3D printed materials have come a long way in the last decade or so as printers have become more and more mainstream. Printers can use all kinds of different plastics with varying physical characteristics, and there are even printers now for other materials like concrete and metal. But even staying within the realm of the plastic printer can do a lot of jobs you might not expect. [Camden Bowen] recently 3D printed a single-piston engine which nearly worked, and is back with some improvements to it thanks to a small carburetor.
The carburetor itself isn’t 3D printed (although not from lack of trying) — it’s on loan from a weed eater, and is helping to solve a problem with the fuel-air mixture of his original design. Switching from butane to a liquid fuel also solved some problems as well, and using starter fluid also helped to kick off the ignition. Although it ran for a short period of time over several starts, the valve train suffered some damage with the exhaust valves melting in place to the head. This is actually a problem common to any internal combustion engine like this, especially if the fuel-air mixture is too lean, there’s incomplete combustion, the valves aren’t adjusted properly, or any number of other problems. In this case it seems to have been caused by improper engine timing.
It’s actually noteworthy though that the intake valves weren’t burned, meaning that if the engine can be tuned to allow for complete combustion before the exhaust gasses leave the combustion chamber, the plastic 3D printed head and valve train will likely survive much longer operational periods. We’ll certainly look forward to the next iteration of this engine build to see if that’s the case. If 3D printed piston engines aren’t your speed, though, take a look at this jet engine which uses a 3D printed compressor.
For most of us, vacuum tubes haven’t appeared in any of our schematics or BOMs in — well, ever. Once mass-manufacturing made reliable transistors cheap enough for hobbyists, vacuum tubes became pretty passe, and it wasn’t long before the once mighty US tube industry was decimated, leaving the few remaining tube enthusiasts to ferret out caches of old stock, or even seek new tubes from overseas manufacturers.
Regardless of the mythical qualities that are all too often attributed to vacuum tubes, they are still components that can be damaged and wear out over time. Much like with transistors and kin, they come with a stack of datasheets, containing various curves detailing their properties and performance. These curves will change as a part ages, and validating these curves can help with debugging a vacuum tube-based circuit. This is where one can either spend an enormous sum on a commercial curve tracer like the Tektronix 570, or build your own, as [Basin Street Design] has done.
A semi-retired electronics design engineer by trade, he has previously covered the development of the curve tracer on Instructables for the version 1 and version 1.1. What this device essentially allows you to do is sweep the connected tube through its input parameter ranges, while observing the resulting curves on an attached (external) oscilloscope. Here a storage oscilloscope (or DSO) is immensely helpful to capture the curves.
In the project pages, the in-depth theory and functioning of the circuitry is explained, along with the schematics and a number of builds. The project has been around since before the VBA tracer which we covered last year, both of which are infinitely more affordable than a genuine Tektronix 570.
Before you could just put a drum machine app on your phone, or fire up Garage Band, there were breakthroughs like the Roland 808 drum machine. But that’s not where it all started. In 1959 a company called Wurlitzer (known for things like juke boxes, pianos, and giant pipe organs) produced a new device that had musicians worried it would put drummers out of a job: The 1959 Wurlitzer Sideman. And in the video below the break, we have the joy of watching [LOOK MUM NO COMPUTER] open up, explain, and play one of these marvelous machines.
It’s noteworthy that in 1959, almost none of the advancements we take for granted had made it out of the laboratory. Transistors? Nope. Integrated Circuits? Definitely not. What does that leave us with? Vacuum tubes (Valves for those across the pond), resistors, capacitors, relays, and… motors? Yep. Motors.
The unit is artfully constructed, and we mean that quite literally- the build was clearly done with care and it is easy to see an early example of circuit sculpture around the 3 minute mark. Electromechanical mechanisms take on tasks that we’d probably use a 555 for these days, but for any of you working on mechanical projects, take note: Wurlitzer really knew what they were doing, and there are some excellent examples of mechanical and electrical engineering throughout this primordial beat box.
As those of us who work in electronics are grappling with a semiconductor shortage making common devices unobtainable and less common ones very expensive, it’s worth noting that there’s another supply crunch playing out elsewhere in the electronics industry. It’s not one that should trouble most readers but it’s a vexing problem in the guitar amp business, as guitar.com reports. At its root is the Chinese Shuguang factory, which it is reported has been forced to close down and move its operations. There’s nothing about this on the Shuguang website, so we hope that the plant has been relocated successfully and production will resume.
The specialist audio market that forms the lion’s share of tube customers in 2021 is a relatively tiny corner of the electronics business, but it’s interesting to note that the three major plants which supply it, in Slovakia, Russia, and China, are still not enough to prevent it being vulnerable when one of them fails. The likelihood of a fourth tube plant emerging somewhere else in the 2020s to take up the slack is not high, but it’s evident that the demand remains healthy enough.
For most of us, electronic technology comes in the form of solid state devices. Transistors, integrated circuits, microcontrollers. But for the first sixty years or so of the field existing, these devices either hadn’t been invented yet or were at too early a stage in their development to be either cost-effective, or of much use. Instead a very different type of electronic component ruled the roost, the vaccum tube.
A set of electrodes in an evacuated glass envelope whose electrical properties depended on the modulation of the flow of electrons through them, these were ubiquitous in consumer electronics up until the 1960s, and clung on in a few mass-market applications even as far as the mid 1970s. As cheaper and more versatile semiconductors superseded them they faded from electronic parts catalogues, and the industry that had once produced them in such numbers disappeared in favour of plants producing the new devices. Consumer products no longer contained them, and entire generations of engineers grew up never having worked with them at all. If you were building a tube amplifier in the early 1990s, you were a significant outlier. Continue reading “Just Who Makes Tubes These Days?”→
The vacuum tube is largely ignored in modern electronic design, save for a few audio applications such as guitar and headphone amps. The transistor is smaller, cheaper, and inordinately easier to manufacture. By comparison, showing us just how much goes into the manufacture of a tube, [glasslinger] decided to make a wire-element pilotron – from scratch!
To say this is an involved build is an understatement. Simply creating the glass tube itself takes significant time and skill. [glasslinger] shows off the skills of a master, however – steadily working through the initial construction, before showing off advanced techniques necessary to seal in electrodes, produce the delicate wire grid, and finally pull vacuum and seal the tube completely.
The project video is an hour long, and no detail is skipped. From 2% thoriated tungsten wire to annealing torches and grades of glass, it’s all there. It’s enough that an amateur could reproduce the results, given enough attempts and a complete shop of glassworking equipment.
The pilotron may be a forgotten design, but in 2018 it once again gets its day in the sun. Overall, it’s a testament to [glasslinger]’s skill and ability to be able to produce such a device that not only looks the part, but is fully functional on an electronic level, as well.