Author: Jenny List

2967 Articles

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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The Automatic Battery Charger You Never Knew You Needed

December 2, 2024 by 47 Comments

When we saw [Max.K]’s automatic NiMh battery charger float past in the Hackaday tips line, it brought to mind a charger that might be automatic in the sense that any modern microcontroller based circuit would be; one which handles all the voltages and currents automatically. The reality is far cooler than that, a single-cell charger in which the automatic part comes in taking empty cells one by one from a hopper on its top surface and depositing them charged in a bin at the bottom.

Inside the case is a PCB with an RP2040 that controls the whole shop as well as the charger circuitry. A motorized cam with a battery shaped insert picks up a cell from the bin and moves it into the charger contacts, before dumping it into the bin when charged. What impresses us it how slick this device is, it feels like a product rather than a project, and really delivers on the promise of 3D printing. We’d want one on our bench, and after watching the video below the break, we think you will too.

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A Free Speed Boost For Your Pi 5

December 2, 2024 by 25 Comments

The world of the overclocker contains many arcane tweaks to squeeze the last drops of performance from a computer, many of which require expert knowledge to understand. Happily for Raspberry Pi 5 owners the Pi engineers have come up with a set of tweaks you don’t have to be an overclocker to benefit from, working on the DRAM timings to extract a healthy speed boost. Serial Pi hacker [Jeff Geerling] has tested them and thinks they should be good for as much as 20% boost on a stock board. When overclocked to 3.2 GHz, he found an unbelievable 32% increase in performance.

We’re not DRAM experts here at Hackaday, but as we understand it they have been using timings from the Micron data sheets designed to play it safe. In consultation with Micron engineers they were able to use settings designed to be much faster, we gather by monitoring RAM temperature to ensure the chips stay within their parameters. Best of all, there’s no need to get down and dirty with the settings, and they can be available to all with a firmware update. It’s claimed this will help Pi 4 owners to some extent as well as those with a Pi 5, so even slightly older boards get some love. So if you have a Pi 5, don’t wait for the Pi 6, upgrade today, for free!

When Transistor Count Mattered

December 1, 2024 by 29 Comments

Many Hackaday readers have an interest in retro technology, but we are not the only group who scour the flea markets. Alongside us are the collectors, whose interest is as much cultural as it is technological, and who seek to preserve and amass as many interesting specimens as they can. From this world comes [colectornet], with a video that crosses the bridge between our two communities, examining the so-called transistor wars of the late 1950s and through the ’60s. Just as digital camera makers would with megapixels four or five decades later, makers of transistor radios would cram as many transistors as they could into their products in a game of one-upmanship.

A simple AM transistor radio can be made with surprisingly few components, but for a circuit with a reasonable performance they suggest six transistors to be the optimal number. If we think about it we come up with five and a diode, that’s one for the self-oscillating mixer, one for IF, an audio preamplifier, and two for the audio power amplifier, but it’s possible we’re not factoring in the relatively low gain of a 1950s transistor and they’d need that extra part. In the cut-throat world of late ’50s budget consumer electronics though, any marketing ploy was worth a go. As the price of transistors tumbled but their novelty remained undimmed, manufacturers started creating radios with superfluous extra transistors, even sometimes going as far as to fit transistors which served no purpose. Our curious minds wonder if they bought super-cheap out-of-spec parts to fill those footprints.

The video charts the transistor wars in detail, showing us a feast of tiny radios, and culminating in models which claim a barely credible sixteen transistors. In a time when far more capable radios use a fraction of the board space, the video below the break makes for a fascinating watch.

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