Mr. Carlson Gets Zapped By Snow

January 25, 2020 by 47 Comments

As a Canadian, [Mr. Carlson] knows a thing or two about extreme winter weather. Chances are good, though, that he never thought he’d get zapped with high voltage generated by falling snow.

[Mr. Carlson]’s shocking tale began with a quiet evening in his jam-packed lab as a snowstorm raged outside. He heard a rhythmic clicking coming from the speakers of his computer, even with the power off. Other speakers in the lab were getting into the act, as was an old radio receiver he had on the bench. The radio, which was connected to an outdoor antenna by a piece of coax, was arcing from a coil to the chassis in the front end of the radio. The voltage was enough to create arcs a couple of millimeters long and bright blue-white, with enough current to give [Mr. Carlson] a good bite when he touched the coax. The discharges were also sufficient to destroy an LED light bulb in a lamp that was powered off but whose power cord was unlucky enough to cross the antenna feedline.

Strangely, the coil from which the arc sprang formed a 36-ohm shunt to the radio’s chassis, giving the current an apparently easy path to ground. But it somehow found a way around that, and still managed to do no damage to the sturdy old radio in the process. [Mr. Carlson] doesn’t offer much speculation as to the cause of the phenomenon, but the triboelectric effect seems a likely suspect. Whatever it is, he has set a trap for it, to capture better footage and take measurements should it happen again. And since it’s the Great White North, chances are good we’ll see a follow-up sometime soon.

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Failed: Air Umbrella

January 25, 2020 by 43 Comments

About five years ago, a Kickstarter popped up for the air umbrella. It wasn’t long before the project fell apart and the company made at least some refunds. Old news, we know. But [The Action Lab] recently explored the physics behind the air umbrella and why it wouldn’t be very practical. (Video, embedded below.)

Notice we said not very practical, not unworkable. It is possible to shoot rain away from you by using pressurized air. The problem is you need a lot of air pressure. That means you also need a lot of battery. In particular, [The Action Lab] used a leaf blower and even with that velocity, there was only minimal water deflection. In other words, you are still going to get wet.

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Advanced Timber Architecture Gives New Life To Wooden Structures

January 25, 2020 by 62 Comments

When it comes to building materials, wood doesn’t always draw the most attention as the strongest in the bunch. That honor usually goes to concrete and steel – steel embedded in concrete provides support and a foundation for tall buildings, while concrete increases tensile strength and can be formed into a variety of shapes with the help of rebar. Wood, on the other hand, decays and is vulnerable to moisture damage and fire.

That’s not necessarily the case anymore, thanks to the development of advanced timber. New materials like glulam, or sheets of timber bonded with moisture-resistant structural adhesives, can be produced using two to three times less energy than steel, making them environmentally-friendly alternatives to other building materials. Granted, this requires the beams to be burned at the end of their lifespan, but glulam still has an equivalent or better environmental profile compared to steel, not to mention a lower cost.

Among engineered wood, there are some varieties more commonly used among hobbyists – MDF, plywood, or particle board for instance. Others, like Cross-Laminated Timber (CLT) are more common among building materials. While CLT buildings have existed for decades, recently major cities like Stockholm and Vancouver have seen a resurgence of timber construction. Since wood can theoretically store carbon for the entire length of its lifespan, up to 0.8 tons in a cubic meter of spruce, some architecture firms like Oslotre are building houses with a negative carbon footprint.

Projects like Sidewalk Labs and Masthamnen are proposing entire neighborhoods and skyscrapers built from advanced timber. Compared to International Style architecture, characterized by gray concrete, shiny metal, and glass, this movement could be a step towards returning to natural architectural forms. Given the stress reducing effects of green spaces in cities, engineered wood buildings could bridge the gap between modern architectural styles and natural woodlands.

 

THAT Preamp

January 25, 2020 by 2 Comments

It is easy to cobble together projects these days. ICs make it simple and microcontrollers even easier. However, we always respect a project that really goes from concept to finished product and that’s what we liked about [Curt Yengst’s] “THAT” Thing microphone preamp.

In part 1 of his post about it, he talks about the basic ideas including the chips from THAT — a small but high-end audio chipmaker — he uses. The first chip is a low-noise audio preamp and the other is a balanced line driver.

In part 2, we get to see [Curt] go from breadboard testing to PCB fabrication all the way to the finished rack-mounted device with a good looking front panel. It worked, but like all designers, [Curt] was already thinking about the next version.

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A Commmand Center For Children With Sensory Needs

January 25, 2020 by 4 Comments

Toys for children are meant to be fun and interactive, but they’re even better if they’re educational as well. For [carrola1], a parent of a 4-year-old suffering from from medical disabilities, sensory needs, and autism, a more personalized approach seemed best. The electrical engineer built a wall-mounted command center with plenty of switches, buttons, and knobs to trigger to keep any child happy.

Apart from basic inputs, the device also has a color sensor – the command center can ask the child for an object of a particular color and congratulate them with a song when they’ve successfully acquired one.

The software for the audio and light controls was written in C for a STM32L0 series MCU, with CMSIS as the hardware abstraction layer and STM32CubeIDE as the IDE. The design uses SPI and I2C for serial communication and I2S for communicating between the digital audio devices. Physical inputs include toggle switches, rotary switches, and key switches to provide variety, with all physical hardware connected to the MCU on a custom PCB.

The audio output, sourced from a library of wav files, seems like the most challenging part of the build: the amps needed to be changed from left channel mono configuration to stereo, the output had to be LC filtered, and the code for had to be optimized for size to allow the audio files to play.

You can check out a video of the command center in action on the Reddit post.

 

Feel The Force With A Pocket Magnetometer

January 24, 2020 by 12 Comments

With the rise of affordable 3D printers, we just don’t see the projects in Tic Tac boxes that we used to. That’s kind of a shame. Not only are you upcycling existing plastic when you use one, they’re decently sized component vessels for pocket builds such as [rgco]’s portable magnetometer, especially if you can get the 100-count box. Best of all, they’re see-through!

Sure, you could get a magnetometer app for your phone to test out the strength of your Buckyballs, but this is more fun, and you can use it in more places. This build doesn’t take much — an Arduino Nano reads from a Hall effect sensor and outputs the magnetic flux density in militeslas (mT) on an OLED. Fortifying the sensor by mounting it inside the body of an old (also see-through!) ballpoint pen body is a nice touch.

In order to calibrate it, [rgco] made a solenoid by wrapping a length of PVC with magnet wire. The code for this very portable and low-cost magnetometer measures the magnetic field 2000 times in under three-tenths of a second, and outputs both the mean and the standard deviation of these measurements.

Magnetometers can ID all kinds of things from submarines to Suburbans. Here’s an ESP8266 magnetometer that opens a driveway gate when it detects the car.

Little Hex Tricks Make Little Displays A Little Easier

January 24, 2020 by 16 Comments

Depending on the device in hand and one’s temperament, bringing up a new part can be a frolic through the verdant fields of discovery or an endless slog through the grey marshes of defeat. One of the reasons we find ourselves sticking with tried and true parts we know well is that interminable process of configuration. Once a new display controller is mostly working, writing convenience functions to make it easier to use can be very satisfying, but the very first thing is figuring out how to make it do anything at all. Friend of Hackaday [Dan Hienzsch] put together a post describing how to use a particular LED controller which serves as a nice walkthrough of figuring out the right bitmath to make things work, and includes a neat trick or two.

The bulk of the post is dedicated to describing the way [Dan] went about putting together his libraries for a 7-segment display demo board he makes. At its heart the board uses the IS31FL3728 matrix driver from ISSI. We love these ISSI LED controllers because they give you many channels of control for relatively low cost, but even with their relative simplicity you still need to do some bit twiddling to light the diodes you need. [Dan]’s post talks about some strategies for making this easier like preconfigured lookup tables with convenient offsets and masking bits to control RGB LEDs.

There’s one more trick which we think is the hidden star of the show; a spreadsheet which calculates register values based on “GUI” input! Computing the bit math required to control a display can be an exercise in frustration, especially if the logical display doesn’t fit conveniently in the physical register map of the controller. A spreadsheet like this may not be particularly sexy but it gets the job done; exactly the kind of hack we’re huge fans of here. We’ve mirrored the spreadsheet so you can peek at the formulas inside, and the original Excel document is available on his blog.