A microscope objective is sitting on a spool of solder in a metal tin, in front of a circuit board which has wires running away from it.

Watching Radioactive Decay With A Homemade Spinthariscope

November 17, 2025 by Aaron Beckendorf 2 Comments

Among the many science toys that have fallen out of fashion since we started getting nervous around things like mercury, chlorinated hydrocarbons, and radiation is the spinthariscope, which let people watch the flashes of light on a phosphor screen as a radioactive material decayed behind it. In fact, they hardly expose their viewers to any radiation, which makes [stoppi]’s homemade spinthariscope much safer than it might first seem.

[Stoppi] built the spinthariscope out of the eyepiece of a telescope, a silver-doped zinc sulfide phosphor screen, and the americium-241 capsule from a smoke detector. A bit of epoxy holds the phosphor screen in the lens’s focal plane, and the americium capsule is mounted on a light filter and screwed onto the eyepiece. Since americium is mainly an alpha emitter, almost all of the radiation is contained within the device.

After sitting in a dark room for a few minutes to let one’s eyes adjust, it’s possible to see small flashes of light as alpha particles hit the phosphor screen. The flashes were too faint for a smartphone camera to pick up, so [stoppi] mounted it in a light-tight metal box with a photomultiplier and viewed the signal on an oscilloscope, which revealed many small pulses.

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Tech In Plain Sight: Pneumatic Tubes

November 17, 2025 by Al Williams 28 Comments

Today, if you can find a pneumatic tube system at all, it is likely at a bank drive-through. A conversation in the Hackaday bunker revealed something a bit surprising. Apparently, in some parts of the United States, these have totally disappeared. In other areas, they are not as prevalent as they once were, but are still hanging in there. If you haven’t seen one, the idea is simple: you put things like money or documents into a capsule, put the capsule in a tube, and push a button. Compressed air shoots the capsule to the other end of the tube, where someone can reverse the process to send you something back.

These used to be a common sight in large offices and department stores that needed to send original documents around, and you still see them in some other odd places, like hospitals or pharmacy drive-throughs, where they may move drugs or lab samples, as well as documents. In Munich, for example, a hospital has a system with 200 stations and 1,300 capsules, also known as carriers. Another medical center in Rotterdam moves 400 carriers an hour through a 16-kilometer network of tubes. However, most systems are much smaller, but they still work on the same principle.

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[Usagi Electric] and his home brew computer

TMS9900-based Home Brew Computer

November 17, 2025 by John Elliot V 3 Comments

[Usagi Electric] is known for minicomputers, but in a recent video, he shows off his TMS9900-based homebrew computer. The TMS9900 CPU was an early 16-bit CPU famously used in the old TI-99/4A computer, but as the video points out, it wasn’t put to particularly good use in the TI-99/4A because its RAM was hidden behind an inefficient interface and it didn’t leverage its 16-bit address space.

The plan is for this computer to have 2K words of ROM, 6K words of RAM, and three serial lines: one for the console terminal, another for a second user console terminal, and the third for access to a tape drive.

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Reverse Engineering The Miele Diagnostic Interface

November 17, 2025 by Maya Posch 18 Comments

Since modern household appliances now have an MCU inside, they often have a diagnostic interface and — sometimes — more. Case in point: Miele washing machines, like the one that [Severin] recently fixed, leading to the firmware becoming unhappy and refusing to work. This fortunately turned out to be recoverable by clearing the MCU’s fault memory, but if you’re unlucky, you will have to recalibrate the machine, which requires very special and proprietary software.

Naturally, this led [Severin] down the path of investigating how exactly the Miele Diagnostic Utility (MDU) and the Program Correction (PC) interface communicate. Interestingly, the PC interface uses an infrared LED/receiver combination that’s often combined with a status LED, as indicated by a ‘PC’ symbol. This interface uses the well-known IrDA standard, but [Severin] still had to track down the serial protocol.

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A photo of a brushed motor and brushless motor with a brushless controller board

An Introduction To DC Motor Technology

November 16, 2025 by John Elliot V 4 Comments

[Thinking Techie] takes us back to basics in a recent video explaining how magnets, coils, brushed DC motors, and brushless DC motors work. If this is on your “to learn” list, or you just want a refresher, you can watch the video below. It’ll be ten minutes well-spent.

The video covers the whole technology stack behind the humble DC motor in its various incarnations. Starting with basic magnetic effects, it then proceeds through 2-wire brushed DC motors and finally into 3-wire brushless DC motors (BLDC motors).

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Supersized Calculator Brings The Whole Intel 4004 Gang Together

November 16, 2025 by Tyler August 14 Comments

Though mobile devices and Apple Silicon have seen ARM-64 explode across the world, there’s still decent odds you’re reading this on a device with an x86 processor — the direct descendant of the world’s first civilian microprocessor, the Intel 4004. The 4004 wasn’t much good on its own, however, which is why [Klaus Scheffler] and [Lajos Kintli] have produced super-sized discrete chips of the 4001 ROM, 4002 RAM, and 4003 shift register to replicate a 1970s calculator at 10x the size and double the speed, all in time for the 4004’s 50th anniversary.

We featured this project a couple of years back, when it was just a lonely microprocessor. Adding the other MSC-4 series chips enabled the pair to faithfully reproduce the logic of a Busicom 141-PF calculator, the very first to market with Intel’s now-legendary microprocessor. Indeed, this calculator is the raison d’etre for the 4004: Busicom commissioned the whole Micro-Computer System 4-bit (MCS-4) set of chips specifically for this calculator. Only later, once they realized what they had made, did Intel buy the rights back from the Japanese calculator company, and the rest, as they say, is history.

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Hackaday Links: November 16, 2025

November 16, 2025 by Dan Maloney 11 Comments

We make no claims to be an expert on anything, but we do know that rule number one of working with big, expensive, mission-critical equipment is: Don’t break the big, expensive, mission-critical equipment. Unfortunately, though, that’s just what happened to the Deep Space Network’s 70-meter dish antenna at Goldstone, California. NASA announced the outage this week, but the accident that damaged the dish occurred much earlier, in mid-September. DSS-14, as the antenna is known, is a vital part of the Deep Space Network, which uses huge antennas at three sites (Goldstone, Madrid, and Canberra) to stay in touch with satellites and probes from the Moon to the edge of the solar system. The three sites are located roughly 120 degrees apart on the globe, which gives the network full coverage of the sky regardless of the local time.

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