Dwingeloo telescope with sun shining through

Dwingeloo To Venus: Report Of A Successful Bounce

March 28, 2025 by Heidi Ulrich 13 Comments

Radio waves travel fast, and they can bounce, too. If you are able to operate a 25-meter dish, a transmitter, a solid software-defined radio, and an atomic clock, the answer is: yes, they can go all the way to Venus and back. On March 22, 2025, the Dwingeloo telescope in the Netherlands successfully pulled off an Earth-Venus-Earth (EVE) bounce, making them the second group of amateurs ever to do so. The full breakdown of this feat is available in their write-up here.

Bouncing signals off planets isn’t new. NASA has been at it since the 1960s – but amateur radio astronomers have far fewer toys to play with. Before Dwingeloo’s success, AMSAT-DL achieved the only known amateur EVE bounce back in 2009. This time, the Dwingeloo team transmitted a 278-second tone at 1299.5 MHz, with the round trip to Venus taking about 280 seconds. Stockert’s radio telescope in Germany also picked up the returning echo, stronger than Dwingeloo’s own, due to its more sensitive receiving setup.

Post-processing wasn’t easy either. Doppler shift corrections had to be applied, and the received signal was split into 1 Hz frequency bins. The resulting detections clocked in at 5.4 sigma for Dwingeloo alone, 8.5 sigma for Stockert’s recording, and 9.2 sigma when combining both datasets. A clear signal, loud and proud, straight from Venus’ surface.

The experiment was cut short when Dwingeloo’s transmitter started failing after four successful bounces. More complex signal modulations will have to wait for the next Venus conjunction in October 2026. Until then, you can read our previously published article on achievements of the Dwingeloo telescope.

General Fusion Claims Success With Magnetized Target Fusion

March 27, 2025 by Maya Posch 21 Comments

It’s rarely appreciated just how much more complicated nuclear fusion is than nuclear fission. Whereas the latter involves a process that happens all around us without any human involvement, and where the main challenge is to keep the nuclear chain reaction within safe bounds, nuclear fusion means making atoms do something that goes against their very nature, outside of a star’s interior.

Fusing helium isotopes can be done on Earth fairly readily these days, but doing it in a way that’s repeatable — bombs don’t count — and in a way that makes economical sense is trickier. As covered previously, plasma stability is a problem with the popular approach of tokamak-based magnetic confinement fusion (MCF). Although this core problem has now been largely addressed, and stellarators are mostly unbothered by this particular problem, a Canadian start-up figures that they can do even better, in the form of a nuclear fusion reactors based around the principle of magnetized target fusion (MTF).

Although General Fusion’s piston-based fusion reactor has people mostly very confused, MTF is based on real physics and with GF’s current LM26 prototype having recently achieved first plasma, this seems like an excellent time to ask the question of what MTF is, and whether it can truly compete billion-dollar tokamak-based projects.

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Building The Simplest Atomic Force Microscope

March 23, 2025 by Elliot Williams 22 Comments

Doing it yourself may not get you the most precise lab equipment in the world, but it gets you a hands-on appreciation of the techniques that just can’t be beat. Today’s example of this adage: [Stoppi] built an atomic force microscope out of mostly junk parts and got pretty good results, considering. (Original is in German; read it translated here.)

The traditional AFM setup uses a piezo micromotor to raise and lower the sample into a very, very fine point. When this point deflects, it reads the height from the piezo setup and a motor stage moves on to the next point. Resolution is essentially limited by how fine a point you can make and how precisely you can read from the motion stages. Here, [stoppi]’s motion stage follows the traditional hacker avenue of twin DVD sleds, but instead of a piezo motor, he bounces a laser off of a mirror on top of the point and reads the deflection with a line sensor. It’s a clever and much simpler solution.

A lot of the learnings here are in the machine build. Custom nichrome and tungsten tips are abandoned in favor of a presumably steel compass tip. The first-draft spring ended up wobbling in the X and Y directions, rather than just moving in the desired Z, so that mechanism got reinforced with aluminum blocks. And finally, the line sensors were easily swamped by the laser’s brightness, so neutral density filters were added to the project.

The result? A nice side effect of the laser-bouncing-off-of-mirror setup is that the minimum resolvable height can be increased simply by moving the line sensors further and further away from the sample, multiplying the deflection by the baseline. Across his kitchen, [stoppi] is easily able to resolve the 35-um height of a PCB’s copper pour. Not bad for junk bin parts, a point from a crafts store, and a line sensor.

If you want to know how far you can push a home ~~AFM~~ microscope project, check out [Dan Berard]’s absolutely classic hack. And once you have microscope images of every individual atom in the house, you’ll, of course, want to print them out.

Microscopic view of chiral magnetic material

Twisting Magnetism To Control Electron Flow

March 22, 2025 by Heidi Ulrich 11 Comments

If you ever wished electrons would just behave, this one’s for you. A team from Tohoku, Osaka, and Manchester Universities has cracked open an interesting phenomenon in the chiral helimagnet α-EuP₃: they’ve induced one-way electron flow without bringing diodes into play. Their findings are published in the Proceedings of the National Academy of Sciences.

The twist in this is quite literal. By coaxing europium atoms into a chiral magnetic spiral, the researchers found they could generate rectification: current that prefers one direction over another. Think of it as adding a one-way street in your circuit, but based on magnetic chirality rather than semiconductors. When the material flips to an achiral (ferromagnetic) state, the one-way effect vanishes. No asymmetry, no preferential flow. They’ve essentially toggled the electron highway signs with an external magnetic field. This elegant control over band asymmetry might lead to low-power, high-speed data storage based on magnetic chirality.

If you are curious how all this ties back to quantum theory, you can trace the roots of chiral electron flow back to the early days of quantum electrodynamics – when physicists first started untangling how particles and fields really interact.

There’s a whole world of weird physics waiting for us. In the field of chemistry, chirality has been covered by Hackaday, foreshadowing the lesser favorable ways of use. Read up on the article and share with us what you think.

Biosynthesis Of Polyester Amides In Engineered Escherichia Coli

March 22, 2025 by Maya Posch 8 Comments

Polymers are one of the most important elements of modern-day society, particularly in the form of plastics. Unfortunately most common polymers are derived from fossil resources, which not only makes them a finite resource, but is also problematic from a pollution perspective. A potential alternative being researched is that of biopolymers, in particular those produced by microorganisms such as everyone’s favorite bacterium Escherichia coli (E. coli).

These bacteria were the subject of a recent biopolymer study by [Tong Un Chae] et al., as published in Nature Chemical Biology (paywalled, break-down on Arstechnica).

By genetically engineering E. coli bacteria to use one of their survival energy storage pathways instead for synthesizing long chains of polyester amides (PEAs), the researchers were able to make the bacteria create long chains of mostly pure PEA. A complication here is that this modified pathway is not exactly picky about what amino acid monomers to stick onto the chain next, including metabolism products.

Although using genetically engineered bacteria for the synthesis of products on an industrial scale isn’t uncommon (see e.g. the synthesis of insulin), it would seem that biosynthesis of plastics using our prokaryotic friends isn’t quite ready yet to graduate from laboratory experiments.

Producing Syngas From CO2 And Sunlight With Direct Air Capture

March 21, 2025 by Maya Posch 17 Comments

The prototype DACCU device for producing syngas from air. (Credit: Sayan Kar, University of Cambridge)

There is more carbon dioxide (CO₂) in the atmosphere these days than ever before in human history, and while it would be marvelous to use these carbon atoms for something more useful, capturing CO₂ directly from the air isn’t that easy. After capturing it would also be great if you could do something more with it than stuff it into a big hole. Something like producing syngas (CO + H₂) for example, as demonstrated by researchers at the University of Cambridge.

Among the improvements claimed in the paper as published in Nature Energy for this direct air capture and utilization (DACCU) approach are that it does not require pure CO₂ feedstock, but will adsorb it directly from the air passing over a bed of solid silica-amine. After adsorption, the CO₂ can be released again by exposure to concentrated light. Following this the conversion to syngas is accomplished by passing it over a second bed consisting of silica/alumina-titania-cobalt bis(terpyridine), that acts as a photocatalyst.

The envisioned usage scenario would be CO2 adsorption during the night, with concentrated solar power releasing it the day with subsequent production of syngas. Inlet air would be passed only over the adsorption section before switching the inlet off during the syngas generating phase. As a lab proof-of-concept it seems to work well, with outlet air stripped from virtually all CO₂ and very high conversion ratio from CO₂ to syngas.

Syngas has historically been used as a replacement for gasoline, but is also used as a source of hydrogen (e.g. steam reformation (SMR) of natural gas) where it’s used for reduction of iron ore, as well as the production of methanol as a precursor to many industrial processes. Whether this DACCU approach provides a viable alternative to SMR and other existing technologies will become clear once this technology moves from the lab into the real world.

Thanks to [Dan] for the tip.

Current Mirrors Tame Common Mode Noise

March 17, 2025 by Heidi Ulrich 12 Comments

If you’re the sort who finds beauty in symmetry – and I’m not talking about your latest PCB layout – then you’ll appreciate this clever take on the long-tailed pair. [Kevin]’s video on this topic explores boosting common mode rejection by swapping out the old-school tail resistor for a current mirror. Yes, the humble current mirror – long underestimated in DIY analog circles – steps up here, giving his differential amplifier a much-needed backbone.

So why does this matter? Well, in Kevin’s bench tests, this hack more than doubles the common mode rejection, leaping from a decent 35 dB to a noise-crushing 93 dB. That’s not just tweaking for tweaking’s sake; that’s taking a breadboard standard and making it ready for sensitive, low-level signal work. Instead of wrestling with mismatched transistors or praying to the gods of temperature stability, he opts for a practical approach. A couple of matched NPNs, a pair of emitter resistors, and a back-of-the-envelope resistor calculation – and boom, clean differential gain without the common mode muck.

If you want the nitty-gritty details, schematics of the demo circuits are on his project GitHub. Kevin’s explanation is equal parts history lesson and practical engineering, and it’s worth the watch. Keep tinkering, and do share your thoughts on this.

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