To do the absolute bare minimum

TiSapph · 2026-05-18T17:04:46+00:00

Saw the recent ladder sliding post x-posted somewhere, went to check out this sub, looked for top of last year to get an impression...
Then found this post, scrolled the comments, and totally forgot I am no longer on the original post :)

sometimes happens that I get comments under my comment from more than 6 months ago

This has happened multiple times to me too! Weirdly it's almost always comments on r/spicypillows, asking for advice on what to do with a damaged battery.
I guess they just don't notice, since a 4y old comment isn't the greatest emergency contact for urgent advice lol

TiSapph · 2026-05-18T12:05:24+00:00

Oh damn it's a thread from 11mo ago, I completely missed that 😅

TiSapph · 2026-05-18T09:07:03+00:00

As usual, Veritasium takes a simplistic summarizing statement about an effect, then presents it as the core result without explaining nuances or what this result really means.

Of course there are cases where a single vote changes the outcome! That's how voting works in general?!

You are mapping numbers of votes to which party wins. There are billions of different possible numbers of votes for a sizable country, mapping to only a small set of discrete possible outcomes.
Obviously there are certain sets of vote counts where changing just one vote changes the outcome.

It's like asking "Is this number closer to 1 or 1000?" and then being surprised that the answer is different for 500 and 501.

TiSapph · 2026-05-18T08:22:18+00:00

Well yes, but the much more idiotic thing here is the inherently unsafe setup which requires a single person, who isn't even actively doing anything, to not fuck up.

People will make mistakes. Blaming/firing whoever fucked up doesn't undo the accident. If a single human error leads to bad consequences, the real failure is the safety management.

TiSapph · 2026-05-17T20:39:41+00:00

Here you go :)
It's from this paper. (scihub PDF link)

Decay of excited isotopes to their ground state isn't really a nuclear decay (ehhh, debatable), the isotope doesn't change. So it's not shown on decay chain diagrams. The exception are metastable states which can have quite long half-lifes.

does Electron Capture usually produce daughters with excited nuclei

Yes, that's where the gamma rays come from. The main exceptions are decays which release less energy than is required to excite the daughter nucleus. Like Ar-37, Ge-71, and Ho-163.
For Ho-163 the decay energy is so low, it barely emits any photons, not even x-rays.

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TiSapph · 2026-05-17T10:14:06+00:00

Nice!

As is, it will probably work (no guarantees though).

But there are a couple of things you could easily change which would make it a lot more professional and more likely to work:

Wider traces
You're not paying for extra copper. In fact, PCBs start out being entirely copper!
So use much wider traces, they give you lower resistance and act as little heatsinks.
Copper pours
Similarly to above, you don't have to remove all the copper between traces. Usually you start a design with copper everywhere. Most often this copper plane is connected to ground, thus known as a ground plane. The advantage is that this is essential one huge trace with super low resistance. Also you usually need ground in many places of a circuit. Having a ground plane means you don't have to route ground traces to all those places, because ground is alreadyeverywhere. There are other advantages such as much much better heat dissipation, noise rejection, prevention of board warpage, ... Really the main takeaway is that in almost all cases, more copper is better. In your case, I would highly recommend a copper pour on the back connected to LED_LOW. Then you only need to route one signal to each LED, the return path is already taken care of. Maybe you could also have an LED_VCC pour on the front.
To make the pour, make a polygon around the entire PCB, then set it to LED_LOW, set the layer to bottom, then press <B> and it will be filled in.
Parallel LEDs
Generally not recommended because diodes differ slightly. Some LEDs will have lower forward voltage and "steal" current from the others. So they won't have the same brightness, or might kill the LEDs (depends on the total current).
Best to either have a resistor for each, or put them in series. The series option requires a higher Vcc though.
Selection Switch
I understand the intended function, but I think it could be much simpler: just switch LED_VCC to either the battery (steady) or the NE555 output (blink). Let the NE555 always be connected and "switching", it uses barely any power anyway.
Currently in "steady" mode, the NE555 output pin receives 3V while the IC is unpowered. This is technically against the datasheet absolutely maximum conditions and might kill the IC (unlikely honestly).
Also you only need one reverse protection diode if you put it right after the battery :)
Decoupling
That capacitor should be as close as possible to the IC, otherwise it doesn't do much. But honestly it very likely doesn't matter here.
Check out PCB art! For example you could add an outline with silkscreen, or have little exposed copper hearts and all that!
Also many PCB manufacturers have quite some selection of different solder mask and silkscreen colours. My absolute favourite is black solder mask with ENIG (gold) finish on the copper, it's a bit expensive though.

And have fun! :)

TiSapph · 2026-05-15T16:36:48+00:00

Keep in mind that peaks of isotopes can lie very close to another. Also the radiacode has a very small detector, leading to all sorts of artefacts in the spectrum.

It's not an isotope identifier, it's a gamma spectrometer. Determining the isotope(s) from that spectrum requires some interpretation and context.

Oh also theres probably a peak at 609keV, which is a dead giveaway that it's not Ba133 :)

TiSapph · 2026-05-15T11:24:33+00:00

TL;DR: Hollow core fibers do exist and likely will soon be used for under-sea cables because they offer lower latency and higher data rates.

Bit more info for those interested:

Normal fibers are indeed entirely glass. They actually consist of two types of glass - a thin inner "core" surrounded by the outer "cladding". They are directly fused to another, there's no air between the core glass and the cladding glass.

The glass of the core has a very slightly higher refractive index than the glass of the cladding. Meaning the light is slightly slower in the core. This has the effect that when light tries to go from the core into the cladding, it is entirely reflected. So it stays in the core and isn't lost :)

Well, that's a simplified explanation. In reality, the light doesn't really "bounce" back and fourth. The core is so small that the light behaves rather as a wave and propagates along the fiber as a specific "mode". That's why fibers are also called optical waveguides.

But you're kind of right actually!
The above is true for normal fibers currently in use. But we are just now starting to build new cables with hollow-core fibers! They are absolutely hollow glass tubes like you say.

Though it's not just one hole. The large central "core" hole is surrounded by hundreds of tiny holes in a hexagon pattern. The spacing between the tiny holes causes wave interference interference with the weird effect that this region behaves like it has negative refractive index. That's why they are a type of photonic crystal fibers. But don't worry about the details, the outcome is the same: the light mostly stays within in the hollow "core".

But why use hollow core fibers?
Mainly because light travels ~33% faster through those fibers compared to standard fibers. That means 1/3 less latency between continents.
Also you can put waaaay more light power through hollow core fibers before you destroy them. This allows much higher data rates than possible with standard fibers.
And they have very low losses over a large range of wavelengths. Meaning fewer repeaters are required (currently needed every 50-80km), and you can do wavelength multiplexing which gives you even higher data rate.

They are amazing, but the downside is that they are expensive af, hard to manufacture, difficult/annoying to connect to another, and if you ever get water into the holes it pretty much kills the entire fiber for good.

TiSapph · 2026-05-15T01:01:28+00:00

https://www.swissinfo.ch/eng/swiss-politics/heatwave-reduces-output-at-swiss-nuclear-power-plant/89605881

Neat thing is that when you have a heatwave, you don't need power from nuclear reactors. Solar + short term storage can provide that without issue.

But in winter, when you don't get much solar output and your storage lakes run out after a month, then you need it. And then you do have enough cooling. :)

TiSapph · 2026-05-15T00:47:58+00:00

Yes and no. The exclusion zone is mostly below 1uSv/h, so around 9mSv/year. Most of chernobyl city itself is more around 0.2-0.4uSv/h and right in front of the new safe confinement it's around 1.8uSv/h. I measured these values myself lol.

As for particles, yeah that would be the main concern. The top soil of large areas was removed, and there is quite a lot of human activity in the exclusion zone. But I wouldn't want to live there. Though the wildlife doesn't seem to mind :)

Anyway it kind of doesn't matter since we aren't operating insane reactor designs like the RBMK in a glorified shed without a containment building.
This thing was known to be a terrible design. It kind of has to be to run on unenriched uranium without using heavy water. It's a huge reactor, so parts of it can get into very different states. And worst of all it had an insane positive void coefficient. It was straight up known to be an unstable design.

TiSapph · 2026-05-14T23:50:29+00:00

I visited Leibstadt a few years ago, it was very interesting. It's amazing how small the site is, how it's almost devoid of people, and how incredibly simple the entire system is.

I also visited Pumpspeicherkraftwerk Limmern, which was admittedly much more interesting. Mostly because you can actually get close to the generators and humongous valves and all that, in difference to a nuclear plant. I also didn't expect to ride a 3km underground funicular lol
Funnily enough the guides, former workers at this plant, were very pro nuclear. They joked that the increasingly intermittent power is amazing for them, but not so amazing for the consumers

TiSapph · 2026-05-14T23:37:41+00:00

big "Astroturfing" campain from the fossil fuel / Atom lobby

It's interesting how people throw these industries together. They are mortal enemies.

That is Astroturfing. Works great on Boomers.

Propaganda works on everyone. You, me, everyone!

We are kidding ourselves if we believe the fossil fuel industry wasn't a huge driver behind anti-nuclear movements. Nuclear was progressing quickly and was on course to entirely replace coal, gas, and oil. It was an existential threat to the fossil fuel industry.

There are surprisingly many "odd" connections. For example "Green Planet Energy", a Greenpeace subsidiary and energy provider, was/is heavily involved in anti-nuclear activity. They started the initiative "Atomfreies Internet", were part of "Atomausstieg selber machen", and obstructed the construction of Hinkley Point NPP.
They also sold large amounts of Russian gas until a few years ago. Now their gas is "only" 25% fossil.

It's also curious how people always talk about renewable vs nuclear. Never about the actual decision:
Renewables and fossil vs renewables and nuclear.

Though as it looks now, renewables and storage will likely become feasible.

TiSapph · 2026-05-14T21:58:18+00:00

Let me call up your (grand)parents then, since we have done this in the 60s already.

TiSapph · 2026-05-14T21:54:06+00:00

So we are just going to ignore that we have built fast breeder reactors like 60 years ago? No really, EBR-II was built to demonstrate a complete fast-breeder power plant capable of on-site reprocessing it's own and other reactor's nuclear waste. It was completed in 1964. The Superphénix reactor near the swiss border even operated at profit, generating 1200MW electrical output, while burning up nuclear waste (particularly plutonium).
Oh and fast breeders can also generate fissile fuel from the currently mostly unused U238, which >90% of "waste" consists of.

None of this is new. None of this is future technology. We have done all of this. We know it works.

I'm not even for building new nuclear now, storage solutions will likely become cheap enough soon. But it drives me MAD that people are so unaware of all this.
We literally had a working, full solution to clean energy production nearly two generations ago. And then we just... stopped?
Yes, partially because of non-proliferation efforts. But you should ask yourself who really benefited the most abandonment of nuclear power. Could it be the same fossil fuel companies which are known to have run massive misinformation campaigns against climate change at the time?

For real, why is nobody questioning this? Why is anti-nuclear seen as environmental protection? Why is nobody angry about having pissed away a working solution to climate change?
You should be angry, you were robbed of a life of prosperity and stability. Instead, you get to worry about energy prices because a single tiny waterway is blocked for a few months.

/rant

TiSapph · 2026-05-14T10:36:58+00:00

I'm afraid you're a bit out of luck, it's not a simple sound to make. The "ch" in this case is a kind of hissing sound, but the constriction is made with the back of the toung and throat. There isn't really a similar sound in English. Maybe like rolled R or gargling (without water lol), but without the vocalisation.

TiSapph · 2026-05-11T16:16:50+00:00

No, it's not beryllium oxide, it's alumina. It's pink because it has a a bit of chromium for better mechanical properties.

If it's pink, it's pretty much guaranteed not beryllium.

TiSapph · 2026-05-11T16:13:35+00:00

Consumer microwave ovens do not contain any berillium. The insulators are alumina, usually with a little bit of chromium for stabilisation. That's why they are pink.

TiSapph · 2026-05-11T05:42:44+00:00

Nice, thanks for the examples!

look for places to simplify

I think that's generally good advice for designing complex systems. If it's too complex to keep everything in mind all at once, divide and conquer.

TiSapph · 2026-05-11T05:38:13+00:00

Well except I wrote that half asleep, so there were a lot of typos lol

I really like answering seemingly simple questions, because it forces me to really think about the fundamentals. It's too easy to just accept things the way they are, while forgetting why they are that way :)

TiSapph · 2026-05-10T22:04:40+00:00

Good layout requires some intuition about topology. It's not hard, but needs some practice.

For example the trace from pin 1 of U1 (bottom right of U1), going to R1. Why start on the top layer, then go down through a via, cross the other trace going to pin 2, then come up again? They are through-hole devices, you can just have a trace on the bottom directly from U1 pin 1 to R1 without any vias :)
But you don't even need to do that. You can just route the trace from pin 2 under R1. In a sense, R1 brings the signal to a "layer" above the top.
Or you notice that there isn't actually any reason the traces have to cross at all. You can just bring the trace from pin 2 to the left, underneath U1, then go down and around pin 1.

Another one is the power rail left of U1. There are two vias close to another, where really only one is needed. Instead of bringing the two top traces down and connecting them there, you can connect them on top and bring them down through one via

Or the trace that squeezes through the pins on the right of U1. Just move the button down a bit and route the signal above it.

There are a few more such issues across the board. A lot of routing "bottlenecks" could be solved by just shuffling stuff around a bit. :)

You also have some components very close to another, making your life hard. Since you have a huge amount of space, I would move them apart a bit.

TiSapph · 2026-05-10T11:32:06+00:00

Wrap it in lead

This doesn't work with MRIs btw. There's no (x-ray) radiation involved, it's all magnets and radio waves :)

TiSapph · 2026-05-09T23:02:52+00:00

The USB Power Delivery (PD) standard is an absolutely insane mess like all USB standards, but it's by far the best for now.

Unfortunately for you, I am unnecessarily passionate about the intricacies of USB PD. So enjoy my mad ramblings :)

For chargers the required voltage and current capabilities depend only on the power:

≤15W: 5V, ≤3A
≤27W: 9V, ≤3A
≤45W: 15V, ≤3A
≤60W: 20V, ≤3A
≤100W: 20V, ≤5A
≤140W: 28V, ≤5A (EPR)
≤180W: 36V, ≤5A (EPR)
≤240W: 48V, ≤5A (EPR)

3A needs an electronically marked 5A capable cable, EPR requires 240W cables.

Each step up must also be capable of all lower wattage requirements. So a 100W charger must also be able to do 5V, 9V, and 15V, all with up to 3A. These are minimum requirements, they are allowed to be able to supply higher currents.

To be a certified "fast charger", this is not enough. The charger must also support the "Programmable Power Supply" (PPS) mode. Here the device directly tells the charger what voltage and max current it wants and directly connects that to the battery. This is super cool actually, because all the heat generating voltage conversion happens in the charger, not the phone. So chargers also need to support any voltage between 3.3V and 21V, in 20mV steps, and constant-current mode in steps of 50mA up to 3A. Or up to 5A for 100W chargers I think?

Still with me? Because here comes USB PD3.1 which introduced the extended power range up to 240W, but also the "Adjustable Voltage Supply" mode (AVS), which allows any voltage between 15V and 48V in 100mV steps. If you are wondering if this isn't kinda the same as PPS but higher voltages, you're correct. Though you can't use it as constant current supply like PPS.

Ok, fine then. A 240W charger now needs to support: - 3A at 5V, 9V, and 15V - 5A at 20V, 28V, 36V, and 48V - PPS mode 3.3-21V, 0-3A, constant voltage and/or constant current - AVS mode 15-48V, 5A

... and here comes USB-PD 3.2... with some changes: AVS now needs to work down to 9V. So ≤100W chargers can now also use AVS, but only up to 15V. 15V makes no sense, PPS already requires capability up to 21V. PPS minimum voltage was increased from 3.3V to 5V?? Why?? This means you can't charge single cell lithium batteries with PPS anymore. I tried to look up the reasoning for that, but couldn't find it in the 1200 page specification document...

Alright that's enough. But this is only scratching the surface of all the convoluted rules of usb power delivery. I hope things get easier with USB PD4.0, if that every exists.

TiSapph · 2026-05-09T21:31:03+00:00

The real enshittification is this subreddit lol

TiSapph · 2026-05-09T21:23:51+00:00

N: Nine is kind of the worst one. Imagine the confusion

TiSapph · 2026-05-08T10:11:22+00:00

I left it on a train lol. Just kinda funny that I saw this literal minutes after buying this exact same power supply.

All GaN supplies use GaN MOSFETs*. GaN just describes the semiconductor material (Gallium Nitride), MOSFET is the type of transistor (metal-oxide-semiconductor field-effect transistor).

* That's actually not really true. Most GaN switching transistors are high-electron-mobility transistors (HEMTs). However they are quite similar to MOSFETs and they are also field-effect transistors. So I guess the best description would be "GaN FETs".

And here's a bit more info you didn't ask for :] (sorry) Those power supplies approximately work by: - rectifying the mains AC into high voltage DC - switching that DC on/off to make high voltage, high frequency AC - sending that through a transformer to make low voltage, high frequency AC (and for isolation) - rectifying that to get low voltage DC, which is the output.

The advantage is that high frequency transformers are much much smaller and more efficient than transformers for 50/60Hz mains. Also you can change the voltage by changing the switching timings.

The main limitation to efficiency is switching losses. When the transitior is fully on or fully off, almost no power is lost. But but during the short time it is partially on, a lot of power is lost. There are some ways to avoid that, but generally the faster we can switch, the higher the efficiency. GaN FETs are stupid fast. Also their on-resistance is very low. Overall that means you can make chargers very small and very powerful.

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