Lonnie Johnson, Prolific Engineer And Hero To Millions Of Kids (Even If They Don’t Know It)

June 16, 2020 by 29 Comments
The current generation Super Soaker XP30. (Hasbro)
The current generation Super Soaker XP30. (Hasbro)

To be a child in the 1970s and 1980s was to be of the first generations to benefit from electronic technologies in your toys. As those lucky kids battled blocky 8-bit digital foes, the adults used to fret that it would rot their brains. Kids didn’t play outside nearly as much as generations past, because modern toys were seducing them to the small screen. Truth be told, when you could battle aliens with a virtual weapon that was in your imagination HUGE, how do you compete with that.

How those ’80s kids must have envied their younger siblings then when in 1990 one of the best toys ever was launched, a stored-pressure water gun which we know as the Super Soaker. Made of plastic, and not requiring batteries, it far outperformed all squirt guns that had come before it, rapidly becoming the hit toy of every sweltering summer day. The Super Soaker line of water pistols and guns redefined how much fun kids could have while getting each other drenched. No longer were the best water pistols the electric models which cost a fortune in batteries that your parents would surely refuse to replace — these did it better.

You likely know all about the Super Soaker, but you might not know it was invented by an aerospace engineer named Lonnie Johnson whose career included working on stealth technology and numerous projects with NASA.

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A Properly Engineered UV Chamber For PPE Sanitization

June 16, 2020 by 49 Comments

Designed to be used once and then disposed of, personal protective equipment (PPE) such as N95 face masks proved to be in such short supply during the early days of the COVID-19 pandemic that getting a few extra uses out of them by sanitizing them after a shift seemed smart. And so we saw a bunch of designs for sanitizing chambers, mostly based on UV-C light and mostly, sad to say, somewhat dodgy looking. This UV-C disinfection chamber, though, looks like a much better bet.

The link above is to the final installment of a nine-part series by [Jim] from Grass Roots Engineering. The final article has links to all the earlier posts, which go back [Jim]’s early research on UV-C sanitization methods back in March. This led him to settle on an aquarium sanitizer as his UV-C source. A second-hand ultraviolet meter allowed him to quantify the lamp’s output and plan how best to use it, which he did using virtual models of various styles of masks.  Knowing that getting light on every surface of the mask is important, he designed a mechanism to move the mask around inside a reflective chamber. The finished chamber, which can be seen in the video below, is 3D-printed and looks like it means business, with an interlock for safety and a Trinket for control.

We love the level of detail [Jim] put into these posts and the thoughtful engineering approach he took toward this project. And we appreciate his careful testing, too — after all, it wouldn’t do to use a germicidal lamp that actually doesn’t emit UV-C.

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Why You (Probably) Won’t Be Building A Replica Amiga Anytime Soon

June 16, 2020 by 68 Comments

Early in 2019, it  became apparent that the retro-industrial complex had reached new highs of innovation and productivity. It was now possible to create entirely new Commdore 64s from scratch, thanks to the combined efforts of a series of disparate projects. It seems as if the best selling computer of all time may indeed live forever.

Naturally, this raises questions as to the C64’s proud successor, the Amiga. Due to a variety of reasons, it’s less likely we’ll see scratch-build Amiga 500s popping out of the woodwork anytime soon. Let’s look at what it would take, and maybe, just maybe, in a few years you’ll be firing up Lotus II (or, ideally, Jaguar XJ220: The Game) on your brand new rig running Workbench 1.3. Continue reading “Why You (Probably) Won’t Be Building A Replica Amiga Anytime Soon” →

Tackling Trunked Radio With Software

June 16, 2020 by 12 Comments

For those starting to wade into radio as a hobby, one of the first real technical challenges is understanding trunked radio systems. On the surface, it seems straightforward: A control channel allows users to share a section of bandwidth rather than take up one complete channel, allowing for greater usage of the frequency range. In practice though it can be difficult to follow along, but now it’s slightly easier thanks to software defined radio.

This guide comes to us from [AndrewNohawk], who is located in San Francisco and is using his system to monitor police, fire, and EMS activity. These groups typically used trunked radio systems due to the large number of users. For listening in, nothing more than an RTL-SDR setup is needed, and the guide walks us through using this setup to find the control channels, the center frequency, and then identifying the “talk groups” for whichever organization you want to listen in on.

The guide goes into great detail, including lists of software needed to get a system like this started up, and since [AndrewNohawk] is a self-identified “radio noob” the guide is perfectly accessible to people who are new to radio and specifically new to trunked systems like these. Once you get the hang of it, it’s not too hard to scale up, either.

Retrotechtacular: The Nernst Lamp

June 16, 2020 by 56 Comments

After dominating the illumination market for more than a century, it’s easy to think of the glowing filament of the standard incandescent lamp as the only way people found to turn electricity into light. But plenty of fertile minds turned out alternative designs, one of which is the fascinating Nernst lamp, which we’d previously never heard of.

If the name sounds familiar, it’s likely through exposure to [Walther Nernst]’s equation for electrochemistry, or for his “New Heat Theorem” which eventually became the Third Law of Thermodynamics. Pal of [Einstein] and eventual Nobel laureate, [Nernst] was also a bit of a tinkerer, and he came up with a design for an incandescent lamp in 1897 that was twice as efficient as carbon-filament lamps. The video below, from the Edison Tech Center, details the design, which used a ceramic “glower rod” that would incandesce when current flowed through it. The glower, though, was not conductive until it was quite hot, so separate heater coils that gave the glower a start on the process were included; these were switched off by a relay built into the base of the lamp once the glower started conducting.

It’s a complicated design, but its efficiency, coupled with a better light spectrum and the fact that it didn’t need a vacuum bulb since the glower wouldn’t oxidize like a carbon or tungsten filament, gave it certain advantages that let it stake out a decent share of the early market for electric illumination. It was even the light source for one of the first facsimile machines. We find it a very clever use of what were at the time exotic materials, and wonder if this could have lead to something like vacuum tubes without the vacuum.

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Portable Video Looper Is Easy As Pi

June 15, 2020 by 10 Comments

We all have handfuls of thumb drives lying around with only a vague idea of what’s on most of them, right? So why not dust one off, back it up somewhere, and give it a new purpose? That’s exactly what [Cher_Guevara] did to make this portable Raspberry Pi video looper. The hardest part of recreating this one might be coming up with such a good candidate mini CRT TV.

Once powered on, the Pi Zero W stuffed inside this baby Magnavox waits for a thumb drive to be inserted and says as much in nice green text on the screen. Then it displays the number of video files found on the drive and gives a little countdown before looping them all endlessly.

We love how flawlessly [Cher] was able to integrate the USB port and a flush-mounted shutdown button for the Pi into the TV’s control panel on the top. It’s like a portable from another timeline.

[Cher] got lucky because this TV happens to have a video-in jack for connecting up the Pi. If yours doesn’t have one, you might be able to use an RCA to RF converter if the antenna is removable. We’ve got the demo video waiting for you after these messages.

Okay, that’s one thumb drive repurposed. Now find another and experiment with adding USB OtG to it.

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High Speed The Way We Want It

June 15, 2020 by 26 Comments

The one thing we have learned over the current pandemic is that we need the internet, and the faster the better. Though cost is surely a hurdle, the amount of bandwidth available has its bottlenecks rooted from the underlying technology. Enter new technology from an Australian Research team who have claimed to have field tested internet speeds as fast at 44.2 terabits per second.

The breakthrough in bandwidth is attributed to a new optical chip that employs optical frequency combs or micro-comb, and has been published by [Corcoran et al] of Monash University. The team exploits the ability of certain crystals to create resonant optical fields called solitons and these form highly efficient optical transmission system. For the uninitiated, optical frequency combs are an optical spectrum of equidistant lines whose values if fixed, can be used to measure unknown frequencies. The original discovery earned Roy J. Glauber, John L. Hall and Theodor W. Hänsch the Nobel Prize in Physics in 2005, and though it is a relatively new field it has seen a lot of activity in the research community.

The experimental setup has a resonator with a free spectral range spacing of 48.9GHz, and from the generated optical fields or lines, 80 were selected. Using a side-band modulator the bands were doubled and eventually with 64 QAM modulation facilitated a symbol rate of 23 Gigabaud. Now at this point, the paper says that this experiment is still an under-utilization of the available resources. The extra connectivity speed may be helpful in gaming and streaming but we will be needing faster drives to get our emails attachments downloaded faster. If you are inspired and want to play with lasers and optical communications, check out the DIY Laser Optical Link.

Thanks [Anil Pattni] for the tip.