Invasion Of The Tiny Magnetic PCB Vises

February 19, 2018 by Tom Nardi 15 Comments

[Proto G] recently wrote in to share a very slick way of keeping tabs on all the tiny PCBs and devices that litter the modern electronics workbench. Rather than a big bulky PCB vise for each little board, he shows how to make tiny grippers with magnetic bases for only a couple bucks each. Combined with a sheet metal plate under an ESD mat, it allows him to securely position multiple PCBs all over his workspace.

The key to this hack is the little standoffs that are usually used to mount signs to walls. These already have a clamping action by virtue of their design, but the “grip” of each standoff is improved with the addition of a triangular piece of plastic and rubber o-ring.

With the gripping side of the equation sorted, small disc magnets are glued to the bottom of each standoff. With a suitable surface, the magnets are strong enough to stay upright even with a decently large PCB in the jaws.

An especially nice feature of using multiple small vises like this is that larger PCBs can be supported from a number of arbitrary points. It can be difficult to clamp unusually shaped or component-laden PCBs in traditional vises, and the ability to place them wherever you like looks like it would be a huge help.

We’ve recently covered some DIY 3D printed solutions for keeping little PCBs where you want them, but we have to say that this solution looks very compelling if you do a lot of work on small boards.

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A Jukebox For The 21st-Century Kit Blends Raspberry Pi, Sonos, QR Codes

February 19, 2018 by James Hobson 17 Comments

When [Chris Campbell]’s children wanted to play an album in the background over dinner, switching the outputs on his family’s Sonos sound system was perhaps too involved for their budding mastery of technology. This got him thinking about using kid-friendly inputs so they could explore his music collection. Blending QR codes, some LEGO, and a bit of arts and crafts, a kid-friendly QR code reader media controller comes out!

Working with a Raspberry Pi 3 Model B and a cheap camera, [Campbell] whipped up some code to handle producing and reading the QR codes — though he’s running the media server on another computer to maintain fast response times. Once [Campbell] had his QR codes, he printed them out and got his kids involved in cutting and gluing the double-sided cards. Additional cards access different functions — starting a playlist queue, switching output channels, and full album playback, among others. Cue spontaneous dance-parties!

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Scan Your Film The 3D Printed Way

February 19, 2018 by Jenny List 7 Comments

Everyone has a box or two at home somewhere full of family photographs and slides from decades past. That holiday with Uncle Joe in Florida perhaps, or an unwelcome reminder of 1987’s Christmas jumper. It’s fair to say that some memories deserve to be left to gather dust, but what about the others in a world of digital images?

You could of course buy a film scanner to digitize Uncle Joe on the beach, but aside from the dubious quality of so many of them where’s the fun in that? Instead, how about 3D printing one? That’s what [Alexander Gee] did, in the form of an adapter to fit the lens mount of his Sony camera that contains both a 50mm enlarger lens and a mount for the slide. It’s a simple enough print, but he’s made enough parts parametric for users to be able to adjust it to their own camera’s mount.

Sometimes builds do not have to be complex, push boundaries, or contain more computing power than took us to the Moon. This one is simple and well-executed, and for anyone prepared to experiment could deliver results with a variety of cameras and lenses. Of course, you have to have some film to scan before you can use it, so perhaps you’d like to try a bit of home developing.

Tiny Guitar Amp Rebuilt With Tiny Tubes

February 19, 2018 by Tom Nardi 28 Comments

[Blackcorvo] wrote in to tell us how he took a cheap “retro” guitar amplifier and rebuilt it with sub-miniature vacuum tubes. The end result is a tiny portable amplifier that not only looks the part, but sounds it to. He’s helpfully provided wiring schematics, build images, and even a video of the amplifier doing it’s thing.

The original Honeytone amplifier goes for about $26, and while it certainly looks old-school, the internals are anything but. [Blackcorvo] is too much of a gentleman to provide “before” pictures of the internals, but we looked it up and let’s just say it doesn’t exactly scream high quality audio. Reviews online seem to indicate it works about as well as could be expected for an amplifier that costs less than $30, but this is definitely no audiophile gear.

Powering up the miniature vacuum tubes takes a bit of modern support electronics, including a buck converter to provide the high voltage for the tubes as well as a 6V regulator. The plus side is that the new circuit can power the tubes from an input voltage between 12 and 30 volts, meaning the amplifier can still be powered by batteries if you want to take it on the go.

We’ve seen some fantastic tube amplifier builds over the years, proving that some things never go out of style. If you’d like to learn more about the magic that lets these little tubes of hot pixies make beautiful music, the US Army has you covered.

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Handheld GPS Tracks All The Things

February 19, 2018 by James Hobson 9 Comments

With a GPS on every smartphone, one would be forgiven for forgetting that handheld GPS units still exist. Seeking to keep accurate data on a few upcoming trips, [_Traveler] took on a custom-build that resulted in this GPS data logger.

Keeping tabs on [_Traveler] is a Ublox M8N GPS which is on full-time, logging data every 30 seconds, for up to 2.5 days. All data is saved to an SD card, with an ESP32 to act as a brain and make downloading the info more accessible via WiFi . While tracking the obvious — like position, speed, and time — this data logger also displays temperature, elevation, dawn and dusk, on an ePaper screen which is a great choice for conserving battery.

The prototyping process is neat on this one. The first complete build used point-to-point soldering on a protoboard to link several breakout modules together. After that, a PCB design embraces the same modules, with a footprint for the ESP’s castellated edges and header footprints for USB charing board, SD card board, ePaper, etc. All of this finds a hope in a 3D printed enclosure. After a fair chunk of time coding in the Arduino IDE the logger is ready for [_Traveler]’s next excursion!

As far as power consumption in the field, [_Traveler] says the GPS takes a few moments to get a proper location — with the ESP chewing through battery life all the while — and plans to tinker with it in shorter order.

Not all GPS trackers are created equal: sometimes all you need is a stripped-down tracker for your jog, or to know exactly where every pothole is along your route.

[Via /r/electronics]

You All Know Reginald Fessenden. Who?

February 19, 2018 by Al Williams 30 Comments

Quick, name someone influential in the history of radio. Who do did you think of? Marconi? Tesla? Armstrong? Hertz? Perhaps Sarnoff? We bet only a handful would have said Reginald Fessenden. That’s a shame because he was the first to do something that most of us do every day.

Few know this Canadian inventor’s name even though he developed quite a few innovations. Unlike Colpitts and Hartley we don’t have anything named after him. However, Fessenden was the first man to make a two-way transatlantic radio contact (Marconi’s was one way) and he was a pioneer in using voice over the radio.

He did even more than that. He patented transmitting with a continuous wave instead of a spark, which made modern radio practical. This was unpopular at the time because most thought the spark was necessary to generate enough energy. In 1906, John Fleming (who gave us tubes that are sometimes still called Fleming valves) wrote that “a simple sine-curve would not be likely to produce the required effect.” That was in 1906, five years after Fessenden’s patent.

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Predicting Starman’s Return To Earth

February 19, 2018 by Brian Benchoff 31 Comments

There’s a Starman, waiting in the sky. He’d like to come and meet us, but he’ll have to wait several million years until the Yarkovsky effect brings him around to Earth again.

In case you’ve been living under a rock for the past few weeks, SpaceX recently launched a car into space. This caused much consternation and hand-wringing, but we got some really cool pictures of side boosters landing simultaneously. The test launch for the Falcon Heavy successfully lobbed a Tesla Roadster into deep space with an orbit extending out into the asteroid belt. During the launch coverage, SpaceX said the car would orbit for Billions of years. This might not be true; a recent analysis of the random walk of cars revealed a significant probability of hitting Earth or Venus over the next Million years.

The analysis of the Tesla Roadster relies on the ephemerides provided by JPL’s Horizons database (2018-017A), and predicts the orbit over several hundred years. In the short term — a thousand years or so — there is little chance of a collision with anything. In 2091, however, the Tesla will find itself approaching Earth, and after that, the predicted orbits change drastically. As an aside, we should totally bring the Tesla back in 2091.

Even though the Tesla Roadster, its payload adapter, and the booster are inert objects floating in space right now, that doesn’t mean there aren’t forces acting on it. For small objects orbiting near the sun, the Yarkovsky effect is a huge influence on the orbit when measured on a timescale of millennia. In short, the Yarkovsky effect is a consequence of a spinning object being heated by the sun. As an object (a Tesla, or an asteroid) rotates, the side facing the sun heats up. As this side faces away from the sun, this heat is radiated out, imparting a tiny, tiny force. This force, over a period of millions of years, can send the Tesla into resonances with other planets, eventually sending it crashing into Earth, Venus, or the Sun.

The authors of this paper find there is a 6% chance the Tesla will collide with Earth and a 2.5% chance it will collide with Venus in the next one Million years. In three Million years, the probability of a collision with Earth is 11%. These are, according to the authors, extremely preliminary calculations and more observations are needed. If the Tesla were to hit the Earth, it’s doubtful whatever species populates the planet would notice; the mass of the Tesla is only 1250 Kg, and Earth flies through meteoroids weighing that much very frequently.