A Flag-Waving Hat For All Occasions

April 28, 2020 by 5 Comments

When [Taste the Code] saw that his YouTube channel was approaching 1,000 subscribers, it was time to do something special. But celebration is no reason to be wasteful. This flag-waving celebratory hat has endless possibilities for the future.

The build is simple, which is just right for these strange times of scarcity. An Arduino Uno hot-glued to the back of the hat is directly driving a pair of 9g servos on the front. [Taste the Code] made the flags by sticking two stickers back to back with a bamboo skewer in between. The code is flavored such that the flags will wave in one of three randomly-chosen patterns — swing around, swing in reverse, and wild gesticulations.

After the novelty of the whole 1k subs thing wears off, [Taste the Code] can change the flags over to Jolly Rogers to help with social distancing. And someday in the future when things are really looking up, they can be changed over to SARS-CoV-2 victory flags, or fly the colors of a local sports team. We think it would be way cool to program some kind of real semaphore message into the flags, though the mobility might be too limited for that. Check out the build video after the break, which happens picture-in-picture as [Taste the Code] dishes out a channel retrospective and lays out a course for the future.

Even though YouTube messed with subscriber counts, we think it’s still worth making a cool counter. Here’s one with a Tetris twist.

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Get Your Microcontroller Online At The Speed Of Light

April 28, 2020 by 33 Comments

When developing a network-enabled project with the ESP8266 or ESP32, the easiest way to handle WiFi credentials is to just hardcode the access point and encryption key into the program. But that means recompiling the firmware if you ever want to use it on a different network, which isn’t really an option if you’re trying to make something that other people can easily use. If you’re expecting grandma to bust out the UART cable, we’ve got bad news for you.

There are various ways around this problem, but we think the one developed by [Pekka Lehtikoski] is particularly clever. With a simple application, network credentials can be literally “flashed” to the waiting microcontroller by rapidly blinking the flash LED on an Android device. This allows the information to be transferred quickly and easily regardless of the user’s technical proficiency. One could even make the argument that it’s more secure than some of the other methods of doing initial setup, since an eavesdropper would literally need to see you do it if they wanted to steal your encryption key.

[Pekka] has made the source code for the Android application and the “Gazerbeam” library open for anyone who wants to include the capability in their own projects. To pick up the blinking light you just need to add a phototransistor, an opamp, and a handful of passives to your circuit; making this solution cheap enough that you could even use it in a small-scale production run. The concept isn’t limited to network credentials either. Whenever we can hold conferences again, it could be an interesting way to let attendees customize their badge.

Of course, [Pekka] isn’t the first person to use this trick. Hackers well versed in the history of WiFi MCUs may recall that the Electric Imp used a very similar method of configuration called BlinkUp. If you ever come across a device that asks you to put your phone’s screen down on a little window to perform the initial setup, there’s a good chance it has an Imp inside.

Beat Your Coat Hangers Into Antennas, Not Plowshares

April 28, 2020 by 37 Comments

If you are looking for a fun project while you are cooped up and you have some spare coathangers, why not try this 4-element Yagi antenna (PDF)? [Pete N8PR] showed it off at his local ham radio club and it looked like something good for a lazy afternoon. If you aren’t a ham, you could adjust it all for a different VHF or UHF frequency.

For the boom, [Pete] mentions you can use wood, but it isn’t weather resistant. He chose half-inch PVC pipe. He also offers you a choice of material for the elements: #8 wire, welding rod, or — our favorite — coat hangers.

This is a big upgrade from a simple dipole or a vertical made from coax. The yagi should have about 8 dBi gain in the direction it is pointing. The center of the boom doesn’t have any elements, so that simplifies mounting. The insulating boom also makes mounting the driven element a breeze.

If you use the coat hangers, we’ve heard an easy way to get them very straight is to put one end on a vise and the other end in a drill chuck (see the video below). The method will weaken the wire, but the elements won’t have much stress. If it worries you, just go slow on the drill and you might consider annealing the wire with a torch afterward.

It would be easy to make this portable like some other designs we’ve seen. If you want the history and theory behind the venerable yagi antenna, you’ll want to revisit this post.

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NASA Readies New Electric X-Plane For First Flight

April 28, 2020 by 78 Comments

Since 1951, NASA (known in those pre-space days as NACA) and the United States Air Force have used the “X” designation for experimental aircraft that push technological boundaries. The best known of these vehicles, such as the X-1 and X-15, were used to study flight at extreme altitude and speed. Several fighter jets got their start as X-planes over the decades, and a number of hypersonic scramjet vehicles have flown under the banner. As such, the X-planes are often thought of as the epitome of speed and maneuverability.

So the X-57 Maxwell, NASA’s first piloted X-plane in two decades, might seem like something of a departure from the blistering performance of its predecessors. It’s not going to fly very fast, it won’t be making any high-G turns, and it certainly won’t be clawing its way through the upper atmosphere. The crew’s flight gear won’t even be anything more exotic than a polo and a pair of shorts. As far as cutting-edge experimental aircraft go, the X-57 is about as laid back as it gets.

But like previous X-planes, the Maxwell will one day be looked back on as a technological milestone of its own. Just as the X-1 helped usher in the era of supersonic flight, the X-57 has been developed so engineers can better understand the unique challenges of piloted electric aircraft. Before they can operate in the public airspace, the performance characteristics and limitations of electric planes must be explored in real-world scenarios. The experiments performed with the X-57 will help guide certification programs and government rule making that needs to be in place before such aircraft can operate on a large scale.

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A Lego Tensegrity Structure

April 28, 2020 by 14 Comments

Tensegrity structures are an impressive demonstration of how to achieve mechanical stability through tensile forces. Since the topic is currently trending it was probably only a matter of time before somebody like [Alexandre Thiery] came with the idea to build a tensegrity model from Lego.

In the GIF below that [Alexandre Thiery] shared on his Twitter account you can see his kids admiring the model. Tensegrity structures consist of elements under constant tension – in most cases strings – and components under compression, in this case beams of Lego. By combining these elements, one can build stable structures that seem to float in midair. A simple daily-life example for tensegrity is a balloon where the skin is the tensional element while the air inside is the component under compression.

[Alexandre Thiery] has come up with the clever idea to simply clamp the strings between two Lego blocks. This certainly paves the way for other more complicated Lego-based tensegrity structures that we will likely see in the future. [Alexandre Thiery] also recently extended his model by stacking an identical structure on top of it.

If you do not have any Lego at hand just fire up your 3D printer to make a tensegrity physics toy or a floating table.

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Greatest Keycaps And Where To Find Them

April 28, 2020 by 25 Comments

Look at your keyboard. Do the keycaps excite you? That’s what we thought. You pound on that thing day in and day out. Shouldn’t it at least be attractive? Or even happiness-inducing? You don’t necessarily have to replace every single keycap to spark joy. When it comes to artisan keycaps, the point is to have something that stands out.

How about an Escape key that looks like a tall stack of flapjacks or a tiny, intricate cream puff? From a practical standpoint, how about a spiky Escape key that makes you think twice about rage quitting?

If you’re into games or anime, chances are good that there are more than enough artisan keycaps out there to keep you cash-poor for a while. The same goes for scrumptious foodstuffs with Cherry MX-compatible stems.

In this day and age, you can get just about any type of keycap you want, especially those encapsulating pop culture phenomena and fads. Yes there’s a fidget spinner keycap, and it’s adorable.

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Washing Your Hands With 20,000 Volts

April 28, 2020 by 33 Comments

These last few weeks we’ve all been reminded about the importance of washing our hands. It’s not complicated: you just need soap, water, and about 30 seconds worth of effort. In a pinch you can even use an alcohol-based hand sanitizer. But what if there was an even better way of killing bacteria and germs on our hands? One that’s easy, fast, and doesn’t even require you to touch anything. There might be, if you’ve got a high voltage generator laying around.

In his latest video, [Jay Bowles] proposes a novel concept: using the ozone generated by high-voltage corona discharge for rapid and complete hand sterilization. He explains that there’s plenty of research demonstrating the effectiveness of ozone gas a decontamination agent, and since it’s produced in abundance by coronal discharge, the high-voltage generators of the sort he experiments with could double as visually striking hand sanitizers.

Looking to test this theory, [Jay] sets up an experiment using agar plates. He inoculates half of the plates with swabs that he rubbed on his unwashed hands, and then repeats the process after passing his hands over the high-voltage generator for about 15 seconds. The plates were then stored at a relatively constant 23°C (75°F), thanks to the use of his microwave as a makeshift incubator. After 48 hours, the difference between the two sets of plates is pretty striking.

Despite what appears to be the nearly complete eradication of bacteria on his hands after exposing them to the ozone generator, [Jay] is quick to point out that he’s not trying to give out any medical advice with this video. This simple experiment doesn’t cover all forms of bacteria, and he doesn’t have the facilities to test the method against viruses. The safest thing you can do right now is follow the guidelines from agencies like the CDC and just wash your hands the old fashioned way; but the concept outlined here certainly looks worthy of further discussion and experimentation.

Regular viewers of his channel may notice that the device in this video as actually a modified version of the hardware he used to experiment with electrophotography last year.

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