Author: Dan Maloney

3359 Articles

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Hackaday Links: March 2, 2025

March 2, 2025 by 4 Comments

It’s been quite a week for asteroid 2024 YR4, which looked like it was going to live up to its “city killer” moniker only to be demoted to a fraction of a percent risk of hitting us when it swings by our neighborhood in 2032. After being discovered at the end of 2024, the 55-meter space rock first popped up on the (figurative) radar a few weeks back as a potential risk to our home planet, with estimates of a direct strike steadily increasing as more data was gathered by professional and amateur astronomers alike. The James Webb Space Telescope even got in on the action, with four precious hours of “director’s discretionary” observation time dedicated to characterizing the size and shape of the asteroid before it gets too far from Earth. The result of all this stargazing is that 2024 YR4 is now at a Level 1 on the Torino Scale of NEO collision risk, with a likely downgrade to 0 by the time the asteroid next swings through again in 2028. So, if like us you were into the whole “Fiery Space Rock 2032” thing, you’ll just have to find something else to look forward to.

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Custom Frame Grabber Gets Vintage Kodak Digital Camera Back In The Game

February 25, 2025 by 6 Comments

What do you do with a four-megapixel monochrome digital camera from the 90s that needed a dedicated PC with a frame grabber card to do anything useful? Easy — you turn it into a point-and-shoot by building your own frame grabber.

At least that’s what [Frost Sheridan] did with a vintage Kodak MegaPlus 4.2i, a camera that was aimed at the industrial and scientific market at a time when everyone was still using film for snapshots. Making this workhorse ride again meant diving into the manual, luckily still available after all these years, and figuring out what pins on the 68 pin connector would be useful. [Frost] worked out the pins for serial commands plus the 10-bit parallel interface, although he settled for the eight most significant bits to make things simpler. A Teensy with some extra RAM and a serial interface chip takes care of sending commands to the camera and pulling pixels off the parallel interface, and a 128×160 LCD provides a much-needed viewfinder.

With a battery pack mounted the whole thing is reasonably portable, if a bit of a chore to use. It’s worth the effort, though; the picture quality is fantastic, with a wide dynamic range and plenty of contrast. Hats off to [Frost] for bringing this beauty back to life without making any permanent modifications to it.

PCB Dielectric Constant Measurements, Three Ways

February 25, 2025 by 6 Comments

FR4 is FR4, right? For a lot of PCB designs, the answer is yes — the particular characteristics of the substrate material don’t impact your design in any major way. But things get a little weird up in the microwave range, and having one of these easy methods to measure the dielectric properties of your PCB substrate can be pretty handy.

The RF reverse-engineering methods [Gregory F. Gusberti] are deceptively simple, even if they require some fancy test equipment. But if you’re designing circuits with features like microstrip filters where the permittivity of the substrate would matter, chances are pretty good you already have access to such gear. The first method uses a ring resonator, which is just a PCB with a circular microstrip of known circumference. Microstrip feedlines approach but don’t quite attach to the ring, leaving a tiny coupling gap. SMA connectors on the feedline connect the resonator to a microwave vector network analyzer in S21 mode. The resonant frequencies show up as peaks on the VNA, and can be used to calculate the effective permittivity of the substrate.

Method two is similar in that it measures in the frequency domain, but uses a pair of microstrip stubs of different lengths. The delta between the lengths is used to cancel out the effect of the SMA connectors, and the phase delay difference is used to calculate the effective permittivity. The last method is a time domain measurement using a single microstrip with a couple of wider areas. A fast pulse sent into this circuit will partially reflect off these impedance discontinuities; the time delay between the reflections is directly related to the propagation speed of the wave in the substrate, which allows you to calculate its effective permittivity.

One key takeaway for us is the concept of effective permittivity, which considers the whole environment of the stripline, including the air above the traces. We’d imagine that if there had been any resist or silkscreen near the traces it would change the permittivity, too, making measurements like these all the more important.

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Hackaday Links: February 23, 2025

February 23, 2025 by 7 Comments

Ho-hum — another week, another high-profile bricking. In a move anyone could see coming, Humane has announced that their pricey AI Pin widgets will cease to work in any meaningful way as of noon on February 28. The company made a splash when it launched its wearable assistant in April of 2024, and from an engineering point of view, it was pretty cool. Meant to be worn on one’s shirt, it had a little bit of a Star Trek: The Next Generation comm badge vibe as the primary UI was accessed through tapping the front of the thing. It also had a display that projected information onto your hand, plus the usual array of sensors and cameras which no doubt provided a rich stream of user data. Somehow, though, Humane wasn’t able to make the numbers work out, and as a result they’ll be shutting down their servers at the end of the month, with refunds offered only to users who bought their AI Pins in the last 90 days.

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Tricked Out Miter Fence Has All The Features

February 22, 2025 by 3 Comments

“World’s best” is a mighty ambitious claim, regardless of what you’ve built. But from the look of [Marius Hornberger]’s tricked-out miter fence, it seems like a pretty reasonable claim.

For those who have experienced the torture of using the standard miter fence that comes with machine tools like a table saw, band saw, or belt sander, any change is likely to make a big difference in accuracy. Miter fences are intended to position a workpiece at a precise angle relative to the plane of the cutting tool, with particular attention paid to the 90° and 45° settings, which are critical to creating square and true joints.

[Marius] started his build with a runner for the T-slot in his machine tools, slightly undersized for the width of the slot but with adjustment screws that expand plastic washers to take up the slack. An aluminum plate equipped with a 3D printed sector gear is attached to the runner, and a large knob with a small pinion mates to it. The knob has 120 precisely positioned slots in its underside, which thanks to a spring-loaded detent provide positive stops every 0.5°. A vernier scale also allows fine adjustment between positive stops, giving a final resolution of 0.1°.

Aside from the deliciously clicky goodness of the angle adjustment, [Marius] included a lot of thoughtful touches. We particularly like the cam-action lock for the angle setting, which prevents knocking your fine angle adjustment out of whack. We’re also intrigued by the slide lock, which firmly grips the T-slot and keeps the fence fixed in one place on the machine. As for the accuracy of the tool, guest meteorologist and machining stalwart [Stefan Gotteswinter] gave it a thumbs-up.

[Marius] is a veteran tool tweaker, and we’ve featured some of his projects before. We bet this fence will see some use on his much-modified drill press, and many of the parts for this build were made on his homemade CNC router.

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Acoustic Engine Harnesses The Power Of Sound

February 21, 2025 by 35 Comments

If you think sonic booms from supersonic aircraft are a nuisance, wait until the sky is full of planes propelled by up-scaled versions of this interesting but deafening audio resonance engine.

Granted, there’s a lot of work to do before this “Sonic Ramjet” can fly even something as small as an RC plane. Creator [invalid_credentials] came up with the idea for a sound-powered engine after listening to the subwoofers on a car’s audio system shaking the paint off the body. The current design uses a pair of speaker drivers firing into 3D printed chambers, which are designed based on Fibonacci ratios to optimize resonance. When the speakers are driven with a low-frequency sine wave, the chambers focus the acoustic energy into powerful jets, producing enough thrust to propel a small wheeled test rig across a table.

It’s fair to ask the obvious question: is the engine producing thrust, or is the test model moving thanks to the vibrations caused by the sound? [invalid_credentials] appears to have thought of that, with a video showing a test driver generating a powerful jet of air. Downloads to STL files for both the large and small versions of the resonating chamber are provided, if you want to give it a try yourself. Just be careful not to annoy the neighbors too much.

Thanks to [cabbage] for the tip via [r/3Dprinting].

Pulsed Deposition Points A Different Path To DIY Semiconductors

February 19, 2025 by 1 Comment

While not impossible, replicating the machines and processes of a modern semiconductor fab is a pretty steep climb for the home gamer. Sure, we’ve seen it done, but nanoscale photolithography is a demanding process that discourages the DIYer at every turn. So if you want to make semiconductors at home, it might be best to change the rules a little and give something like this pulsed laser deposition prototyping apparatus a try.

Rather than building up a semiconductor by depositing layers of material onto a silicon substrate and selectively etching features into them with photolithography, [Sebastián Elgueta]’s chips will be made by adding materials in their final shape, with no etching required. The heart of the process is a multi-material pulsed laser deposition chamber, which uses an Nd:YAG laser to ablate one of six materials held on a rotating turret, creating a plasma that can be deposited onto a silicon substrate. Layers can either be a single material or, with the turret rapidly switched between different targets, a mix of multiple materials. The chamber is also equipped with valves for admitting different gases, such as oxygen when insulating layers of metal oxides need to be deposited. To create features, a pattern etched into a continuous web of aluminum foil by a second laser is used as a mask. When a new mask is needed, a fresh area of the foil is rolled into position over the substrate; this keeps the patterns in perfect alignment.

We’ve noticed regular updates on this project, so it’s under active development. [Sebastián]’s most recent improvements to the setup have involved adding electronics inside the chamber, including a resistive heater to warm the substrate before deposition and a quartz crystal microbalance to measure the amount of material being deposited. We’re eager to see what else he comes up with, especially when those first chips roll off the line. Until then, we’ll just have to look back at some of [Sam Zeloof]’s DIY semiconductors.