Mechanisms: Mechanical Seals

February 22, 2018 by 36 Comments

On the face of it, keeping fluids contained seems like a simple job. Your fridge alone probably has a dozen or more trivial examples of liquids being successfully kept where they belong, whether it’s the plastic lid on last night’s leftovers or the top on the jug of milk. But deeper down in the bowels of the fridge, like inside the compressor or where the water line for the icemaker is attached, are more complex and interesting mechanisms for keeping fluids contained. That’s the job of seals, the next topic in our series on mechanisms.

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OBD-Sniffing A Caddy PHEV

February 22, 2018 by 25 Comments

The Cadillac ELR is a plug-in hybrid car with a bit of class, it has the beating heart of a Chevy Volt in a nice coupé body with some up-market styling and a nice interior. Since it wasn’t on the market for long and some consumers are still wary of cars with electric motors, it also represents something of a sweet spot: according to [Andrew Rossignol] you can pick them up for less outlay than you might imagine. He bought one, and being an inquisitive soul decided to probe its secrets through its OBD-II ports.

OBD-II sniffing is nothing especially new, but his write-up provides an interesting run-down of the methodology used to identify the different proprietary pieces of data that it makes available. His Python script attempted to parse the stream as though it were multi-byte words of different lengths, plotting its results as graphs, It was then a straightforward process of identifying the graphs by eye that contained useful data and rejecting those that were obviously garbage. He was able to pick out the figures in which he was interested, and write an interface for his little Sony VAIO UX to display them on the move.

We’ve covered OBD hacks too numerous to mention over the years, but perhaps you’d like to read our history of the standard.

At 71,572 KM, You Won’t Beat This LoRa Record

February 22, 2018 by 29 Comments

A distance record for LoRa transmission has been set that you probably won’t be able to beat. Pack up your gear and go home, nothing more to achieve here. At a superficial reading having a figure of 71,572 km (44,473 miles) seems an impossible figure for one of the little LoRa radio modules many of us have hooked up to our microcontrollers, but the story isn’t quite what you’d expect and contains within it some extremely interesting use of technology.

So the folks at Outernet have sent data over LoRa for that incredible distance, but they did so not through the little ISM band modules we’re used to but over a suitably powerful Ku-band uplink to a geostationary satellite. They are also not using the LoRaWAN protocols of the earthbound systems, but simply the LoRa modulation scheme. So it’s not directly comparable to terrestrial records such as the 702 km we reported on last year, and they are the first to admit that.

Where their achievement becomes especially interesting though is in their choice of receiver. We are all used to Ku-band receivers, you may even have one on your house somewhere for satellite TV. It will probably involve a parabolic dish with a narrow beam width and an LNB whose horn antenna is placed at its focus. It would have required some skill and effort to set up, because it has to be pointed very carefully at the satellite’s position in the sky. Outernet’s mission of delivering an information service with the lowest possible barrier to entry precludes the extra expense of shipping a dish and providing trained staff to align it, so they take a very different approach. Their receiver uses either an LNB horn or a small patch antenna pointing at the satellite, with none of the dishes or phased arrays you might be used to in a Ku-band installation.

You might wonder how such a receiver could possibly work with such a meagre antenna, but the secret lies in LoRa’s relatively tiny bandwidth as well as the resistance to co-channel interference that is a built-in feature of the LoRa modulation scheme. Even though the receiver will be illuminated by multiple satellites at once it is able to retrieve the signal and achieve a 30 kb/s data rate that they hope with technical refinements to increase to 100 kb/s. This rate will be enough over which to push an SD video stream to name just one of the several examples of the type of content they hope to deliver.

It’s likely that the average Hackaday reader will not be hiring satellite uplink time upon which to place their LoRa traffic. But this story does provide a demonstration of LoRa’s impressive capabilities, and will make us look upon our humble LNBs with new eyes.

Via ABOpen.

Relive Radio Shack’s Glory Days By Getting Goofy

February 21, 2018 by 32 Comments

The Golden Age of Radio Shack was probably sometime in the mid-1970s, a time when you could just pop into the local store and pay 49 cents for the resistors you needed to complete a project. Radio Shack was the place to go for everything from hi-fi systems to CB radios, and for many of us, being inside one was very much a kid in a candy store scenario.

That’s not to say that Radio Shack was perfect, but one thing it did very well was the education and grooming of the next generation of electronics hobbyists, primarily through their “Science Fair” brand. Some of us will recall the P-Box kits from that line, complete projects with all the parts and instructions in a plastic box with a perfboard top. These kits were endlessly entertaining and educational, and now [NetZener] has recreated the classic neon “Goofy Light” P-Box project.

As it was back in the day, the Goofy Light is almost entirely useless except for learning about DC-DC converters, multivibrators, RC timing circuits, and the weird world of negative resistance. But by using the original Science Fair instructions, compiling a BOM that can be filled from Mouser or Digikey, and making up a reasonable facsimile of the original P-Box chassis, [NetZener] has done a service to anyone looking for a little dose of nostalgia.

It would be interesting if someone brought back the P-Box experience as a commercial venture, offering a range of kits with circuits like the originals. If that happens, maybe some of the offerings will be based on that other classic from Radio Shack’s heyday.

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Retrocomputing For The Forgotten

February 21, 2018 by 56 Comments

The world runs on marketing hype. Remember the public relations swirl around the Segway? Before it rolled out we were led to believe it was going to be remembered as fire, the wheel, and Segway. Didn’t really happen. Microsoft and IBM had done something similar with OS/2, which you may not even remember as the once heir-apparent to MS-DOS. OS/2 was to be the operating system that would cure all the problems with MS-DOS just as IBM’s new Microchannel Architecture would cure all the problems surrounding the ISA bus (primarily that they couldn’t stop people from cloning it). What happened? OS/2 died a slow agonizing death after the Microsoft/IBM divorce. But for whatever reason [Ryan C. Gordon] decided to write a Linux emulation layer for OS/2 call 2ine (twine).

We like retrocomputing projects even if they aren’t very practical, and this one qualifies. The best analog for 2ine is it is Wine for OS/2, which probably has something to do with the choice of name. You might be ready to click away since you probably don’t have any OS/2 programs you want to run, but wait! The good news is that the post has a lot of technical detail about how Linux and OS/2 programs load and execute. For that reason alone, the post is well worth a read.

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Linux Adds CH341 GPIO

February 21, 2018 by 64 Comments

There was a time when USB to serial hardware meant one company: FTDI. But today there are quite a few to choose from and one of the most common ones is the WCH CH341. There’s been support for these chips in Linux for a while, but only for use as a communication port. The device actually has RS232, I2C, SPI, and 8 general purpose I/O (GPIO) pins. [ZooBaB] took an out-of-tree driver that exposes the GPIO, and got it working with some frightening-looking CH341 boards.

He had to make a slight mod to the driver to get six GPIOs in /sys/class/gpio. Once there though, it is easy to manipulate the pins using a shell script or anything that can write to the virtual files corresponding to the GPIO pins.

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Vintage Sewing Machine To Computerized Embroidery Machine

February 21, 2018 by 19 Comments

It is February of 2018. Do you remember what you were doing in December of 2012? If you’re [juppiter], you were starting your CNC Embroidery Machine which would not be completed for more than half of a decade. Results speak for themselves, but this may be the last time we see a first-generation Raspberry Pi without calling it retro.

The heart of the build is a vintage Borletti sewing machine, and if you like machinery porn, you’re going to enjoy the video after the break. The brains of the machine are an Arduino UNO filled with GRBL goodness and the Pi which is running CherryPy. For muscles, there are three Postep25 stepper drivers and corresponding NEMA 17 stepper motors.

The first two axes are for an X-Y table responsible for moving the fabric through the machine. The third axis is the flywheel. The rigidity of the fabric frame comes from its brass construction which may have been soldered at the kitchen table and supervised by a big orange cat. A rigid frame is the first ingredient in reliable results, but belt tension can’t be understated. His belt tensioning trick may not be new to you, but it was new to some of us. Italian translation may be necessary.

The skills brought together for this build were vast. There was structural soldering, part machining, a microcontroller, and motion control. The first time we heard from [juppiter] was December 2012, and it was the result of a Portable CNC Mill which likely had some influence on this creation. Between then, he also shared his quarter-gobbling arcade cabinet with us.

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