BlueSCSI: Not Just For Apple

October 13, 2025 by 11 Comments

Anyone into retro Macintosh machines has probably heard of BlueSCSI: an RP2040-based adapter that lets solid state flash memory sit on the SCSI bus and pretend to contain hard drives. You might have seen it on an Amiga or an Atari as well, but what about a PC? Once upon a time, higher end PCs did use SCSI, and [TME Retro] happened to have one such. Not a fan of spinning platters of rust, he takes us through using BlueSCSI with a big-blue-based-box.

Naturally if you wish to replicate this, you should check the BlueSCSI docs to see if the SCSI controller in your PC is on their supported hardware list; otherwise, your life is going to be a lot more difficult than what is depicted on [TME Retro]. As is, it’s pretty much the same drop-in experience anyone who has used BlueSCSI on a vintage Macintosh might expect. Since the retro-PC world might not be as familiar with that, [TME Retro] gives a great step-by-step, showing how to set up hard disk image files and an iso to emulate a SCSI CD drive on the SD card that goes into the BlueSCSIv2.

This may not be news to some of you, but as the title of this video suggests, not everyone knows that BlueSCSI works with PCs now, even if it has been in the docs for a while. Of course PCs owners are more likely to be replacing an IDE drive; if you’d rather use a true SSD on that bus, we’ve got you covered.

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Building The LEM’s Legs

October 13, 2025 by 12 Comments

If you built a car in, say, Germany, for use in Canada, you could assume that the roads will be more or less the same. Gravity will work the same. While the weather might not be exactly the same, it won’t be totally different. But imagine designing the Lunar Excursion Module that would land two astronauts on the moon for the first time. No one had any experience landing a craft on any alien body before.

The LEM was amazing for many reasons, but as [Apollo11Space] points out, the legs were a particularly thorny engineering problem. They had to land on mostly unknown terrain, stay upright, allow for the ascent module to take off again, and, of course, not weigh down the tiny spaceship. They also had to survive the blast of the LEM’s engine.

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A metal needle tip comes to a point against a white background. A scale bar in the lower left shows a 300 micrometer length.

Etching Atomically Fine Needle Points

October 13, 2025 by 22 Comments

[Vik Olliver] has been extending the lower resolution limits of 3D printers with the RepRapMicron project, which aims to print structures with a feature size of ten micrometers. A molten plastic extruder would be impractical at such small scales, even if a hobbyist could manufacture one small enough, so instead [Vik]’s working on a system that uses a very fine needle point to place tiny droplets of UV resin on a substrate. These points have to be sharper than anything readily available, so his latest experiments have focused on electrochemically etching his own needles.

The needles start with a fine wire, which a 3D-printed bracket holds hanging down into a beaker of electrolyte, where another electrode is located. By applying a few volts across the circuit, with the wire acting as an anode, electrochemical erosion eventually wears through the wire and it drops off, leaving an atomically sharp point. Titanium wire performs best, but Nichrome and stainless steel also work. Copper wire doesn’t work, and by extension, nor does the plated copper wire sometimes sold as “stainless steel” by sketchy online merchants.

The electrolyte was made from either a 5% sodium chloride solution or 1% nitric acid. The salt solution produced a very thin, fine point, but also produced a cloudy suspension of metal hydroxides around the wire, which made it hard to tell when the wire had broken off. The goal of nitric acid was to prevent hydroxide formation; it produced a shorter, blunter tip with a pitted shaft, but it simply etched the tip of the wire to a point, with the rest of the wire never dropping off. Some experimentation revealed that a mixture of the two electrolyte solutions struck a good balance which etched fine points like the pure salt solution, but also avoided cloudy precipitates.

If you’re interested in seeing more of the RepRapMicron, we’ve looked at a previous iteration which scribed a minuscule Jolly Wrencher in marker ink. On a more macro scale, we’ve also seen one 3D printer which used a similar resin deposition scheme.

SMD Soldering With Big Iron

October 13, 2025 by 32 Comments

You have some fine pitch soldering to do, but all you have on hand is a big soldering iron. What do you do? There are a few possible answers, but [Mr SolderFix] likes to pull a strand from a large wire, file the point down, and coil it around the soldering iron. This gives you a very tiny hot tip. Sure, the wire won’t last forever, but who cares? When it gives up, you can simply make another one.

Many people have done things like this before — we are guilty — but we really liked [Mr Solder Fix’s] presentation over two videos that you can see below. He coils his wire over a form. In his case, he’s using a screwdriver handle and some tape to get to the right size. We’ve been known to use the shanks of drill bits for that purpose, since it is easy to get different sizes.

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waverider

Waverider: Scanning Spectra One Pixel At A Time

October 13, 2025 by 12 Comments

Hyperspectral cameras aren’t commonplace items; they capture spectral data for each of their pixels. While commercial hyperspectral cameras often start in the tens of thousands of dollars, [anfractuosity] decided to make his own with the Waverider.

To capture spectral data from every pixel location in the camera, [anfractuosity] first needed a way to collect that data — for that, he used an AFBR-S20M2WV, a miniature USB spectrometer he picked up second-hand. This sensor allows for the collection of data from 225 nm all the way up to 1000 nm. Of course, the sensor can only do that for one single input, so to turn it into a camera, [anfractuosity] added a stepper-driven x-y stage controlled by a Raspberry Pi Pico and some TMC2130 stepper drivers.

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Give Your Microscope Polarized $5 Shades To Fight Glare

October 13, 2025 by 15 Comments

Who doesn’t know the problem of glare when trying to ogle a PCB underneath a microscope of some description? Even with a ring light, you find yourself struggling to make out fine detail such as laser-etched markings in ICs, since the scattered light turns everything into a hazy mess. That’s where a simple sheet of linear polarizer film can do wonders, as demonstrated by [northwestrepair] in a recent video.

Simply get one of these ubiquitous films from your favorite purveyor of goods, or from a junked LCD screen or similar, and grab a pair of scissors or cutting implements. The basic idea is to put this linear polarizer film on both the light source as well as on your microscope’s lens(es), so that manipulating the orientation of either to align the polarization will make the glare vanish.

This is somewhat similar to the use of polarizing sunshades, only here you also produce specifically the polarized light that will be let through, giving you excellent control over what you see. As demonstrated in the video, simply rotating the ring light with the polarizer attached gives wildly different results, ranging from glare-central to a darkened-but-clear picture view of an IC’s markings.

How to adapt this method to your particular microscope is left as your daily arts and crafts exercise. You may also want to tweak your lighting setup to alter the angle and intensity, as there’s rarely a single silver bullet for the ideal setup.

Just the thing for that shiny new microscope under the Christmas tree. Don’t have a ring light? Build one.

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A vertically-mounted black disk with a concentric pattern of reflective disks is illuminated under a red light. A large number of copper wires run away from the the disk to a breadboard.

Deforming A Mirror For Adaptive Optics

October 13, 2025 by 16 Comments

As frustrating as having an atmosphere can be for physicists, it’s just as bad for astronomers, who have to deal with clouds, atmospheric absorption of certain wavelengths, and other irritations. One of the less obvious effects is the distortion caused by air at different temperatures turbulently mixing. To correct for this, some larger observatories use a laser to create an artificial star in the upper atmosphere, observe how this appears distorted, then use shape-changing mirrors to correct the aberration. The physical heart of such a system is a deformable mirror, the component which [Huygens Optics] made in his latest video.

The deformable mirror is made out of a rigid backplate with an array of linear actuators between it and the thin sheet of quartz glass, which forms the mirror’s face. Glass might seem too rigid to flex under the tenth of a Newton that the actuators could apply, but everything is flexible when you can measure precisely enough. Under an interferometer, the glass visibly flexed when squeezed by hand, and the actuators created enough deformation for optical purposes. The actuators are made out of copper wire coils beneath magnets glued to the glass face, so that by varying the polarity and strength of current through the coils, they can push and pull the mirror with adjustable force. Flexible silicone pillars run through the centers of the coils and hold each magnet to the backplate.

A square wave driven across one of the actuators made the mirror act like a speaker and produce an audible tone, so they were clearly capable of deforming the mirror, but a Fizeau interferometer gave more quantitative measurements. The first iteration clearly worked, and could alter the concavity, tilt, and coma of an incoming light wavefront, but adjacent actuators would cancel each other out if they acted in opposite directions. To give him more control, [Huygens Optics] replaced the glass frontplate with a thinner sheet of glass-ceramic, such as he’s used before, which let actuators oppose their neighbors and shape the mirror in more complex ways. For example, the center of the mirror could have a convex shape, while the rest was concave.

This isn’t [Huygens Optics]’s first time building a deformable mirror, but this is a significant step forward in precision. If you don’t need such high precision, you can also use controlled thermal expansion to shape a mirror. If, on the other hand, you take it to the higher-performance extreme, you can take very high-resolution pictures of the sun.