Growing Up With Computers

June 19, 2021 by Elliot Williams 78 Comments

My son is growing up with computers. He’s in first grade, and had to list all of the things that he knows how to do with them. The list included things like mousing around, drawing ghosts with the paint program, and — sign of the times — muting and unmuting the microphone when he’s in teleconferences. Oh yeah, and typing emojis. He loves emojis.

When I was just about his age, I was also getting into computers. But home computers back then were in their early years as well. And if I look back, I’ve been getting more sophisticated about computers at just about the same pace that they’ve been getting more sophisticated themselves. I was grade school during the prime of the BASIC computers — the age of the Apple II and the C64. I was in high school for the dawn of the first Macs and the Amiga. By college, the Pentiums’ insane computational abilities just started to match my needs for them to solve numerical differential equations. And in grad school, the rise of the overclockable multi-cores and GPUs powered me right on through a simulation-heavy dissertation.

When I was a kid, they were playthings, and as a grownup, they’re powerful tools. Because of this, computers have never been intimidating. I grew up with computers.

But back to my son. I don’t know if it’s desirable, or even possible, to pretend that computers aren’t immensely complex for the sake of a first grader — he’d see right through the lie anyway. But when is the right age to teach kids about voice recognition and artificial neural networks? It’s a given that we’ll have to teach him some kind of “social media competence” but that’s not really about computers any more than learning how to use Word was about computers back in my day. Consuming versus creating, tweeting versus hacking. Y’know?

Of course every generation has its own path. Hackers older than me were already in high-school or college when it became possible to build your own computer, and they did. Younger hackers grew up with the Internet, which obviously has its advantages. Those older than me made the computers, and those younger have always lived in a world where the computer is mature and taken for granted. But folks about my age, we grew up with computers.

Tell Time The Cistercian Way

June 19, 2021 by Jenny List 10 Comments

It’s rare for the fields of the engineer and the mediaevalist to coincide, but there’s a clock project bringing the two fields together. The Cistercian monastic order used an intriguing number system from the 13th century onwards that could represent any four-digit number as a series of radicals expressed in the four corners of a single composite symbol, and it’s this number system that’s used by the clock to render the full range of 24 hour time on a large 5×7 LED matrix mounted on a wooden base.

Behind the scenes is an Arduino and a DS3231 real-time clock, and all the code can be found in a handy GitHub repository. There’s even a PCB from everyone’s favourite vendor of purple PCBs, The result is certainly an interesting clock that makes the break from the usual binary and Nixie timepieces with some style. It also provides an introduction to this fascinating but obscure numerical system, in the event that any of us might have missed the one other such clock that has made it to these pages.

Is It A Plasma Tweeter Or A Singing Tesla Coil?

June 19, 2021 by Jenny List 6 Comments

When our ears resolve spatial information, we do so at the higher treble frequencies rather than the bass. Thus when setting up your home cinema you can put the subwoofer almost anywhere, but the main speakers have to project a good image. The theoretical perfect tweeter for spatial audio is a zero mass point source, something that a traditional speaker doesn’t quite achieve, but to which audio engineers have come much closer with the plasma tweeter. This produces sound by modulating a small ball of plasma produced through high-voltage discharge, and it’s this effect that [mircemk] has recreated with his HF plasma tweeter.

A look at the circuit diagram and construction will probably elicit the response from most of you that it looks a lot like a Tesla coil, and in fact that’s exactly what it is without the usual large capacitor “hat” on top. This arrangement has been used for commercial plasma tweeters using both tubes and semiconductors, and differs somewhat from the singing Tesla coils you may have seen giving live performances in that it’s designed to maintain a consistent small volume of discharge rather than a spectacular lightning show to thrill an audience.

You can see it in operation in the video below the break, and it’s obvious that this is more of a benchtop demonstration than a final product with RF shielding, It’s not the most efficient of devices either, but given that audiophiles will stop at nothing in their pursuit of listening quality, we’d guess that’s a small price to pay. Efficiency can be improved with a flyback design, but for the ultimate in showing off how about a ring magnet to create the illusion of a plasma sheet?

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A Model Of Dry Humor

June 18, 2021 by Brian McEvoy 5 Comments

If you want to see a glorious combination of model bananas in a treehouse mixed with a lot of tongue-in-cheek humor, you will appreciate [Studson]’s build video. Video also after the break. He is making an homage to Donkey Kong 64 from 1999, which may be a long time ago for some folks’ memory (Expansion Pak). Grab a piece of your favorite banana-flavored fruit and sit tight for joke delivery as dry as his batch of baked bark.

The treehouse uses a mixture of found material and crafting supplies. In a colorful twist, all the brown bark-wielding sticks are green, while the decorative greenery came from a modeling store shelf. It all starts with a forked branch pruned from the backyard and a smooth-sided container lid that might make you look twice the next time you nuts are buying a bin of assorted kernels. If you thought coffee stirrers couldn’t be used outside their intended purpose, prepare to have your eyes opened, but remember to wear eye protection as some of the wood clippings look like they could achieve escape velocity. The key to making this look like an ape abode, and not a birdhouse, is the color choices and finishing techniques. Judging by the outcome and compared to the steps, making a model of this caliber is the sign of an expert.

If you wish to binge on wooden Donkey Kong, we can grant your desire, but if you prefer your treehouses life-sized, this may launch your imagination.

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3D Printing Food University Style

June 18, 2021 by Al Williams 5 Comments

While refitting a 3D printer for food printing isn’t really a new idea, we liked the detailed summary that appeared from a team from the University of Birmingham which converted an i3 clone printer to use a syringe extruder.

The syringe in question was meant for veterinarian use and is made of metal. The paper suggests that the metal is a better thermal conductor, but it was’t clear to us if they included a heating element for the syringe. In the pictures, though, it does appear to have some insulation around it. In any case, we imagine a metal syringe is easier to keep clean, which is important if you are depositing something edible.

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Check Soil Moisture At A Glance With This Useful Display

June 18, 2021 by Lewin Day 6 Comments

Keeping soil moist is key to keeping most plants happy. It can be a pain having to dip one’s fingers into dirty soil on the regular, so it’s desirable to have a tool to do the job instead. [Andrew Lamchenko] built a capable soil moisture monitor, and equipped it with an E-ink display for easy readings at a glance.

The device is built around the NRF52810 or other related NRF52 microcontrollers, which run the show. Rather than using an off-the-shelf sensor to determine soil conditions, an LMC555CMX timer chip is used, a variant of the classic 555 timer designed for low power consumption. Combined with the right PCB design, this can act as a moisture sensor by detecting capacitance changes in the soil. The sensor is also able to send data using the MySensor protocol, allowing it to be used as a part of a home automation system.

The soil is tested periodically with the moisture sensor, and displayed on the attached e-ink screen. Since the e-ink display requires no electricity except when rewriting the display, this allows the sensor to operate for long periods without using a lot of battery power. The soil can be checked, the display updated, and then the entire system can be put to sleep, using tiny amounts of power until it’s time to test the soil again.

It’s a great example of design for low power applications, where component selection really is everything. We’ve featured [Andrew]’s projects before; he’s long been a fan of using e-ink displays to create long-lasting, low power budget sensor platforms. Video after the break.

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Just How Water Resistant Is The Casio F91W?

June 18, 2021 by Lewin Day 25 Comments

Water resistance is an important feature of a modern watch. It makes wearing the watch far more practical in this modern world of sudden rainstorms and urban water balloon ambushes. The Casio F91W, one of the company’s most popular watches, is claimed to be water resistant to “30 meters”, which in ISO parlance, means it is suitable for splashes and rain resistance only. [Rostislav Persion] wanted to get a better idea of what this really meant, so set about investigating for himself.

The first step was to simply immerse the watch under 5.5″ of cold tap water while pressing the buttons and observing for any signs of water ingress. Already, the watch proved it is far more than just rain resistant, so [Rotislav] decided to disassemble the watch and learn how it achieved this.

Disassembly revealed that the watch’s case was entirely sealed, except for three buttons. The buttons, however, are specially designed in order to seal with the plastic case of the watch. Each button consists of a stainless steel pin, machined to be larger on the outside-facing side than the inside. The buttons also have a rubber O-ring seal to allow them to move in the case without allowing water to leak inside. [Rotislav] then compares the simple design to buttons used on watches with higher water resistance ratings, which boast multiple O-ring seals and more complex designs.

Given [Rotislav’s] results, we’d be far more confident getting our affordable Casio watches a little wet. Obviously, we wouldn’t expect to make a warranty claim if damage occurred from use outside the specs, but it’s clear the watch is far more capable than standards might suggest. If that’s not enough though, you can always set about modifying the watch to improve its water resistance even further.