Year: 2018

Buy A Baofeng While You Still Can? FCC Scowls At Unauthorized Frequency Transmitters

September 25, 2018 by 93 Comments

There was a time when a handheld radio transceiver was an object of wonder, and a significant item for any radio amateur to own. A few hundred dollars secured you an FM walkie-talkie through which you could chat on your local repeater, and mobile radio was a big draw for new hams. Thirty years later FM mobile operation may be a bit less popular, but thanks to Chinese manufacturing the barrier to entry is lower than it has ever been. With extremely basic handheld radios starting at around ten dollars and a capable dual-bander being yours for somewhere over twice that, most licencees will now own a Baofeng UV5 or similar radio.

The FCC though are not entirely happy with these radios, and QRZ Now are reporting that the FCC has issued an advisory prohibiting the import or sale of devices that do not comply with their rules. In particular they are talking about devices that can transmit on unauthorised frequencies, and ones that are capable of transmission bandwidths greater than 12.5 kHz.

We’ve reported before on the shortcomings of some of these radios, but strangely this news doesn’t concern itself with their spurious emissions. We’re guessing that radio amateurs are not the problem here, and the availability of cheap transceivers has meant that the general public are using them for personal communication without a full appreciation of what frequencies they may be using. It’s traditional and normal for radio amateurs to use devices capable of transmitting out-of-band, but with a licence to lose should they do that they are also a lot more careful about their RF emissions.

Read the FCC statement and you’ll learn they are not trying to restrict the sale of ham gear. However, they are insisting that imported radios that can transmit on other frequencies must be certified. Apparently, opponents of these radios claim about 1 million units a year show up in the US, so this is a big business. The Bureau warns that fines can be as high as $19,639 per day for continued marketing and up to $147,290 — we have no idea how they arrive at those odd numbers.

So if you’re an American who hasn’t already got a Baofeng or similar, you might be well advised to pick one up while you still can.

UV5-R image via PE1RQM

Productivity, Unfinished Projects, And Letting Go

September 25, 2018 by 64 Comments

Most of us have been there, some projects just don’t get finished. Everyone shelves an in-progress build from time to time, and some hackers drop almost every project for fully finishing it. Why does it happen? What can we do about it? Or does it even matter? My own most memorable one is the wine glass rack I was making for my sister’s birthday, still sitting incomplete on a shelf eleven years later.

The answer may lie in what you consider to be a “done” project. Is it a fully completed build with every possible feature implemented and polished? With that rubric you could be counting all of your completed projects on one hand. What are you really getting out of your personal projects? It’s an interesting topic to consider as pivoting your mindset can end up boosting your productivity. So let’s dig in!

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Trials And Tribulations In Sending Data With Wires

September 25, 2018 by 14 Comments

When working on a project that needs to send data from place to place the distances involved often dictate the method of sending. Are the two chunks of the system on one PCB? A “vanilla” communication protocol like i2c or SPI is probably fine unless there are more exotic requirements. Are the two components mechanically separated? Do they move around? Do they need to be far apart? Reconfigurable? A trendy answer might be to add Bluetooth Low Energy or WiFi to everything but that obviously comes with a set of costs and drawbacks. What about just using really long wires? [Pat] needed to connect six boards to a central node over distances of several feet and learned a few tricks in the process.

When connecting two nodes together via wires it seems like choosing a protocol and plugging everything in is all that’s required, right? [Pat]’s first set of learnings is about the problems that happen when you try that. It turns out that “long wire” is another way to spell “antenna”, and if you happen to be unlucky enough to catch a passing wave that particular property can fry pins on your micro.

Plus it turns out wires have resistance proportional to their length (who would have though!) so those sharp square clock signals turn into gently rolling hills. Even getting to the point where those rolling hills travel between the two devices requires driving drive the lines harder than the average micro can manage. The solution? A differential pair. Check out the post to learn about one way to do that.

It looks like [Pat] needed to add USB to this witches brew and ended up choosing a pretty strange part from FTDI, the Vinculum II. The VNC2 seemed like a great choice with a rich set of peripherals and two configurable USB Host/Peripheral controllers but it turned out to be a nightmare for development. [Pat]’s writeup of the related troubles is a fun and familiar read. The workaround for an incredible set of undocumented bad behaviors in the SPI peripheral was to add a thick layer of reliability related messaging on top of the physical communication layer. Check out the state machine for a taste, and the original post for a detailed description.

That TRS Jack On Your Graphing Calculator Does More Than You Think

September 25, 2018 by 28 Comments

It’s not Apple IIs, and it’s not Raspberry Pis. The most important computing platform for teaching kids programming is the Texas Instruments graphing calculator. These things have been around in one form or another for almost three decades, and for a lot of budding hackers out there, this was the first computer they owned and had complete access to.

As hacking graphing calculators is a favorite for Maker Faires, we were pleased to see Cemetech make it out to this year’s World Maker Faire in New York last weekend. They’re the main driving force behind turning these pocket computers with truly terrible displays into usable computing platforms.

As you would expect from any booth, Cemetech brought out the goods demonstrating exactly what a graphing calculator can do. The most impressive, at least from a soldering standpoint, is their LED cube controlled by a graphing calculator. The electronics are simple, and just a few 595s and transistors, but this LED cube is taking serial data directly from the link cable on a graphing calculator. Of course, the PCB for the LED cube is designed as an Arduino shield for ease of prototyping, but make no mistake: this is an LED cube controlled by a calculator.

If you can send serial data to a shift register from a graphing calculator, that means you can send serial data to anything, bringing us to Cemetech’s next great build featured this year. It’s an N-gauge model train, with complete control over the locomotive.

There’s a lot more to controlling model trains these days than simply connecting a big ‘ol variac to the tracks. This setup uses Direct Cab Control (DCC), a system that modulates commands for locomotives while still providing 12-15V to the tracks. There’s a good Arduino library, and when you have that, you can easily port it to a graphing calculator.

Cemetech is one of the perennial favorites at Maker Faire, and over the years we’ve seen everything from the Ultimate TI-83+ sporting an RGB backlight and a PS/2 port to a game of graphing calculator Whac-A-Mole. It’s all a great example of what you can do with the programmable computer every 90s kid had, and an introduction to computer programming education, something Cemetech is really pushing out there with some hard work.

Self-Solving Rubik’s Cube

September 24, 2018 by 48 Comments

Rubik’s Cube has been around for what seems like forever now, and has spawned an entire subculture devoted to solving the puzzle with automation. Most Rubik robots put the cube in a specially designed cradle bristling with actuators and sensors, and while those rigs are impressive, they don’t come close to this robotic Rubik solver built into the cube itself.

Fair warning that [Human Controller] doesn’t provide much detail on this build other than pictures; even translating the Japanese web page doesn’t offer much more information. But there are pictures, plus the video below, which reveal the engineering masterpiece encased within the standard sized Rubik’s cube. The internal mechanism of the original cube had been replaced by a spherical assembly around which the cube’s faces rotate. The sphere, which appears to be 3D-printed, houses six motors and gear trains, along with a microcontroller board and what appear to be Hall sensor boards to detect the position of each face. Everything is wired up with magnet wire to keep bundles to a minimum size, and buried deep inside is a LiPo battery pack. A disassembly video offers further clues to this ingenious device’s inner workings.

Once the cube senses that it has been scrambled, it sets to work on the solution, walking all over the table in the process. It’s clearly not just recording the scrambling steps and playing them back in reverse; the video below shows far more moves to solve the cube than the 15 it took to scramble it.

While we’re always impressed by marvels of speed like this robot with a 637 millisecond solve time, putting everything needed to solve the cube inside it is a feat worth celebrating. Here’s hoping that a build log shows up soon to satisfy our need for details.

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Infection? Your Smartphone Will See You Now

September 24, 2018 by 8 Comments

When Mr. Spock beams down to a planet, he’s carrying a tricorder, a communicator, and a phaser. We just have our cell phones. The University of California Santa Barbara published a paper showing how an inexpensive kit can allow your cell phone to identify pathogens in about an hour. That’s quite a feat compared to the 18-28 hours required by traditional methods. The kit can be produced for under $100, according to the University.

Identifying bacteria type is crucial to prescribing the right antibiotic, although your family doctor probably just guesses because of the amount of time it takes to get an identification through a culture. The system works by taking some — ahem — body fluid and breaking it down using some simple chemicals. Another batch of chemicals known as a LAMP reaction mixture multiplies DNA and will cause fluorescence in the case of a positive result.

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Cheating The Perfect Wheelie With Sensors And Servos

September 24, 2018 by 8 Comments

Everyone remembers popping their first wheelie on a bike. It’s an exhilarating moment when you figure out just the right mechanics to get balanced over the rear axle for a few glorious seconds of being the coolest kid on the block. Then gravity takes over, and you either learn how to dismount the bike over the rear wheel, or more likely end up looking at the sky wondering how you got on the ground.

Had only this wheelie cheating device been available way back when, many of us could have avoided that ignominious fate. [Tom Stanton]’s quest for the perfect wheelie led him to the design, which is actually pretty simple. The basic idea is to apply the brakes automatically when the bike reaches the critical angle beyond which one dares not go. The brakes slow the bike, the front wheel comes down, and the brakes release to allow you to continue pumping along with the wheelie. The angle is read by an accelerometer hooked to an Arduino, and the rear brake lever is pulled by a hobby servo. We honestly thought the servo would have nowhere near the torque needed, but in fact it did a fine job. As with most of [Tom]’s build his design process had a lot of fits and starts, but that’s all part of the learning. Was it worth it? We’ll let [Tom] discuss that in the video, but suffice it to say that he never hit the pavement in his field testing, although he appeared to be wheelie-proficient going into the project.

Still, it was an interesting build, and begs the question of how the system could be improved. Might there be some clues in this self-balancing motorized unicycle?

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