### Re: "Circuit Diagram" Discussion

Posted:

**Thu May 27, 2010 9:45 pm UTC**glitterbug12 wrote:This amuses me... reminds me of this piece.

Oh yes, completely analogous... you beat me to this one. And the 666 timer made me speechless.

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Posted: **Thu May 27, 2010 9:45 pm UTC**

glitterbug12 wrote:This amuses me... reminds me of this piece.

Oh yes, completely analogous... you beat me to this one. And the 666 timer made me speechless.

Posted: **Fri May 28, 2010 3:49 pm UTC**

I loved "not a resistor, wire just does this" in particular. Mainly because I'm not an electical engineer or anything like that and don't know what most of the other stuff would or would not do.

Posted: **Tue Aug 10, 2010 1:24 pm UTC**

Everyone can rest easy; I have done the hard work for you. The equivalent resistance of the mass of resistors (to 4 places) is 0.7479 Ohms! How did I do it? As my profs used to say, that is an exercise left for the students to solve.

Posted: **Tue Aug 10, 2010 1:57 pm UTC**

Maybe you read the thread you responded to? http://forums.xkcd.com/viewtopic.php?f=7&t=59374&start=200

Posted: **Tue Aug 24, 2010 4:13 am UTC**

No I missed that post. Had I seen it, I would not have bothered to enter the circuitry into a freebee spice clone.

Posted: **Wed Aug 25, 2010 4:37 pm UTC**

glitterbug12 wrote:This amuses me... reminds me of this piece.

The "remove cattle from stage" direction is my favorite.

Posted: **Sat Jan 08, 2011 5:01 am UTC**

Still don't see the flux capacitor.

Where I live, I95 does split for a good long while

Love the thunderdome reference, the 666 timer, and the other small handful of joke I get after one semester of digital, sure I'm still missing a good amount though.

Where I live, I95 does split for a good long while

Love the thunderdome reference, the 666 timer, and the other small handful of joke I get after one semester of digital, sure I'm still missing a good amount though.

Posted: **Thu Feb 10, 2011 6:50 am UTC**

forrestv wrote:

http://im.forre.st/resistors.jpg

I got 347 ohms for that circuit made of 463 ohm resistors, so 347/463 or about 0.749 ohms.

Epic, sir. Truly epic. How long did that take?

Posted: **Tue Feb 15, 2011 7:02 pm UTC**

Steve the Pocket wrote:helo darqness wrote:sometimes xkcd lowers my self-esteem, as comics like this are so esoteric, i feel completely out of the loop and uneducated.

It's not supposed to mean anything; it's just a fake circuit design made out of nonsense.

Basically it's the electrical engineering equivalent of http://www.whitetreeaz.com/gibber/faeries_aire_and_death_waltz.jpg]this little beauty.

The percussion instructor here is going to see that.

(weird, wouldn't let me post without breaking the link)

Posted: **Tue Feb 15, 2011 10:52 pm UTC**

SteevyT wrote:Steve the Pocket wrote:helo darqness wrote:sometimes xkcd lowers my self-esteem, as comics like this are so esoteric, i feel completely out of the loop and uneducated.

It's not supposed to mean anything; it's just a fake circuit design made out of nonsense.

Basically it's the electrical engineering equivalent of http://www.whitetreeaz.com/gibber/faeri ... _waltz.jpg]this little beauty.

The percussion instructor here is going to see that.

(weird, wouldn't let me post without breaking the link)

low post count

It's an anti-spam measure, post some more and you'll be able to link urls.

Posted: **Tue Mar 29, 2011 5:55 pm UTC**

I go to UMass Amherst, and for our circuits problem set in Physics E&M, our prof (an obvious xkcd fan) decided to go ahead and give us the problem: "Use Kirchoff's laws to solve for the current through and voltage drop across all elements in this circuit. For help, email Randall Munroe directly" and gave us this diagram as the circuit. Answers are worth 1 point and are in essay format via MasteringPhysics online submissions.

I wonder how many e-mails from absolutely baffled students Randall will be getting? xD

I wonder how many e-mails from absolutely baffled students Randall will be getting? xD

Posted: **Tue Mar 29, 2011 7:47 pm UTC**

jslegers wrote:...So, I too confirmed the resistor blob value of 25265/33783 ohms using MATLAB symbolics and a reduced admittance-matrix [Zeq = (Ynn - (Ynr Yrr^-1 Yrn))^-1]. As mentioned above, this rounds to ~0.7479 ohms. And, while I appreciate the sentiment, It can only be ROUNDED to 1.337 mhos, and that likely happened by accident. Also, I now have an unmitigated desire to form a band called L337 Mhos.

You would likely not be interested to know that, for 5% normally-distributed resistors, this equivalent resistance would be ~ 0.7479 +- 0.0065 ohms. For 1% resistors, it would be +-0.0013 ohms. This comes from simulation in MATLAB.

Just thought I'd weigh in.

Your logic is flawed, since 5% resistors do not have a normal distribution. They have a big "hole" from -2% to +2%, as that is where 2%, 1% and .1% resistors are taken from.

See this article: http://sigcon.com/Pubs/edn/SevenPercent.htm

Posted: **Sun Nov 27, 2011 9:57 pm UTC**

What's the symbol next to 3 Liters? It looks like some kind of capacitor, but I'm not sure if it's one I don't know, or one that's made up, since it's ages since I've done any electronics.

Posted: **Sun Nov 27, 2011 11:55 pm UTC**

It's semi-made-up, I think... a similar symbol with a straight line and just one of the two curvy lines is a polarised capacitor... having two of them like that I guess would mean having two polarised capacitors in series, with opposite orientations, as a single unit. Which wouldn't be particularly useful, as a thing. But then, given it appears to have a capacity (measured in litres) rather than a capacitance, who knows.

Posted: **Thu Nov 27, 2014 8:42 pm UTC**

I made a modelica simulation of the resistor mess and I got 0.747861 Ohms.

I'm going to try to solve the equations by hand to try to get a real answer.

I'm going to try to solve the equations by hand to try to get a real answer.