this post was submitted on 30 Mar 2025
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[–] My_IFAKs___gone@lemmy.world 135 points 1 week ago (1 children)

Just put two π ohm resistors in series duh

[–] InternetCitizen2@lemmy.world 41 points 1 week ago (1 children)
[–] My_IFAKs___gone@lemmy.world 41 points 1 week ago (13 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

[–] RadicalEagle@lemmy.world 26 points 1 week ago (8 children)

Barely passed your English classes as well I assume. /s

[–] My_IFAKs___gone@lemmy.world 12 points 1 week ago (3 children)
[–] unemployedclaquer@sopuli.xyz 2 points 3 days ago

Math is a liquid. Or a language.

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[–] abcd@feddit.org 77 points 1 week 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 week 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 week ago* (last edited 1 week ago) (9 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.

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

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[–] CausticFlames@sopuli.xyz 76 points 1 week ago (8 children)

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

[–] ThePyroPython@lemmy.world 71 points 1 week 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 32 points 1 week ago (1 children)
[–] HowAbt2morrow@futurology.today 26 points 1 week ago (1 children)

True. Would the effort have any beneficial application? Aside from being bad ass.

[–] LodeMike@lemmy.today 20 points 1 week ago (1 children)
[–] InternetCitizen2@lemmy.world 22 points 1 week ago (1 children)

Therefore we should do it anyway.

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[–] expatriado@lemmy.world 22 points 1 week ago (1 children)

9 significant figures? good luck!

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[–] disguy_ovahea@lemmy.world 18 points 1 week ago

The tolerance would be greater than the difference anyway.

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[–] FreeBeard@slrpnk.net 70 points 1 week ago (6 children)

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

[–] slackassassin@sh.itjust.works 3 points 6 days ago

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

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

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

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

Sounds like a 6 ohm resistor solution.

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[–] deranger@sh.itjust.works 53 points 1 week ago (6 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.

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

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

[–] PrimeErective@startrek.website 13 points 1 week ago (1 children)

Pi r not square. Pi r round. Cornbread r square

[–] DragonTypeWyvern@midwest.social 17 points 1 week ago (2 children)
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[–] kayzeekayzee@lemmy.blahaj.zone 14 points 1 week ago (1 children)

I actually really like physics, and it's 100% because I'm fucked up and evil

[–] deranger@sh.itjust.works 28 points 1 week ago (1 children)

Respect. Physics is way up there in terms of hard science nerd cred.

[–] PropaGandalf@lemmy.world 12 points 1 week ago (1 children)

the philosopher floating on a cloud: So how do you guys really know what's real?

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[–] andros_rex@lemmy.world 10 points 1 week ago* (last edited 1 week 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.

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[–] frezik@midwest.social 45 points 1 week ago (5 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?

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

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

[–] Zron@lemmy.world 20 points 1 week 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 6 days ago

Only if it isn't applied physics.

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[–] unemployedclaquer@sopuli.xyz 37 points 1 week ago (3 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.

[–] tacobellhop@midwest.social 16 points 1 week 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.

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[–] badcommandorfilename@lemmy.world 22 points 1 week ago* (last edited 1 week ago) (2 children)

Ah yes, the old "send the new guy out to buy an isotropic antenna and an electron trap" on their first day

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[–] phr@discuss.tchncs.de 12 points 1 week ago

maybe there should be?!

[–] hardcoreufo@lemmy.world 11 points 1 week 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.

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