Know Audio: A Loudspeaker Primer

As we’ve started out on our journey through the world of Hi-Fi audio from a strictly practical and engineering viewpoint without being misled by any audiophile woo, we’ve already taken a look at the most important component in any audio system: the listener’s ear. It’s time to move down the chain to the next link; the loudspeaker.

Sound is pressure waves in the air, and the purpose of a loudspeaker is to move the air to create those waves. There are a variety of “exotic” loudspeaker technologies including piezoelectric and electrostatic designs, here we’ll be considering the garden variety moving-coil speaker. It’s most usually used for the large bass or smaller mid-range drivers in a typical speaker system. Continue reading “Know Audio: A Loudspeaker Primer”

This Week In Security: Schemeflood, Modern Wardialing, And More!

There’s been yet another technique discovered to fingerprint users, and this one can even work in the Tor browser. Scheme flooding works by making calls to application URLs, something like steam://browsemedia. If your machine supports the requested custom URL, a pop-up is displayed, asking permission to launch the external application. That pop-up can be detected by JavaScript in the browser. Detect enough apps, and you can build a reasonable fingerprint of the system the test is run on. Unlike some previous fingerprinting techniques, this one isn’t browser dependent — it will theoretically give the same results for any browser. This means even the Tor browser, or any browser being used over the Tor network, can give your potentially unique set of installed programs away.

Now for the good news. The Chrome devs are already working on this issue, and in fact, Chrome on my Linux desktop didn’t respond to the probes in a useful way. Feel free to check out the demo, and see if the results are accurate. And as for Tor, you really should be running that on a dedicated system or in a VM if you really need to stay anonymous. And disable JavaScript if you don’t want the Internet to run code on your computer.
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Piezo Pickup Makes Wax Records Easy To Digitize

Sound recording and playback have come a long way in the last century or so, but it’s fair to say there’s still a lot of interesting stuff locked away on old recordings. Not having a way to play it back is partly to blame; finding an antique phonograph that plays old-timey cylinder recordings is pretty hard. But even then, how do you digitize the output of these fragile, scratchy old recordings?

As it happens, [Jan Derogee] is in a position to answer these questions, with an antique phonograph and a bunch of Edison-style wax cylinders with voices and music from a bygone era locked away on them. It would be easy enough to just use the “reproducer” he previously built and set up a microphone to record the sound directly from the phonograph’s trumpet, but [Jan] decided to engineer a better solution. By adding the piezo element from an electronic greeting card to his reproducer, potted with liberal quantities of epoxy and padded with cotton, the piezo pickup was attached to the phonograph arm in place of the original stylus and trumpet. The signal from the piezo element was strong enough to require a shunt resistor, allowing it to be plugged directly into the audio input jack on a computer. From there it’s just an Audacity exercise, plus dealing with the occasional skipped groove.

We appreciate [Jan]’s effort to preserve these recordings, as well as the chance to hear some voices from the past. We’re actually surprised the recording sound as good as they do after all this time — they must have been well cared for.

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PipeWire, The Newest Audio Kid On The Linux Block

Raise your hand if you remember when PulseAudio was famous for breaking audio on Linux for everyone. For quite a few years, the standard answer for any audio problem on Linux was to uninstall PulseAudio, and just use ALSA. It’s probably the case that a number of distros switched to Pulse before it was quite ready. My experience was that after a couple years of fixing bugs, the experience got to be quite stable and useful. PulseAudio brought some really nice features to Linux, like moving sound streams between devices and dynamically resampling streams as needed.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Chinese Typewriter

As much as I’d like to devote an article to each and every bit of keyboard-related what-have-you that I come across in my travels through the intertubes, there just aren’t enough hours. And after all, this isn’t Clack-a-Day. To that end, I gained editorial approval to bring you a periodic round-up of news and other tidbits on the keyboard and keyboard accessories front, and here we are. So let’s get to it!

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Hackaday Podcast 122: Faster Than Wind Travel, Sisyphish, ALU Desktop Calculator, And Mice In Space

Hackaday editors Elliot Williams and Mike Szczys marvel at the awesome hacks from the past week. We had way too much fun debating whether a wind-powered car can travel faster than the wind, and whether or not you can call that sailing. Low-temperature desoldering was demystified: it’s the bismuth! And we saw a camera gimbal solve the problem of hand tremor during soldering. Ford just wants to become your PowerWall. And the results are in from NASA’s mission to spin mice up in a centrifuge on the ISS.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (around 55 MB)

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Ello Is A Tiny Computer With A C — Interpreter?

When we talk about a retrocomputer, it’s our normal practice to start with the hardware. But with [KnivD]’s ELLO 1A while the hardware is interesting enough it’s not the stand-out feature. We are all used to microcomputers with a BASIC interpreter, but how many have we seen with a C interpreter? The way C works simply doesn’t lend itself to anything but a compiler and linker, so even with a pared-down version of the language it still represents a significant feat to create a working interpreter.

The hardware centres around a PIC32MX, and has onboard SD card, VGA, sound, and a PS/2 keyboard port. The PCB is a clever design allowing construction with either through-hole or surface-mount components to allow maximum accessibility for less advanced solderers. Full information can be found on the project’s website, but sadly for those wanting an easy life only the PCB is as yet available for purchase.

We’re privileged to see a huge array of retrocomputing projects here at Hackaday, but while they’re all impressive pieces of work it’s rare for one to produce something truly unexpected. This C interpreter certainly isn’t something we’ve seen before, so we’re intrigued to see what projects develop around it.