Analog Engineer’s Pocket Reference Needs A Big Pocket

We always admire when companies produce useful tools or documentation that aren’t specific to their products. For example, consider LTSpice. Sure, it has the company’s models baked in. But there’s no reason you can’t use it for anything. Thanks! We were interested to see Texas Instrument’s fifth edition of the “Analog Engineer’s Pocket Reference” is still freely available. While we aren’t sure a book with nearly 200 pages in it is a “pocket reference,” we do think you’ll enjoy it, even if you don’t want to use TI’s offerings. This book has been around for 50 years, but it is updated periodically, and this version is the fifth iteration.

The book has several sections ranging from conversion between units and color codes to amplifier noise calculations and understanding ADC settling times. Want to know more about PCB microstrips? Page 85.

Continue reading “Analog Engineer’s Pocket Reference Needs A Big Pocket”

Pimp My Pot Redux, Now Cheaper And Even Better

If there’s one thing we like around here more than seeing an improved version of a project we’ve already covered, it’s when the improvements make the original project cheaper. In the case of this LED ring light for pots and encoders, not only is it cheaper than its predecessors, it’s better looking and easier to integrate into your projects.

Right from its start, [upir]’s “Pimp My Pot” project has been all about bringing some zazzle to rotary controls. Knobs with a pointer and a scale on the panel are okay — especially when they go to eleven — but more lights mean more fun. The fun comes at a price, though; the previous version of “PMP” used an off-the-shelf LED ring light with a unit cost of about $10. Not the end of the world, perhaps, but prohibitive, and besides, where’s the fun in just buying a component specifically made for rotary control indication?

The new version shown in the video below is pin-compatible with the driver board [upir] used for the previous version, which is based on the MAX7219 display driver. Modifying the previous board to accommodate 32 white 0402 LEDs over a 270° arc was no mean feat. [upir] covers both creating the schematic and the PCB layout in some detail, providing his usual trove of tool-chain tips for minimizing the amount of manual work needed.

Wisely, [upir] chose to get his boards assembled by the vendor; getting all those LEDs to line up perfectly is a job best left to the robots. While the board is designed for use with pots that mount on either side, we much prefer mounting the pot’s shaft through the board, as it keeps the LEDs closer to the knob. The final price per board works out to about $6.30 in quantities of ten and falls to a trivial $1.70 each for lots of 1,000. Pretty sweet savings on a pretty sweet-looking build.

This is a cool use of a ring of LEDs, but if you prefer the finger kind, you can make that, too. You can do it the easy way or the hard way.

Continue reading “Pimp My Pot Redux, Now Cheaper And Even Better”

Wooden Desk Lamp Uses Unusual Dimmer

One of the problems with laser cutting projects is that while they look good, they often look like they were laser cut. [Timber Rough] has a wooden desk lamp that not only looks good but has one of the most unusual dimming features we’ve seen.

One thing that stands out is the lamp is made of different kinds of wood, and that helps. But the dimmer is a magnet and Hall effect sensor that levitates. It is hard to explain, but a quick look at the video below will clarify it.

Continue reading “Wooden Desk Lamp Uses Unusual Dimmer”

Pi 5 And SDR Team Up For A Digital Scanner You Can Actually Afford

Listening to police and fire calls used to be a pretty simple proposition: buy a scanner, punch in some frequencies — or if you’re old enough, buy the right crystals — and you’re off to the races. It was a pretty cheap and easy hobby, all things considered. But progress marches on, and with it came things like trunking radio and digital modulation, requiring ever more sophisticated scanners, often commanding eye-watering prices.

Having had enough of that, [Top DNG] decided to roll his own digital trunking scanner on the cheap. The first video below is a brief intro to the receiver based on the combination of an RTL-SDR dongle and a Raspberry Pi 5. The Pi is set up in headless mode and runs sdrtrunk, which monitors the control channels and frequency channels of trunking radio systems, as well as decoding the P25 digital modulation — as long as it’s not encrypted; don’t even get us started on that pet peeve. The receiver also sports a small HDMI touchscreen display, and everything can be powered over USB, so it should be pretty portable. The best part? Everything can be had for about $250, considerably cheaper than the $600 or so needed to get into a purpose-built digital trunking scanner — we’re looking at our Bearcat BCD996P2 right now and shedding a few tears.

The second video below has complete details and a walkthrough of a build, from start to finish. [Top DNG] notes that sdrtrunk runs the Pi pretty hard, so a heat sink and fan are a must. We’d probably go with an enclosure too, just to keep the SBC safe. A better antenna is a good idea, too, although it seems like [Top DNG] is in the thick of things in Los Angeles, where LAPD radio towers abound. The setup could probably support multiple SDR dongles, opening up a host of possibilities. It might even be nice to team this up with a Boondock Echo. We’ve had deep dives into trunking before if you want more details.

Continue reading “Pi 5 And SDR Team Up For A Digital Scanner You Can Actually Afford”

The Usage Of Embedded Linux In Spacecraft

As the first part of a series, [George Emad] takes us through a few examples of the Linux operating system being used in spacecraft. These range from SpaceX’s Dragon capsule to everyone’s favorite Martian helicopter. An interesting aspect is that the freshest Linux kernel isn’t necessarily onboard, as stability is far more important than having the latest whizzbang features. This is why SpaceX uses Linux kernel 3.2 (with real-time patches) on the primary flight computers of both Dragon and its rockets (Falcon 9 and Starship).

SpaceX’s flight computers use the typical triple redundancy setup, with three independent dual-core processors running the exact same calculations and a different Linux instance on each of its cores, and the result being compared afterwards. If any result doesn’t match that of the others, it is dropped. This approach also allows SpaceX to use fairly off-the-shelf (OTS) x86 computing hardware, with the flight software written in C++.

NASA’s efforts are similar, with Ingenuity in particular heavily using OTS parts, along with NASA’s open source, C++-based F’ (F Prime) framework. The chopper also uses some version of the Linux kernel on a Snapdragon 801 SoC, which as we have seen over the past 72 flights works very well.

Which is not to say using Linux is a no-brainer when it comes to use in avionics and similar critical applications. There is a lot of code in the monolithic Linux kernel that requires you to customize it for a specific task, especially if it’s on a resource-constrained platform. Linux isn’t particularly good at hard real-time applications either, but using it does provide access to a wealth of software and documentation — something that needs to be weighed up against the project’s needs.

One Project At A Time, Or A Dozen?

We got a bunch of great food for thought in this week’s ask-us-anything on the Hackaday Podcast, and we all chewed happily. Some of my favorite answers came out of the question about how many projects we all take on at once. Without an exception, the answer was “many”. And while not every one of the projects that we currently have started will eventually reach the finish line, that’s entirely different from saying that none of them ever do. On the contrary, Tom Nardi made the case for having a number of irons simultaneously in the fire.

We all get stuck from time to time. That’s just the nature of the beast. The question is whether you knuckle down and try to brute-force power your way through the difficulty, or whether you work around it. A lot of the time, and this was Dan Maloney’s biggest bugaboo, you lack the particular part or component that you had in mind to get the job done. In that situation, sometimes you just have to wait. And what are you going to do while waiting? Work on Project B! (But take good notes of the state of Project A, because that makes it a lot easier to get back into the swing of things when the parts do arrive.)

Al and I both weighed in on the side of necessity, though. Sometimes, no matter how many attractive other projects you’ve got piled up, one just needs to get out the door first. My recent example was our coffee roaster. Before I start a big overhaul, I usually roast a couple days’ worth of the evil bean. And then the clock starts ticking. No roasting equals two unhappy adults in this household, so it’s really not an option. Time pressure like that helps focus the mind on the top-priority project.

But I’m also with Tom. It’s a tremendous luxury to have a handful of projects in process, and be able to hack on one simply because you’re inspired, or in love with the project at that moment. And when the muse calls, the parts arrive, or you finally figure out what was blocking you on Project A, then you can always get back to it.

Minitel, The 1980s Console Game Platform You Never Had

We’ve made no secret over the years here at Hackaday of our admiration for the Minitel. The ubiquitous CRT terminals which made 1980s France the most connected country in the world never made it to where we grew up, but OH! how we wanted them to! We’ve seen quite a few Minitels repurposed as serial terminals here, but for the time being we think [Louis H] has won the Minitel Internet with his plugin game console cartridges. These have a DIN plug to fit the Minitel serial port, and present themselves as a serial game.

The cartridge itself is an extremely simple affair, a tube which fits over the DIN plug body, containing a slim PCB with an ATmega328 and its supporting components. The games must be programmed such that their gameplay can work over a serial interface, so as an example the first game is a version of 2048.

We applaud both the simplicity and creativity of this project, and we love it that a new 1980s console we never knew we had has been unearthed, without the need for hardware modification. Meanwhile if you’d like to peer inside an Alcatel Telic 1, we can take you there.