Earth Day Challenge: A Better Way To Wrangle Water

March 25, 2021 by 26 Comments

How far do you have to go for a glass of clean water? Not very? Just go to a sink and turn on the faucet? We would venture to guess that is the case for most Hackaday readers. Maybe you even have a water softener, or a filter on your tap to make your drinking water even more palatable and free of heavy metal.

In Ethiopia and many other countries, people do not have access to clean, flowing water and must walk several kilometers to fetch it from somewhere that does. And they’re not doing this on paved roads, either — these women are cutting treacherous paths across mountains and through muddy, rocky terrain that make wheeled transport nearly impossible. How do you comfortably lug around 25 kg (~55 lbs) worth of sloshing water? You don’t, unless you have [Anteneh Gashaw]’s ingenious jerrycan.

As you can see in the video below, the current crop of jerrycans are just big plastic jugs that have to be carried on top of the head or the shoulder, both of which are bad for bodies. [Anteneh]’s can evenly distributes the weight by wrapping it completely around the person carrying it and suspending it from both shoulders like a beer-and-peanuts vendor’s carrying case. Basically, it’s a PVC inner tube with shoulder straps. Simple, cheap, and effective = absolute genius in our book. Ideally, everyone would have free access to clean water, both cold and hot. Until that time, [Anteneh]’s entry into our Earth Day Challenge is a great workaround that will no doubt save a lot of spines.

Potable water may be closer than you think. Build a portable potability predictor and you might not have to travel so far.

Continue reading “Earth Day Challenge: A Better Way To Wrangle Water” →

Vibration Isolation Helps Improve FPV Video Feed

March 25, 2021 by 7 Comments

First-person view technology has become hugely popular in the RC community, letting the user get a vantage point as though they were actually within their tiny scale vehicle. It can be difficult to get a good, clean video feed though, particularly in models that have a lot of drivetrain vibration. [Engineering After Hours] decided to tackle this problem with a simple vibration isolator design. (Video, embedded below.)

The first step is to analyse the vibration to get an idea of the frequencies that are most important to target. WIth that done, a simple 3D printed camera mount is designed with three flexible joints between the camera and the base which is rigidly coupled to the RC boat or car’s body. The modal analysis tools in Fusion 360 were used to get a rough idea of the frequency response of the system, helping to get things in the ballpark with a minimum of fuss.

The final design does help cut down on vibrations, though it is unable to counteract heavy vibration from driving on extremely rough surfaces. In these cases, [Engineering After Hours] recommends the use of a gimbal instead. Proper damping can be a godsend in many applications; bricks can make a huge difference for your 3D printer, for example.

Continue reading “Vibration Isolation Helps Improve FPV Video Feed” →

CNC Scroll Saw Add-On Cuts Beautiful Wooden Spirals

March 25, 2021 by 23 Comments

If there’s one thing that woodworkers have always been good at, it’s coming up with clever jigs and work-holding solutions. Most jigs, however, are considerably simpler and more static than this CNC-controlled scroll saw add-on that makes cool wooden spirals a snap.

As interesting as the products of this setup are, what we like about this is the obvious care and craftsmanship [rschoenm] put into making what amounts to a hybrid between a scroll saw and a lathe. Scroll saws are normally used to make narrow-kerf cuts in thin, delicate materials, often with complicated designs using very tight radius turns. In this case, though, stock is held between centers on the lathe-like carriage. The jig uses a linear slide driven by a stepper and a lead screw to translate the workpiece perpendicular to the scroll saw blade while a geared headstock rotates it. Starting with the blade inserted into a through-hole, the saw slowly cuts a beautiful nested spiral down the length of the workpiece. An Uno, a GRBL shield, and some stepper drivers let a little G-code control the two axes of the jig.

The video below shows it in action; things do get a bit wobbly as the cut progresses, but in general the jig works wonderfully and results in some lovely pieces. At first we thought these would purely be objets d’art, but then we thought about this compression screw grinder for DIY injection molding machines and realized these wooden screws look pretty similar.

Continue reading “CNC Scroll Saw Add-On Cuts Beautiful Wooden Spirals” →

The $50 Ham: WSPR-ing Around The World

March 25, 2021 by 18 Comments

Everybody has a bucket list,  things to be accomplished before the day we eventually wake up on the wrong side of the grass. Many bucket-list items are far more aspirational than realistic; very few of us with “A trip to space” on our lists are going to live to see that fulfilled. And even the more realistic goals, like the trip to Antarctica that’s been on my list for ages, become less and less likely as your life circumstances change — my wife hates the cold.

Luckily, instead of going to Antarctica by myself — and really, what fun would that be? — I’ve recently been getting some of the satisfaction of world travel through amateur radio. The last installment of “The $50 Ham” highlighted weak-signal digital modes using WSJT-X; in that article, I mentioned a little about the Weak Signal Propagation Reporter, or WSPR. It’s that mode that let me test what’s possible with very low-power transmissions, and allowed me to virtually visit six continents including Antarctica and Sweden-by-way-of-Alaska.

Continue reading “The $50 Ham: WSPR-ing Around The World” →

The Future’s So Bright, You Gotta Wear Arduglasses

March 25, 2021 by 21 Comments

Tiny OLED displays are an absolute must-have in the modern parts bin, so what better way to show your allegiance to the maker movement than with a pair of Arduino-compatible OLED glasses? Created by Arduboy mastermind [Kevin Bates], these digital spectacles might not help you see any better — in fact, you’ll see a bit worse — but they’ll certainly make you stand out in the crowd at the next hacker con. (Whenever we can have one of those again, anyway.)

The key to this project is a pair of transparent CrystalFonts OLED displays, just like the ones [Sean Hodgins] recently used to produce his gorgeous volumetric display. In fact, [Kevin] says it was his success with these displays that inspired him to pursue his own project. With some clever PCB design, he came up with some boards that could be manufactured by OSH Park and put together with jewelry box hinges. Small flexible circuits, also from OSH Park, link the boards and allow the frames to fold up when not being worn.

The Arduglasses use the same ATmega32U4 microcontroller as the Arduboy, and with a few basic controls and a small 100 mAh rechargeable battery onboard, they can technically run anything from the open source handheld’s extensive software library. Of course, technically is the operative word here. While the hardware is capable of playing the games, [Kevin] reports that the OLED displays are too close to the wearer’s eyes to actually focus on them. That said the ability to easily create software for these glasses offers plenty of opportunity for memes, as we see in the video below.

For reasons that are probably obvious, [Kevin] considers the Arduglasses an experiment and isn’t looking to turn them into a commercial product or kit. But if there’s interest, he’s willing to put the design files up on GitHub for anyone who wants to add a pair of Arduino glasses to their cyberpunk wardrobe.

Continue reading “The Future’s So Bright, You Gotta Wear Arduglasses” →

How Fast Is The Universe Expanding? The Riddle Of Two Values For The Hubble Constant

March 25, 2021 by 44 Comments

In the last decades, our understanding of the Universe has made tremendous progress. Not long ago, “precision astronomy” was thought to be an oxymoron. Nowadays, satellite experiments and powerful telescopes on earth were able to measure the properties of our Universe with astonishing precision. For example, we know the age of the Universe with an uncertainty of merely 0.3%, and even though we still do not know the origin of Dark Matter or Dark Energy we have determined their abundance with a precision of better than 1%.

There is, however, one value that astronomers have difficulty in pinning down: how fast our universe is expanding. Or, more precisely, astronomers have used multiple methods of estimating the Hubble constant, and the different methods are converging quite tightly on two different values! This clearly can’t be true, but nobody has yet figured out how to reconcile the results, and further observations have only improved the precision, deepening the conflict. It’s likely that we’ll need either new astronomy or new physics to solve this puzzle.

The Discovery of the Expanding Universe

In the 1920s Edwin Hubble used the newly built telescope at Mount Wilson Observatory to study fuzzy objects known as nebulae. Back then, astronomers were arguing whether these nebulae are clouds of stars within our Milky Way or if they are whole different galaxies. Hubble discovered stars within these nebulae whose brightness slowly fades in and out. These were known as Cepheids and previously studied by Henrietta Levitt who showed that there was a tight relationship between the star’s intrinsic brightness and the period of its variation. This means Cepheids could be used as so-called standard candles which refers to objects whose absolute brightness is known. Since there is a simple relationship between how the brightness of an object decreases with distance, Hubble was able to calculate the distance of the Cepheids by comparing their apparent and intrinsic brightness. He showed that the Cepheid stars were not located within our galaxy and that nebulae are actually distant galaxies.

Hubble also measured the velocity at which these distant galaxies are moving away from us by observing the redshifts of spectral lines caused by the Doppler effect. He found that the further away the galaxy is located, the faster it is moving away from us described by a simple linear relationship.

\bf v = H_0 d

The parameter H0 is what is known as the Hubble constant. Later the Belgian priest and physicist Georges Lemaître realized that the velocity-distance relationship measured by Hubble was evidence for the expansion of the Universe. Since the expansion of space itself causes other galaxies to move away from us we are not in any privileged location but the same effect would be measured from any other place in the Universe. An effect that is sometimes illustrated by drawing points on a balloon, when it is inflated the points move away from each other at a speed that depends on their distance. It is also better not to think of the cosmological redshift as being caused by a real velocity as the parameter v in the above equation can easily exceed the speed of light. Continue reading “How Fast Is The Universe Expanding? The Riddle Of Two Values For The Hubble Constant” →

3D Printed Wobbly Wheels Put Through Their Paces

March 25, 2021 by 8 Comments

When we talk about wheels, the vast majority of the time we’re talking about ho-hum cylindrical rollers as seen on all manner of human conveyances. However, there are all manner of wild and wacky shapes that roll, and having had some experience with them, [Maker’s Muse] decided to take a shot at having a robot drive on them. (Video, embedded below.)

The benefit of a 3D printer is that it makes producing these parts with strange geometries a cinch. The video shows a variety of designs, from the wobbly “Nightshades” to the entertaining “Prongle” wheels being put through a variety of tests. In an attempt to equalise the playing field, each design was matched in its surface area so as not to artificially bias the results.

While the wobbly designs look strange, they also come with some benefits over simple disc wheels, providing extra traction on both carpet and sand. Particularly impressive was the performance of the 8-spoke wheels on the beach, though as this design mimics real-world sand tyres, we’re not surprised at the results. We’ve seen similar 3D printed parts do the job for driving on water, too.

Continue reading “3D Printed Wobbly Wheels Put Through Their Paces” →