Marionette 3D Printer Replaces Linear Rails With String

October 8, 2023 by Danie Conradie 28 Comments

In the early days of FDM 3D printing, the RepRap project spawned all sorts of weird and and wonderful designs. In the video after the break [dizekat] gives us a throwback to those times with the Marionette 3D printer, completely forgoing linear rails in favor of strings.

The closest thing to a linear guide found on the Marionette is a pane of glass against which the top surface of the print head slides. A pair of stepper motors drive the printhead in the XY-plane, similar in concept to the Maslow CNC router, but in this case two more strings are required to keep the mechanism in tension. To correctly adjust the length of the string across the full range of motion, [dizekat] uses a complex articulating pulley mechanism that we haven’t seen before. The strings are also angled slightly downward from the spool to the print head, holding it in place against the glass.

The bed print bed is also suspended and constrained using string, with no rigid mechanical member attaching it to the frame of the printer. Six strings connected to the sides and bottom of the bed frame constrain it in 6-DOF, and pass through another pulley arrangement to three more strings and finally to a single stepper driven belt.

We can’t see any particular advantage to forgoing the linear rails, especially when the mechanisms have to be this complex, but it certainly make for an interesting engineering challenge. Whatever the reason, the end result is fascinating to watch move, and the print quality even looks decent.

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Polish Up Your Product With Graphic Overlays

October 8, 2023 by Donald Papp 17 Comments

[Kevin Hunckler] recently did some in-house manufacturing for a product and shared his experiences in adding high-quality custom graphic overlays or acrylic panels to give the finished units a professional look. The results look great and were easy to apply, making his product more attractive without needing much assembly work.

A graphic overlay with transparent areas, a cutout, and adhesive backing to fit an off-the-shelf Hammond enclosure.

Sadly, when doing initial research he was disappointed to find very little information on the whole process. While in the end it isn’t terribly complex, it still involved a lot of trial and error before he zeroed in on what the suppliers in the industry expect. Fortunately, everything can be done with tools most hackers probably already have access to.

The process seems to us somewhat reminiscent of having PCBs manufactured. One defines the product housing, outlines the overlay, creates the artwork, defines an adhesive layer, and makes a design document explaining each layer and important feature. [Kevin] provides examples of his work, one of which fits an off-the-shelf Hammond enclosure.

Professionally-made acrylic panels or graphic overlays is something worth keeping in mind for hobbyists and those who might engage in desktop manufacturing, as long as the costs are acceptable. Rather like PCBs, costs go down as quantities go up. [Kevin]’s 50 mm x 50 mm overlay cost about 1 USD each in quantity 200, but only 0.50 USD each when buying 500.

These may be great for low or middling quantities, but that doesn’t mean one is out of options for prototypes or micro quantities. We have seen fantastic results adding full-color images to 3D prints, and even using a 3D printer to draw labels directly onto prints.

Designing A Macintosh-to-VGA Adapter With An LM1881

October 7, 2023 by Maya Posch 3 Comments

Old-school Macintosh-to-VGA adapter. Just solve for X, set the right DIP switches and you’re golden.

If you’re the happy owner of a vintage Apple system like a 1989 Macintosh IIci you may know the pain of keeping working monitors around. Unless it’s a genuine Apple-approved CRT with the proprietary DA-15-based video connector, you are going to need at least an adapter studded with DIP switches to connect it to other monitors. Yet as [Steve] recently found out, the Macintosh’s rather selective use of video synchronization signals causes quite a headache when you try to hook up a range of VGA-equipped LCD monitors. A possible solution? Extracting the sync signal using a Texas Instruments LM1881 video sync separator chip.

Much of this trouble comes from the way that these old Apple systems output the analog video signal, which goes far beyond the physical differences of the DA-15 versus the standard DE-15 D-subminiature connectors. Whereas the VGA standard defines the RGB signals along with a VSYNC and HSYNC signal, the Apple version can generate HSYNC, VSYC, but also CSYNC (composite sync). Which sync signal is generated depends on what value the system reads on the three sense pins on the DA-15 connector, as a kind of crude monitor ID.

Theoretically this should be easy to adapt to, you might think, but the curveball Apple throws here is that for the monitor ID that outputs both VSYNC and HSYNC you are limited to a fixed resolution of 640 x 870, which is not the desired 640 x 480. The obvious solution is then to target the one monitor configuration with this output resolution, and extract the CSYNC (and sync-on-green) signal which it outputs, so that it can be fudged into a more VGA-like sync signal. Incidentally, it seems that [Steve]’s older Dell 2001FP LCD monitor does support sync-on-green and CSYNC, whereas newer LCD monitors no longer list this as a feature, which is why now more than a passive adapter is needed.

Although still a work-in-progress, so far [Steve] has managed to get an image on a number of these newer LCDs by using the LM1881 to extract CSYNC and obtain a VSYNC signal this way, while using the CSYNC as a sloppy HSYNC alternative. Other ICs also can generate an HSYNC signal from CSYNC, but those cost a bit more than the ~USD$3 LM1881.

Sine-wave Speech Demonstrates An Auditory One-way Door

October 7, 2023 by Donald Papp 41 Comments

Sine-wave speech can be thought of as a sort of auditory illusion, a sensory edge case in which one’s experience has a clear “before” and “after” moment, like going through a one-way door.

Sine-wave speech (SWS) is intentionally-degraded audio. Here are the samples, and here’s what to do:

Choose a sample and listen to the sine-wave speech version (SWS). Most people will perceive an unintelligible mix of tones and beeps.
Listen to the original version of the sentence.
Now listen to the SWS version again.

Most people will hear only some tones and beeps when first listening to sine-wave speech. But after hearing the original version once, the SWS version suddenly becomes intelligible (albeit degraded-sounding).

These samples were originally part of research by [Chris Darwin] into speech perception, but the curious way in which one’s experience of a SWS sample can change is pretty interesting. The idea is that upon listening to the original sample, the brain — fantastic prediction and learning engine that it is — now knows better what to expect, and applies that without the listener being consciously aware. In fact, if one listens to enough different SWS samples, one begins to gain the ability to understand the SWS versions without having to be exposed to the originals. In his recent book The Experience Machine: How Our Minds Predict and Shape Reality, Andy Clark discusses how this process may be similar to how humans gain fluency in a new language, perceiving things like pauses and breaks and word forms that are unintelligible to a novice.

This is in some ways similar to the “Green Needle / Brainstorm” phenomenon, in which a viewer hears a voice saying either “green needle” or “brainstorm” depending on which word they are primed to hear. We’ve also previously seen other auditory strangeness in which the brain perceives ever-increasing tempo in music that isn’t actually there (the Accelerando Illusion, about halfway down the list in this post.)

Curious about the technical details behind sine-wave speech, and how it was generated? We sure hope so, because we can point you to details on SWS as well as to the (free) Praat software that [Chris] used to generate his samples, and the Praat script he wrote to actually create them.

Implementing Commodore’s IEC Bus Protocol On A KIM-1 Single Board Computer

October 7, 2023 by Maya Posch 3 Comments

Although the PET is most likely the more well-known of Commodore’s early computer systems, the KIM-1 (Keyboard Input Monitor) single board computer was launched a year prior, in 1976. It featured not only the same MOS 6502 MPU as later Commodore systems, but also an MCS6530 PIO IC that contained the ROM, RAM and programmable I/O, reminiscent of later I/O chips on Commodore systems. As the KIM-1 was only designed to be used with an external tape drive (and a terminal for fancy users), adding a floppy drive like the ubiquitous 1541 with its IEC bus interface was not a first-party accessory. How the IEC bus can be retrofitted to a KIM-1 system is demonstrated in this video by the Commodore History channel.

The Commodore KIM-1 hardware is almost directly compatible with the C64 hardware. (Credit: Commodore History on YouTube)

What is most notable is just how similar the KIM-1 hardware is to later PET and VIC hardware, with the CIA and PIO ICs featuring the same requisite pins for this purpose, and requiring only the addition of an inverting (SN7406) IC and an EPROM featuring the new code to support the proprietary Commodore IEC bus protocol, which was mostly pilfered byte-for-byte from a C64 kernal ROM.

With some creative breadboarding in place and using nothing more than the on-board LED display and keyboard matrix, it was then possible to write to the inserted floppy disk, and also to read back from it. What’s interesting here is that this essentially replaces the tape drive as target for the KIM-1, which thus retains a lot of the original functionality, but with a big performance boost. While perhaps only interesting as an academic exercise, it’s definitely an interesting look at the early beginnings of what would blossom into the Commodore 64.

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Playing The Guitar Of DOOM

October 7, 2023 by Kristina Panos 7 Comments

Over the years, we’ve seen DOOM run on pretty much everything from an 8088 to a single keycap. We’ve also written up one or two controllers, but we don’t think we’ve ever seen anything like this — playing DOOM with an electric guitar.

The guitar in question is a Schecter Hellraiser Deluxe, which seems like a great choice to us. In order to get the notes to control the game, [DOS Storm] converted a handful of notes to MIDI using a VST plugin called Dodo MIDI 2 and the Reaper DAW. Then it was a matter of converting MIDI to keystrokes. This took two programs — loopMIDI to do take the MIDI data and route it elsewhere, and MIDIKey2Key to actually convert the MIDI to the keystrokes that control DOOM.

The result is that the notes that move Doomguy around are mostly in an A-major bar chord formation, with some controls up in the solo range of the fret board. Be sure to check out the demo video below and watch [DOS Storm] clear level one in a fairly impressive amount of time, considering their controller is a guitar.

That key cap isn’t even the most ridiculous thing we’ve seen DOOM running on. It’s probably a toss-up between that and the LEGO brick.

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Hats Off To Another Weird Keyboard From Google Japan

October 7, 2023 by Kristina Panos 10 Comments

As portable as keyboards have gotten, you still need some place to put the thing — some kind of bag for travel, and a flat surface for using it. Well, it doesn’t get much more portable than a hat keyboard, now does it?

Every October 1st, Google Japan likes to celebrate the 101-key keyboard by building something revolutionary off the top of their heads. (10/1… 101… get it?) This year was no exception — they created the GCAPS, a ballcap-like device with a single switch inside.

In order to use it, you spin the hat left and right until the desired character is reached, and the rotation is detected by a gyroscope. Then you press down on the top of the hat to send the key codes via Bluetooth.

Under the hood, the hat uses an M5Stick C Plus and, to our dismay, a micro switch that wasn’t even made by Cherry. Oh well — we landed on the clicky side, so that’s great in our book. Surprisingly, there exists a skull cap/hat skeleton thing on which to build a platform for pressing down on the switch. Just like the teaboard and the long boi keyboards, this thing is completely open source.

Since it types in Japanese, there’s no word on whether it types in all caps, though we like to think that it would given the object it represents. Be sure to check out the product reveal video after the break.

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