More On Wave Overhangs For 3D Printing

August 16, 2026 by Al Williams 2 Comments

We’ve heard of wave overhangs before. It is a new technique for printing horizontal overhangs with no supports. Building on some other techniques like arc overhangs. The idea is to teach the slicer not to try to draw overhangs in the middle of free space. Instead, when the slicer realizes there is a horizontal overhang, it tries to “grow” the overhang from the main part. You can see an overview in the video below.

For example, imagine printing a letter ‘T’ vertically. The stem of the T is no problem, but when you try to print the arms it will normally need support. But if you could just print the arms starting at the stem with slight overlapping, the arms could grow as they hang onto either the stem or the last overhang line.

That makes sense, but it only works for very simple cases. Arc overhangs can fill more complex cases, but suffer from little dimples at the center of each arc. The realization for wave overhangs is to replace the arcs with waves as you would see in a pond. The waves diffract around holes and corners.

Perfect? Not quite. They are still experimenting with settings, but there seems to be some increase in warping. If you want to experiment, you can download a fork of Orca and contribute your results to the community.

We looked at this technique earlier, but we haven’t seen much about it in practice yet. Let us know in the comments if you’ve tried it and how it worked for you. There are more details in the paper on the subject, or you can jump right to the software.

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Another Radio On A Chip Design

August 16, 2026 by Al Williams 12 Comments

It used to be a rite of passage to build some sort of AM radio receiver. Many people started with a crystal radio, of course, but you’d graduate to maybe a TRF or superhet design. FM radio projects were not as common, because demodulating an FM signal was harder, as was making things work in the 100 MHz range. These days, though, you can get everything on a chip like the TEA5767, and [turtushig22-blip] has an open design that uses that device on a breakout board, a display, a knob, and an external amplifier. An ESP-32 pulls it together. You can see two videos about the project below.

Unlike older FM radio designs, the TEA5767 doesn’t require any adjustments. RF goes in, and stereo audio goes out. You can control the device through I2C or a 3-wire serial interface.

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Radio Shack Toy Returns To Life

August 15, 2026 by Al Williams 22 Comments

[The Modern Rogue] found an old childhood friend in a closet: a Radio Shack 200-in-1 electronic kit. Along with [Josh Nass], he put it through its paces and made a few repairs along the way. As you might expect, the batteries had long ago leaked out their magic juice.

If you missed these, they were a host of real electronic components with springs connected to the leads. To make a circuit, you bend the spring over, insert a wire, and let go of the spring. By changing the wiring, you could make radios, alarms, computer circuits, and more

There were dozens of these kits, some more capable than others. This was a particularly nice one with a loaded front panel and several exotic components. In the end, they made a code practice oscillator, and it worked.

While you can’t find kits exactly like these anymore, you can make your own. Or try Snap Circuits and print your own modules. You take solderless breadboards for granted today, but they haven’t always been around or affordable.

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Mauchly And Eckert’s Other Computers

August 14, 2026 by Al Williams 5 Comments

If you ask a random person who [John Mauchly] or [J. Presper Eckert] were, you’d probably get a blank stare. Ask a Hackaday reader, and you have a better shot. People who know will tell you that the two were behind the famous ENIAC, which may or may not have been the first computer, but was certainly influential in kicking off the modern computer era. They worked at Penn, and now [Holly Mengel] of Penn’s Kislak Center for Special Collections, Rare Books, and Manuscripts wants to introduce us to the other computers they worked on after ENIAC.

We will admit that we knew about EDVAC and UNIVAC. But we’ll also confess we didn’t know about BINAC or Skeduflo, a computer in a rather large suitcase. BINAC can claim to be the first digital computer that was commercialized, although you could argue that since it was fairly limited and, reportedly, never worked after it was delivered. Supposedly, the customer disassembled it, shipped it to a secure facility, and hired a freshly graduated engineer to rebuild it, which didn’t go very well.

We couldn’t find much about Skeduflo, other than that it was a 75-pound analog computer made for critical path method (CPM) analysis. You set up the problem with a patchboard and potentiometers, and the result came out on an analog plotter. Those details are from a PMI interview with [Morgan Walker] and [Jim Kelley].

It makes sense that these inventors didn’t just finish off ENIAC and retire to a tropical island. While UNIVAC had a good bit of success and EDVAC was very influential, the others are arguably fairly obscure. UNIVAC even has a Disney connection.

Bladerunners And The Mother Of Invention

August 13, 2026 by Al Williams 27 Comments

There are plenty of stories about inventors who see a problem and decide they can do better. But Van Phillips had a little more motivation than most. The problem was his own leg. In 1976, Phillips was a 21-year-old college student when a water-skiing accident cost him his left leg below the knee. If that wasn’t bad enough, the prosthetic leg he received afterward wasn’t exactly a technological marvel. Prosthetic limbs of the era were generally designed to look and act something like a biological leg and foot, but “act” might be giving them too much credit. They were passive structures that provided something to stand on and roll over while walking.

Phillips wanted to do more than walk. There was just one problem: he wasn’t an engineer. Before the accident, he had been studying business. So, if he was going to build a better leg, first he was going to have to learn how.

Back To School

Traditional prosthetic feet (public domain)

Phillips became fascinated with prosthetics and eventually studied prosthetic design at Northwestern University’s Prosthetic-Orthotic Center. He also worked at the University of Utah’s prosthetics laboratory, where he had access to both the people and equipment he needed to experiment.

The conventional wisdom was that a prosthetic foot should imitate a human foot. That seems perfectly reasonable — evolution has had quite a long time to work on the design. But there’s a problem with simply copying the shape. A real foot isn’t just a foot-shaped object attached to the bottom of your leg. Muscles, tendons, and ligaments store and release energy as you walk or run. Your Achilles tendon, in particular, acts very much like a spring. A conventional prosthetic foot might look right, but it didn’t have anything corresponding to that spring.

Phillips eventually stopped worrying so much about making something that looked like a foot. Instead, he decided to make something that worked like one.

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Watch Today’s Eclipse At Home

August 12, 2026 by Al Williams 6 Comments

In a few hours, there is a solar eclipse that will be visible with a track that goes from Spain up through Greenland. Too late to travel for it, but thanks to [jonty], you can find all the webcams that will have a view.

This may be ideal. No funny glasses. No looking at a projected image on a card. Of course, many, if not all, of these cameras aren’t looking directly at the sun, so it isn’t clear if you’ll be able to see the actual eclipse or just the effect it has on the surroundings.

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PC-1: The 1954 Computer With No Tubes, Relays, Or Transistors

August 11, 2026 by Al Williams 32 Comments

However you make a digital computer, you need something to represent a binary digit. Usually this is some form of switch: a relay, a tube, or a transistor, although there have been other ways to represent state. In 1954, [Eiichi Goto] of Japan invented the parametron, a resonant circuit using a ferrite core and a capacitor that could be moved between two phases.

According to [Goto’s] 1959 paper, the device is effectively a parametric oscillator, similar to some used at UHF frequencies by hams. The idea is that a tuned circuit is set to some frequency and driven with twice that frequency.

A What?

A parametron is essentially a resonant circuit made with inductors or capacitors whose reactance is varied at twice its resonant frequency. That “pumping” causes the circuit to oscillate at half the pump frequency. The neat trick is that there are two equally stable oscillation states at half the pump frequency, separated from each other by 180° of phase. Those two phases become binary 0 and 1. Depending on the incoming signals, one phase will win over the others.

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