Repairing A BPS-305 30V Bench Power Supply

When [Tahmid Mahbub] recently reached for his ‘Lavolta’ BPS-305 bench supply, he was dismayed to find that despite it being a 30V, 5A-rated unit, the supply refused to output more than 15V. To be fair, he wasn’t sure that he had ever tried to push it beyond 15V in the years that he had owned it, but it had better live up to its specs. Ergo out came the screwdriver to open the power supply to see what had broken, and hopefully to fix it.

After some more probing around, he discovered that the unit had many more issues, including a highly unstable output voltage and output current measurement was completely wrong. Fortunately this bench power supply turns out to be very much like any number of similar 30V, 5A units, with repair videos and schematics available.

While [Tahmid] doesn’t detail his troubleshooting process, he does mention the culprits: two broken potentiometers (VR104 and VR102). VR104 is a 5 kOhm pot in the output voltage feedback circuit and VR102 (500 Ohm) sets the maximum output current. With no 500 Ohm pot at hand, a 5 kOhm one was combined with a 470 Ohm resistor to still allow for trimming. Also adjusted were the voltage and current trimpots for the front display as they were quite a bit off. Following some testing on the reassembled unit, this power supply is now back in service, for the cost of two potentiometers and a bit of time.

Experimental setup and measured optical depth. (Credit: Josiah Sinclair et al,, PRX Quantum, 2022)

Quantum Mechanics And Negative Time With Photon-Atom Interactions

Within our comfortable world of causality we expect that reactions always follow an action and not vice versa. This why the recent chatter in the media about researchers having discovered ‘negative time’ with photons being emitted before the sample being hit by source photons created such a stir. Did these researchers truly just crack our fundamental concepts of (quantum) physics wide open? As it turns out, not really.

Much of the confusion stems from the fact that photons aren’t little marbles that bounce around the place, but are an expression of (electromagnetic) energy. This means that their resulting interaction with matter (i.e. groupings of atoms) is significantly more complicated, often resulting in the photonic energy getting absorbed by an atom, boosting the energy state of its electron(s) before possibly being re-emitted as the excited electrons decay into a lower orbit.

This dwell time before re-emission is what is confusing to many, as in our classical understanding we’d expect this to be a very deterministic process, while in a quantum world it most decidedly is not.

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Different potato varieties. – The potato is the vegetable of choice in the United States. On average, Americans devour about 65 kg of them per year. New potato releases by ARS scientists give us even more choices of potatoes to eat. (Credit: Scott Bauer, USDA ARS)

Re-engineering Potatoes To Remove Their All-Natural Toxins

Family Solanum (nightshade) is generally associated with toxins, and for good reasons, as most of the plants in this family are poisonous. This includes some of everyone’s favorite staple vegetables: potatoes, tomatoes and eggplant, with especially potatoes responsible for many poisonings each year. In the case of harvested potatoes, the chemical responsible (steroidal glycoalkaloids, or SGA) is produced when the potato begins to sprout. Now a team of researchers at the University of California have found a way to silence the production of the responsible protein: GAME15.

The research was published in Science, following earlier research by the Max Planck Institute. The researchers deleted the gene responsible for GAME15 in Solanum nigrum (black nightshade) to confirm that the thus modified plants produced no SGA. In the case of black nightshade there is not a real need to modify them as – like with tomatoes – the very tasty black berries they produce are free of SGA, and you should not eat the SGA-filled and very bitter green berries anyway, but it makes for a good test subject.

Ultimately the main benefits of this research appear to be in enriching our general understanding of these self-toxicity mechanisms of plants, and in making safer potatoes that can be stored without worries about them suddenly becoming toxic to eat.

Top image: Different potato varieties. (Credit: Scott Bauer, USDA ARS)

Full Color 3D Printing With PolyDye And Existing Inkjet Cartridges

The PolyDye system installed on an Elegoo Neptune 2 printer. (Credit: Teaching Tech, YouTube)

Being able to 3D print FDM objects in more than one color is a feature that is rapidly rising in popularity, assisted by various multi-filament systems that allow the printer to swap between differently colored filaments on the fly. Naturally, this has the disadvantage of being limited in the number of colors, as well as wasting a lot of filament with a wipe tower and filament ‘poop’. What if you could print color on the object instead? That’s basically what the community-made PolyDye project does, which adds an inkjet cartridge to an existing FDM printer.

In the [Teaching Tech] video the PolyDye technology is demonstrated, which currently involves quite a few steps to get the colored 3D model from the 3D modelling program into both OrcaSlicer (with custom profile) and the inkjet printing instructions on the PolyDye SD card. After this the 3D object will be printed pretty much as normal, just with each layer getting a bit of an ink shower.

Although it could theoretically work with any FDM printer, currently it’s limited to Marlin-based firmware due to some prerequisites. The PolyDye hardware consists of a main board, daughter board, printed parts (including inkjet cartridge holder) and some wiring. A Beta Test unit is available for sale for $199, but you should be able to DIY it with the files that will be added to the GitHub project.

Even for a work-in-progress, the results are quite impressive, considering that it only uses off-the-shelf translucent filament and inkjet cartridges as consumables. With optimizations, it could give multi-filament printing a run for its money.

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Experimental sequence for the Ramsey-type phonon anharmonicity measurement. (Credit: Yu Yang et al., Science, 2024)

Creating A Mechanical Qubit That Lasts Longer Than Other Qubits

Among the current challenges with creating quantum computers is that the timespan that a singular qubit remains coherent is quite limited, restricting their usefulness. Usually such qubits consist of an electromagnetic resonator (boson), which have the advantage of possessing discrete energy states that lend themselves well to the anharmonicity required for qubits. Using mechanical resonators would be beneficial due to the generally slower decoherence rate, but these have oscillations (phonons) that are harmonic in nature. Now researchers may have found a way to use both electromagnetic qubits and mechanical resonators to create a hybrid form that acts like a mechanical qubit, with quite long (200 µs) coherence time.

As per the research paper by [Yu Yang] and colleagues in Science (open access preprint), their experimental mechanical qubit (piezoelectric disc and superconducting qubit on sapphire) was able to be initialized and read out, with single-qubit gates demonstrated. The experimental sequence for the phonon anharmonicity measurement is shown in the above image (figure 2 in the paper), including the iSWAP operations which initialize the hybrid qubit. Effectively this demonstrates the viability of such a hybrid, mechanical qubit, even if this experimental version is not impressive yet compared to the best electromagnetic qubit. Those have managed to hit a coherence time of 1 ms.

The lead researcher, [Yu Yang] expresses his confidence that they can improve this coherence time with more optimized designs and materials, with future experiments likely to involve more complex quantum gates as well as sensor designs.

The TimeChi Never Shipped, But You Can Build One From Scratch

What do you do when a crowdfunded product you really liked gets cancelled? Naturally, you take the idea and build your own version of it. That’s what [Salim Benbouziyane] did when the TimeChi project on Kickstarter saw its launch cut short. This device allows you to set a ‘no distractions’ timer, during which notifications on one’s phone and elsewhere are disabled, making it something similar to those Pomodoro timers. What this dial also is supposed to do is integrate with home automation to set up clear ‘focus’ periods while the timer runs.

A quick prototype of the newly minted Focus Dial project was set up using an ESP32 and other off-the-shelf components. The firmware has to run the timer, toggle off notifications on iOS and trigger firewall traffic rules to block a batch of social media addresses. Automating this with iOS was the hardest part, as Apple doesn’t make such automation features easy at all, ultimately requiring a Bluetooth audio board just to make iOS happy.

After this prototyping phase, the enclosure and assembly with the modules were drawn up in Autodesk Fusion 360 before the plastic parts were printed with a resin printer. The end result looks about as good as the Kickstarter one did, but with a few changes, because as [Salim] notes, if you are going to DIY such a failed crowdfunding project, why not make it work better for you?

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Battery-Electric Ships: Coming Soon To A Harbor Near You?

When ships moved from muscle- and wind power to burning coal and other fossil fuels for their propulsion, they also became significantly faster and larger. Today’s cargo ships and ferries have become the backbone of modern civilization, along with a range of boat types. Even though tugs and smaller pleasure vessels are a far cry from a multi-thousand ton cargo or cruise ship, one would be hard-pressed to convert these boats back to a pure muscle or wind-based version. In short, we won’t be going back to the Age of Sail, but at the same time the fossil fuel-burning engines in these boats and ship come with their own range of issues.

Even if factors like pollution and carbon emissions are not something which keep you up at night, fuel costs just might, with these and efficiency regulations increasing year over year. Taking a page from alternative propulsion systems in cars and trucks, the maritime industry has been considering a range of replacements for diesel and steam engines. Here battery-electric propulsion is somewhat of an odd duck, as it does not carry its own fuel and instead requires on-shore recharging stations. Yet if battery-electric vehicles (BEVs) can be made to work on land with accompanying low ‘refueling’ costs, why not ships and boats?

A recent study by Lawrence Berkeley National Laboratory (LBNL) researchers Hee Seung Moon et al. as published in Nature Energy claims that a significant part of US maritime traffic can be electrified this way. Yet as a theoretical model, how close does it hit to the harsh realities imposed by this physical world which we live in?

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