Science

1237 Articles

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 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.

Continue reading “Watching Radioactive Decay With A Homemade Spinthariscope” →

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

An Introduction To DC Motor Technology

November 16, 2025 by 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).

Continue reading “An Introduction To DC Motor Technology” →

WWII Secret Agents For Science

November 14, 2025 by 9 Comments

We always enjoy [History Guy]’s musing on all things history, but we especially like it when his historical stories intersect with technology. A good example was his recent video about a small secret group during the Second World War that deployed to the European Theater of Operations, carrying out secret missions. How is that technology related? The group was largely made of scientists. In particular, the team of nineteen consisted of a geographer and an engineer. Many of the others were either fluent in some language or had been through “spy” training at the secret Military Intelligence Training Center at Camp Ritchie, Maryland. Their mission: survey Europe.

Continue reading “WWII Secret Agents For Science” →

I/V plot at various voltage levels

2025 Component Abuse Challenge: Reverse Biasing An NPN BJT

November 6, 2025 by 10 Comments

For the Component Abuse Challenge our hacker [Tim Williams] observes that N-P-N reads the same way forwards and backwards, so… what happens if we reverse bias one? (Note: this remark about N-P-N reading the same forward and backward is a lighthearted joke; in fact the level of doping in the emitter and collector is different so those Ns are not fungible and will exhibit different properties and have different characteristics.)

What happens if we reverse bias an NPN transistor?In the margin you can see how the question was originally posed by Bob Pease back in March 18, 1996.

In his article [Tim] mentions that some transistors are specifically designed to operate when reverse biased, which [Tim] calls “inverted mode”, whereas most transistors are not designed to work in this fashion and that’s the sort of abuse that could damage the component and lead it to malfunction.

But what is Vout? [Tim] reports that he measured approximately -0.4 volts using his high-impedance meter. We tried this experiment in the lab ourselves but we were not able to duplicate [Tim]’s result; however there is a long list of potential reasons for such an outcome. If you do this experiment yourself we would love to hear about your results in the comments section!

If you’re still learning about transistors you might like to check out our five part series on transistors as amplifiers, starting here: Won’t Somebody, Please, Think Of The Transistors!

Thanks to [Tim] for his submission, we wish him the best of luck in the competition!

2025 Hackaday Component Abuse Challenge

Medieval Iron, Survivorship Bias And Modern Metallurgy

November 5, 2025 by 44 Comments

When you hear it said that “Modern steel is disposable by design”, your ears perk up, as you just caught the unmistakable sound of faux romanticism along with ‘lost ancient technology‘ vibes. Although it happens sometimes that we did lose something important, as with for example the ancient Roman concrete that turns out to have self-healing properties as a result of so-called hot mixing, this is decidedly an exception.

We nearly lost that technology because of the technological and scientific bonfire that was the prelude to a thousand years of darkness over Europe: called the Dark Ages, Middle Ages as well as the medieval period. Thus when you come across a slideshow video with synthesized monotonal voice-over which makes the bold claim that somehow medieval iron was superior and today’s metallurgy both worse and designed to break, you really have to do a spit-take. The many corrections in the comment section further reinforces the feeling that it’s more slop than fact.

One of the claims made is that the bloomery furnace beats the blast furnace, due to beneficial additives to the iron. Considering that the video cites its sources, it’s at least worthy of a dive into the actual science here. Are modern iron and steel truly that inferior and disposable?

Continue reading “Medieval Iron, Survivorship Bias And Modern Metallurgy” →

An aluminium box is visible on the left side of the image, with a power supply on the right side, and a lamp ballast in the middle. A man's hand is holding the end of an optical fiber in the lower left corner, and it is emitting a white light.

Building A Xenon Lamp For Spectroscopy

November 2, 2025 by 29 Comments

Before a spectrometer can do any useful work, it needs to be calibrated to identify wavelengths correctly. This is usually done by detecting several characteristic peaks or dips in a well-known light source and using these as a reference to identify other wavelengths. The most common reference for hobbyists is the pair of peaks produced by a mercury-vapor fluorescent light, but a more versatile option is a xenon-bulb light source, such as [Markus Bindhammer] made in his latest video.

A xenon gas discharge produces a wide band of wavelengths, which makes it a useful illumination source for absorbance spectroscopy. Even better, Xenon also has several characteristic spikes in the infrared region. For his light source, [Markus] used an H7 xenon bulb meant for a vehicle headlight. The bulb sits in the center of the source, with a concave mirror behind it and a pair of converging lenses in front of it. The converging lenses focus the light onto the end of an optical cable made of PMMA to better transmit UV. A few aluminum brackets hold all the parts in place. The concave mirror is made out of a cut-open section of aluminum pipe. The entire setup is mounted inside an aluminum case, with a fan on one end for cooling. To keep stray light out of the case, a light trap covers the fan’s outlet.

[Markus] hadn’t yet tested the light source with his unique spectrometer, but it looks as though it should work nicely. We’ve seen a wide variety of amateur spectrometers here, but it’s also illuminating to take a look at commercial scientific light sources.

UK’s MAST Upgrade Tokamak Stabilizes Plasma With Edge Magnetic Fields

October 22, 2025 by 16 Comments

Although nuclear fusion is exceedingly easy to achieve, as evidenced by desktop fusors, the real challenges begin to pop up whenever you try to sustain a plasma for extended periods of time, never mind trying to generate net energy output. Plasma instability was the reason why 1950s UK saw its nuclear fusion hopes dashed when Z-pinch fusion reactors failed to create a stable plasma, but now it seems that another UK fusion reactor is one step closer to addressing plasma instability, with the MAST Upgrade tokamak demonstrating the suppressing of ELMs.

ELMs, or edge localized modes, are instabilities that occur at the edge of the plasma. A type of magnetohydrodynamic instability, ELMs were first encountered after the switch to high-confinement mode (H-mode) to address instability issues encountered in the L-mode operating regime of previous tokamaks. These ELMs cause damage on the inside of the reactor vessel with these disturbances ablating the plasma-facing material.

One of the solutions proposed for ELMs are resonant magnetic perturbations (RMPs) using externally applied magnetic fields, with the South-Korean KSTAR tokamak already suppressing Type I ELMs using this method in 2011. Where the KSTAR and MAST Upgrade tokamaks differ is that the latter is a spherical tokamak, different from the more typical toroidal tokamak. As the name suggests, a spherical tokamak creates a sphere-like plasma rather than a doughnut-shape, with potential efficiency improvements.

All of this means that the MAST Upgrade tokamak can continue its testing campaign, as tokamaks around the globe keep trying to hit targets like the Greenwald Density Limit and other obstacles that stand in the way of sustained net energy production. Meanwhile stellarators seem to be surpassing one milestone after another, with the German Wendelstein 7-X being the current flagship project.

Top image: Inside MAST Upgrade,  showing the magnetic field coils used to control ELMs. Credit: United Kingdom Atomic Energy Authority