Without using fancy components: Just simply adding a 6.2 and a 2400 Ohm resistor in parallel already gives you 6.18402 Ohm ⚡️
Virgin Physicists
Submitted 2 months ago by InternetCitizen2@lemmy.world to [deleted]
https://lemmy.world/pictrs/image/035603ce-dacd-4e9b-b206-ca0529f63a00.jpeg
Comments
abcd@feddit.org 2 months ago
Cornelius_Wangenheim@lemmy.world 2 months ago
Real world resistors usually have a tolerance of ±5%, so you’ll never get anything that precise.
lemming741@lemmy.world 2 months ago
That’s why I keep a spool of 20 AWG nichrome on hand. Spool off 9.7195853528209 feet and it’ll be bang on.
duckythescientist@sh.itjust.works 2 months ago
I’ve actually found 1% to be a lot more common nowadays.
WolfLink@sh.itjust.works 2 months ago
Grab a box full and test a bunch until you find one that works well for your use case. That way you end up with a resistor that’s much better than the rated tolerance you’d get if you just grabbed one resistor at random.
CausticFlames@sopuli.xyz 2 months ago
couldnt you technically fine tune a potentiometer to be this resistance if you were precise enough?
ThePyroPython@lemmy.world 2 months 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.
LodeMike@lemmy.today 2 months ago
Yes
HowAbt2morrow@futurology.today 2 months ago
True. Would the effort have any beneficial application? Aside from being bad ass.
expatriado@lemmy.world 2 months ago
9 significant figures? good luck!
MelodiousFunk@slrpnk.net 2 months ago
You’ll make do with three and you’ll like it!
disguy_ovahea@lemmy.world 2 months ago
The tolerance would be greater than the difference anyway.
Croquette@sh.itjust.works 2 months ago
Don’t sneeze right next to it with that kind of precision.
takeda@lemm.ee 2 months ago
Sure, except the resistance will constantly change with time, temperature and other environmental variables.
Aceticon@lemmy.dbzer0.com 2 months ago
For starters resistance changes with temperature.
Also even in a multi-turn potentiometer, getting a precision of 1 in 10^9 would require an equal level of precision in the angle you rotate that potentiometer to (for example, a 0.1 degree error in a 10 turn potentiometer - which I believe is more turns than anything that actually can be bought - translates into a 1 in 36,000 error in resistance, so about 3000 larger than 10^9) even if you had a perfect material whose resistance doesn’t change with temperature.
The joke here isn’t even specifically about resistances and electronics, it’s that the real world has all sorts of limitations that when you’re doing things whole in the mathematical world you don’t have to account for, and that’s a hard realisation for Physicists (having gone to study Physics at uni and then half way in my degree changing to Electronics Engineering I can tell you that’s one of the shocks I had to deal with in the transition).
(In a way, it’s really a joke about Theoretical Physicists)
See also the “assuming this chicken is a spherical ovoid” kind of joke.
Retro_unlimited@lemmy.world 2 months ago
I had a potentiometer on a circuit board that adjusted a timer, but I found that the timer varied in timing. I ended up replacing with a few resistors and it corrected the variations.
FreeBeard@slrpnk.net 2 months ago
I’m a physicist. If you are an engineer that sounds like a “you” problem.
SnekZone@lemmy.blahaj.zone 2 months ago
Not using the correct resistors does cause a U problem every once in a while.
nilclass@discuss.tchncs.de 2 months ago
Or an I problem, depending on your perspective
GreatAlbatross@feddit.uk 2 months ago
Sounds like a 6 ohm resistor solution.
interdimensionalmeme@lemmy.ml 2 months ago
They’re 5.6 or 6.8 ohms usually
captainlezbian@lemmy.world 2 months ago
OK, the solution is “how accurate will make the physicist and accountants both only kinda mad”
InternetCitizen2@lemmy.world 2 months ago
I’m not an engineer
Nalivai@lemmy.world 2 months ago
This is also a “you” problem. Fix that at your earliest convenience.
slackassassin@sh.itjust.works 2 months ago
Too true, and my problem is about to be your problem and the cycle continues comrade.
deranger@sh.itjust.works 2 months ago
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.
empireOfLove2@lemmy.dbzer0.com 2 months ago
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”
deranger@sh.itjust.works 2 months ago
Eh, it’s just fundamentally ugly to me and that really turned me off. Rounding doesn’t help, that’s like turning the lights off for sex. Engineering is still very cool to me, and I have huge respect for those who do it, but I’d never have made it. It’s physics but even further perverted by reality. Math was beautiful to me because of how “pure” it was. Just straight logic, divorced from the messy world we live in. Tidy coefficients and elegant derivations.
captainlezbian@lemmy.world 2 months ago
The difficult part of engineering is figuring out what number you have to round then multiply by 1.2 or 0.8
kayzeekayzee@lemmy.blahaj.zone 2 months ago
I actually really like physics, and it’s 100% because I’m fucked up and evil
deranger@sh.itjust.works 2 months ago
JuxtaposedJaguar@lemmy.ml 2 months ago
The trick is to round everything. Pi? Basically 3.
GoatTnder@lemmy.world 2 months ago
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.”
andros_rex@lemmy.world 2 months 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 things electric and magnetic fields work.
frezik@midwest.social 2 months ago
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?
MehBlah@lemmy.world 2 months ago
Its funny the first thing I thought of was at what temperature.
Zron@lemmy.world 2 months ago
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 2 months ago
Only if it isn’t applied physics.
JayDee@lemmy.sdf.org 2 months ago
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 2 months ago
You can’t tell me that there isn’t a good reason that 0.001% resistors exist. Otherwise why sell them?
unemployedclaquer@sopuli.xyz 2 months ago
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.
tacobellhop@midwest.social 2 months 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.
dejected_warp_core@lemmy.world 2 months ago
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).
unemployedclaquer@sopuli.xyz 2 months ago
I’m fond of the gentle expert dudes who are so old they heard about the mad Max signal intrusion that day
badcommandorfilename@lemmy.world 2 months ago
Ah yes, the old “send the new guy out to an isotropic antenna and an electron trap” on their first day
InternetCitizen2@lemmy.world 2 months ago
Can we do a fraction of an electron boss? The economy is kind of rough. Guy on the phone says he can do a time share too.
badcommandorfilename@lemmy.world 2 months ago
Sorry, we need two electrons with identical spin and orbitals. Better check the place across town.
hardcoreufo@lemmy.world 2 months ago
The only application I can think of off the top of my head that would require that precision is a R2R DAC.
Just sort through a bin until you find one.
phr@discuss.tchncs.de 2 months ago
maybe there should be?!
Allero@lemmy.today 2 months ago
Rheostat, my dudes
Madison420@lemmy.world 2 months ago
Trimmable precision resistor.
Allero@lemmy.today 2 months ago
Even better I just came up with the absolute dumb simple solution :D
nilclass@discuss.tchncs.de 2 months ago
Until finding out about finite measurement resolution
ThisIsAManWhoKnowsHowToGling@lemmy.dbzer0.com 2 months ago
This guy looks like the dude from Programmers Are Human Too
InternetCitizen2@lemmy.world 2 months ago
I can assure you they are not.
A_A@lemmy.world 2 months ago
Quantum Ampere Standard
www.nist.gov/noac/…/quantum-ampere-standard
.
there also been research for defining a quantum volt and quantumly stable resistorswww.nist.gov/noac/technology/current-and-voltage
Quantum-based measurements for voltage and current are moving toward greater miniaturizationHenry@lemmy.ca 2 months ago
Nerd
usualsuspect191@lemmy.ca 2 months ago
Wait until they connect something to a battery.
zipzoopaboop@lemmynsfw.com 2 months ago
It’s been a while, but are ginger bread houses really that complex now?
My_IFAKs___gone@lemmy.world 2 months ago
Just put two π ohm resistors in series duh
InternetCitizen2@lemmy.world 2 months ago
Whats wrong with your 3!
My_IFAKs___gone@lemmy.world 2 months ago
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