Parametric Design With Tinkercad

April 26, 2023 by 32 Comments

Tinkercad is like the hamburger helper of 3D design. You hate to admit you use it, and you know you should put in more effort, but — darn it — it’s easy, and it tastes pretty good. While I use a number of CAD programs for serious work, sometimes, when I just want a little widget like a flange for my laser cutter’s exhaust, it is just easier to do it in a few minutes with Tinkercad. However, I heard someone complaining the other day that it wasn’t of any use anymore because they took away custom shape generators. That statement is only partially true. Codeblocks allow you to easily create custom parametric items for use in Tinkercad.

A Tinkercad-designed flange

There was a time when you could write Javascript to create custom shapes, and it is true that they removed that feature. However, they replaced it with Codeblocks which is much easier to use for their target audience — young students — and still very powerful.

If you’ve used parametric design in a professional package or even used something like OpenSCAD, you probably don’t need to be sold on the benefit. This is, of course, a simple form of it, but the idea is to define things as mathematical relationships. As an example, suppose you have a front panel with two rows of four holes for switches evenly spaced and centered. That would be easy to draw. But if you later decide the top row needs five holes and the bottom only needs three, it will be a fair amount of work. But if you have the math defining it right, you change a few variables, and the computer does the rest. Continue reading “Parametric Design With Tinkercad” →

Jac Goudsmit and Ralf Porankiewicz at Supercon 2022

2022 Supercon: Jac And Ralf Explore The Secrets Of The Digital Compact Cassette

March 30, 2023 by 8 Comments

During the 1990s, music was almost invariably stored on CDs or cassette tapes. When the new millennium came around, physical formats became obsolete as music moved first to MP3 files, and later to network streams. But a few years before that big transition, there were several attempts at replacing the aging cassette and CD formats with something more modern. You might remember the likes of MiniDisc and Super Audio CD, but there were a few other contenders around.

The Digital Compact Cassette, or DCC, was one such format. Released by Philips in 1992 as a replacement for the analog audio cassette, it failed to gain traction in the market and disappeared before most people had even heard of it. Not so for [Jac Goudsmit] and [Ralf Porankiewicz] however, who have spent years researching all aspects of the DCC system and shared some of the results in their 2022 Supercon talk.

[Ralf] is the curator of the DCC Museum in Cathedral City, California, which owns examples of all DCC equipment ever released, as well as several devices that never made it to market. He also aims to document the history of audio recording and DCC’s contribution to it, which goes further than you might think. For example, the audio compression format used in the DCC system, called PASC, was an early version of what would later become MP3 – though most histories of audio compression ignore this fact.

[Jac], for his part, made an extensive study of all the technical features of the DCC format. He has written numerous articles about his findings, first in the DCC FAQ and later by maintaining the relevant Wikipedia articles. He is running several projects aimed at keeping the format alive, often in collaboration with the DCC Museum.

[Jac] and [Ralf] begin their talk with a brief introduction to the system and its media. DCC players were designed to be compatible with analog audio cassettes, so DCC cartridges are the same basic size, though with a different type of tape inside. Playback devices contain a complex set of magnetic heads to read either the analog signals from classic tapes, or the digital data stored on DCCs.

One unique feature of DCC is Interactive Text Transfer Service, or ITTS, which is a separate data area on the tape that can hold additional information like song lyrics or even simple animations. It was intended to be displayed on players that supported it, but no such devices were ever released. Luckily, [Jac] and [Ralf] managed to find a rare ITTS decoder system used in a tape mastering facility, and were able to reveal the contents of this “secret track”, which is present on all prerecorded tapes, for the first time.

User-recorded tapes never had any ITTS data, and differed from prerecorded ones in several other ways, too. The most obvious difference was that professionally-made tapes could be indexed by song title, while home-made ones could only jump to track numbers. [Jac] and [Ralf] are however working to enable all the professional features on home-made tapes as well, through a number of software and hardware projects.

The most basic software needed is an encoder and decoder for the PASC format, which [Jac] developed from existing MP1 sofware. But to explore some of the more obscure hardware features, he had to reverse-engineer several different DCC players. This led him to discover many interesting half-finished features: the ITTS data sector is one example, but he also found out that some players send ready-to-use VU meter data to their front panel, even though they are unable to display that information.

[Jac] was also one of the first people to buy the DCC-175 portable DCC player when it was released in 1995. This was the only DCC player ever sold with a computer interface, allowing direct transfer of digital audio between a computer and a DCC tape. The parallel port interface and its accompanying Windows 9x software are completely obsolete and unusable with modern PCs, so [Jac] is working on directly accessing the data from the DCC-175 through a custom cable. He’s making good progress: he already figured out the electrical interface and wrote some software that enables him to control the tape recorder directly.

We can’t help but be impressed by the amount of effort both [Jac] and [Ralf] have put into understanding and documenting all the intricacies of a long-obsolete audio format. Thanks to their efforts, we can still appreciate the impressive technology behind DCC – even if it never came close to replacing its analog cousin.

Continue reading “2022 Supercon: Jac And Ralf Explore The Secrets Of The Digital Compact Cassette” →

Assembly Language 80’s Minicomputer Style

March 6, 2023 by 19 Comments

In the days before computers usually used off-the-shelf CPU chips, people who needed a CPU often used something called “bitslice.” The idea was to have a building block chip that needed some surrounding logic and could cascade with other identical building block chips to form a CPU of any bit width that could do whatever you wanted to do. It was still harder than using a CPU chip, but not as hard as rolling your own CPU from scratch. [Usagi Electric] has a Centurion, which is a 1980s-vintage minicomputer based on a bitslice processor. He wanted to use it to write assembly language programs targeting the same system (or an identical one). You can see the video below.

Truthfully, unless you have a Centurion yourself, the details of this are probably not interesting. But if you have wondered what it was like to code on an old machine like this, you’ll enjoy the video. Even so, the process isn’t quite authentic since he uses a more modern editor written for the Centurion. Most editors from those days were more like CP/M ed or DOS edlin, which were painful, indeed.

The target program is a hard drive test, so part of it isn’t just knowing assembly but understanding how to interface with the machine. That was pretty common, too. You didn’t have a lot of help from canned routines in those days. For example, it was common to read an entire block from a hard drive, tape, or drum and have to figure out what part of it you were actually interested in instead of, say, opening a file and reading a stream of characters.

If nothing else, fast forward over to the 25-minute mark and see what a hard drive from that era looked like. Guess how much storage was on that monster? If you guessed more than 10 MB, you probably didn’t live through the 1980s. We won’t even guess what the price tag was, but you can bet it was spendy.

If you think entering programs like this is painful, try a front panel. That made paper tape seem like a great thing.

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A Loving Look Inside Vacuum Fluorescent Displays

February 26, 2023 by 20 Comments

Everyone knows we’re big fans of displays that differ from the plain old flat-panel LCDs that seem to adorn most devices these days. It’s a bit boring when the front panel of your widget is the same thing you stare at hour after hour while using your phone. Give us the chunky, blocky goodness of a vacuum fluorescent display (VFD) any day of the week for visual interest and retro appeal.

From the video below, it seems like [Posy] certainly is in the VFD fandom too, rolling out as he does example after example of unique and complicated displays, mostly from audio equipment that had its heyday in the 1990s. In some ways, the video is just a love letter to the VFD, and that’s just fine with us. But the teardowns do provide some insights into how VFDs work, as well as suggest ways to tweak the overall look of a VFD.

For example, consider the classy white VFDs that graced a lot of home audio gear back in the day. It turns out, the phosphors used in those displays weren’t white, but closer to the blue-green color that VFDs are often associated with. But put a pink filter between the display and the world, and suddenly those turquoise phosphors look white. [Posy] does a lot of fiddling with the stock filters to change the look of his VFDs, some to good effect, others less so.

As for the internals of VFDs, [Posy]’s look at a damaged display reveals a lot about how they work. With a loose scrap of conductor shorting one of the cathodes inside the tube, the damaged VFD isn’t much to look at, and is beyond reasonable repair, but it’s kind of cool to examine the spring mechanisms that take up slack as the cathodes heat up and expand.

Thanks to [Posy] for this heartfelt look into the VFDs of yesterday. If you need more about how VFDs work, we’ve covered that before, too.

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Sailing On A Sea Of Seven-Segment Displays

February 23, 2023 by 39 Comments

The amount of information the humble seven-segment display can convey is surprising. There are the ten numerals, dead-ringers or reasonable approximations for about half the alphabet, and even a few not-quite-canonical symbols. But when you put 12,288 segments to work, you get all that and much more.

Behold Sea of Segments, an art piece by [Will Gallia] that really pushes what’s possible with seven-segment displays. The piece, which looks about the size of a decent flat-panel TV, is composed of an 8×6 array of PCBs, each of which holds an 8×4 array of white LED seven-segment displays; each board also holds two TLC5920 LED drivers. [Will] designed the PCBs to tile horizontally and vertically, making it possible to take data either from the top or right side and output to the bottom or left. Power is distributed to the modules through a series of steel bus bars, which also provide structural support for the display. The whole thing lives in an enclosure with a smoked acrylic front panel, and hangs from a pair of steel cables that also provide power.

Under the hood, a PocketBeagle does all the heavy lifting of talking to the display and translating images onto the display. [Will] came up with an encoding scheme that gives about five bits of grayscale, and built a program to figure out which segments should be lit to create an image. The result is a smooth and convincing reproduction of videos of waves on a beach, which is where the project gets its name. Check out the results in the video below.

[Will] says he drew inspiration for this build from the DigitGrid by [Skot9000]. That was a great project too, but Sea of Segments takes the concept to another level.

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Original Controller Ports In Custom Case Means Retro Gaming In Style

January 28, 2023 by 34 Comments

Some careful measuring and a little extra effort can be all that separates what looks like a hack job from a slick end product, and that is apparent in [Eric Sorensen]’s classy retrogaming rig, complete with ports for original console controllers.

Neatly housing these components in a case makes all the difference.

[Eric] likes his vintage gaming, and was terrifically pleased with MiSTer, an open-source project that recreates various classic computers, game consoles and arcade machines using modern FPGA-based hardware. Of course, what makes retro gaming even better is using a platform’s genuine original controllers, which just takes a little extra hardware and wiring.

But [Eric] found that all the required accessories and peripherals started to look awfully cluttered. He solved this issue by packing everything carefully into a specialty PC case called the Checkmate A1500 Plus, which gives off a strong 80s design vibe. As a bonus, the front panels are all removable and that’s where [Eric] decided to house the custom controller ports.

First [Eric] carefully measured each controller connector to create CAD models, then designed matching front panels to house the connectors and 3D printed them. Once that was done, post-processing the panels was a long process of apply Bondo, sand, paint, and repeat as needed. The results looks fantastic, and this project is a prime example of how aesthetics and finish can matter.

Find yourself in a similar situation? [Tom Nardi] has shown us all that 3D prints don’t have to look 3D-printed, and careful application of paint and primer can really put the ‘pro’ in prototyping.

DIY capacitor leakage tester nestled among neighbours all mounted underneath a shelf

DIY Capacitor Leakage Tester With A Professional Finish

January 22, 2023 by 7 Comments

[Manuel Caldeira] has built a nice electronics work area that would be the envy of many, complete with an under-shelf rail of custom-built instruments that are specific to the needs of areas of electronics that [Manuel] is involved with. The highlighted project here is a capacitor leakage tester, which is very handy for sorting through piles of old parts looking for anything still within spec, or just verifying a part on a board is the culprit you suspect it is.

The thing is, certain types of capacitors have a limited life both in operation and in storage. Usually, we’re talking about electrolytics here, where the electrolyte solution can leak out or dry out, but also the passive oxide layer on the anode plate can deteriorate if the device is left unpowered for long periods — the oxide disintegrates, and the capacitor will start to leak current. Eventually, the breakdown can be bad enough for the capacitor to conduct so well that it overheats and the result can be a surprisingly violent experience. So, if you deal with capacitors a lot, especially electrolytics, then a leakage tester is a very good instrument to own.

We like [Manuel]’s construction method here, with custom PCBs nestled inside a simple bent aluminium enclosure. No need for a top or sides, as these, are intended to bolt underneath a shelf, and butt up against their neighbor. The front panel graphics are done in a simple but very effective manner, using printable sticker sheets, with a clear adhesive over-sheet. They certainly have a professional finish, and this is definitely a construction method worth considering.

For those a little unfamiliar with this important component, why not leap into some theory with this handy dive into the simple parallel plate capacitor? Next, may we suggest a little overview of the different capacitor types and how to best make use of them?

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