The Greengate DS:3 Part 2: Putting A Retro Sampler To Use

October 14, 2024 by 2 Comments

The Greengate DS:3 had been re-created in the form of the Goodgreat. Now [Bea Thurman] had to put it to use. If the Greengate DS:3 card was rare,  the keyboard was nearly impossible to find. After a long search, [Bea] bought one all the way from Iceland.  The card of course came courtesy of [Eric]. 

It was time to connect the two together.  But there was a problem — a big problem. The GreenGate has a DB-25 connected via a ribbon cable to the board’s 2×10 connector. The keyboard that shipped with those cards would plug right in.  Unfortunately, [Bea’s] keyboard had a DIP-40 IDC connector crimped on its ribbon cable.  What’s more the connectors for the sustain and volume pedals were marked, but never drilled out. The GreenGate silk screen was still there though. 

Maybe it was a prototype or some sort of modified hardware. Either way, the 40-pin DIP connector had to go if the keyboard ever were to work with the card. What followed were a few hours of careful wire tracing 

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Solving A Retrocomputing Mystery With An Album Cover: Greengate DS:3

October 14, 2024 by 10 Comments

[Bea Thurman] had a retro music conundrum. She loved the classic Greengate DS:3 sampler, but couldn’t buy one, and couldn’t find enough information to build her own. [Bea’s] plea for help caught the attention of [Eric Schlaepfer], aka  [TubeTime]. The collaboration that followed ultimately solved a decades-old mystery. 

In the 1980s, there were two types of musicians: Those who could afford a Fairlight CMI and everyone else. If you were an Apple II owner, the solution was a Greengate DS:3. The DS:3 was a music keyboard and a sampler card for the Apple II+ (or better). The plug-in card was a bit mysterious, though. The cards were not very well documented, and only a few survive today. To make matters worse, some chips had part numbers sanded off. It was a bit of a mystery until [Bea and Tubetime] got involved. 

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Calculating The True Per Part Cost For Injection Molding Vs 3D Printing

October 14, 2024 by 45 Comments

At what point does it make sense to 3D print a part compared to opting for injection molding? The short answer is “it depends.” The medium-sized answer is, “it depends on some back-of-the-envelope calculations specific to your project.” That is what [Slant 3D} proposes in a recent video that you can view below.  The executive summary is that injection molding is great for when you want to churn out lots of the same parts, but you have to amortize the mold(s), cover shipping and storage, and find a way to deal with unsold inventory. In a hypothetical scenario in the video, a simple plastic widget may appear to cost just 10 cents vs 70 cents for the 3D printed part, but with all intermediate steps added in, the injection molded widget is suddenly over twice as expensive.

In the even longer answer to the question, you would have to account for the flexibility of the 3D printing pipeline, as it can be used on-demand and in print farms across the globe, which opens up the possibility of reducing shipping and storage costs to almost nothing. On the other hand, once you have enough demand for an item (e.g., millions of copies), it becomes potentially significantly cheaper than 3D printing again. Ultimately, it really depends on what the customer’s needs are, what kind of volumes they are looking at, the type of product, and a thousand other questions.

For low-volume prototyping and production, 3D printing is generally the winner, but at what point in ramping up production does switching to an injection molded plastic part start making sense? This does obviously not even account for the physical differences between IM and FDM (or SLA) printed parts, which may also have repercussions when switching. Clearly, this is not a question you want to flunk when it concerns a business that you are running. And of course, you should bear in mind that these numbers are put forth by a 3D printing company, so at the scale where molding becomes a reasonabe option, you’ll also want to do your own research.

While people make entire careers out of injection molding, you can do it yourself in small batches. You can even use your 3D printer in the process. If you try injection molding on your own, or with a professional service, be sure to do your homework and learn what you can to avoid making costly mistakes.

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The Biological Motors That Power Our Bodies

October 14, 2024 by 50 Comments

Most of us will probably be able to recall at least vaguely that a molecule called ATP is essential for making our bodies move, but this molecule is only a small part of a much larger system. Although we usually aren’t aware of it, our bodies consist of a massive collection of biological motors and related structures, which enable our muscles to contract, nutrients and fluids to move around, and our cells to divide and prosper. Within the biochemical soup that makes up single- and multi-cellular lifeforms, it are these mechanisms that turn a gooey soup into something that can do much more than just gently slosh around in primordial puddles.

There are many similarities between a single-cell organism like a bacteria and eukaryotic multi-cellular organisms like us humans, but the transition to the latter requires significantly more complicated structures. An example for this are cilia, which together with motor proteins like myosin and kinesin form the foundations of our body’s basic functioning. Quite literally supporting all this is the cytoskeleton, which is a feature that our eukaryotic cells have in common with bacteria and archaea, except that eukaryotic cytoskeletons are significantly more complex.

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Using The 555 For Everything

October 14, 2024 by 26 Comments

The 555 timer is one of the most versatile integrated circuits available. It can generate PWM signals, tones, and single-shot pulses. You can even put one in a bi-stable mode similar to a flip flop. All of these modes are available by only changing a few components outside of the IC itself. It’s also dirt cheap, so it finds its way into all kinds of applications its original inventors never imagined. There’s a bit of a trope around here as well that you ought not to use a microcontroller when one of these will do, and while it’s a bit of a played-out comment, it’s often more true than it seems. This video shows a few uncommon ways of using these circuits instead of putting a microcontroller to work.

After a brief overview of the internals of the hallowed 555, [Doctor Volt] walks us through some of its uses, starting with applications for digital inputs, including a debounce circuit and a toggle switch. From there, he moves on to demonstrating a circuit that can protect batteries from deep discharge, and a small change to that circuit can turn the 555 into a resetting fuse that can protect against short circuit events. Finally, the PWM capabilities of this small integrated circuit are put to work as an audio amplifier, although perhaps not one that would pass muster for the most devout audiophiles among us.

Even though it’s possible to offload a lot of the capabilities of a 555 onto a microcontroller, there’s certainly an opportunity to offload some things to the 555, even if your project still needs a microcontroller. However, offloading tasks like debounce or input latching to hardware rather than spending microcontroller cycles or pins can make a project more robust, both from reliability and software points of view. For some other useful circuits, some of which have been forgotten in the modern microcontroller age, it’s worth taking a look at some of these antique circuit books as well. While we are sure the 555 designers hoped it would be a big hit, no one imagined this giant one.

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A stylized image of Haskell code from the article

Alphabet Soup: Haskell’s Single-Letter Naming Quirks

October 14, 2024 by 14 Comments

When you used punch cards or tape to write a computer program, brief variable names were the norm. Your compiler or assembler probably only allowed six letters, anyway. But times change, and people who, by habit, give array indices variable names like I, J, or K get a lot of grief. But [Jack Kelly] points out that for highly polymorphic languages like Haskell, you often don’t know what that variable represents anyway. So how are you supposed to name it? He provides a guide to one-letter variable names commonly used by Haskell developers and, sometimes, others.

Haskell’s conventions are particularly interesting, especially with i, j, and k, which are borrowed from mathematical tradition to signify indices or integers and passed on via Fortran. The article also highlights how m often refers to Monads and Monoidal values, while t can represent both traversables and text values. Perhaps more obscurely, p can denote profunctors and predicates, giving a glimpse into Haskell’s complex yet efficient type system. These naming conventions are not formal standards but have evolved into a grass-roots lexicon.

Of course, you can go too far. We see a lot of interesting and strange things written in Haskell, including this OpenSCAD competitor.

Portable Pi Palmtop Provides Plenty

October 13, 2024 by 11 Comments

We’ve seen many portable laptops using the Raspberry Pi series of boards in the decade-plus since its launch. The appeal of a cheap board that can run a desktop Linux distro without requiring too much battery is hard not to fall for. Over the years, the bar has been raised from a Pi stuck to the back of one of those Motorola netbook accessories, through chunky laptops, to some very svelte and professional-looking machines. A recent example comes from [Michael Mayer], whose Portable Pi 80 is a palmtop design that we’d be happy to take on the road ourselves.

At its heart is a Pi Zero 2, combining as it does a tiny form factor with the useful power of its Pi 3-derived processor. This is mated to a Waveshare 7-inch display, and in the bottom half of the machine sits a 40% mechanical keyboard. Alongside this are a pair of 18650 cells and their associated power modules. The little Arduino, which normally handles the keyboard, has been relocated due to space constraints, which brings us to the case. A project like this one is, in many ways, a task of assembling a set of modules, and it’s in the case that the work here really shines. It’s a 3D-printable case that you can download from Printables, and it’s very nice indeed. As we said, we’d be happy to use one of these.

Portable computing has come a very long way. Often the keyboard can make it or break it.