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Keeping Alive The Future Of Cars, 1980s Style

Here at Hackaday we’re a varied bunch of writers, some of whom have careers away from this organ, and others whose work also appears on the pages of other publications in different fields. One such is our colleague [Lewin Day], and he’s written a cracking piece for The Autopian about the effort to keep an obscure piece of American automotive electronic history alive. We think of big-screen control panels in cars as a new phenomenon, but General Motors was fitting tiny Sony Trinitron CRTs to some models back in the late 1980s. If you own one of these cars the chances are the CRT is inoperable if you’ve not encountered [Jon Morlan] and his work repairing and restoring them.
Lewin’s piece goes into enough technical detail that we won’t simply rehash it here, but it’s interesting to contrast the approach of painstaking repair with that of replacement or emulation. It would be a relatively straightforward project to replace the CRT with a modern LCD displaying the same video, and even to use a modern single board computer to emulate much of a dead system. But we understand completely that to many motor enthusiasts that’s not the point, indeed it’s the very fact it has a frickin’ CRT in the dash that makes the car.We’ll probably never drive a 1989 Oldsmobile Toronado. But we sure want to if it’s got that particular version of the future fitted.
Lewin’s automotive writing is worth watching out for. He once brought us to a motorcycle chariot. […]

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An Open-Source Gaming Mouse

It’s a shame, that peripherals sold as of higher performance for gaming so often deliver little but aggressive styling. [Wareya] became frustrated with the fragile switches on his choice of gaming mouse, so decided to design his own. In the video that he’s placed below the break, he takes us through all the many choices and pitfalls inherent to these devices
After quite a few iterations he arrived upon a design featuring an RP2040 and an optical sensor easily found in relatively inexpensive mice. The whole design is open source and can be found in a GitHub repository, but for us perhaps the most interesting part of the explanation lies in the use of a three-contact switch, and how the third contact is used to aid in debouncing. In an application in which latency is of paramount importance this is a key design feature of a gaming mouse.
Perhaps it’s a mark of how good computer mice are in general that we see so relatively few projects building them from scratch rather than modifying exiting ones, but despite that a few have made it to these pages.
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How Do You Make A Repairable E-Reader

Mobile devices have become notorious for their unrepairability, with glued-together parts and impossible-to-reach connectors. So it’s refreshing to see something new in that field from the e-book reader brand Kobo in the form of a partnership with iFixit to ensure that their new reader line can be fixed.
Naturally, we welcome any such move, not least because it disproves the notion that portable devices are impossible to make with repairability in mind. However, the linked article is especially interesting because it includes a picture of a reader, and its cover has been removed. We’re unsure whether or not this is one of the new ones, but it’s still worth looking at it with reparability eyes. Just what have they done to make it easier to repair?

The first thing which strikes us is that the screws securing the board are larger than on many devices and positioned for easy access. Then the battery connector isn’t the tiny snap-in connector we’re used to seeing on phones, but wires and an easy-to-use small two-pin plug. The digitiser and screen cables remain flexible PCB connectors, but despite finding those flip-up latches to be fragile at best, we’re guessing there’s little alternative to be found there.
We hope that these readers will be successful enough that other manufacturers may take up the idea and even that it might educate the public that such a thing is possible. […]

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M17 Digital Communications Go From Strength To Strength

The world of amateur radio is like many other fields in that there has been a move underway from analogue to digital modes. In fact, amateur radio has often led the way in digital innovation.  There’s a snag, though: many of the digital speech modes are proprietary. To address this along comes the M17 project, an effort to create an open digital communication protocol for radio amateurs. We’ve looked at them more than once in the past few years, and as they’ve come up with several pieces of new hardware it’s time for another peek.
First up is the Remote Radio Unit, described as “a comprehensive, UHF FM/M17 “repeater in a box,” optimally designed for close antenna placement, enhancing signal strength and reliability.” The repeater forms the “other half” of the UHF handheld radio chain and will be crucial to the uptake of the protocol.

Then there’s OpenHT , their take on an SDR dual-band handheld radio for M17, and perhaps most interestingly for radio amateurs with existing radios, the Module 17 and its miniaturised Micro17 cousin, which are encoders and modems for any radio capable of handling 9600 baud serial communication.
You can read some of our previous M17 coverage here, and it’s very encouraging to see that this project is going places. If you want to see what they’ve been up to lately, check out their YouTube channel which has some older tests including the one below.
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Who’s Afraid Of A CRT?

Older consumer electronic devices follow a desirability curve in which after they fall from favour they can’t be given away. But as they become rarer, they reach a point at which everyone wants them. Then, they can’t be had for love nor money. CRT TVs are now in the first stage, they’re bulky and lower-definition than modern sets, and thus thrift stores and dumpsters still have them in reasonable numbers. To retrogamers and other enthusiasts, this can be a bonanza, and when he saw a high-end late-model JVC on the sidewalk [Chris Person] wasted no time in snapping it up. It worked, but there were a few picture issues, so he set about fixing it.

The write-up is largely a tale of capacitor-swapping, as you might expect from any older electronics, and it results in a fine picture and a working TV. But perhaps there’s another story to consider there, in that not so many of us here in 2024 are used to working with CRTs. We all know that they conceal some scary voltages, and indeed, he goes to significant lengths to discharge his CRT. It’s worth remembering though, that there’s not always a need to discharge the CRT if no attempt will be made to disconnect it, after all the connector and cable to the flyback transformer are secured by hefty insulation for a good reason. It’s a subject we’ve looked at here at Hackaday in the past. You could argue that, in some ways, newer TVs are harder to get into than these old CRTs. […]

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A Bend Sensor Developed With 3D Printer Filament

PhD students spend their time pursuing whatever general paths their supervisor has given them, and if they are lucky, it yields enough solid data to finally write a thesis without tearing their hair out. Sometimes along the way they result in discoveries with immediate application outside academia, and so it was for [Paul Bupe Jr.], whose work resulted in a rather elegant and simple bend sensor.
The original research came when shining light along flexible media, including a piece of transparent 3D printer filament. He noticed that when the filament was bent at a point that it was covered by a piece of electrical tape there was a reduction in transmission, and from this he was able to repeat the effect with a piece of pipe over a narrow air gap in the medium.
Putting these at regular intervals and measuring the transmission for light sent along it, he could then detect a bend. Take three filaments with  the air-gap-pipe sensors spaced to form a Gray code, and he could digitally read the location.
He appears to be developing this discovery into a product. We’re not sure which is likely to be more stress, writing up his thesis, or surviving a small start-up, so we wish him luck. […]

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Rabbit Sighted In The Wild

Here at Hackaday we’re suckers for old abandoned technologies, the more obscure the better. The history of the telephone has plenty to capture our attention, and it’s from that arena that something recently floated past our timeline. [IanVisits] reports a sighting of a Rabbit in a London Underground station. The bunny in question definitely isn’t hopping though, it’s been dead for more than three decades. It’s a base station for a failed digital mobile phone system.
We’ve had a look in the past at CT2, the system this Rabbit base station once formed part of. It was an attempt to make an inexpensive phone system by having the handsets work with fixed base stations rather than move from cell to cell. It was one of the first public digital mobile phone systems, but the convenience of a phone that could both receive calls and make them anywhere without having to find a base station meant that GSM phones took their market.
The one in Seven Sisters tube station is a bit grubby looking, but it’s not the only survivor out there in the field. We have to admit to being curious as to whether it’s still powered on even though its backhaul will be disconnected, as in our experience it’s not uncommon for old infrastructure to be left plugged into the wall for decades, unheeded. Does anyone fancy sniffing for it with a Flipper Zero? […]

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Do You Trust Your Cheap Fuses?

When a fuse is fitted in a power rail, it gives the peace of mind that the circuit is protected. But in the case of some cheap unbranded fuses of the type that come in kits from the usual online suppliers that trust can be illusory, as they fail to meet the required specification.
[Andreas Speiss] has used just these fuses for protection for years as no doubt have many of you, so it was something of a shock for him to discover that sometimes they don’t make the grade. He’s taken a look at the issue for himself, and come up with an accessible way to test your fuses if you have any of those cheap ones.
It’s an interesting journey into the way fuses work, as we’re reminded that the value written on the fuse isn’t the current at which it blows but the maximum it’s intended to take. The specification for fuses should have a graph showing how quickly one should blow at what currents above that level, and the worry was that this time would be simply too long for the cheap ones.
In the video below the break he looks at the various set-ups required to test a fuse, and instead of an bank of large power supplies he came up with a circuit involving an 18650 cell and three one ohm resistors in parallel. The resulting 1/3 ohm resistor should pass in the region of 10 A when connected across the 18650, so with a 5 A fuse in that circuit and a storage ‘scope he’s able to quickly test a few candidates. He found that the cheap fuses he had were slower to blow than a Bosch part, but weren’t as worrisome as he’d at first thought. If you have any of these parts, maybe you should take a look at them too?

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Bye Bye Green Screen, Hello Monochromatic Screen

It’s not uncommon in 2024 to have some form of green background cloth for easy background effects when in a Zoom call or similar. This is a technology TV and film studios have used for decades, and it’s responsible for many of the visual effects we see every day on our screens. But it’s not perfect — its use precludes wearing anything green, and it’s very bad at anything transparent.
The 1960s Disney film makers seemingly had no problem with this as anyone who has seen Mary Poppins will tell you, so how did they manage to overlay actors with diaphanous accessories over animation? The answer lies in an innovative process which has largely faded from view, and [Corridor Crew] have rebuilt it.
Green screens, or chroma key, to give the effect its real name, relies on the background using a colour not present in the main subject of the shot. This can then be detected electronically or in software, and a switch made between shot and inserted background. It’s good at picking out clean edges between green background and subject, but poor at transparency such as a veil or a bottle of water. The Disney effect instead used a background illuminated with monochromatic sodium light behind the subject illuminated with white light, allowing both a background and foreground image to be filmed using two cameras and a dichroic beam splitter. The background image with its black silhouette of the subject could then be used as a photographic stencil when overlaying a background image.
Sadly even Disney found it very difficult to make more than a few of the dichroic prisms, so the much cheaper green screen won the day. But in the video below the break they manage to replicate it with a standard beam splitter and a pair of filters, successfully filming a colourful clown wearing a veil, and one of them waving their hair around while drinking a bottle of water. It may not find its way back into blockbuster films just yet, but it’s definitely impressive to see in action.

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A Spark Gap Transmitter, Characterized

When we think of a spark gap radio transmitter, most of us immediately imagine an early twentieth century ship’s radio room or similar. Most of us know these transmitters as the first radio systems, and from there we’ll probably also know that they were phased out when better circuits arrived, because of their wide bandwidth. So it’s rare in 2024 to find anyone characterizing a spark gap transmitter, as [Baltic Lab] has.
The circuit is simple enough, a high voltage passes through an RC network to a spark gap, the other side of which is a tuned circuit. The RC network and the spark gap form a simple low frequency relaxation oscillator, with the C being charged until the spark gap triggers, forcing the subsequent discharge of the capacitor and causing the spark to extinguish and the cycle to repeat. The resulting chain of high voltage pulses repeatedly energizes the tuned circuit, with each pulse causing a damped oscillation at its resonant frequency. The resulting RF signal is a crude AM tone which can be received fairly simply.
The mathematics behind it all is pretty interesting, revealing both the cause of the bandwidth spread in the low Q factor of the tuned circuit, and the presence of a large spurious frequency spike on an interaction with the capacitor in the RC circuit. It’s all in the video below the break, and we have to admit, it taught us something about radio we didn’t know.
Meanwhile spark gaps weren’t the only early radio transmitter technology. How about an alternator?

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