Author: Jenny List

2956 Articles

Magic Eye Images In Your Spreadsheet

December 8, 2024 by 56 Comments

Ah, the 1990s. It was a simpler time, when the web was going to be democratic and decentralised, you could connect your Windows 95 PC to the internet without worrying much about it being compromised, and freely download those rave music MP3s. Perhaps you had a Global Hypercolor T-shirt and spent a summer looking like the sweaty idiot you were, and it’s certain you desperately squinted at a magic eye image in a newspaper (remember newspapers?) trying to see the elephant or whatever it was. If you’d like to relive that experience, then [Dave Richeson] has a magic eye image generator for Microsoft Excel.

Unfortunately a proportion of the population including your scribe lack the ability to see these images, a seemingly noise-like pattern of dots on the page computationally generated to fool the visual processing portion of your brain to generate a 3D image. The Excel sheet allows you to create the images, but perhaps most interesting is the explanation of the phenomenon and mathematics which go along with it. Along with a set of test images depicting mathematical subjects, it’s definitely worth a look.

You can download a template and follow the instructions, and from very limited testing here we can see that LibreOffice doesn’t turn its nose up at it, either. Give it a go, and learn afresh the annoyance of trying to unfocus your eyes.

The Audiophile Carrot

December 8, 2024 by 31 Comments

The widely quoted carrot factoid that the vegetable’s orange colour is the result of patriotic Dutch farmers breeding them that way may be an urban myth, but it’s certainly true that they can pass an audio signal in a time of need. [Julian Krause] follows up on a Reddit meme of a carrot being used to join two phono plugs, and appears to find the organic interconnect to be of good quality.

We had to admit a second look at a calendar to be sure that it’s not April 1st, but while his manner is slightly tongue in cheek it seems he’s really characterising the audio performance of a carrot. What he finds is a bit of attenuation, some bass cut, and an intrusion of RF interference pickup, but surprisingly, not a bad distortion figure.

Of course, we’re guessing the real point of the exercise is to poke fun at the world of excessive hi-fi equipment, something we’ve been only too glad to have a go at ourselves from time to time. But if the tests are to be taken at face value it seems that in a pinch, a carrot will do as a means to hook together line level audio cables, no doubt lending a sweet and crunchy overtone to the result. The video is below the break, for your entertainment.

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A Look Inside IKEA’s Vallhorn Motion Sensor Teardown

December 7, 2024 by 24 Comments

A good source of hackable home automation parts has come for a while in the form of inexpensive modules offered by large retailers such as Lidl, or IKEA. They’re readily available and easy to play with, they work with open source hubs, so what’s not to like! As an example, [Circuit Valley] has an IKEA Vallhorn motion sensor for a teardown, it’s as you might expect, a passive infrared sensor (PIR) sensor coupled with a Zigbee interface.

Inside the ultrasonic welded case is a small PCB and a Fresnel lens on the inside of the top cover, and a small PCB for the electronics. We applaud the use of a Swiss Army knife can opener as a spudger. The interesting part comes in identifying the individual components: the Silicon Labs EFR32MG21 SoC is easy enough, but another mystery 8-pin chip is more elusive. The part number suggests an Analog Devices op-amp for signal conditioning the PIR output, but the pinout seems not to support it and from here we think it’s too expensive a part for a budget item like this.

There’s a handy header for talking to the SoC, which we’d love to report is open and ready to be hacked, but we’re not getting too optimistic. Even if not hackable though, we’re guessing many of you find uses for these things. Continue reading “A Look Inside IKEA’s Vallhorn Motion Sensor Teardown” →

A Hundred Year Old Solid State Amplifier

December 5, 2024 by 21 Comments

Conventional wisdom has it that the solid state era in electronics began in 1948 with the invention of the transistor, or if you wish to split hairs, with the 1930s invention by the Russian [Oleg Losev] of an early form of tunnel diode. But there’s an earlier amplifier technology that used a solid state circuit which is largely forgotten, and [AWA Communication Technologies Museum] has featured it in a new video. We’re talking of course about the carbon microphone amplifier, a piece of telephone technology which made its way into consumer electronics.

The carbon microphone is a container of loosely packed carbon granules acted upon by a diaphragm. Vibrations from sound compress and decompress the granules, changing the electrical resistance of the carbon. It was the standard microphone used in telephone handsets for most of the twentieth century. Being a resistor it can be placed in a potential divider circuit that produces some significant voltage swings, so when the vibrations come from a high-impedance earpiece it can make an amplifier. It’s not a very good amplifier, it has lousy bandwidth, distortion, and noise characteristics, but it was just about good enough to be paired with a 1920s crystal set. In the video below the break we see a variety of the devices, and even hear them in action sounding very tinny indeed. At the time it must have seemed miraculous to be at the forefront of the new technology though, and we can’t help admiring some of the construction intricacies.

Carbon microphone amplifiers may be rare today, but for all that we’ve touched on them before.

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Unconventional Oil Production, All You Need To Know

December 5, 2024 by 48 Comments

It’s fair to say that climate change is perhaps the greatest challenge facing our planet, and while much attention is directed towards solutions to the problems it presents, perhaps there’s less attention given to the the other side of the equation in the hydrocarbon industry. For example we all think we know something about hydraulic fracking wells, but how much do we really know?

[John Thurmond] is a geologist who has recently completed a long career in the oil industry, and he gave an informative talk on the matter at the summer’s EMF Camp in the UK. It makes for an interesting watch, as he leads the viewer through the process in detail, before discussing what should and shouldn’t cause worry.

We learn that fracking has two parts: first the hydraulic fracking itself, and then the re-injection of the toxic fracking well water released from underground along with the oil or gas. It seems the water released from the rocks a 10,000 ft depth contains all manner of toxic and even radioactive compounds, and the usual means of disposal is to inject it back into the ground at a much lower depth. He makes the point that while the hazards associated with the fracking are low, those of the re-injection are high.

The talk finishes up with perhaps the most interesting point, by looking at the nature of opposition to fracking, or indeed any other controversial development. Such things are inevitably surrounded by a swirling mess of half-truths, and his point is that identifying those easily deflected as not true is key to understanding the whole thing. It’s presented from an expert and factual perspective that’s so often lacking in this arena, and thus we think it’s worth a watch.

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Runway-to-Space No More, Reaction Engines Cease Trading

December 4, 2024 by 49 Comments

It’s not often that the passing of a medium sized company on an industrial estate on a damp and soggy former airfield in southern England is worthy of a Hackaday mention, but the news of hypersonic propulsion company Reaction Engines ceasing trading a few weeks ago is one of those moments that causes a second look. Their advanced engine technology may have taken decades to reach the point of sustainable testing, but it held the promise of one day delivering true spaceplanes able to take off from a runway and fly to the edge of the atmosphere before continuing to orbit. It seems their demise is due to a failure to secure more funding.

We’ve written about their work more than once in the past, of their hybrid engines and the development of the advanced cooling system required to deliver air to a jet engine working at extreme speeds.  The rights to this tech will no doubt survive the company, and given that its origins lie in a previously canceled British Aerospace project it’s not impossible that it might return. The dream of a short flight from London to Sydney may be on hold for now then.

Writing this from the UK there’s a slight air of sadness about this news, but given that it’s not the first time a British space effort has failed, we should be used to it by now.

Header: Science Museum London / Science and Society Picture Library, CC BY-SA 2.0

From Cans To Sheet Metal, With Ease

December 2, 2024 by 56 Comments

Aluminium drinks cans make a great source of thin sheet metal which can be used for all manner of interesting projects, but it’s safe to say that retrieving a sheet of metal from a can is a hazardous process. Cut fingers and jagged edges are never far away, so [Kevin Cheung]’s work in making an easy can cutter is definitely worth a look.

Taking inspiration from a rotary can opener, he uses a pair of circular blades in an adjustable injection moulded plastic frame. If you’ve used a pipe cutter than maybe you are familiar with the technique, as the blade rotates round the can a few times it slowly scores and cuts through the metal. Doing the job at both ends of the can reveals a tube, which cna be then cut with scissors and flattened to make a rectangular metal sheet. Those edges are probably sharp, but nothing like the jagged finger-cutters you’d get doing the same by hand. The full video can be seen below the break, and the files to 3D print the plastic parts of the cutter can be found at the bottom of a page describing the use of cans to make a shingle roof.

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