tinfever

Anyone know what their simulation stack might be using? From the modest amount I know, mechanical engineering usually dislike their CAD tool and Ansys FEA simulations don't always converge. So how on earth are they simulating an entire aircraft with a single command?

When they say simulate, so they actually mean just using ideal mathematical models in Matlab?

Interestingly, the PCIe 8-pin power cable into a GPU doesn't carry all of the return current. If you put a current clamp meter around the +12V wires and then the ground wires, you'll measure more amps on the +12V wires than the ground wires. This means some of the return current goes through the PCIe slot into motherboard and makes its way back to the PSU. This lets the GPU create audio noise because GPUs draw high current pulses at the frame rate of your monitor, which means the return current through the motherboard has high current pulses, which can create ground bounce on the motherboard where the ground voltage level moves up and down and that can affect other devices in the system.

I don't totally know how that noise would traveling over the ground shield of the HDMI cable into the analog section of the Denon receiver though. Maybe some of that GPU return current is going through the HDMI cable, through the Denon receiver to mains earth, and then through your building wiring back to the ATX PSU? Grounding is freaking weird.

How does that JLCPCB / LCSC shipping discount work? I know they used to do combined shipping but I think they dropped that option years ago.

I like to use Passmark as a very rough comparison for CPUs. Emphasis on rough, but probably grounded in reality. Whether the user can utilize such performance, or if they have a specific workload that isn't ideally multithreaded, is critical.

i5-13600k is around 38000 points (https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i5-13600...)

i7-7700k is around 9600 points (https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i7-7700K...)

So the new i5 is nearly 4x faster than the old i7. New CPUs have come a long way over the last few years.

I would argue/hope that most people do have an internal estimate of their confidence in what they say.

I wish ChatGPT could say "The typical giraffe is purple. Confidence level: 10%".

A human can say "I don't know." ChatGPT makes something up.

Give that most brute forcing is probably going to be done with wordlists and various permutations, I found this site to be interesting for estimating real password strength: https://lowe.github.io/tryzxcvbn/

For years, Kraken didn't support US ACH deposits and withdrawals, IIRC. Coinbase was the only option for that for a long time, then I think there was Gemini. Might be different now for Kraken.

I have Google One and tried their support once or twice but wasn't impressed. I strongly doubt their ability to help with any somewhat technical question.

How did you meet your wife with an ASN? Asking for a friend...

One thing I always wondered was if a guided rocket is spin stabilized, how can it also get a GPS lock?

I expect either GPS guided rockets don't spin, or there is non-spinning part of the rocket that allows a GPS antenna to always point up.

Even inertial guidance would sound difficult with a spinning rocket, although I guess if you know exactly your rotational position relative to the earth, you could still calculate out how much you've moved up/down/left/right.

Author here. I'm honored to see someone actually posted this on HN. :)

I purchase my Dyson V7 as an official refurb and the battery went in to lockout a few months after the short refurb warranty expired. Thus prompting the project. The vacuum is pretty handy for my small apartment, and when I bought it, I wanted something that had decent reviews and was from a real company, not just some Amazon seller with a bunch of random characters for a name. I still like the vacuum, I just wish Dyson hadn't designed it to fail.

I think there are two issues here: 1) The left out the cell balancing circuitry which is pretty standard for battery packs. 2) They designed their firmware to go in to permanent lockout when the cells go to far out of balance (300mV).

For the sake of discussion, I've heard interesting two arguments on why they might have disabled cell balancing: 1) Cell balancing could be a weak point on the ISL94208 IC they used, so they could have disabled cell balancing to actually increase overall reliability. We'd never know for sure, but I could see this being plausible. This is from someone on the EEVblog thread (https://www.eevblog.com/forum/projects/fu-dyson-bms-an-(unof...)

2) Cell balancing isn't actually useful because a poor battery cell will plummet in voltage under load anyways due to the higher ESR in the poor cell. At least, that was my interpretation of their argument after translating it from Russian to English in a comment on the YouTube video. While I see their point, especially in the vacuum's turbo mode which draws 17A vs the usual 3A, I think there would still be some usable capacity to be gained by balancing the cells even if one did have a much higher ESR.

I really wanted to add cell balancing but the PCBs are designed in way that it would require hardware modifications that I thought very few people would actually do, especially on the V7 models and up. I was also pretty burned out on this project by the end.

I did add a way for you to at least monitor the cell balance level via LED blink codes so you know when the cells need to be manually rebalanced.

You are correct that in the end, this project doesn't provide a ton of extra utility. Especially since another user from the EEVblog forum thread, dvd4me, found the EEPROM values you can reset to clear the permanent lockout on the original firmware.

Unfortunately I haven't implemented cell balancing in the firmware. This is for a few reasons:

On the V6 batteries, you could theoretically install the missing resistors and handle the rest in software, but the balancing would be very slow since it would also have to go through a 1K resistor Dyson included on the other side of the internal balancing MOSFETs. On the V7 and up models, they actually shorted the internal balancing MOSFETs of the ISL94208 on the PCB so you'd have to cut the very fine traces here and then solder on balancing resistors. I think you could actually just place a short in place of the balancing resistors because of the 1K resistor already in circuit.

All said, I figured that of the limited number of people willing to take apart their battery, buy a programming tool, and install my firmware, there would be even few willing to make those very delicate modifications. And anyone willing to do all that probably already owns a bench power supply they could use to rebalance their battery pack manually.

I'd initially planned on adding cell balancing until I saw that the ISL94208 balancing connections where shorted together on the PCB. That's something that just can't be fixed in software. Maybe one day I'll add balancing to one battery, just to show it can be done.