Blinks Are Useful In VR, But Triggering Blinks Is Tricky

April 9, 2023 by 8 Comments

In VR, a blink can be a window of opportunity to improve the user’s experience. We’ll explain how in a moment, but blinks are tough to capitalize on because they are unpredictable and don’t last very long. That’s why researchers spent time figuring out how to induce eye blinks on demand in VR (video) and the details are available in a full PDF report. Turns out there are some novel, VR-based ways to reliably induce blinks. If an application can induce them, it makes it easier to use them to fudge details in helpful ways.

It turns out that humans experience a form of change blindness during blinks, and this can be used to sneak small changes into a scene in useful ways. Two examples are hand redirection (HR), and redirected walking (RDW). Both are ways to subtly break the implicit one-to-one mapping of physical and virtual motions. Redirected walking can nudge a user to stay inside a physical boundary without realizing it, leading the user to feel the area is larger than it actually is. Hand redirection can be used to improve haptics and ergonomics. For example, VR experiences that use physical controls (like a steering wheel in a driving simulator, or maybe a starship simulator project like this one) rely on physical and virtual controls overlapping each other perfectly. Hand redirection can improve the process by covering up mismatches in a way that is imperceptible to the user.

There are several known ways to induce a blink reflex, but it turns out that one novel method is particularly suited to implementing in VR: triggering the menace reflex by simulating a fast-approaching object. In VR, a small shadow appears in the field of view and rapidly seems to approach one’s eyes. This very brief event is hardly noticeable, yet reliably triggers a blink. There are other approaches as well such as flashes, sudden noise, or simulating the gradual blurring of vision, but to be useful a method must be unobtrusive and reliable.

We’ve already seen saccadic movement of the eyes used to implement redirected walking, but it turns out that leveraging eye blinks allows for even larger adjustments and changes to go unnoticed by the user. Who knew blinks could be so useful to exploit?

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Debouncing For Fun And… Mostly, Just For Fun

April 9, 2023 by 13 Comments

In our minds and our computer screens, we live in an ideal world. Wires don’t have any resistance, capacitors don’t leak, and switches instantly make connections and break them. The truth is, though, in the real world, none of those things are true. If you have a switch connected to a lightbulb, the little glitches when you switch are going to be hard to notice. Hook that same switch up to a processor that is sampling it constantly, and you will have problems. This is the classic bane of designing microcontroller circuits and is called switch bounce. [Dr. Volt] covers seven different ways of dealing with it in a video that you can see below.

While you tend to think of the problem when you are dealing with pushbuttons or other kinds of switches for humans, the truth is the same thing occurs anywhere you have a switch contact, like in a sensor, a mechanical rotary encoder, or even relay contacts. You can deal with the problem in hardware, software, or both.

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Homemade Scope Does Supercapacitor Experiments

April 8, 2023 by 12 Comments

We’ve always been a little sad that supercapacitors aren’t marked with a big red S on a yellow background. Nevertheless, [DiodeGoneWild] picked up some large-value supercapacitors and used his interesting homemade oscilloscope to examine how they worked. You can watch what he is up to in his workshop in the video below.

Supercapacitors use special techniques to achieve very high capacitance values. For example, the first unit in the video is a 500 F capacitor. That’s not a typo — not microfarads or even millifarads — a full 500 Farads. With reasonable resistance, it can take a long time to charge 500F, so it is easier to see the behavior, especially with the homemade scope, which probably won’t pick up very fast signals.

For example, A 350 mA charging current takes about an hour to bring the capacitor up to 2.6 V, just under its maximum rating of 2.7 V. Supercapacitors usually have low voltage tolerance. Their high capacity makes them ideal for low-current backup applications where you might not want a rechargeable battery because of weight, heat, or problems with long-term capacity loss.

The real star of the video, though, is the cast of homemade test equipment, including the oscilloscope, a power supply, and a battery analyzer. To be fair, he also has some store-bought test gear, too, and the results seem to match well.

Supercapacitors are one of those things that you don’t need until you do. If you haven’t had a chance to play with them, check out the video or at least watch it to enjoy the homebrew gear. We usually look to [Andreas Spiess] for ESP32 advice, but he knows about supercaps, too. If you really like making as much as you can, you can make your own supercapacitors.

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Revisiting Borland Turbo C And C++

April 8, 2023 by 76 Comments

Looking back on what programming used to be like can be a fascinatingly entertaining thing, which is why [Tough Developer] decided to download and try using Turbo C and C++, from version 1.0 to the more recent releases. Borland Turbo C 1.0 is a doozy as it was released in 1987 — two years before the C89 standardization that brought us the much beloved ANSI C that so many of us spent the 90s with. Turbo C++ 1.0 is from 1991, which precedes the standardization of C++ in 1998. This means that both integrated development environments (IDEs) provide a fascinating look at what was on the cutting edge in the late 80s and early 90s.

Online help and syntax coloring in Turbo C++.

It wasn’t until version 3.0 that syntax highlighting was added, with the IDE’s focus being mostly on features such as auto-indentation and tool integration. Version 2.0 added breakpoints and further integration with the debugger and other tools, as well as libraries such as the Borland Graphics Interface (BGI). Although even editors like Notepad++ and Vim probably give these old IDEs a run for their money nowadays, they were totally worth the money asked.

Those of us that have been around long enough to have gotten their start in C++ by using the free Turbo command line tools in the 1990s, or lived through the rough, early days of GCC 2.x+ on Linux, will remember that a development environment that Just Worked© was hard to obtain without shelling out some cash. Within that environment Turbo C and C++ and later Visual Studio and others served a very grateful market indeed.

Beyond the IDE itself, these also came with language documentation, as in the absence of constant internet access, referencing APIs and syntax was done using dead-tree reference books or online documentation. Here “online” meaning digital documentation that came provided on a CD and which could be referenced from within the IDE.

[Tough Developer] walks the reader through many features of the IDE, which includes running various demos to show off what the environment was capable of and how that in turn influenced contemporary software and games such as Commander Keen in Keen Dreams. While we can’t say that a return to Turbo C is terribly likely for the average Hackaday reader, we do appreciate taking a look back at older languages and development environments — if for no other reason than to appreciate how far things have come since then.

Web Server Like It’s 1998 With This Restored Internet Appliance

April 8, 2023 by 20 Comments

Hackaday readers fit into two broad categories: those who experienced the wild and woolly early days of the Internet, and those who are jealous that they missed it. And it’s safe to say that both groups will get something out of this aggressively Web 1.0 retro experience, courtesy of a server that was actually part of it.

This comes to us via The Serial Port, a virtual museum dedicated to 90s technology, where curators [Mark] and [Ben] managed to find a pair of Cobalt RaQ 3 servers from the late 1990s. The RaQ was the first true “Internet appliance,” designed to be as simple as possible to set up and operate. If you wanted to get your small business online, machines like these were just the ticket. They were designed to be as plug-and-play as possible, and they did a pretty good job of it, at least for the time.

The machines that showed up were quite the worse for the wear, which is understandable given the decades since they were last relevant, but that just makes it all the more fun to get them going again. One didn’t even come close to booting, but the other showed more promise.

The video below is the first of a three-part series, and has a nice introduction to the RaQ and its important place in the early Internet, as well as a peek inside the two machines. That revealed some leaky caps that needed replacement in Part 2; after that minor surgery and a little persuasion, the 300-MHz screamer was ready for a test run. It worked, and The Serial Port put it right to work in Part 3 hosting a gloriously retro home page. Hit the link at the top of the article and enjoy the 90s all over again — the visitor counter, the mixed fonts, the “Under Construction” animated GIF, and the reminder to bookmark this page in your browser, which was probably Netscape Navigator. We love the guestbook, too. But — no marquee?

Nice job, [Mark] and [Ben], and kudos for keeping this little slice of computing history alive.

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Russia’s New Mystery Shortwave Station

April 8, 2023 by 36 Comments

The Buzzer, also known as UVB-76 or UZB-76, has been a constant companion to anyone with a shortwave radio tuned to 4625 kHz. However, [Ringway Manchester] notes that there is now a second buzzer operating near in frequency to the original. Of course, like all mysterious stations, people try to track their origin. [Ringway] shows some older sites for the Buzzer and the current speculation on the current transmitter locations.

Of course, the real question is why? The buzzing isn’t quite nonstop. There are occasional voice messages. There are also jamming attempts, including one, apparently, by Pac Man.

Some people think the new buzzer is an image, but it doesn’t seem to be the same signal. The theory is that the buzzing is just to keep the frequency clear in case it is needed. However, we wonder if it isn’t something else. Compressed data would sound like noise.  Other theories are that the buzzing studies the ionosphere or that it is part of a doomsday system that would launch nuclear missiles. Given that the signal has broken down numerous times, this doesn’t seem likely.

What’s even stranger is that occasional background voices are audible on the signal. That implies that buzzing noise isn’t generated directly into the transmitter but is a device in front of a microphone.

We’ve speculated on the buzzer and the jamming efforts around it before. Not exactly a numbers station, but the same sort of appeal.

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Mechanical GIF Animates With The Power Of Magnets

April 8, 2023 by 16 Comments

It doesn’t matter how you pronounce it, because whichever way you choose to say “GIF” is guaranteed to cheese off about half the people listening. Such is the state of our polarized world, we suppose, but there’s one thing we all can agree on — that a mechanical GIF is a pretty cool thing.

What’s even better about this thing is that [Mitch], aka [Hack Modular], put some very interesting old aircraft hardware to use to make it. He came upon a set of cockpit indicators from a Cold War-era RAF airplane — sorry, “aeroplane” — that used a magnetically driven rack and pinion to swivel a set of prism-shaped pieces to one of three positions. Which of the three symbols displayed depended on which faces were turned toward the pilot; they were highly visible displays that were also satisfyingly clicky.

After a teardown in which [Mitch] briefly discusses the mechanism behind these displays, he set about customizing the graphics. Rather than the boring RAF defaults, he chose three frames from the famous Horse in Motion proto-motion picture by [Eadweard Muybridge]. After attaching vertical strips from each frame to the three sides of each prism, [Mitch] came up with a driver for the display; he could have used a 555, but more fittingly chose series-connected relays to do the job. Capacitors slow down the switching cascade and the frame rate; a rotary switch selects different caps to make the horse appear to be walking, trotting, cantering, or galloping — yes, we know they’re each physically distinct motions, but work with us here.

The whole thing looks — and sounds — great mounted in a nice plastic enclosure. The video below shows it in action, and we find it pretty amazing the amount of information that can be conveyed with just three frames. And we’re surprised we’ve never seen these displays before; they seem like something [Fran Blanche] or [Curious Marc] would love.

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