No DAC? Try PDM

January 6, 2024 by 16 Comments

Ever notice that the ESP32-S3 doesn’t have a digital-to-analog converter? [Chris] did and asserts that he doesn’t care because he can just use the PDM system to get the same result. PDM — pulse density modulation — is similar to PWM and, like PWM, requires a filter that could range from a simple RC network to an active filter. You can see the result in the video below.

There are several ways [Chris] could produce the output he wanted. PWM was one choice, and some example code uses a timer to do PDM. However, that is not very efficient. The other alternative is to use the I2S output. However, this does require a few workarounds.

In particular, the I2S output is always stereo and incorporates a clock output that isn’t needed for this application. [Chris] simply output the same value on both channels and routed the clock to some pins that are normally used for startup options. That means they can’t easily be used for your own inputs, but it’s OK to use them for unimportant outputs.

We always enjoy seeing solutions like this because it can give you ideas for use in your own projects. Of course, this won’t apply to every project where you need a DAC, but it still might give you some ideas.

We have looked at PDM before. You could, too, build your own DAC hardware.

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3D Printed Eel Could Cost Less At Scale

January 6, 2024 by 38 Comments

Be it a matter of cost, principle, or just plain being landlocked, the idea of 3D printed vegan eel over the real deal is quite an attractive development. An Israeli company called Steakholder Foods has introduced this very thing — something they claim is the world’s first plant-based, printed eel.

One thing to note about eel is that they are quite intricately textured, a problem which seems tailored for 3D printing. The company say they achieve similarity through precise layering and “a unique combination of materials”, which are proprietary. Although the current product is based solely on plant materials, the plan is to incorporate eel cells in the future. Right now, the company is looking to collaborate by providing printers and ink so that participants can create short-term revenue.

While it’s unclear whether the eel is printed and then cooked, or print-cooked like this chicken, it sure looks tasty. Would you eat printed food? Have you done so already? Let us know in the comments.

Video And Audio Playback On Low-End MS-DOS Machines

January 5, 2024 by 13 Comments

For most people the phrases ‘MS-DOS’ and ‘video playback’ probably aren’t commonly associated, yet it was quite normal as those of us who were watching full-motion video with games like Command & Conquer can attest to. These audiovisual experiences did however require somewhat more capable hardware than something like an original, 4.77 MHz IBM PC. More recently, however, the removal of these limitations has been turned into a challenge that has been gleefully accepted by hackers, including [Scali] whose recent tinkering with getting not only real-time video but also audio working on these old beasts has been documented on their blog.

Unlike existing early video formats like FLIC from the 1990s, the XDC format developed over the past years enables real-time, 60 FPS video and audio playback on an 8088 IBM PC that has a SoundBlaster 2 and CGA card installed. As [Scali] notes, the SB2 card is convenient, because it enables DMA transports for the audio data, which saves a lot of precious CPU cycles. Unlike the original SB card, it also fixes some teething issues, but an SB2 is hardly ‘low-end’ for an early 1980s PC, so it has to go.

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3D Printed Cookies, Sort Of

January 5, 2024 by 1 Comment

Are there any cookies that taste better than the ones you make yourself? Well, maybe, but there’s a certain exquisite flavoring to effort. Just ask [jformulate], who created these custom chocolate-topped butter cookies using a mixture of 3D printing, silicone, and of course, baking and tempering.

[jformulate] did this project along with a makerspace group, and the first thing they did was decide on some images for the cookies. Once a hexagon-shaped mold was created in Fusion360, the images were added in. Some had to be height-adjusted in order for the detail to come out.

Once these positives were printed, it was time to make the food-safe silicone molds that would form the custom chocolate toppers. If you don’t have a vacuum de-gasser, [jformulate] recommends pouring a thin stream from a high place to avoid air bubbles. You can always tap the mold several times on a flat surface as well to bring trapped air to the top.

Finally, it’s time to make cookies. [jformulate] has good instructions for tempering chocolate, as well as a recipe for the butter cookies that support the designs. As a bonus, [jformulate] shows how to make a fish-shaped hot chocolate bomb, and made Jolly Rancher (sadly not Wrencher) medallions using the silicone molds and a microwave.

For the semi-disappointed, directly 3D printing cookies is definitely a thing.

Teardown Of Two Russian Missile Sensors

January 5, 2024 by 22 Comments

Recently [Michel] received two packages from Ukraine containing some salvaged Russian electronics that once belonged to (presumably) a 9K38 Igla, Vympel R-27 or similar infrared homing missile, as well as a Fiber Optic Gyroscope (FOG) from an unknown missile, though possibly from the Tornado family of MRLSes. The latter uses the Sagnac effect to detect the phase shift between two laser beams being injected into the same fiber when the fiber, and thus the device, are rotating. The advantage of such a gyroscope is that it is effectively solid-state, requiring only some optical components, amplifier stage and as shown here an Altera Cyclone II FPGA to integrate the results.

The 16-channel linear infrared array sensor is more basic, with a matching amplification channel for each optical receiver element, which are fed into a multiplexer IC in a rather remarkable looking ceramic-gold packaged DIP format, with what looks like a 2004 date code (‘0424’). Although both are rather damaged, [Michel] figures that he might be able to restore the FOG to working condition, assuming no crucial and irreplaceable parts are missing. As useful as FOGs are in missiles, they also have countless uses outside of military applications.

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Digital Master Tapes Seek Deck

January 5, 2024 by 16 Comments

As a nerdy kid in the 90s, I spent a fair bit of time watching the computer-themed cartoon Reboot. During the course of making a documentary about the show, [Jacob Weldon] and [Raquel Lin] have uncovered the original digital master tapes of the show.

This is certainly exciting news for fans of the show, but there’s a bit of a wrinkle. These digital masters are all on D-1 digital cassette tapes which the studio doesn’t have a player for anymore. The dynamic duo are on the hunt for a Bosch BTS-D1 to be able to recapture some of this video for their own film while also heavily hinting to the studio that a new box set from the masters would be well-received.

As the first CGI TV series, Reboot has a special place in the evolution of entertainment, and while it was a technical marvel for its time, it was solid enough to last for four seasons and win numerous awards before meeting a cliffhanger ending. If you’re an expert in D-1 or have a deck to lend or sell, be sure to email the creators.

Feeling nostalgic for the electromechanical era? Why not check out some hidden lyrics on Digital Compact Cassettes (DCC) or encoding video to Digital Audio Tapes (DAT)?

[via Notebookcheck]

The ScottoKatana Keyboard Is Cutting-Edge

January 5, 2024 by 9 Comments

The lovely thing about a hobby like keyboard building is that the melting pot of designs manages to never turn into a nasty porridge. Rather, it remains a tasty chili that keeps getting more flavorful with time. It’s a simple recipe, really; someone becomes dissatisfied enough with their peripherals to do something about it, often trying various designs until they either settle on one, or come up with yet another awesome variant that suits their needs — and possibly someone else’s down the line.

The inimitable [Joe Scotto] has happened upon the katana layout, which has an inverse left-hand row stagger that lends symmetry to the design, and Scotto-ized it into a 33-key build that he says is the best-sounding one yet with lubed Gateron Milky Yellows.

The case and the keycaps are both 3D-printed, and as with all Scotto builds, it is beautifully hand-wired. This one uses an RP2040 Pro Micro, but an ATMega Pro Micro will work, too.

Everything is available on GitHub, and [Joe] promises a typing test soon, as well as a gasket version that foregoes the integrated plate.

Do you need a fast keyboard? Like, ridiculously fast? Then you should use an FPGA.

Via KBD and Make: