Arbitrary Waveforms On The Cheap

August 12, 2023 by Al Williams 26 Comments

A signal generator that can produce the usual sine, square, and triangle waves is handy and has been a staple of electronic benches for decades. Being able to craft custom signals opens up new horizons, but historically, these instruments were expensive. The price has come down, though, and [Rishin Goswami] made a 5 MHz 8-bit signal generator with 131K data points of arbitrary waveform for a low price: about $20. If you want to spend a bit more, you can improve the output DAC and op amps, but even that should cost well under $100, all in.

This is one of those projects that seems easy until you start digging into it. For example, storing some points and generating signals using any microcontroller isn’t a big deal. But minimizing jitter and maximizing speed with a conventional processor is difficult. That’s why [Rishin] uses a Raspberry Pi Pico. The programmable I/O units are perfect for generating waveform data fast and reliably. You can see the project go through its paces in the video below.

The Pi streams data to an 8-bit DAC. However, it would be easy to improve resolution with a different converter. The DAC0808 also limits the instrument’s sample rate. The processor could likely go much faster if it had a DAC accommodating higher speeds.

This is just a proof-of-concept, so don’t expect fancy GUIs or the ability to import spreadsheets. You control the device from a command-line-like interface. Still, a good example of how to take advantage of the Pi’s hardware. We took a shot at a similar device nearly a decade ago. Those programmable I/O blocks are finding uses in some surprising applications.

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Throw FreeCAD Some Curves

August 12, 2023 by Al Williams 43 Comments

[Mango Jelly] got a question from someone trying to model a phone box with a complex curved roof. We have to admit that when we saw it, we knew it would be hard to model well. Naturally, there are several ways it could be one, but [Mango Jelly] used the curves workbench in FreeCAD to produce a wireframe of the shape, and you can see how that works in the video below.

The curve bench didn’t sound familiar to us, and that’s because it is an add-on workbench. He starts with a sketch of a curve, constrained to be symmetrical. Then the draft workbench allowed a rotation to convert the curve into a nice skeleton of the curved roof.

The curves workbench can create a Gordon surface over that skeleton. You can extrude that into a solid object. There are still some details to add, though, and you’ll see how each part of the roof takes shape.

Watching videos like this reminds us that we use a small fraction of what FreeCAD can do. You’ll probably pick up at least one tip from this video. If you need a quick basic tutorial, try the one from [NovaSpirit]. Or, try a longer one.

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A Little Bit Of Science History Repeating Itself: Boyle’s List

August 11, 2023 by Al Williams 24 Comments

In a recent blog post, [Benjamin Breen] makes an interesting case that 2023 might go down in history as the start of a scientific revolution, and that’s even if LK-99 turns out to be a dud. He points to several biomedical, quantum computing, and nuclear fusion news items this year as proof.

However, we aren’t as convinced that these things are here to stay. Sure, LK-99 was debunked pretty quickly, but we swim in press releases about new battery technologies, and new computer advances that we never hear about again. He does mention that we aren’t alone in thinking that as [Tyler Cowen] coined the phrase “Great Stagnation” to refer to the decline in disruptive tech since 1945. Still, [Benjamin] argues that people never know when they live through a scientific revolution and that the rate of science isn’t as important as the impact of it.

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Ku-Go: The World War II Death Ray

August 11, 2023 by Al Williams 66 Comments

Historians may note that World War II was the last great “movie war.” In those days, you could do many things that are impossible today, yet make for great movie drama. You can’t sneak a fleet of ships across the oceans anymore. Nor could you dig tunnels right under your captor’s nose. Another defining factor is that it doesn’t seem we seek out superweapons anymore.

A Churchill Bullshorn plough for clearning minefields — one of Hobart’s “Funnies”

Sure, we develop better planes, tanks, submarines, and guns. But we aren’t working on anything — that we know of — as revolutionary as a rocket, an atomic bomb, or even radar was back in the 1940s. The Germans worked on Wunderwaffe, including guided missiles, jets, suborbital rocket bombers, and a solar-powered space mirror to burn terrestrial targets. Everyone was working on a nuclear bomb, of course. The British had Hobart’s Funnies as well as less successful entries like the Panjandrum — a ten-foot rocket-driven wheel of explosives.

Death Ray

Perhaps the holy grail of all the super weapons — both realized and dreamed of was the “death ray.” Of course, Tesla claimed to have one that didn’t use rays, but particles, but no one ever successfully built one and there was debate if it would work. Tesla didn’t like the term death ray, partly because it wasn’t a ray at all, but also because it required a huge power plant and, therefore, wasn’t mobile. He envisioned it as a peacekeeping defensive weapon, rendering attacks so futile that no one would dare attempt them.

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Hackaday Podcast 231: Harnessing Sparks, Hacking Food, And Leaving Breadcrumbs

August 11, 2023 by Al Williams No comments

Editor-in-Chief Elliot Williams and Al Williams don’t always agree on the best text editor to use, but they do — usually — agree on what makes a great hack. This week, they found plenty of Hackaday posts to discuss, ranging from exotic eavesdropping on keyboards, oscilloscopes, and several posts of interest to anyone who wants to build good-looking prototypes. If you are like mechanics, you’ll hear about an escapement-like mechanism and a Hobson’s coupler. If you crave more traditional hacks, you can learn more about maximizing battery life and etching PCBs.

In addition to a flurry of hacks, Elliot and Al also share their picks for the best original posts from Hackaday’s staff. This week, we find out how Arya Voronova documents projects and hear what Tom Nardi thinks of his Beepy — a ready-made display and Blackberry keyboard waiting for a Raspberry Pi.

Did you miss anything? Check out the links below. Be sure to send your favorite hacks our way, and let us know in the comments how you liked this episode. Hear it here:

Or download it yourself and listen while testing room-temperature superconductors!

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A Hobson’s Coupler Leads To A Weird Engine

August 10, 2023 by Al Williams 19 Comments

You want to join two shafts. What do you need? A coupler, of course. If the shafts don’t line up, you might consider an Oldham coupler. But what if the shafts are at a 90-degree angle to each other? Then you need a Hobson’s coupler. [Robert Murray-Smith] has the 3D printed hookup for you and a video that you can see below.

The part isn’t all 3D printed, though. You do need some bearings and steel rods. [Robert] proposes using this to couple a windmill’s blades to a generator, although we assume some loss is involved compared to a standard shaft. However, we’ve heard that the coupler, also called a Hobson’s joint or a stirrup joint, is actually pretty efficient. However, you rarely see these in practice because most applications will use a gear train employing a bevel gear.

While it may not be practical, the second video below shows an elbow engine that would look undeniably cool on your desk. By making some changes, you can create a Cardan joint which happens to be half of what you think of as a universal joint. The Hobson coupler and the Cardan joint seem to be made for each other, as you’ll see in the video.

We aren’t sure what we want to make with all these mechanisms, but as [Robert] points out, with new materials and techniques, these mechanisms might have a role to play in future designs, even though they have been mostly discarded.

There are, of course, many kinds of couplings. Then again, not all useful joints have to move.

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Canadian Engineers? They Have A Ring About Them

August 10, 2023 by Al Williams 100 Comments

How can you spot an engineer? It can be tricky, but it is a little easier in Canada. That’s because many Canadian engineers have been through the Ritual of the Calling of an Engineer and wear an iron or steel ring to symbolize their profession. The ring has a very odd history that originated in 1922 as the brainchild of Professor H. E. T. Haultain. While he may not be a recognizable name, at least one famous person was involved with creating the Ritual.

The ring itself has facets on the outer surface, and you wear it on the little finger of your dominant hand. Originally handmade, the ring reminds the wearer of the engineer’s moral, ethical, and professional commitment. In addition to being a visible reminder, the ring is made to drag slightly as you write or draw, as a constant reminder of the engineer’s obligation. With more experience, the ridges wear down, dragging less as you get more experience.

There is a rumor that the first rings were made from the metal of a bridge that collapsed due to poor design, but this appears untrue. The presentation ceremony is understated, with limited attendance and very little publicity.

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