EEVblog #25 - The Infinite Resistor Puzzle

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  • Опубліковано 17 січ 2025

КОМЕНТАРІ • 125

  • @Falney
    @Falney 9 років тому +34

    "I am not a math man" Says the man with a calculator fascination.

  • @JanicekTrnecka
    @JanicekTrnecka 10 років тому +70

    My favorite programming language ?
    Solder !

    • @iamdarkyoshi
      @iamdarkyoshi 10 років тому +13

      This needs to be a poster.

  • @johnclawed
    @johnclawed 6 років тому +7

    In the early 80's there was an article about an artist who did 3D sculptures made of components. They were real circuits. One of them detected someone passing by and made strange noises that varied with their position and speed.

  • @carmelpule6954
    @carmelpule6954 9 років тому +21

    Congratulations for being so practical.
    This reminds me of the historic story when Edison was manufacturing light bulbs and for some reason he wanted to calculate the volume of the complex shape of a glass light bulb. Apparantly the mathematicians came up with some approximations but were not so sure about the accuracy of their result. Then Edison who was a very practical man came along and filled one glass bulb with water and he knew the volume of the water and also floated or immersed the glass bulb in water thus displacing the water according to Archemedes principle and again he found the outside volume of the bulb , hence he could find the volume of the glass used in the bulb. Mathematiics are very useful but being practical sometimes gets quicker results.

    • @imdeadserious6102
      @imdeadserious6102 8 років тому +1

      practical mathematics

    • @airgliderz
      @airgliderz 8 років тому +1

      Edison was on a camping trip in 1887 near Rawlings Wyoming, Battle Lake when he dropped the tip of his bamboo fishing pole in the cap finite noticing the glowing car nixed fishing pole tip.... I've driven by the spit many times it is marked with a historical marker. Story is a bit iffy but makes for a good tail..
      That's why I go fishing, to be inspired to invent the next big thing, my story to my wife and I'm sticking to it...!
      😊

    • @MarkMcDaniel
      @MarkMcDaniel 5 років тому

      The definition of applied mathematics.

  • @t33th4n
    @t33th4n 9 років тому +14

    Dave could not resist to do it :)

    • @MarkMcDaniel
      @MarkMcDaniel 5 років тому +1

      And, we haven't the capacitance to resist the clickbait.

  • @flutestarz
    @flutestarz 14 років тому +2

    Effective resistance across the single resistor is 2R/M. M is the number of resistors (R) connecting to each junction. For your square mesh M=4. If the 2D mesh was actually a 3D cube, then M=6

  • @k6eep593
    @k6eep593 10 років тому +18

    I made a 3D version using 1K resistors. The resistance across diagonal corners is 1K.

    • @EscapeMCP
      @EscapeMCP 9 років тому +2

      +K6EEP Diagonal on the face (i.e. min path=2), or across the cube (min path=3)??

    • @k6eep593
      @k6eep593 9 років тому +6

      +EscapeMCP This was a huge cube. 20 resistors across at least. So a facing side was a 20x20 array. The idea was to guess resistance from corner to the opposite corner across the cube. (min path=3 in your example) Some one had donated a thousands of preformed 1K resistors I kept growing it until my soldering hand got tired.

  • @EEVblog
    @EEVblog  15 років тому +3

    It made it onto the Hack-A-Day website, so a huge influx of new viewers and subscribers!

  • @absurdengineering
    @absurdengineering 5 років тому +3

    The infinite resistor grids (in 2D, 3D, 4D, …) are awesome to demonstrate how physical structures give rise to sums of infinite series. Conversely, as a rule of thumb, if you have a series and can think of a resistor network where resistance between some two nodes is a sum of the series, then the series converges. This can actually be mathematically proven, no less.

  • @FisicacomRenatoBrito
    @FisicacomRenatoBrito 11 років тому +2

    Dave
    I am a brazilian physics teacher.
    In Brazil most of people do not speak English.
    Would you mind if I use just a single of this video, around 3 minutes of it, translate your voice comments into portuguese to present it to my pupils ? I used my own voice in portuguese.
    Do you authorize me to use a peace of this video with this little changes ?
    In the end of the video, I gave all the credits to you, to your excelente Blog, I showed the URL of you blog here in UA-cam.

  • @holycatsbatman
    @holycatsbatman 15 років тому +2

    Beautiful, elegant, scientific. This is how an engineer solves math puzzles.

  • @grlg2
    @grlg2 14 років тому +1

    Hi Dave, This is fantastic (along with all your other videos). I like your comment about practicality and actually doing something as opposed to endless calculations.
    Cheers,
    Greg.

  • @yuppiehi
    @yuppiehi 8 років тому +4

    I'm going to build this at this year's Mini Maker Faire in Honolulu. I already bought 500 10K 1/4-watt metal film 1-percent resistors. It'll be interesting to see how many people will actually stop by and ask what the heck I'm doing. Have soldering iron, will travel...

  • @codeprose
    @codeprose 15 років тому +3

    Seeing you love measuring stuff, how about applying a voltage (say 10.000V) to the central resistor, and then measuring the voltage at various locations around the grid.

  • @spodule6000
    @spodule6000 12 років тому +1

    My own thought too. A geometric toroid. Intuitively i would think it would - then you could shrink that down to just a few resistors and solve it theoretically too.

  • @springgraphicstx
    @springgraphicstx 7 років тому +3

    I know this video is old, but I just recently found your channel. Amazing that the result is 2/pi. I like your practical approach. Would be interesting to see how the result changes if you gradually chop it down to smaller networks: 12x12, then 10x10, etc. Or if I get around to build one, maybe take measurements as it is being put together.

    • @absurdengineering
      @absurdengineering 5 років тому +2

      David Scott Any finitely sized network has resistances that are a truncated sum of an infinite series. It’s possible to prove that by induction. The convergence rates depend, among other things, on how many dimensions does the resistor grid have. Try going from a 2D grid to a 3D grid with roughly same number of resistors. Then a 4D grid. Then try going from a hyper cube (square, cube, …) to hyper sphere shape (circle, sphere, …). You’ll get quite a tour of various forms of infinite series, and can then ponder questions such as “does the circular grid converge similarly like a square grid would”. While doing so you’ll rediscover some cool theorems in calculus. All from a “simple” resistor network. I urge anyone who’s so inclined to try it out. Sometimes having a physical object to think about makes the math easier to understand. That’s certainly the case for me. When I took a mechanical vibrations course, in my mind I modeled everything with electrical circuits :)

  • @cberge8
    @cberge8 2 роки тому

    It would be really interesting to see reading as the grib was being built to show the convergence of the solution as every new row/column is added

  • @thegrandmuftiofwakanda
    @thegrandmuftiofwakanda 9 років тому +3

    The pubs weren't open at the time right?

  • @davidhoekje7842
    @davidhoekje7842 8 років тому +1

    As people have asked about three dimensional versions of this it occurs to me that if the lead lengths were constant, the resistance value between any two points might well be a constant percentage of the value of one resister. I initially expected the diagonal value to be 1/2 of the square root of 2 or .7, which it is nearly is. If lead lengths are all the same, then we can probably model this as a solid block of conductive material.

  • @ryanoconnor7957
    @ryanoconnor7957 9 років тому +3

    This is definitely taking practicality to its limits.

  • @Aadhyacedt
    @Aadhyacedt 9 років тому +3

    Could you please describe how to derive equivalent resistance for diagonal case?

  • @ArumesYT
    @ArumesYT 5 років тому

    How sturdy is that grid? If you want to keep it for decoration, maybe you can also use it to hang other components onto to add a bit of variation.

  • @WillstDuNichtWissen
    @WillstDuNichtWissen 8 років тому +2

    Somehow I want to make a giant version of this with 0201 resistors and then put it under a glass table.

  • @AnthonyShuker
    @AnthonyShuker 8 років тому +21

    420 resistors? now we know how you came up with the idea

    • @davidhoekje7842
      @davidhoekje7842 8 років тому

      Yea, I was scratching my head about that one too. lol

  • @tomsgypsy
    @tomsgypsy 15 років тому

    Really good work mate.
    nice to see some fellow aussies getting themselves out there. love hearing measurements in millimeters and grams saves having to try and guess the values the yanks are talking about all the time.
    What company are you working at currently?

  • @DirtbagD
    @DirtbagD 15 років тому

    Good video. What about making it in to a cube?

  • @BTom16
    @BTom16 9 років тому +2

    I call this, "Dave's Tholian Web Episode."

  • @Desmaad
    @Desmaad 14 років тому +1

    Behold: the Jones Resistive Gridiron!

  • @hansolduron
    @hansolduron 15 років тому +1

    Nice work,
    plus more than 50 "you know"s in this video
    :)

  • @frankieboyo1969
    @frankieboyo1969 8 років тому +4

    What would it be in 3 dimensions? 4?

    • @bzduso
      @bzduso 5 років тому

      @@pahom2 if "R" is the resistance on each edge, then the resistance between nearest neighbor vertices in a "D"-dimensional hypercube lattice is $R/D$.

  • @azyfloof
    @azyfloof 12 років тому +1

    I want to see this built with a million 0402 SMT packages :P
    Pick and Place workout much? :D

  • @Devalis
    @Devalis 11 років тому +3

    could you build a cube out of six of those and get the infinite properties?

    • @orbik_fin
      @orbik_fin 11 років тому +4

      I think the topological equivalent of the infinite grid would be a torus rather than a cube. Anyway, when you measure the resistance, that topology changes again so that there are also infinite zero-resistance "connections" between points at equal distances in the equivalent infinite grid.

    • @slinkytreekreeper
      @slinkytreekreeper 10 років тому +3

      An ifinite resistor torus with Rodin coil alignment would surely wet daves practical appetite and would look stunning

    • @unlost117
      @unlost117 9 років тому

      +orbik Nicely said. If a grid of perfect zero tolerance resistors were overlayed on a toroid, would the measurement on any resistor or diagonal measurement (as dave did on 2D sheet he made) remain constant anywhere measured on the toroid? I expect it does. But can we apply a constant knowing how many resistors are in the grid and still get daves formula ?

    • @friedmule5403
      @friedmule5403 6 років тому +1

      unlost117 I think that depending on the size, it will show an not perfect value, but it will show the same error value no matter where you measure. :-)

    • @chaos.corner
      @chaos.corner 6 років тому +2

      It doesn't work. If you think of a torus of only a small number of resistors (say 9 or perhaps less), it quickly becomes clear you can't make resistors apply multiple times in a way that makes it look like an infinite grid.

  • @LaraSchilling
    @LaraSchilling 14 років тому

    My friend and I are going to totally make an infinite resistor grid out of 0Ω resistors for the lulz. It'll make a cool necklace and stump people :)
    (EEV isn't supposed to be -VEE backwards, is it? :P)

  • @laidman2007
    @laidman2007 Рік тому

    This was a great demo.

  • @Adotbook
    @Adotbook 12 років тому +1

    Wouldn't it be easier to use an electrolyte solution for testing? Maybe salt water.

  • @chaosopher23
    @chaosopher23 9 років тому

    That Infinite Resistor Network you built is almost close enough to keep Rhode Island mosquitoes out. And... 420 of them to make up a problem that could keep a stoned engineer busy for hours!

  • @chandin69
    @chandin69 14 років тому

    how did a pi come into this?
    i just cant picture where the number came from

    • @absurdengineering
      @absurdengineering 5 років тому

      Write out formulas for progressively larger networks, and you’ll see that the resistance is a sum of an infinite series. And the infinite series happens to be the one whose sum is some constant times the reciprocal of pi. Ou arises in many infinite series sums with nested fractions. Conversely, you could ask how to calculate pi using nothing but a 4-function calculator. This resistor network is a physical model for that :)

  • @pratherat
    @pratherat 12 років тому

    Why not connect the ends of each row and column, such that electrically there would be no center. Each resistor would be attached to the same number of resistors in every direction, kind of like a scrolling game. Would this work?

  • @mattlambert3118
    @mattlambert3118 10 років тому

    I'm really glad I saw this.Brilliant. I also agree with crapcbm, a circle would be great. I'd do it if I had a big box o" resistors laying around. Cheers

  • @novafawks
    @novafawks 6 років тому

    I'm new to EE so I'm confused. How does pi come in to play with 2 of them?

    • @absurdengineering
      @absurdengineering 5 років тому

      Nova Fawks PI usually a comes into play in discrete systems when some quantity is effectively a sum of an infinite series (or a nested fraction). PI appears in sums or limits of quite a few series.

  • @neonharp
    @neonharp 9 років тому +2

    That reminds me of going to school . The teacher drew up a 3 D cube of 100 ohm resistors , and said that anyone in the class who could solve it , would get an " A " grade . I didn't build the thing , I just did the math ! and got an " A " grade in the class ! anyway ,
    Cheers , take care , and have a good day !...73
    Ray aka KE8CWT & PG1920311

  • @6612770
    @6612770 2 роки тому +1

    Array For Dave!!

  • @Tutoelectro1
    @Tutoelectro1 15 років тому

    Haha, nice work!

  • @DigGil3
    @DigGil3 12 років тому

    I wonder if this is the kind of problem/solution one would find while measuring the resistance on 2 points in a flat conductor.
    I've thought the closest thing to an infinite grid in real world would be a grid along the surface of a sphere. What do you think?

  • @apprenticemart2
    @apprenticemart2 11 років тому

    What would happen if you made a 3d shape like a cube?

  • @sk88-p7n
    @sk88-p7n 15 років тому

    What did he exactly say after .5 an ohm? @1:15
    did he say "not .5 *R "

    • @jtoddowen
      @jtoddowen 3 роки тому

      "naught" is another work for zero. wikipedia.org/wiki/0

  • @davidhoekje7842
    @davidhoekje7842 8 років тому +1

    I'm always curious what causes people to give a thumbs down to a video like this. I suppose the end of the bell curve needs data, and perhaps it's best not looked at too closely.

  • @gman76utube
    @gman76utube 11 років тому +1

    Use LTspice to get answer quickly.

  • @rich1051414
    @rich1051414 7 років тому

    Would the ACTUAL formula for calculating the opposite node of a grid this be:
    n / (π * R * (n - 1))
    Where n = Number of dimensions, and R = resistance of resistors?

  • @jasperheijer7452
    @jasperheijer7452 6 років тому

    what about a spherical infinite resistor dave?

  • @friedmule5403
    @friedmule5403 6 років тому +1

    It is irresistible :-)

  • @jan.tichavsky
    @jan.tichavsky 15 років тому

    I prefer less math and more practical things too :) I was thinking if anyone build it and how large and then you showed it, pretty nice :)
    The measurement is close enough, you don't need like 5 digits for most things anyway

    • @absurdengineering
      @absurdengineering 5 років тому

      The math is very nifty though, and it’s not much more than good high school level math. It’s really cool how far simple math can go in modeling fairly complex physically realizable structures.

  • @TheAmmoniacal
    @TheAmmoniacal 11 років тому

    Wouldn't you expect the tolerance to increase over the total number of resistors? If the tolerance is 1% per resistor you are using, it would be 5% if using 5 resistors?

    • @datagawa
      @datagawa 10 років тому

      Not if the tolerance is normally distributed. If its skewed or rounded, you would be correct.

    • @n031
      @n031 10 років тому +5

      Not necessarily, actual tolerance calculations are more complicated, but just look it this way, if you have 1% 1ohm resistors, you expect them to be within 0.99 and 1.01ohm. If you use five of them in series, your expected result would be within 4.95 and 5.05ohm, which is still 5ohm 1% tolerance

    • @imdeadserious6102
      @imdeadserious6102 8 років тому

      +Daniel T sadly most companies have a tendency to lean to being high or low still writing spec

  • @TunioMir
    @TunioMir 13 років тому

    Great Video!!

  • @riscy00
    @riscy00 9 років тому

    I wondered anyone done math, can they post solution and derivation?

  • @jeremyo1457
    @jeremyo1457 9 років тому +21

    ok dave, 420 resistors... we get it you vape bro :P

  • @precycler
    @precycler 5 років тому

    How about if the outer most resistors on the perimeter were 5K to 'terminate' the grid since that's what the expected resistance would be.

  • @TheOysterjam
    @TheOysterjam 12 років тому

    i dont think thats the same. you would simply measure the resistance between the two probes, without taking parallel paths into account. just a guess tho

  • @TinLethax
    @TinLethax 2 роки тому +1

    Hello from the future xD

  • @imaginacion2009
    @imaginacion2009 11 років тому

    What about a cap's grid measures?? in a cubic form, I mean 6 sides

  • @Afrotechmods
    @Afrotechmods 15 років тому +3

    AHahahha!

  • @RandyLott
    @RandyLott 13 років тому

    What about a cube? :)

  • @RobertGallop
    @RobertGallop 15 років тому

    Hehehehe, I like this one, nice puzzle and excellent answer to it :)

  • @FrozenHaxor
    @FrozenHaxor 12 років тому

    Now send it to Photonicinduction and tell him to make some HV barbecue cooking with it! Just imagine cooking a steak on this! :D

  • @GRAHAMAUS
    @GRAHAMAUS 14 років тому +1

    @chandin69 pi crops up in all sorts of apparently unlikely situations. It's really quite remarkable. Read "The Life Of Pi", it's a fascinating read.

  • @bertblankenstein3738
    @bertblankenstein3738 Рік тому

    Question is asked, the person opens up a briefcase and pulls out the resistor network and a multimeter...

  • @hla27b
    @hla27b 15 років тому

    365 resistors.....
    I'd rather do the math
    By the way I am reading your "PCB Design Tutorial"
    which is simply brilliant
    put it on the tube mate
    it will be useful to a lot of people on the tube

  • @pierQRzt180
    @pierQRzt180 2 роки тому

    please revisit the topic after so many years of youtube!

  • @rolfts5762
    @rolfts5762 8 років тому

    Haha :D ..thank you Dave!
    (..just watching this video now, and just 'had' to stop at plbckPos 3m20sec and coment it. Starting to watch again the rest.. )

    • @rolfts5762
      @rolfts5762 8 років тому

      +RolfT S --> And..Yes, frame it :) ..its electronics-art

  • @tutman96
    @tutman96 12 років тому +1

    Infinite capacitor network next please!

  • @XciterD
    @XciterD 12 років тому

    because shorted out caps will be so much fun? ;)

  • @alm9373
    @alm9373 6 років тому

    I watched the #1000th EEVBlog Video, then the UA-cam suggest me this video...coincidence?

  • @MrYamashici
    @MrYamashici 11 років тому

    great vid, so funny xD

  • @DreitTheDarkDragon
    @DreitTheDarkDragon 6 років тому

    Would be interesting to make cylinder or globe :)

    • @mathman8494
      @mathman8494 4 роки тому

      Actually, you can build an icosahedron or any other platonic solid as an approximation of a globe. Such networks have an interesting duality property, see ua-cam.com/video/PfIsWtXWNX4/v-deo.html. This property was found by my student Martina Furrer and was later generalized in a joint paper with Norbert Hungerbühler and Simon Jantschgi: arxiv.org/pdf/1805.01380.pdf
      And one can of course also verify the duality theorem experimentally, as done in hsr.othello.ch/duality.pdf (in german, but see page 7).

  • @meiskam
    @meiskam 13 років тому

    @GRAHAMAUS i remember reading "The Life Of Pi" about 5 years ago, and it was about some dude lost at sea .. nothing to do with math

  • @wolfgangerichwolfgang6275
    @wolfgangerichwolfgang6275 10 років тому +8

    Cool! 420 Resistors :-)

  • @immortalsofar5314
    @immortalsofar5314 8 років тому

    For my next trick I present - Schrodinger's cat! Urgh!

  • @therugburnz
    @therugburnz 8 років тому

    Sorry bout the rant. I was on Facebook typing to my friends just a bit earlier and we were dissing guitarists. (I am one) We let it get a bit out of hand and I had to leak it instead of shunting it. Peace be with you my siblings in internet fun. the rugburnz 😰

  • @npopson
    @npopson 15 років тому

    He said "naught", as in zero.

  • @sk88-p7n
    @sk88-p7n 15 років тому

    Thanks much :)

  • @VoidHalo
    @VoidHalo 6 років тому

    Good. Now let's analyze the whole circuit if you put 5v on one corner and ground the other. Every single junction for current and voltage drop.

    • @absurdengineering
      @absurdengineering 5 років тому

      Nothing\ The analysis of any particular size of it is instructive, but it gets even more instructive when you see the patterns that are a series sum, and then you can get an analytic answer for an infinite grid without building one - and you can inductively prove that the answer you get indeed represents the result for an infinite grid.

  • @rolobotoman
    @rolobotoman 9 років тому

    now i want the maths!

  • @Neverforget71324
    @Neverforget71324 4 місяці тому

    Classic!

  • @EddieRodJr
    @EddieRodJr 8 років тому +1

    Never imagined he was a pothead! lol

  • @miaudottk9080
    @miaudottk9080 6 років тому

    Forget math!
    Build bigger resistor array!

  • @hansolduron
    @hansolduron 13 років тому

    you know, I counted more than 30 "you know"s half way to the video :)

  • @TheOysterjam
    @TheOysterjam 12 років тому

    that would only be a 40 cm by 40 cm square, neglecting connecting traces. thats a pretty big pcb, but lets do a 10x10 of those squares and get 100 million lol

  • @helloriker
    @helloriker 10 років тому +1

    Interesting... I wonder what would happen if instead of building it as a 2 dimensional grid if you made it a 3 dimensional cube. Could be interesting.

    • @davidhoekje7842
      @davidhoekje7842 8 років тому +1

      You'd want to get all Buckminster Fuller and build a geodesic form.

  • @PauloConstantino167
    @PauloConstantino167 7 років тому

    I'm your host, Dave fucking Jones.

  • @laernulienlaernulienlaernu8953
    @laernulienlaernulienlaernu8953 4 роки тому

    You can tell you're not s mathematician. If you were you'd have made a 3D representation of a 4 dimensional resistor network!

  • @GoldSrc_
    @GoldSrc_ 9 років тому

    Interesting.
    Also 51,000 view, noice.

  • @_general_error
    @_general_error 2 роки тому

    But your expeimental method soes not give you the theory behind the mechanics of the problem... Though I like your arts skills!

  • @m000nd
    @m000nd 11 місяців тому

    i created a series of videos on that topic: ua-cam.com/play/PLoGRr8ff1uXESrWh6z0BNTYpc4Y-hlBOm.html starting with EE basics. at the end also some numeric simulation with numpy.

  • @ElectronicsPubVideos
    @ElectronicsPubVideos 12 років тому

    Do the math please :D

  • @jaro6985
    @jaro6985 15 років тому

    hah, beautiful

  • @therugburnz
    @therugburnz 8 років тому

    fun fun fun. However, approach infinity at your peril ! infinity is not a number is it aka + fun - fun + fun - fun... is it. + ( fund fun+ fun ) or -(-fun +fun -fun). ! ! ! ! IDK 1fun+2fun+3fun+4fun... = -1/12 fun = LESS THAN NO FUN @ ALL. math is easy. engineering is hard! AKA @ the end of the day something needs to get built. AKA when the arrogant lead guitarist's $13000 hand soldered by children paid $7.89 per day tag board tube amp doesn't work it is YOUR FAULT. It is NOT at all the sales rep's that told him UNDERATED output transformers and 25watt super Distortionated double doped SELLestions are conservatively rated! "Make it work nerd!" is his polite response. OH SH!T I IS ON A RANT I'll stop sorry.

  • @Aleksandr_Shevchenko
    @Aleksandr_Shevchenko 4 роки тому

    #420

  • @rescuecatHQ
    @rescuecatHQ 8 років тому

    87th!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!