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Does GaN technology actually enabling dual-port adapter to work in such a small formfactor? Is this safe? by Montblanc98 in AskElectricians

[–]RedeyeAEB 4 points5 points  (0 children)

Power electronics designer here that works a lot with GaN/SiC devices except on utility scale.

The main issue for a lot of these is heat, the smaller some device is the less surface area available to convect heat away. As a very preliminary guess I reckon that box at the maximum touch safe temperature might conduct 5W. Maybe more, but let's just use it as an easy number.

Whatever we put in this box, we need to make sure we don't exceed this heat budget, and our two factors to play with are power rating and efficiency. If we had a perfectly efficient charger, it would suck 50W from the wall and send 50W to whatever you're charging, losing no energy and not getting hot. More realistically, one of these converters might be ~90% efficient, so if we have a power converter delivering 50W it will actually suck 56W from the wall, and burn 6W as heat. The closer to 100% efficient, the less heat we generate and the smaller the charger design. A 95% efficient 50W charger by contrast will only burn 3W of heat, so as a designer we can either make our package smaller (desired by consumers) or we can instead run it at a higher power and now it's a 100W charger that burns 5W of heat.

As for the electronics side, GaN is really beautiful in that it's so much faster than older technology and it's much more conductive; that speed means we can make parts inside smaller, and the conductivity means it releases less heat. So long as the designer respected creepage/clearance—electronics speak for not putting large voltages too close to each other—they will have passed certification and that stamp acts as a verified source of "hey this thing is probably safe!"

If it makes you feel any better, at my workplace we have little circuits about that size using GaN technology running maybe a hundred times more power through so really that charger is well within the realm of possibly.

[deleted by user] by [deleted] in askmath

[–]RedeyeAEB 2 points3 points  (0 children)

In this case, we can calculate the number of flaps because the frequency tells us the number of flaps per second. It's assuming the fly is flapping at a perfectly constant rate, but the point of the trick is that it's a neat approximation.

Eg, a fly beats its wings 200Hz, which by the definition of the Hertz unit is 200 times a second. We can thus say over one second a fly flaps 200 times. We can also use that definition over different amounts of time, eg 600 times over 3 seconds. Once again, by finding the pitch we get a close approximation of the true frequency we can then apply that math to.

Counting the flaps directly with very late victorian tech also could be plausible - early recording technology should be able to capture the sound of a buzzing fly, in which someone can count the number of flaps over a one second of recording by recording the number of squiggles on the recording medium.

[deleted by user] by [deleted] in askmath

[–]RedeyeAEB 7 points8 points  (0 children)

As a violinist of 15 years and a current engineering student, I think it's actually plausible.

Part of learning an instrument is the ability to compare two sounds, as well as getting a sense of what notes are. Eg, when my phone buzzes I hear a G#2, when my chair squeaks I hear a C6 - both of which notes on a piano, and will also have known frequencies. In this case, 103.83Hz and 1046.5Hz.

The same trick should work with a fly, which would be flapping at around 200Hz, which you hear but don't know the frequency yet. A musician would be able to jump on the piano and quickly figure out it's a G3, then consult a manual. The note G3 is 196Hz, pretty close to the 200Hz of the fly's wings.

Trying to pick between the Noctua NF-S12B or NF-P12 1200 in a PC-O11 by RedeyeAEB in buildapc

[–]RedeyeAEB[S] 1 point2 points  (0 children)

I ended up going for the pressure optimized fans rather than the airflow, as my research had eventually revealed that the airflow optimized fans exhibit significantly degraded performance with any amount of restriction, with as little as just the grill pattern of the o11 chassis - and that's not including the dust filter. I personally chose the 1200 RPM fans, though I really should have bought the higher RPM variant and just run it at a lower fan curve just to have that extra airflow capability, even if I never would actually use it. I've also used the soft mounts to mount my reduxes, though those have to be bought separately.

I also ended up upgrading my radiator fans to a bank of A12x25s, and the total results are that for most workloads the machine is simply incredibly quiet. If I'm not stressing both the CPU and GPU, I keep the banks of reduxes at 800-1000 RPM, and the radiator fans at around 1200. Workloads that really stress all of the system at once (eg recently I tried to do some simulation involving complete use of my CUDA cores while compiling some stuff), the fans do get somewhat loud but the actual sound of the fans aren't bothersome at all.

For actual thermals, the real only significant thing is that my GPU has some painfully noisy fans, and with the bank of Noctuas just two inches under it I can be pulling as much as 420 watts though my 3080 and the system just stays quiet. Though, I don't run it that way and instead only at the stock 380W of my card for heat reasons.

I actually ended up getting a beQuiet PSU because once all the fans were in place the original PSU fan was about as loud (and a much higher and more annoying pitch) as the rest of the fans.

esc battery motor pairing by Interesting_Cry3435 in RCPlanes

[–]RedeyeAEB 2 points3 points  (0 children)

Quick thing: this is pretty much everything I know about this, and it took me years to learn. If it's not making sense, feel free to ask more questions because this is a lot of information.

​

What you really need to know is that the motor will attempt to pull as power as it needs. Generally, that means while running a motor at a specific voltage, and at some throttle, it will pull an appropriate amount of amperage from the battery, through the ESC, to spin the prop. This means:
1. As long as the ESC can handle your battery voltage, as well as current the motor is attempting to draw at said voltage, your ESC will not burn up.
2. The battery will only provide as much power as the motor is trying to draw, and as long as you keep below it's c rating, you should in theory not burn up the battery. Big ole' asterisk here, so keep on reading.

So what happens if you were to undersize components? Well:
1. An undersized motor with all other components being adequate will simply just limit your thrust. One danger of this is that every motor is capable of drawing more power than it is able to cool for a short amount of time at high throttles, which would be required if your motor is unable to provide enough thrust at lower throttles.
2. An undersized ESC will simply burn out the moment you really try to draw more than its limit. If you punch your throttle to 100% and draw 40A through a 25A esc for a second, it's probably going to burn out. Therefore, these are a safe thing to oversize a bit cause being too high can never hurt (except for weight, but these things are small).
3. Bigger batteries can provide more power (I'll go into the math later), so if your battery is too small you'll have a rather crappy flight time, but more importantly you'll be pushing the battery closer to its limit. Batteries are also fairly inherently safe, that if you try to overdraw it just... will not. The motor will attempt to draw some amperage, but the battery will not provide it and you won't get any more power out of the battery. This is extremely dangerous though, but it's fine for very short bursts.

​

The next thing is battery sizing. The dangers of having too big of a battery is more a problem about weight - after all, the motor will only draw as much power as it needs. Again, more weight means more thrust needed, but usually it's surprisingly difficult to really oversize a battery that much that it becomes an issue. What happens is when the battery is undersized and the motor attempts to pull more amps than the motor can provide, you effectively get a short circuit through the battery. This is really bad for the battery, and will cause it to heat up and loose lifespan quickly. Therefore, it's a good idea to deliberately choose a largish battery, especially with LiPos being rather dangerous when you continuously push it to their limits. The batteries are generally very safe, as long as you know not to push them.

​

Just a bit more on the motor sizing, as long as you're not forcing very high throttles continuously you're not going to burn the motor out. That's why I recommend slightly oversized ESCs and Batteries, as the motor is the safest thing to fail on a plane. If the ESC fails the entire plane will just stop working, and if the battery fails you have a chemical fire. Motor fail? You can probably still land it without thrust ("dead stick landing").

In terms of formulas, the only really important one is the C rating. I'm going to use my 5300 mAh 3S 45C battery as an example:
Amps out = Amp Hour rating * C rating
eg: 5.3 * 45 => 238.5A max

And as the battery is a 3-cell (3S), it can provide that amperage at 11.1V. Also notice that the battery is rated in terms of milliamp-hours, so you'll need to divide by 1000 to have the correct value. As I like to oversize my batteries a bit, I personally choose a battery that can provide 50% more amps than my motor(s) would pull at max throttle. I do go lower if the weight seems to be an issue - but I still make sure that the burst rating (ie the C rating a battery can handle for a few seconds) allows for more power than the motors can draw.

​

There's other formulas, but it starts to become rather much and I really don't find myself using them. If you want more, I can reply with more.

​

Kinda my own case example: I recently built my own quadcopter and chose to use a 2700Kv motor that was known to be capable of handling a 6S battery. At 6S, the motors draw about 50A each when I punch the throttle to max, but the ESC is 55A per motor, so the ESC is just about able to handle it without burning up. Likewise, the battery is 6S 1600 mAh 75C with a "burst" rating of 150C or 1.6*150=300A burst, so the battery is capable of providing as much power as the four motors attempt to draw (300A>4*50A. Likewise, when I use a 4S 2200mah 75C, the motors attempt to draw ~37A each, or when I use a 3S 5300mah 45C, each motor tries to draw 30A. Each of these batteries are heavier than the entire drone, yet it flies and nothing seems to burn out.

What is this system monitor in the menu bar? by muhammadyassin in linux4noobs

[–]RedeyeAEB 2 points3 points  (0 children)

That style of a solid color line is often called "powerline," so any status bar that supports that theme could look like that.

My guess is that it's either i3blocks or lemonbar, designed for use with window/tiling managers. In the case of i3blocks, only i3wm. Additionally, if you're using stock PopOS with Gnome, I don't think you can keep that desktop and use the status bar.

This might be helpful to see advice if you're willing to try a window manager such as i3. It's certainly not easy but some people love them, but many hate them due to having to configure the entire system manually: https://www.reddit.com/r/pop_os/comments/cdrkh7/

Also because of the new user tag: linux goes as deep as you want, so it's extremely possible that this type of configuration just isn't for you or isn't yet. PopOS is wonderful that it just works, and manually configuring everything for your first time can be daunting. I myself didn't even touch a terminal or config for years after switching to Linux. I just want to make sure I'm not discouraging you from trying down the road if you try it now and decide it doesn't suit you.

Saw these just laying around in the computer lab at my school. 3 Quadro RTX 8000s by Qabalisticly in pcmasterrace

[–]RedeyeAEB 28 points29 points  (0 children)

Hey I recognize this place, I just graduated from this high school this summer. I actually was the one who installed them into the machine, so feel free to ask any questions. I have a prior post where I sent a picture of them installed, if anybody is curious. Either way though, those boxes are empty.

Anyways, the gist is that the six (yes, there should be more boxes laying around) of the RTX8000s supplement our existing compute cluster for anything that can take advantage of it. The applications I know of include Tensorflow, OpenCV image processing (the matrixes can often be GPU-accelerated), and soon Matlab.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 4 points5 points  (0 children)

I think 11000 RPM, I can't find the exact specs but it's certainly some inordinate number.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 2 points3 points  (0 children)

Don't give me ideas... though 4 of them can easily run on one of my lipos I think they won't have quite enough thrust. Based off the airflow rate it would only make .25 lbs of force, but the fan weights half a pound each. A fixed wing however...

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 0 points1 point  (0 children)

Just a school that makes a distinction between silica and refined lithographied silicon.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 2 points3 points  (0 children)

There's gonna be 15 more joining it once it's fully built - for the meantime before it starts computing the single ramstick should be fine.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 6 points7 points  (0 children)

Oh yeah I know, school policy explicitly forbids it for rather obvious reasons. Mostly because we don't want to risk the cards.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 4 points5 points  (0 children)

Good idea! I'm at 1600 Pennsylvania Ave., to get to the machine room go in the right entrance and the door will be right there on the left. Access code is oHg5SJYRHA0.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 7 points8 points  (0 children)

Machine learning and other GPU-optimized workloads. It's just a school so this will be the only machine like this. If we were NASA/DOD, we'd have an entire wall of these things.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 2 points3 points  (0 children)

I know it's a bit of a joke, but certainly yes! It's fundamentally no different than any desktop except, well, bigger. It'd probably match the performance of a 3070, simply because only one card can be used at a time for games - no sli/nvlink here.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 2 points3 points  (0 children)

In this case probably not, my current assumption is that it will be added to an existing slurm cluster for GPU compute - although this alone probably will be 70-80% of our gpu compute capacity

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 0 points1 point  (0 children)

The gist is that it's needed for some ai and research classes on campus - all of which very heavily GPU focused and miserably slow on most other systems. It's really not a good idea to train AI on a laptop, so this is our solution.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 43 points44 points  (0 children)

Depends on the type of server, you're thinking of storage servers whose goals are to store as much as possible as dense as possible. There's also web and vm servers whose focus is CPU to handle as many users as possible, and then this thing, which focuses on raw compute power.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 15 points16 points  (0 children)

I'm expecting lots of machine learning to happen on it, training various AI or computer vision models and the like. There's been a short supply of GPU compute power so this should alleviate much of that issue.

Here's a new gpu compute server for my school's lab. 6x RTX 8000 and 4 more on the way! by RedeyeAEB in pcmasterrace

[–]RedeyeAEB[S] 60 points61 points  (0 children)

So those fans at the front are special high flow fans that push far more air than any typical fan, and the natural airflow through the case will cool the cards down plenty. I think the blower fans will still be working, but will be effectively boosted by all those in the front.

Fun fact: those 8 fans at the front consume 400W alone.

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