know that the EU takes a dim view of these types of practices and has been strong on the right to repair. Who knows, Polish trains may contribute further to the rights of all Europeans.

Dry Ice From Seashells, The Hard (But Cheap) Way

December 6, 2023 by Dan Maloney 11 Comments

[Hyperspace Pirate] wants to make his own dry ice, but he wants it to be really, really cheap. So naturally, his first stop is… the beach?

That’s right, the beach, because that’s where to find the buckets of free seashells that he turned into dry ice. Readers may recall previous efforts at DIY dry ice, which used baking soda and vinegar as a feedstock. We’d have thought those were pretty cheap materials for making carbon dioxide gas, but not cheap enough for [Hyperspace Pirate], as the dry ice he succeeded in making from them came out to almost ten bucks a pound. The low yield of the process probably had more to do with the high unit cost, in truth, so cheaper feedstocks and improved yield would attack the problem from both ends.

With a supply of zero-cost calcium carbonate from the beach and a homemade ZVS-powered induction heater tube furnace at the ready, [Hyperspace Pirate] was ready to make quicklime and capture the CO₂ liberated in the process. That proved to be a little more difficult than planned since the reaction needed not just heat but a partial vacuum to drive the CO₂ off. An oil-free vacuum pump helped, yielding a little CO₂, but eventually he knuckled under and just doused the shells in vinegar. This had the fun side effect of creating calcium acetate, which when distilled not only corrodes the copper still plumbing but also makes a lousy but still flammable grade of acetone. Once enough CO₂ was stored in a couple of beach balls, the process of cooling and condensing it into dry ice was pretty much the same as the previous method, except for taking advantage of the Joule-Thomson cryocooler he built a while back.

The result is a hundred or so grams of dry ice snow, which isn’t great but still shows promise. [Hyperspace Pirate] feels like the key to improving this process is more heat to really drive the calcination reaction. Might we suggest a DIY tube furnace for that job?

Continue reading “Dry Ice From Seashells, The Hard (But Cheap) Way” →

Directional Antenna Stands Tall

December 5, 2023 by Al Williams 7 Comments

When you think of directional ham radio antennas, you probably think of a Yagi, cubical quad, or a log-periodic antenna. These antennas usually are in a horizontal configuration up on a high tower. However, it is possible to build beams with a vertical orientation and, for some lower frequencies, it is far more practical than mounting the elements on a boom. [DXCommander] shows us his 40 meter two-element vertical antenna build in the video below.

A typical Yagi is just a dipole with some slightly longer or shorter elements to direct or reflect the signal. A normal vertical, however, is nothing more than half of a dipole that uses the ground as the other half. So it is possible to create reflectors and directors with a vertical-driven element.

Continue reading “Directional Antenna Stands Tall” →

Inside A Rubidium Frequency Standard

December 5, 2023 by Al Williams 14 Comments

We think of crystals as the gold standard of frequency generation. However, if you want real precision, you need something either better than a crystal or something that will correct for tiny errors — often called disciplining the oscillator. [W3AXL] picked up a rubidium reference oscillator on eBay at a low cost, and he shows us how it works in the video you can see below. He started with a GPS-disciplined oscillator he had built earlier and planned to convert it to discipline from the rubidium clock.

The connector looks like a D-shell connector superficially, but it has a coax connector in addition to the usual pins. The device did work on initial powerup, and using a lissajous pattern to compare the existing oscillator with the new device worked well.

Continue reading “Inside A Rubidium Frequency Standard” →