Retrotechtacular: How Not to Design With Transistors

Consider the plight of a mid-career or even freshly minted electrical engineer in 1960. He or she was perched precariously between two worlds – the proven, practical, and well-supported world of vacuum tube electronics, and the exciting, new but as yet unproven world of the transistor. The solid-state devices had only started making inroads into electronic products relatively recently, and mass production techniques were starting to drive the cost per unit down enough to start including them in your designs. But, your company has a long history with hot glass and no experience with flecks of silicon. What to do?

To answer that question, you might have turned to this helpful guide, “Tubes and Transistors: A Comparative Guide” (PDF link). The fancy booklet, with a great graphic design that our own [Joe Kim] would absolutely love, was the product of the Electron Tube Information Council, an apparently defunct group representing the interests of the vacuum tube manufacturers. Just reading the introduction of this propaganda piece reveals just how worried companies like RCA, General Electric, and Westinghouse must have been as the 1950s turned into the 1960s. The booklet was clearly aimed directly at engineers and sought to persuade them of the vacuum tube’s continued relevance and long-term viability. They helpfully explain that tubes are a reliable, proven technology that had powered decades of designs, and that innovations such as heaterless cathodes and miniaturization were just around the corner. Transistors, we’re told, suffer from “spread of characteristics” that correctly describes the state of materials engineering of silicon and germanium at the time, a thornier problem than dealing with glass and wires but that they had to know would be solved within a few years.

With cherry-picked facts and figures, the booklet makes what was probably in 1960 a persuasive case for sticking with tubes. But the Electron Tube Information Council was fighting a losing battle, and within a decade of swamping engineers with this book, the industry had largely shifted to the transistor. Careers were disrupted, jobs disappeared, and fortunes were lost, but the industry pressed forward as it always does. Still, it’s understandable why they tried so hard to stem the tide with a book like this. The whole PDF is worth a look, and we’d love to have a hard copy just for nostalgia’s sake.

Thanks to [David Gustafik] for the tip.

The Thrill of Building Space Hardware to Exceptionally High Standards

It’s fair to say that the majority of Hackaday readers have not built any hardware that’s slipped the surly bonds of Earth and ventured out into space proper. Sure we might see the occasional high altitude balloon go up under the control of some particularly enterprising hackers, but that’s still a far cry from a window seat on the International Space Station. Granted the rapid commercialization of space has certainly added to that exclusive group of space engineers over the last decade or so, but something tells us it’s still going to be quite some time before we’re running space-themed hacks with the regularity of Arduino projects.

Multi-use Variable-G Platform

That being the case, you might assume the protocols and methods used to develop a scientific payload for the ISS must seem like Latin to us lowly hackers. Surely any hardware that could potentially endanger an orbiting outpost worth 100+ billion dollars, to say nothing of the human lives aboard it, would utilize technologies we can hardly dream of. It’s probably an alphabet soup of unfamiliar acronyms up there. After all, this is rocket science, right?

There’s certainly an element of truth in there someplace, as hardware that gets installed on the Space Station is obviously held to exceptionally high standards. But Brad Luyster is here to tell you that not everything up there is so far removed from our Earthly engineering. In fact, while watching his 2018 Hackaday Superconference talk “Communication, Architecture, and Building Complex Systems for SPAAACE”, you might be surprised just how familiar it all sounds. Detailing some of the engineering that went into developing the Multi-use Variable-G Platform (MVP), the only centrifuge that’s able to expose samples to gravitational forces between 0 and 1 g, his talk goes over the design considerations that go into a piece of hardware for which failure isn’t an option; and how these lessons can help us with our somewhat less critically important projects down here.

Check out Brad’s newly published talk video below, and then join me after the break for a look at the challenges of designing hardware that will live in space.

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Hackaday Superconference: 3D Printing For Electronics

For her day job, Amie D Dansby works as a software simulation developer, creating simulations for video games. In her free time, she’s implanting the key to her Tesla in her arm, building cordwood jewelry and cosplay swords, and seeking out other adventures in electronics and 3D printing. Amie has made a name for herself in the 3D printing community, and she is surrounded by fans when she attends the RepRap meetups and Maker Faires.

She was also popular at this year’s Hackaday Superconference, where she gave a talk on the integration of 3D printing and electronics. Amie’s work concentrates on props and cosplay, which is a skill unto itself, and you only need to look at some of the old Mythbusters, the documentary footage from ILM, or even model makers to realize this is an arcane art that takes a lot of skill. Lucky for us, Amie was there to show us the tricks she’s picked up over the years to make building a one-off piece easier than you could imagine.

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Designing A Toilet Roll Holder

Everything needs to be designed, at one point or another. There are jobs for those who design kitchens, and stadiums, and interplanetary spacecraft. However, there are also jobs for those who design cutlery, hose fittings, and even toilet roll holders. [Eric Strebel] is here to share just such a story.

[Eric] covers the whole process from start to finish. In the beginning, a wide variety of concepts are drawn up and explored on paper. Various ideas are evaluated against each other and whittled down to a small handful. Then, cardboard models are created and the concepts further refined. This continues through several further phases until it gets down to the fun part of choosing colours and materials for the final product.

Watching the effects of cost and manufacturing process shape the finished item is instructive as to how the design process works in the real world. The toilet paper holder itself is an interesting unit, too – using adjustable magnetic detents to enable one-handed use, as well as including a cell phone holder.

We’ve seen [Eric]’s work before – such as his primer on the value of cardboard in design. Video after the break.

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Ask Hackaday: Help Me Pick A CAD Package

Of all the skills that I have picked up over the years as an engineer, there is one that has stayed with me and been a constant over the last three decades. It has helped me work on electronic projects, on furniture, on car parts, robots, and even garments, and it is likely that I will continue using it periodically for the rest of my career. You see, I am a trained PAD expert.

Don't build this, it's fundamentally flawed! Sometimes the front of an envelope is as effective as its back.
Don’t build this, it’s fundamentally flawed! Sometimes the front of an envelope is as effective as its back.

PAD, you ask? OK, it’s an acronym of my own coinage, it stands for Pencil Aided Design, and it refers to the first-year undergraduate course I sat many years ago in which I learned technical drawing to the old British standard BS308. If I’m making something then by far the quickest way for me to visualise its design is to draw it, first a freehand sketch to get a feel of how everything will sit, then a series of isometric component drawings on graph paper with careful attention to dimensions and angles. Well, maybe I lied a little there, the graph paper only comes in when I’m doing something very fancy; the back of an envelope is fine as long as the dimensions on the diagram are correct.

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Young Entrepreneurs Learn What Really Goes Into Making a Product

Just to be clear, the primary goal of the Papas Inventeurs (Inventor Dads) was to have the kids make something, have fun, and learn. In that light, they enjoyed a huge success. Four children designed, made, and sold laser-cut napkin rings from a booth at the Ottawa Maker Faire as a fun learning process (English translation, original link in French.) [pepelepoisson] documented the entire thing from beginning to end with plenty of photos. Things started at proof of concept, then design brainstorming, prototyping, manufacture, booth design, and finally sales. While adults were involved, every step was done by the kids themselves.

It all began when the kids were taken to a local fab lab at the École Polytechnique and made some laser-cut napkin holders from plywood for personal use. Later, they decided to design, manufacture, and sell them at the Ottawa Maker Faire. Money for the plywood came from piggy banks, 23 different designs made the cut, and a total of 103 rings were made. A display board and signs made from reclaimed materials rounded out the whole set.

In the end, about 20% of people who visited and showed interest made a purchase, and 60 of the 103 pieces were sold for a profit of $126. Of course, the whole process also involved about 100 hours of combined work between the kids and parents and use of a laser cutter, so it’s not exactly a recipe for easy wealth. But it was an incredibly enriching experience, at least figuratively, for everyone involved.

Possibly the biggest takeaway was the way manufacturing involved much more than just pressing “GO” on a laser cutter. Some pieces needed sanding after laser cutting, and each piece got two coats of varnish. If you missed it, [Bob Baddeley] showed how labor, and not materials, ends up being the most expensive part of a product.

Lessons Learned From A 1-Day RTL-SDR Enclosure Project

[ByTechLab] needed an enclosure for his R820T2 based RTL-SDR, which sports an SMA connector. Resolving to design and 3D print one in less than a day, he learned a few things about practical design for 3D printing and shared them online along with his CAD files.

The RTL-SDR is a family of economical software defined radio receivers, and [ByTechLab]’s’ enclosure (CAD files available on GrabCAD and STL on Thingiverse) is specific to his model. However, the lessons he learned are applicable to enclosure design in general, and a few of them specifically apply to 3D printing.

He started by making a basic model of the PCB and being sure to include all large components. With that, he could model the right voids inside the enclosure to ensure a minimum of wasted space. The PCB lacks any sort of mounting holes, so the model was also useful to choose where to place some tabs to hold the PCB in place. That took care of the enclosure design, but it also pays to be mindful of the manufacturing method so as to play to its strengths. For FDM 3D printing, that means most curved shapes and rounded edges are trivial. It also means that the biggest favor you can do yourself is to design parts so that they can be printed in a stable orientation without any supports.

This may be nothing that an experienced 3D printer and modeler doesn’t already know, but everyone is a novice at some point and learning from others’ experiences can be a real timesaver. For the more experienced, we covered a somewhat more in-depth guide to practical 3D printed enclosure design.

[ByTechLab]’s desire for a custom enclosure was partly because RTL-SDR devices come in many shapes and sizes, as you can see in this review of 19 different units (of which only 14 actually worked.)