Science

1291 Articles

Pendulum Powered Battery

February 8, 2026 by 22 Comments

While the average person would use a standard charger to top off their phone, [Tom Stanton] is no average man. Instead, he put mind to matter with an entire pendulum battery system.

Using the inductive effects of magnets on copper coils, [Tom] found the ability to power small components. With that in mind, the only path was forward with a much larger pendulum. A simple diode rectifier and capacitors allow for a smoother voltage output. The scale of the device is still too small to power anything insane, even the phone charging test is difficult. One thing the device can do is juice up the electromagnetic launcher he put together a couple years back to hurl an RC plane into the air.

The useful applications of pendulum power storage might not be found in nationwide infrastructure, but the application on this scale is certainly a fun demonstration. [Tom] has a particular fascination with similar projects where practical application comes second to novelty. For a perfect example of this, check out his work with air powered planes!

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A graph of current versus time for circuits with and without inductors

A Deep Dive Into Inductors

February 5, 2026 by 5 Comments

[Prof MAD] runs us through The Hidden Power of Inductors — Why Coils Resist Change.

The less often used of the passive components, the humble and mysterious inductor is the subject of this video. The essence of inductance is a conductor’s tendency to resist changes in current. When the current is steady it is invisible, but when current changes an inductor pushes back. The good old waterwheel analogy is given to explain what an inductor’s effect is like.

There are three things to notice about the effect of an inductor: increases in current are delayed, decreases in current are delayed, and when there is no change in current there is no noticeable effect. The inductor doesn’t resist current flow, but it does resist changes in current flow. This resistive effect only occurs when current is changing, and it is known as “inductive reactance”.

After explaining an inductor’s behavior the video digs into how a typical inductor coil actually achieves this. The basic idea is that the inductor stores energy in a magnetic field, and it takes some time to charge up or discharge this field, accounting for the delay in current that is seen.

There’s a warning about high voltages which can be seen when power to an inductor is suddenly cut off. Typically a circuit will include snubber circuits or flyback diodes to help manage such effects which can otherwise damage components or lead to electric shock.

[Prof MAD] spends the rest of the video with some math that explains how voltage across an inductor is proportional to the rate of change of current over time (the first derivative of current against time). The inductance can then be defined as a constant of proportionality (L). This is the voltage that appears across a coil when current changes by 1 ampere per second, opposing the change. The unit is the volt-second-per-ampere (VsA-1) which is known as the Henry, named in honor of the American physicist Joseph Henry.

Inductance can sometimes be put to good use in circuits, but just as often it is unwanted parasitic induction whose effects need to be mitigated, for more info see: Inductance In PCB Layout: The Good, The Bad, And The Fugly.

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Big Heat Pumps Are Doing Big Things

February 5, 2026 by 57 Comments

The heat pump has become a common fixture in many parts of modern life. We now have reverse-cycle air conditioning, heat pump hot water systems, and even heat pump dryers. These home appliances have all been marketed as upgrades over simpler technologies from the past, and offer improved efficiency and performance for a somewhat-higher purchase price.

Heat pumps aren’t just for the home, though. They’re becoming an increasingly important part of major public works projects, as utility providers try to do ever more with ever less energy in an attempt to save the planet. These days, heat pumps are getting bigger, and will be doing ever grander things in years to come. Continue reading “Big Heat Pumps Are Doing Big Things” →

Detecting Helium Leaks With Sound In A Physics-Based Sensor

February 4, 2026 by 11 Comments

Helium is inert, which makes it useful in a lot of different industries. But helium’s colorless and odorless non-reactivity also means traditional gas sensing methods don’t work. Specialized detectors exist, but are expensive and fussy. Thankfully, researcher [Li Fan] and colleagues found a physics-based method of detecting helium that seems as elegant as it is simple.

The new sensor relies on a topological kagome structure, and doesn’t depend on any chemical reaction or process whatsoever. The cylinders in the structure are interconnected; air can flow in and speakers at the three corners inject sound.

Sound waves propagate through the air within the structure at a fixed rate, and as helium enters the sensor it changes how fast the sound waves travel. This measurable shift in vibration frequency indicates the concentration of helium. It’s stable, calibration-free, doesn’t care much about temperature, and resets quickly. Even better, the three corners act as separate sensors, making it directional. It’s even quite rugged. Just as a basket weaved in a kagome pattern is stable and resistant to damage or imperfections in the individual strips that make up the pattern, so too is this sensor only marginally affected by physical defects.

The sensor design has been tested and shown to work with helium, but could possibly be applied to other gases. More detail is available at ResearchGate, with some information about the math behind it all in a supplemental paper.

Optical Combs Help Radio Telescopes Work Together

February 3, 2026 by No comments

Very-long baseline interferometry (VLBI) is a technique in radio astronomy whereby multiple radio telescopes cooperate to bundle their received data and in effect create a much larger singular radio telescope. For this to work it is however essential to have exact timing and other relevant information to accurately match the signals from each individual radio telescope. As VLBI is used for increasingly higher ranges and bandwidths this makes synchronizing the signals much harder, but an optical frequency comb technique may offer a solution here.

In the paper by [Minji Hyun] et al. it’s detailed how they built the system and used it with the Korean VLBI Network (VLB) Yonsei radio telescope in Seoul as a proof of concept. This still uses the same hydrogen maser atomic clock as timing source, but with the optical transmission of the pulses a higher accuracy can be achieved, limited only by the photodiode on the receiving end.

In the demonstration up to 50 GHz was possible, but commercial 100 GHz photodiodes are available. It’s also possible to send additional signals via the fiber on different wavelengths for further functionality, all with the ultimate goal of better timing and adjustment for e.g. atmospheric fluctuations that can affect radio observations.

Thomas Edison May Have Discovered Graphene

January 31, 2026 by 13 Comments

Thomas Edison is well known for his inventions (even if you don’t agree he invented all of them). However, he also occasionally invented things he didn’t understand, so they had to be reinvented again later. The latest example comes from researchers at Rice University. While building a replica light bulb, they found that Thomas Edison may have accidentally created graphene while testing the original article.

Today, we know that applying a voltage to a carbon-based resistor and heating it up to over 2,000 °C can create turbostratic graphene. Edison used a carbon-based filament and could heat it to over 2,000 °C.

This reminds us of how, in the 1880s, Edison observed current flowing in one direction through a test light bulb that included a plate. However, he thought it was just a curiosity. It would be up to Fleming, in 1904, to figure it out and understand what could be done with it.

Naturally, Edison wouldn’t have known to look for graphene, how to look for it, or what to do with it if he found it. But it does boggle the mind to think about graphene appearing many decades earlier. Or maybe it would still be looking for a killer use. Certainly, as the Rice researchers note, this is one of the easier ways to make graphene.

Building Natural Seawalls To Fight Off The Rising Tide

January 30, 2026 by 40 Comments

These days, the conversation around climate change so often focuses on matters of soaring temperatures and extreme weather events. While they no longer dominate the discourse, rising sea levels will nonetheless still be a major issue to face as global average temperatures continue to rise.

This poses unique challenges in coastal areas. Municipalities must figure out how to defend their shorelines, or decide which areas they’re willing to lose. The City of Palo Alto is facing just this challenge, and is building a natural kind of seawall to keep the rising tides at bay.

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