Handwashing Timer Makes Sure The Suds Stay On Long Enough

March 19, 2020 by 21 Comments

“Twinkle, Twinkle, Little Star”? How we wonder why you’d resort to singing a ditty to time your handwashing when you can use your social isolation time to build a touch-free electronic handwash timer that the kids — and you — might actually use.

Over the last few months, pretty much everyone on the planet has been thrust into strange, new, and oftentimes scary practices to limit the spread of the SARS-CoV-2virus and the disease it causes, COVID-19. Judging by the number of people we’ve seen leaving public restrooms without a visit to the washbasin before the outbreak began — and sadly all too often since — we collectively have a lot of work to do in tightening up our handwashing regimens. Time on target and plenty of friction are the keys to that, and [Denis Hennessy]’s “WashTimer” aims to at least help you out with the former. His build is as simple as can be: an Arduino driving an LED matrix when a proximity sensor fires. Wave your dirty paws in front of the unit as you start to scrub up, and the display goes through a nicely animated 20-second countdown, at which time it’s safe to rinse off.

[Denis] purposely made this design as simple and as customizable as possible. Perhaps you’ve got a Neopixel ring lying about rather than the LED matrix, or maybe an ultrasonic sensor would work better for you. Be creative and take this design where it needs to go to suit your needs. We can’t stress enough that handwashing is your number one defense; if you don’t need to moisturize your hands at least three times a day, you’re probably not washing often or long enough. And 20 seconds is way longer than you think it is without a prompt.

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A 555 And A Lighter Make High Voltage

March 19, 2020 by 20 Comments

If you don’t have a ready source of high voltage, here’s an easy way to build one from the aptly-named [HVZapp]. The parts list is pretty simple to acquire, except for the transformer. For that, [HVZapp] raided a broken arc lighter. It took us a minute to realize that the MOSFETs are in parallel. The hand-drawn schematic shows a little “jump” from the drain lead to the source lead, but if you aren’t careful, it looks like the FETs are shorted out, which — of course — they aren’t.

The original arc lighter, of course, did a fine job of creating high voltage, although perhaps not as much as this circuit. Also, it would turn off every 10 seconds, which isn’t very useful if you want to use it as a power supply.

If you aren’t sure what to do with a high voltage, supply, there’s an associated quick and dirty Jacob’s Ladder in the video below. If you want your high voltage in a more natural way, consider harnessing lightning. There are many ways to generate high voltages.

The Corona Clock

March 19, 2020 by 19 Comments

Schools are closed here in Germany until after Easter vacation, and that means that our almost-six-year-old son Max is staying at home with us. The good news is that my wife and I work from home anyway, so it’s not too stressful as long as he can look after himself for eight hours per day. The bad news is that there’s no way a kindergarten kid can take care of himself for such long stretches, and we don’t want to just park him in front of the boob tube. At least there’s two of us.

The new stay-at-home life has required some adjustment, but for at least the first five days (and counting) it’s working out pretty darn well. One trick: my wife came up with the idea of a visual schedule to help Max divide his day up into kindergarten-sized chunks, and then we added an LED strip behind it to turn it into a linear clock of sorts. And we did it with stuff we had lying around the house.

Granted, it’s not a super deep hacky-hack, and some of you out there could probably get it done with a handful of 555 timers. But it was quick, gets the job done, and heck, with NTP sync, it’s the most accurate kiddie clock in the world! So those of you out there who are stuck like we are, trying to balance childcare and working from home, here’s a quick project that can increase familial harmony while giving you an excuse to order more LED strips.

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Do You Smell What The Magic Chef Is Cookin’?

March 19, 2020 by 6 Comments

Automata are already pretty cool, but the ones that can fool us are something extraordinary. The legendary [Greg Zumwalt] has recently turned his toy-making attentions toward illusory automata, and we think he’s off to a great start with his admirable appetizer, the Magic Chef.

The Chef aims to please, and as long as he has the power to do so, he’ll keep offering dishes from his six-item menu of hamburger, hot dog, pizza slice, BLT, sunny-side-up egg, and banded gelatinous chunk we can’t quite identify. Amazingly, this one-man restaurant does everything with a single 6VDC gear motor, some magnets, and 58 printed parts including gears, cams, and levers. The way the food carousel moves on a sort of magnetic slip ring system is the icing on the cake.

If you want to whip up a Magic Chef of your own, all the STL files are available for take-out from the Instructables page. Hungry for more details? go wash up and get situated after the break, ’cause we’re serving up a demo video with some close-up views of the inner workings. Oh, and here’s some automata-brewed coffee for dessert.

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Thousands Of Internet-Connected Satellites Above Us, What Could Possibly Go Wrong!

March 19, 2020 by 55 Comments

Our skies are full of satellites, more full than they have been, that is, because SpaceX’s Starlink and a bevvy of other soon-to-launch operators plan to fill them with thousands of small low-earth-orbit craft to blanket the Earth with satellite Internet coverage. Astronomers are horrified at such an assault on their clear skies, space-watchers are fascinated by the latest developments, and in some quarters they’re causing a bit of concern about the security risk they might present. With a lot of regrettable overuse use of the word “hacker”, the concern is that such a large number of craft in the heavens might present an irresistible target for bad actors, who would proceed to steer them into each other can cause chaos.

Invest in undersea cables, folks, the Kessler Syndrome is upon us, we’re doomed!

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Saving 4 Patients With Just 1 Ventilator

March 19, 2020 by 59 Comments

We all know that COVID-19 is stressing our health system to the limit. One of the most important machines in this battle is the ventilator. Vents are critical for patients experiencing the worst symptoms of respiratory distress from the virus. Most of the numbers predict that hospitals won’t have enough ventilators to keep up with the needs during the height of the pandemic.

Now anyone with a walkman or iPod can tell you what they do when there is one music device and two people who want to listen: Plug in a Y-connector. Wouldn’t it be great if you could do the same thing with a medical ventilator? It turns out you can – – with some important caveats.

Way back in 2006, [Greg Neyman, MD and Charlene Babcock, MD] connected four simulated patients to a single ventilator. Ventilators connect to a patient with two tubes – an inflow and an exhaust. Using common parts available in just about any hospital, the doctors installed “T-tube” splitters on the inflow and exhaust tubes. They tested this with lung simulators and found that the system worked.

There were some important considerations though. The patients must be medically paralyzed, and have similar lung capacity — you couldn’t mix an adult and a child. The tubing length for each patient needs to be the same as well. The suggestion is to place the patients in a star pattern with the ventilator at the center of the star.

[Dr. Charlene Babcock] explains the whole setup in the video after the break.

Interestingly enough, this technique went from feasibility study to reality during the Las Vegas shooting a few years ago. There were more patients than ventilators, so emergency room doctors employed the technique to keep patients alive while equipment was brought in from outside hospitals. It worked — saving lives on that dark day.

The video and technique remind us of Apollo 13 and the CO2 scrubber modifications. Whatever it takes to keep people alive. We’ve already started looking into open source ventilators, but it’s good to see that medical professionals have been working on this problem for years.

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Sweet Streams Are Made Of These: Creating Music On The Command Line

March 19, 2020 by 3 Comments

There are countless ways to create music. In the simplest form, it won’t even require any equipment, as evidenced by beatboxing or a capella. If we move to the computer, it’s pretty much the same situation: audio programming languages have been around for as long as general-purpose high-level languages, and sound synthesis software along with them. And just as with physical equipment, none of that is particularly necessary thanks to sed. Yes, the sed, the good old stream editor, as [laserbat] shows in her music generating script.

Providing both a minified and fully commented version of Bach’s Prelude 1 in C major as example, [laserbat] uses a string representation of the sheet music as the script’s starting point, along with a look-up table of each transformed note’s wavelength. From here, she generates fixed length PCM square wave signals of each of the notes, to be piped as-is to the sound card via ALSA’s aplay or SoX’s play. To keep things simple enough, she stays within the region of printable characters here, using space and tilde as low and high values respectively, providing highest possible volume at the same time this way.

The concept itself is of course nothing new, it’s how .au and .wav files work, as well as these little C lines. And while the fixed note duration takes away some of the smoothness in [laserbat]’s version, adding variable duration might just be a hint too much for a sed implementation, although we’ve certainly seen some more complex scripts in the past.

[via r/programming]