A Super Simple DIY Ozone Generator

April 10, 2022 by Dave Rowntree 38 Comments

[Advanced Tinkering] needed a source of fresh ozone for some future chemistry related projects, and since buying an off-the-shelf unit would be, well, just plain boring, it was obvious what to do (Video, embedded below).

Wire mesh discharge surfaces separated with a glass tube

The concept of the corona-discharge ozone generator is pretty straightforward — a high-voltage AC potential is presented over a large surface area, such that any O₂ in the vicinity has the chance to get a decent dose of electrons ripping it apart and enabling the formation of the desired O₃.

The construction is quite simple, just a pair of cylindrical metal wire mesh electrodes, separated by a glass tube, with a second glass tube surrounding the whole assembly. The use of high voltage AC allows the discharge to form by capacitive coupling across the central tube, giving a very simple construction. A pair of 3D-printed PLA end caps complete the reaction vessel, although it is noted in the video that the PLA is not terribly resistant to the corrosive effects of ozone, and time will tell whether these go the whole mileage.

Feed oxygen from an external generator is pumped into one end cap, at the bottom, with ozone-enriched gas passing out the other end, at the top, giving the gas a more complex path through the assembly and maximizing the contact with discharge. It will be interesting to see what the produced ozone will be used for in these future projects.

We’ve not seen a vast number of ozone hacks, but we’re no strangers to high voltage applications, like this interesting hand disinfection device, and this simple hack that generates a six-figure voltage with little more than some glasses of water, well not much more anyway.

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Best Ways To Make PCB Breakaway Tabs, Revealed

April 9, 2022 by Donald Papp 20 Comments

Most of us are familiar with the concept of producing PCBs in a panel, and snapping them apart afterwards. V-grooves that go most of the way through a PCB are one way to go about this, but a line of perforations along which to snap a tab is another. But what’s the best size and spacing of holes to use? Sparkfun’s [Nick Poole] spent some $400 on PCBs to get some solid answers by snapping each of them apart, and judging the results.

The nice thing about creating a perforation line (or “mouse bites”) is that drill hits are a very normal thing in PCB production, which makes creating this kind of breakaway tab a very straightforward and flexible method. However, it can be tricky to get results that are just right. Too sturdy, and breaking apart is a hassle. Too weak, and the board may break or twist before its time. On top of that, edges must also break cleanly. We’ve covered panelizing PCBs in this way before, but this is the first time we’ve seen someone seriously look into how to create optimal breakaway tabs.

Placing holes tangent to the board edge (as shown above) isn’t the prettiest, but keeps PCB edges free from protrusions. This is best for boards that are rail-mounted, or have tight enclosures.

Data on designing mouse bites was sparse and a bit inconsistent, so [Nick] decided to figure it out empirically and share the results. The full details are available in Building a Better Mousebite (PDF download) but the essence of the recommendations are: 0.015″ unplated holes, spaced 0.025″ apart (center-to-center), tabs a maximum of 0.118″ wide (so as to be compatible with depanelizing tools), and holes that extend into the corners of the breakaway tab to avoid sharp edges. Holes should be placed slightly differently depending on whether one wishes to optimize the cosmetic appearance versus the physical smoothness of the board edge, but those numbers are the core of the guidelines.

To fine tune, [Nick] suggests increasing the spacing between holes to add strength, or just adding additional tabs. What about thickness of PCB? [Nick] tested boards both 0.8 mm and 1.6 mm thick, and while different amounts of torque were needed to snap the boards apart, things still worked as expected regardless of PCB thickness.

When it comes down to it, the best numbers will ultimately be the ones that your process or fab house can most efficiently handle, but [Nick]’s numbers should not steer anyone wrong, and it’s fantastic to see this kind of work go into refining such a common PCB feature.

Night Vision: Now In Color

April 9, 2022 by Al Williams 36 Comments

We’ve all gotten used to seeing movies depict people using night vision gear where everything appears as a shade of green. In reality the infrared image is monochrome, but since the human eye is very sensitive to green, the false-color is used to help the wearer distinguish the faintest glow possible. Now researchers from the University of California, Irvine have adapted night vision with artificial intelligence to produce correctly colored images in the dark. However, there is a catch, as the method might not be as general-purpose as you’d like.

Under normal illumination, white light has many colors mixed together. When light strikes something, it absorbs some colors and reflects others. So a pure red object reflects red and absorbs other colors. While some systems work by amplifying small amounts of light, those don’t work in total darkness. For that you need night vision gear that illuminates the scene with infrared light. Scientists reasoned that different objects might also absorb different kinds of infrared light. Training a system on what colors correspond to what absorption characteristics allows the computer to reconstruct the color of an image.

The only thing we found odd is that the training was on printed pictures of faces using a four-color ink process. So it seems like pointing the same camera in a dark room would give unpredictable results. That is, unless you had a huge database of absorption profiles. There’s a good chance, too, that there is overlap. For example, yellow paint from one company might look similar to blue paint from another company in IR, while the first company’s blue looks like something else. It is hard to imagine how you could compensate for things like that.

Still, it is an interesting idea and maybe it will lead to some other interesting night vision improvements. There could be a few niche applications, too, where you can train the system for the expected environment and the paper mentions a few of these.

Of course, if you have starlight, you can just use a very sensitive camera, but you still probably won’t get color. You can also build your own night vision gear without too much trouble.

Whales Help Scientists Investigate The Mystery Of Menopause

April 6, 2022 by Zoe Skyforest 7 Comments

Menopause is the time of life when menstrual periods come to a halt, and a woman is no longer able to bear children. The most obvious cause of menopause is when the ovaries run out of eggs, though it can also be caused by a variety of other medical processes. While menopause is in many ways well-understood, the biological reason for menopause, or the way in which it evolved in humanity remains a mystery. The process was once thought to be virtually non-existent in the animal kingdom, raising further questions.

Surprisingly recently, however, scientists began to learn that humans are not alone in this trait. Indeed, a small handful of sea-going mammals also go through this unique and puzzling process.

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Magpies Help Each Other Escape Tracking Devices With This One Weird Trick

April 5, 2022 by Zoe Skyforest 19 Comments

Scientists who work with animals love to track their movements. This can provide interesting insights on everything from mating behaviour, food sources, and even the way animals behave socially – or anti-socially, as the case may be.

This is normally achieved with the use of tracking devices, affixed to an animal so that it can be observed remotely while going about its normal business. However, Australian scientists have recently run into some issues in this area, as the very animals they try to track have been removing these very devices, revealing some thought-provoking behaviour in the process.

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Monitor Space Weather And The Atmosphere With Your Cellphone!

April 4, 2022 by Jenny List 9 Comments

Above our heads, the atmosphere is a complex and unpredictable soup of gasses and charged particles subject to the influence of whatever the Sun throws at it. Attempting to understand it is not for the faint-hearted, so it has for centuries been the object of considerable research. A new project from the European Space Agency and ETH Zurich gives the general public the chance to participate in that research in a small way, by crowdsourcing atmospheric data gathering to a mobile phone app. How might a mobile phone observe the atmosphere? The answer lies in their global positioning receivers, which can track minute differences in the received signals caused by atmospheric conditions. By gathering as much of this data as possible, the ESA scientists will gain valuable insights into atmospheric conditions as they change across the globe.

The app requires an Android phone equipped with a dual frequency satnav receiver, and having been duly installed on the trusty Hackaday Motorola it in turn started picking up all the different constellations of satellites. The instructions are to leave it somewhere such as a windowsill with an unobstructed view of the sky and move it as little as possible, to which we’d add clicking the “Log in background” button and connectign a charger. There’s a promise that uploaders can win prizes, so aside from contributing to scientific discovery there might be an unexpected benefit. More details on the app can be found here, meanwhile many readers will know that this isn’t the only crowdsourced atmospheric data gathering effort.

Stresses Revealed With A Polariscope

April 1, 2022 by Bryan Cockfield 13 Comments

There are a lot of ways that stresses can show up, at least when discussing materials science. Cracks in concrete are a common enough example, but any catastrophic failure in a material is often attributable to some stress that couldn’t be withstood. If you’re interested in viewing those stresses before they result in damage to the underlying material, take a look at this DIY polariscope which can view internal stresses in glass and other clear objects.

The polariscope takes its name from the fact that it uses polarized light to view the internal structure of a transparent object such as glass. When the polarized light passes through glass in a certain way, the stresses show up as lighter areas thanks to the stressed glass bending the light back into view. This one is constructed with a polarizing filter placed in front of an LCD screen set to display a completely white image. When glass is placed between the screen and the filter no light is seen through the polariscope unless there are stresses in the glass. Even placing a force on an otherwise un-stressed glass tube can show this effect, and [Advanced Tinkering], this project’s creator, has several other creations which show this effect in striking detail.

The effect can also be observed as colored areas in other plastic materials as well. It’s an interesting tool which can help anyone who frequently works with glass, but it’s also interesting on its own to see clues left behind from the manufacturing process of various household items. We’ve seen some other investigative methods for determining how other household items are mass produced as well, like this project which breaks down the injection molding process.

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