this post was submitted on 30 Mar 2025
858 points (99.3% liked)

Lemmy Shitpost

30418 readers
3880 users here now

Welcome to Lemmy Shitpost. Here you can shitpost to your hearts content.

Anything and everything goes. Memes, Jokes, Vents and Banter. Though we still have to comply with lemmy.world instance rules. So behave!


Rules:

1. Be Respectful


Refrain from using harmful language pertaining to a protected characteristic: e.g. race, gender, sexuality, disability or religion.

Refrain from being argumentative when responding or commenting to posts/replies. Personal attacks are not welcome here.

...


2. No Illegal Content


Content that violates the law. Any post/comment found to be in breach of common law will be removed and given to the authorities if required.

That means:

-No promoting violence/threats against any individuals

-No CSA content or Revenge Porn

-No sharing private/personal information (Doxxing)

...


3. No Spam


Posting the same post, no matter the intent is against the rules.

-If you have posted content, please refrain from re-posting said content within this community.

-Do not spam posts with intent to harass, annoy, bully, advertise, scam or harm this community.

-No posting Scams/Advertisements/Phishing Links/IP Grabbers

-No Bots, Bots will be banned from the community.

...


4. No Porn/ExplicitContent


-Do not post explicit content. Lemmy.World is not the instance for NSFW content.

-Do not post Gore or Shock Content.

...


5. No Enciting Harassment,Brigading, Doxxing or Witch Hunts


-Do not Brigade other Communities

-No calls to action against other communities/users within Lemmy or outside of Lemmy.

-No Witch Hunts against users/communities.

-No content that harasses members within or outside of the community.

...


6. NSFW should be behind NSFW tags.


-Content that is NSFW should be behind NSFW tags.

-Content that might be distressing should be kept behind NSFW tags.

...

If you see content that is a breach of the rules, please flag and report the comment and a moderator will take action where they can.


Also check out:

Partnered Communities:

1.Memes

2.Lemmy Review

3.Mildly Infuriating

4.Lemmy Be Wholesome

5.No Stupid Questions

6.You Should Know

7.Comedy Heaven

8.Credible Defense

9.Ten Forward

10.LinuxMemes (Linux themed memes)


Reach out to

All communities included on the sidebar are to be made in compliance with the instance rules. Striker

founded 2 years ago
MODERATORS
 
top 50 comments
sorted by: hot top controversial new old
[–] frezik@midwest.social 43 points 1 day ago (3 children)

That level of precision in a resistor would literally be thrown off if you breathed on it. If you actually needed that, then you need to build an extremely controlled environment around it. Even then, the heat from the electricity itself would throw it off. Maybe in a liquid nitrogen bath?

[–] Zron@lemmy.world 19 points 20 hours ago (1 children)

First, assume a spherical resistor in a vacuum, that can also dissipate heat with 100% efficiency.

Now that we’re in physics land, anything is possible.

[–] MehBlah@lemmy.world 1 points 19 hours ago

Only if it isn't applied physics.

[–] MehBlah@lemmy.world 24 points 1 day ago* (last edited 1 day ago)

Its funny the first thing I thought of was, at what temperature.

[–] JayDee@lemmy.sdf.org 3 points 20 hours ago (1 children)

A big aspect of good design is being able to solve an issue as succinctly as possible, with as wide an operating range as possible. Lower tolerance requirements = better.

If you need that level of precision, you might want to reconsider your career in circuit design.

[–] piecat@lemmy.world 1 points 19 hours ago (1 children)

You can't tell me that there isn't a good reason that 0.001% resistors exist. Otherwise why sell them?

[–] JayDee@lemmy.sdf.org 3 points 17 hours ago

4 Sig figs vs 9 Sig figs is a big gap. If you need your resistors in a circuit to be precise to 9 Sig figs, seek a new career.

It is almost always possible to take a system and make it more precise by using more precise parts (just gotta make sure you know what part you are changing to improve what tolerance). You do get diminishing returns with that, but it beats inventing a new system if the tolerances you need are just alittle ways away.

[–] FreeBeard@slrpnk.net 68 points 1 day ago (6 children)

I'm a physicist. If you are an engineer that sounds like a "you" problem.

[–] slackassassin@sh.itjust.works 3 points 16 hours ago

Too true, and my problem is about to be your problem and the cycle continues comrade.

[–] SnekZone@lemmy.blahaj.zone 36 points 1 day ago (1 children)

Not using the correct resistors does cause a U problem every once in a while.

[–] nilclass@discuss.tchncs.de 10 points 1 day ago

Or an I problem, depending on your perspective

[–] captainlezbian@lemmy.world 6 points 1 day ago

OK, the solution is "how accurate will make the physicist and accountants both only kinda mad"

[–] GreatAlbatross@feddit.uk 18 points 1 day ago (1 children)

Sounds like a 6 ohm resistor solution.

[–] interdimensionalmeme@lemmy.ml 10 points 1 day ago

They're 5.6 or 6.8 ohms usually

load more comments (2 replies)
[–] unemployedclaquer@sopuli.xyz 37 points 1 day ago (2 children)

i miss old school radioshack. i did not know what all those bins of tiny electronic hobby parts were for, but I desperately wanted to learn. I did eventually but you have to get all your stuff from some shady oligarch.

i did not know what all those bins of tiny electronic hobby parts were for, but I desperately wanted to learn.

From what I understand, prior to the personal computer boom of the 1980's, HAM radio was kind of a big deal with nerds. The parts were there for all manner of electronics tinkering, but a big mainstay was building and modifying radios. Yeah, you had people tinkering with computers in the 1970's too, but it was more niche (until it wasn't).

[–] tacobellhop@midwest.social 16 points 1 day ago

Yeah we’re living in the ruins of the old America already and have been for like 25 years.

It’s dirty they just use the same business names they did in the 20th century. While making smoke and mirrors versions of the old products.

[–] abcd@feddit.org 77 points 1 day ago (1 children)

Without using fancy components: Just simply adding a 6.2 and a 2400 Ohm resistor in parallel already gives you 6.18402 Ohm ⚡️

[–] Cornelius_Wangenheim@lemmy.world 28 points 1 day ago (3 children)

Real world resistors usually have a tolerance of ±5%, so you'll never get anything that precise.

[–] lemming741@lemmy.world 38 points 1 day ago* (last edited 1 day ago) (6 children)

That's why I keep a roll of 20 AWG nichrome on hand. Spool off 9.7195853528209 feet and it'll be bang on.

[–] Lv_InSaNe_vL@lemmy.world 5 points 1 day ago (1 children)

So 1 inch of your wire would weigh ~0.0987 grams, so to measure down to 8.6350242338508 inches of wire your scale would need to weigh down to ~0.00000000000007 grams. Which is the weight of about a dozen atoms or so.

[–] lemming741@lemmy.world 10 points 1 day ago (1 children)

Yeah which is why you use a Kibble balance. Are you sure you're cut out for this kind of work?

[–] Lv_InSaNe_vL@lemmy.world 3 points 1 day ago (1 children)

I'm not a scientist, I'm just in IT haha

I figured there was a way to measure that small of weight but I didn't know!

[–] lemming741@lemmy.world 3 points 1 day ago

Its akin to having an electon microscope in your kitchen

load more comments (5 replies)

I've actually found 1% to be a lot more common nowadays.

load more comments (1 replies)
[–] My_IFAKs___gone@lemmy.world 135 points 1 day ago (1 children)

Just put two π ohm resistors in series duh

[–] InternetCitizen2@lemmy.world 41 points 1 day ago (1 children)
[–] My_IFAKs___gone@lemmy.world 41 points 1 day ago (22 children)

Ugh, 3 factorial is most definitely not equal to π. It's something more like, idk, 9? Honestly I don't even know how I got here; I majored in Latin and barely past

load more comments (22 replies)
[–] deranger@sh.itjust.works 52 points 1 day ago (7 children)

Numbers like that are why I quit majoring in mechanical engineering. Physics took the beauty of math and made it ugly.

You knew something was wrong in calculus when you got a fucked up coefficient that wasn’t a nice number.

[–] JuxtaposedJaguar@lemmy.ml 10 points 1 day ago (1 children)

The trick is to round everything. Pi? Basically 3.

[–] GoatTnder@lemmy.world 7 points 1 day ago (1 children)

I've heard a story (so like 4th hand at this point) where an astrophysicist was talking about galaxy rotations or something. "And for this model, we can simplify pi to 10."

[–] JuxtaposedJaguar@lemmy.ml 2 points 20 hours ago

My thermodynamics professor made so approximations in his derivations that all of his equations had an “O” term to represent the inaccuracy. Every time he made another approximation he’d say “and, of course, the O sucks up the error”.

[–] empireOfLove2@lemmy.dbzer0.com 54 points 1 day ago (5 children)

Numbers like that should have been why you kept going in mech E.

Once you get past the educational stage, every one of those calculations becomes "OK now round to the closest whole number that gives you the larger factor of safety and move on"

[–] LostXOR@fedia.io 35 points 1 day ago (3 children)

Using π = 4 is only a 27% safety margin, better go for π = 10 just to be safe.

[–] demunted@lemmy.ml 21 points 1 day ago (4 children)

Pi r square, square have 4 sides. No problem found.

load more comments (4 replies)
load more comments (1 replies)
[–] captainlezbian@lemmy.world 2 points 23 hours ago

The difficult part of engineering is figuring out what number you have to round then multiply by 1.2 or 0.8

load more comments (3 replies)
[–] andros_rex@lemmy.world 10 points 1 day ago* (last edited 1 day ago)

After calculus though, they just expect you to cope with fucked up coefficients. In Diff Eq, sometimes you do just get something like 3/111 cos (6/111 x). It gets harder to come up with examples that work out with nice integers.

Physics can also have some really beautiful math, look at Lissajous figures. Once you understand the connections between e, the imaginary plane, and sine/cosine, you get some profound understandings about how electric and magnetic fields work.

load more comments (4 replies)
[–] CausticFlames@sopuli.xyz 76 points 1 day ago (13 children)

couldnt you technically fine tune a potentiometer to be this resistance if you were precise enough?

[–] ThePyroPython@lemmy.world 70 points 1 day ago

Mathematically yes. Practically, right now? No.

So you need a resistor of this value for your widget.

For that many places of precision you're looking at a potentiometer with a 10 nano-ohm precision.

I am not aware of any commercially available resistor that can do that but you could create one using microelectronic structures used for ICs and derive a 10 nano-ohm resistor by design and then chain enough of these elements into a resistor network or potentiometer to create the super precise resistance value you want.

Cool, congratulations.

Now how are you going to use this 10 nano-ohm resistor? What voltage will you be applying across it? What current do you expect it to handle? And therefore what are your power requirements? What are your tolerances, how much can the true value deviate from the designed ideal?

Because power generates heat through losses, and that will affect the resistance value so how tightly do you need to manage the power dissipation?

How will you connect to this resistor to other circuit components? Because a super precise resistor on it's own is nothing but an over-engineered heating element.

If you tried connecting other surface mount devices (SMDs) from the E24 or even E96 series to this super precise resistor then the several orders of magnitude wider tolerances of these other components alone will swallow any of the precision from your super accurate resistor.

So now your entire circuit has to be made to the same precision else all of your design work has been wasted.

Speaking of which, now your heat management solution now needs to be super precise as well and before you know it you've built the world's most accurate widget that probably took billions of dollars/euros/schmeckles and collaboration from the worlds leading engineers and scientists that probably cost more time and money than the Large Hadron Collider.

load more comments (12 replies)
load more comments
view more: next ›