Virgin Physicists

Comments

• My_IFAKs___gone@lemmy.world ⁨1⁩ ⁨month⁩ ago

  Just put two π ohm resistors in series duh

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  • InternetCitizen2@lemmy.world ⁨1⁩ ⁨month⁩ ago

    Whats wrong with your 3!

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    • My_IFAKs___gone@lemmy.world ⁨1⁩ ⁨month⁩ 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

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• abcd@feddit.org ⁨1⁩ ⁨month⁩ ago

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

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  • Cornelius_Wangenheim@lemmy.world ⁨1⁩ ⁨month⁩ ago

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

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    • lemming741@lemmy.world ⁨1⁩ ⁨month⁩ 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.

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    • duckythescientist@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

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

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    • WolfLink@sh.itjust.works ⁨1⁩ ⁨month⁩ 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.

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• CausticFlames@sopuli.xyz ⁨1⁩ ⁨month⁩ ago

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

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  • ThePyroPython@lemmy.world ⁨1⁩ ⁨month⁩ 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.

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  • LodeMike@lemmy.today ⁨1⁩ ⁨month⁩ ago

    Yes

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    • HowAbt2morrow@futurology.today ⁨1⁩ ⁨month⁩ ago

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

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  • expatriado@lemmy.world ⁨1⁩ ⁨month⁩ ago

    9 significant figures? good luck!

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    • MelodiousFunk@slrpnk.net ⁨1⁩ ⁨month⁩ ago

      You’ll make do with three and you’ll like it!

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  • disguy_ovahea@lemmy.world ⁨1⁩ ⁨month⁩ ago

    The tolerance would be greater than the difference anyway.

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  • Croquette@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

    Don’t sneeze right next to it with that kind of precision.

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  • takeda@lemm.ee ⁨1⁩ ⁨month⁩ ago

    Sure, except the resistance will constantly change with time, temperature and other environmental variables.

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  • Aceticon@lemmy.dbzer0.com ⁨1⁩ ⁨month⁩ 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.

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  • Retro_unlimited@lemmy.world ⁨1⁩ ⁨month⁩ 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.

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• FreeBeard@slrpnk.net ⁨1⁩ ⁨month⁩ ago

  I’m a physicist. If you are an engineer that sounds like a “you” problem.

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  • SnekZone@lemmy.blahaj.zone ⁨1⁩ ⁨month⁩ ago

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

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    • nilclass@discuss.tchncs.de ⁨1⁩ ⁨month⁩ ago

      Or an I problem, depending on your perspective

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  • GreatAlbatross@feddit.uk ⁨1⁩ ⁨month⁩ ago

    Sounds like a 6 ohm resistor solution.

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    • interdimensionalmeme@lemmy.ml ⁨1⁩ ⁨month⁩ ago

      They’re 5.6 or 6.8 ohms usually

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  • captainlezbian@lemmy.world ⁨1⁩ ⁨month⁩ ago

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

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  • InternetCitizen2@lemmy.world ⁨1⁩ ⁨month⁩ ago

    I’m not an engineer

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    • Nalivai@lemmy.world ⁨1⁩ ⁨month⁩ ago

      This is also a “you” problem. Fix that at your earliest convenience.

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  • slackassassin@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

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

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• deranger@sh.itjust.works ⁨1⁩ ⁨month⁩ 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.

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  • empireOfLove2@lemmy.dbzer0.com ⁨1⁩ ⁨month⁩ 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”

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    • deranger@sh.itjust.works ⁨1⁩ ⁨month⁩ 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.

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    • captainlezbian@lemmy.world ⁨1⁩ ⁨month⁩ ago

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

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  • kayzeekayzee@lemmy.blahaj.zone ⁨1⁩ ⁨month⁩ ago

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

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    • deranger@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

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

      Image

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  • JuxtaposedJaguar@lemmy.ml ⁨1⁩ ⁨month⁩ ago

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

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    • GoatTnder@lemmy.world ⁨1⁩ ⁨month⁩ 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.”

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  • andros_rex@lemmy.world ⁨1⁩ ⁨month⁩ 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.

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• frezik@midwest.social ⁨1⁩ ⁨month⁩ 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?

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  • MehBlah@lemmy.world ⁨1⁩ ⁨month⁩ ago

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

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  • Zron@lemmy.world ⁨1⁩ ⁨month⁩ 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.

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    • MehBlah@lemmy.world ⁨1⁩ ⁨month⁩ ago

      Only if it isn’t applied physics.

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  • JayDee@lemmy.sdf.org ⁨1⁩ ⁨month⁩ 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.

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    • piecat@lemmy.world ⁨1⁩ ⁨month⁩ ago

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

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• unemployedclaquer@sopuli.xyz ⁨1⁩ ⁨month⁩ 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.

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  • tacobellhop@midwest.social ⁨1⁩ ⁨month⁩ 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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  • dejected_warp_core@lemmy.world ⁨1⁩ ⁨month⁩ 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).

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    • unemployedclaquer@sopuli.xyz ⁨5⁩ ⁨weeks⁩ ago

      I’m fond of the gentle expert dudes who are so old they heard about the mad Max signal intrusion that day

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• badcommandorfilename@lemmy.world ⁨1⁩ ⁨month⁩ ago

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

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  • InternetCitizen2@lemmy.world ⁨1⁩ ⁨month⁩ 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.

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    • badcommandorfilename@lemmy.world ⁨1⁩ ⁨month⁩ ago

      Sorry, we need two electrons with identical spin and orbitals. Better check the place across town.

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• hardcoreufo@lemmy.world ⁨1⁩ ⁨month⁩ 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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• phr@discuss.tchncs.de ⁨1⁩ ⁨month⁩ ago

  maybe there should be?!

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• Allero@lemmy.today ⁨1⁩ ⁨month⁩ ago

  Rheostat, my dudes

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  • Madison420@lemmy.world ⁨1⁩ ⁨month⁩ ago

    Trimmable precision resistor.

    en.m.wikipedia.org/wiki/Laser_trimming

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    • Allero@lemmy.today ⁨1⁩ ⁨month⁩ ago

      Even better I just came up with the absolute dumb simple solution :D

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  • nilclass@discuss.tchncs.de ⁨1⁩ ⁨month⁩ ago

    Until finding out about finite measurement resolution

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• umbrella@lemmy.ml ⁨1⁩ ⁨month⁩ ago

  best they can usually do is three fiddy, and you better love it.

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• ThisIsAManWhoKnowsHowToGling@lemmy.dbzer0.com ⁨1⁩ ⁨month⁩ ago

  This guy looks like the dude from Programmers Are Human Too

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  • InternetCitizen2@lemmy.world ⁨1⁩ ⁨month⁩ ago

    I can assure you they are not.

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• A_A@lemmy.world ⁨1⁩ ⁨month⁩ ago

  Quantum Ampere Standard
  www.nist.gov/noac/…/quantum-ampere-standard
  .
  there also been research for defining a quantum volt and quantumly stable resistors

  www.nist.gov/noac/technology/current-and-voltage
  Quantum-based measurements for voltage and current are moving toward greater miniaturization

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• Henry@lemmy.ca ⁨1⁩ ⁨month⁩ ago

  Nerd

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• usualsuspect191@lemmy.ca ⁨1⁩ ⁨month⁩ ago

  Wait until they connect something to a battery.

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• zipzoopaboop@lemmynsfw.com ⁨1⁩ ⁨month⁩ ago

  It’s been a while, but are ginger bread houses really that complex now?

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