## 0730: "Circuit Diagram"

This forum is for the individual discussion thread that goes with each new comic.

Moderators: Moderators General, Prelates, Magistrates

CorruptUser
Posts: 10485
Joined: Fri Nov 06, 2009 10:12 pm UTC

### Re: "Circuit Diagram" Discussion

pgn674 wrote:
hthall wrote:Title-text: I just caught myself idly trying to work out what that resistor mass would actually be, and realized I had self-nerd-sniped.
Can't believe no one linked to the referenced comic already: xkcd: Nerd Sniping

Yes but it only counts as nerd sniping if he dies a horrible death as a result.

Two9A
Posts: 194
Joined: Sat Jul 26, 2008 11:22 pm UTC
Location: The smogbound wastes of northern England
Contact:

### Re: "Circuit Diagram" Discussion

CorruptUser wrote:Anyone know what number "brown blue orange" is? Last time Randall had a joke about that, it was the dial-a-song phone number.
16,000 for what it's worth.

Maybe! it's just numbers plucked out of thin air.
The Unofficial "Making xkcd Slightly Worse" Archive [Incomplete]: xkcdsw.com
Articles that fall out of my head about once a month: imrannazar.com

Shinyiest
Posts: 7
Joined: Wed Apr 21, 2010 6:16 am UTC

### Re: "Circuit Diagram" Discussion

I just did my physics exams a few hours ago hoping to be free from circuit diagrams, resistors and objects colliding into each other. And here I am looking at this comic and my mind thinks, V=IR solve for R. Randall Get Out of My Head

Link
Posts: 1399
Joined: Sat Mar 07, 2009 11:33 am UTC
Location: ᘝᓄᘈᖉᐣ
Contact:

### Re: "Circuit Diagram" Discussion

Electronics geek here; I love this comic!

The 666 timer, moral rectifier, Arduino for blog cred, "omit this if you're a wimp", sandal/flip-flop and the methyl group were especially great.

pyroman
Posts: 346
Joined: Sun Feb 10, 2008 5:35 am UTC
Location: University at Buffalo
Contact:

### Re: "Circuit Diagram" Discussion

Assuming I didn't mess anything up the resistor blob comes out to 1.3141 Ohms... And now that I have been adequately nerd sniped by Randall, I'm going to sleep. Night all.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety. - Benjamin Franklin

raj4h
Posts: 6
Joined: Thu Sep 11, 2008 10:19 pm UTC

### Re: "Circuit Diagram" Discussion

I'm not a computer nerd, but this thread reminds me of this:
http://www.well.com/user/bryan/waltz.html

hthall
Posts: 95
Joined: Wed Oct 10, 2007 3:40 am UTC

### Re: "Circuit Diagram" Discussion

pyroman wrote:Assuming I didn't mess anything up the resistor blob comes out to 1.3141 Ohms... And now that I have been adequately nerd sniped by Randall, I'm going to sleep. Night all.

I get precisely 167294/195327 ohms. That's approximately .856481694798978123864...

(Apparently I didn't resist the temptation. Thoroughly sniped.)

EDIT: Missed the missing resistor, see below.
Last edited by hthall on Wed Apr 21, 2010 7:27 am UTC, edited 1 time in total.
Look at me, still talking when there's Science to do.

phlip
Restorer of Worlds
Posts: 7569
Joined: Sat Sep 23, 2006 3:56 am UTC
Location: Australia
Contact:

### Re: "Circuit Diagram" Discussion

My result for the mess of resistors is 25265/33783 = 0.747861 Ohms.
Spoiler:

Code: Select all

`#!/usr/bin/pythonfrom fractions import Fraction# The circuit resembles:#              |#              0-----4#             /|\   /|#            / | \ / |#           1--2  3  |#          /|  | /|\ \#         / |  |/ | \ |#        5  |  X  |  \|#        |\ | /| /   ||#        | 7+- |/    ||#        |/ 8--2--9--10#        6  | /|\ | /#         \ |/ | \|/#          11--13-12#              |# numbers represent nodes, all lines are resistors, except the entrance and exit wires,# and the line between the two "2" nodes, which is just a wire#   - that's why there's two "2" nodes (they're really the same node)# + or X represents two wires crossing without a node# Adjacency matrix for this graph:adj_matrix = [   [0,1,1,1,1,0,0,0,0,0,0,0,0,0],   [1,0,1,0,0,1,0,0,1,0,0,0,0,0],   [1,1,0,1,0,0,0,0,1,1,0,1,1,1],   [1,0,1,0,1,0,0,1,0,0,1,0,0,0],   [1,0,0,1,0,0,0,0,0,0,1,0,0,0],   [0,1,0,0,0,0,1,1,0,0,0,0,0,0],   [0,0,0,0,0,1,0,1,0,0,0,1,0,0],   [0,0,0,1,0,1,1,0,0,0,0,0,0,0],   [0,1,1,0,0,0,0,0,0,0,0,1,0,0],   [0,0,1,0,0,0,0,0,0,0,1,0,1,0],   [0,0,0,1,1,0,0,0,0,1,0,0,1,0],   [0,0,1,0,0,0,1,0,1,0,0,0,0,1],   [0,0,1,0,0,0,0,0,0,1,1,0,0,1],   [0,0,1,0,0,0,0,0,0,0,0,1,1,0],]# sanity checksif adj_matrix != [[adj_matrix[i][j] for i in xrange(len(adj_matrix))] for j in xrange(len(adj_matrix[0]))]:   raise "adj_matrix isn't reflexive"if [len([j for j in i if j]) for i in adj_matrix] != [4,4,8,5,3,3,3,3,3,3,4,4,4,3]:   raise "degrees aren't as expected"# build linear equations# since every resistor has the same resistance, this is simple - each node must be the average of its neighbours# Build linear equations as Ax=b, then find x=A^-1 bA = []b = []for n,i in list(enumerate(adj_matrix))[1:-1]: # loop through the nodes that aren't our start and end nodes   i = i[:] # copy list   i[n] = -len([j for j in i if j])   A.append(i)   b.append(0)   # We've just added "sum of all adjacent nodes - n*this node = 0", which is the same as saying this node is the average if its neighbours# Now add two equations for our fixed nodesA.append([1] + [0] * (len(adj_matrix) - 1))b.append(1)A.append([0] * (len(adj_matrix) - 1) + [1])b.append(0)# sanity checkif len(A) != len(A[0]):   raise "A isn't square"# Turn our lists of integers into rationals, for exact divisionsA = [[Fraction(j) for j in i] for i in A]b = [Fraction(i) for i in b]#solve our equations by Gauss-Jordanfor i in xrange(len(A)):   x = A[i][i]   A[i] = [j/x for j in A[i]]   b[i] = b[i]/x   for j in xrange(i+1,len(A)):      x = A[j][i]      A[j] = [l - x*k for k,l in zip(A[i],A[j])]      b[j] = b[j] - x*b[i]for i in xrange(len(A)-1, -1, -1):   for j in xrange(i):      x = A[j][i]      A[j] = [l - x*k for k,l in zip(A[i],A[j])]      b[j] = b[j] - x*b[i]# b is now a vector of the voltage at each node - need to find the current going in the entrance and out the exit# since our resistance on each link is 1 ohm, the current through a resistor is simply the difference of the voltages at each end# The net current at any intermediate node should be 0for node in xrange(1,len(A)-1):   current = 0   for i in xrange(len(A)):      if adj_matrix[node][i]:         current += b[node] - b[i]   if current != 0:      raise "Current at node %d isn't zero" % node# find the node going in the entrance and the current going out the exitin_current = 0for i in xrange(len(A)):   if adj_matrix[0][i]:      in_current += b[0] - b[i]out_current = 0for i in xrange(len(A)):   if adj_matrix[-1][i]:      out_current += b[i] - b[-1]if in_current != out_current:   raise "Entrance and exit currents aren't equal"# Our test voltage was 1V, so our net resistance is 1/currentprint "Equivalent resistance: %s = %f" % (1/in_current,1/in_current)`

Code: Select all

`enum ಠ_ಠ {°□°╰=1, °Д°╰, ಠ益ಠ╰};void ┻━┻︵​╰(ಠ_ಠ ⚠) {exit((int)⚠);}`
[he/him/his]

TheoGB
Posts: 70
Joined: Fri Aug 22, 2008 1:38 pm UTC

### Re: "Circuit Diagram" Discussion

I don't really get it. But I like the UK-centric 240V AC.

That's all I've got.

appleguru
Posts: 5
Joined: Sat Jun 28, 2008 3:47 pm UTC

### Re: "Circuit Diagram" Discussion

phira wrote:Obviously, this circuit would never work without I-95 South eventually turning into 93 North.

Bostonian eh? 95 also happens to be 128... I haven't been home in waay too long!

dragoneye1589
Posts: 39
Joined: Mon Jun 11, 2007 4:08 am UTC

### Re: "Circuit Diagram" Discussion

The magic blue smoke, 120 ohm or to taste resistor and the moral rectifier all made me laugh heartily. I have an instrumentation exam on Monday and I pretty much have to design circuits like the rectifier and choose resistor values using the "to taste" method. I didn't get into Mechanical Engineering for this...

WhiteAvenger
Posts: 14
Joined: Mon Mar 30, 2009 1:00 pm UTC

### Re: "Circuit Diagram" Discussion

I meh'd at this originally. Once I'd seen the below post, though, I looked at it again... it's hilarious!

Steve the Pocket wrote:Basically it's the electrical engineering equivalent of this little beauty.

Still don't see the flux capacitor, though...

hthall
Posts: 95
Joined: Wed Oct 10, 2007 3:40 am UTC

### Re: "Circuit Diagram" Discussion

phlip wrote:My result for the mess of resistors is 25265/33783 = 0.747861 Ohms.

Oops, I missed the one connection without a resistor. I ran my Maple code again and I also get 25265/33783.

In this case, the adjacency matrix is also the matrix of conductances (except that the diagonal should be infinite). From this matrix you can eliminate any column and the corresponding row by taking their outer product (column vector times row vector), dividing it by their common sum (not counting that diagonal entry), and adding the result to the original matrix before crossing out that row and column. Once you have eliminated everything down to a 2 x 2 matrix, the off-diagonal entry is the reciprocal of the resistance between those two nodes.
Look at me, still talking when there's Science to do.

phlip
Restorer of Worlds
Posts: 7569
Joined: Sat Sep 23, 2006 3:56 am UTC
Location: Australia
Contact:

### Re: "Circuit Diagram" Discussion

hthall wrote:I get precisely 167294/195327 ohms. That's approximately .856481694798978123864...

phlip wrote:My result for the mess of resistors is 25265/33783 = 0.747861 Ohms.

Aha! I figured out why our results differ. There's two nodes right in the middle of the mess that are connected by a simple wire, *not* a resistor:
The red bit is a wire.
wire_among_resistors.png (23.28 KiB) Viewed 6242 times

If I replace that wire with a resistor, I get your answer (modified code behind the spoiler)
Spoiler:

Code: Select all

`#!/usr/bin/pythonfrom fractions import Fraction# The circuit resembles:#              |#              0-----5#             /|\   /|#            / | \ / |#           1--2  4  |#          /|  | /|\ \#         / |  |/ | \ |#        6  |  X  |  \|#        |\ | /| /   ||#        | 8+- |/    ||#        |/ 9--3-10--11#        7  | /|\ | /#         \ |/ | \|/#          12--14-13#              |# numbers represent nodes, all lines are resistors, except the entrance and exit wires# The line between 2 and 3 is a wire in the comic, but is being treated as a resistor here as an illustration# + or X represents two wires crossing without a node# Adjacency matrix for this graph:adj_matrix = [   [0,1,1,0,1,1,0,0,0,0,0,0,0,0,0],   [1,0,1,0,0,0,1,0,0,1,0,0,0,0,0],   [1,1,0,1,0,0,0,0,0,0,0,0,0,0,0],   [0,0,1,0,1,0,0,0,0,1,1,0,1,1,1],   [1,0,0,1,0,1,0,0,1,0,0,1,0,0,0],   [1,0,0,0,1,0,0,0,0,0,0,1,0,0,0],   [0,1,0,0,0,0,0,1,1,0,0,0,0,0,0],   [0,0,0,0,0,0,1,0,1,0,0,0,1,0,0],   [0,0,0,0,1,0,1,1,0,0,0,0,0,0,0],   [0,1,0,1,0,0,0,0,0,0,0,0,1,0,0],   [0,0,0,1,0,0,0,0,0,0,0,1,0,1,0],   [0,0,0,0,1,1,0,0,0,0,1,0,0,1,0],   [0,0,0,1,0,0,0,1,0,1,0,0,0,0,1],   [0,0,0,1,0,0,0,0,0,0,1,1,0,0,1],   [0,0,0,1,0,0,0,0,0,0,0,0,1,1,0],]# sanity checksif adj_matrix != [[adj_matrix[i][j] for i in xrange(len(adj_matrix))] for j in xrange(len(adj_matrix[0]))]:   raise "adj_matrix isn't reflexive"if [len([j for j in i if j]) for i in adj_matrix] != [4,4,3,7,5,3,3,3,3,3,3,4,4,4,3]:   raise "degrees aren't as expected"# build linear equations# since every resistor has the same resistance, this is simple - each node must be the average of its neighbours# Build linear equations as Ax=b, then find x=A^-1 bA = []b = []for n,i in list(enumerate(adj_matrix))[1:-1]: # loop through the nodes that aren't our start and end nodes   i = i[:] # copy list   i[n] = -len([j for j in i if j])   A.append(i)   b.append(0)   # We've just added "sum of all adjacent nodes - n*this node = 0", which is the same as saying this node is the average if its neighbours# Now add two equations for our fixed nodesA.append([1] + [0] * (len(adj_matrix) - 1))b.append(1)A.append([0] * (len(adj_matrix) - 1) + [1])b.append(0)# sanity checkif len(A) != len(A[0]):   raise "A isn't square"# Turn our lists of integers into rationals, for exact divisionsA = [[Fraction(j) for j in i] for i in A]b = [Fraction(i) for i in b]#solve our equations by Gauss-Jordanfor i in xrange(len(A)):   x = A[i][i]   A[i] = [j/x for j in A[i]]   b[i] = b[i]/x   for j in xrange(i+1,len(A)):      x = A[j][i]      A[j] = [l - x*k for k,l in zip(A[i],A[j])]      b[j] = b[j] - x*b[i]for i in xrange(len(A)-1, -1, -1):   for j in xrange(i):      x = A[j][i]      A[j] = [l - x*k for k,l in zip(A[i],A[j])]      b[j] = b[j] - x*b[i]# b is now a vector of the voltage at each node - need to find the current going in the entrance and out the exit# since our resistance on each link is 1 ohm, the current through a resistor is simply the difference of the voltages at each end# The net current at any intermediate node should be 0for node in xrange(1,len(A)-1):   current = 0   for i in xrange(len(A)):      if adj_matrix[node][i]:         current += b[node] - b[i]   if current != 0:      raise "Current at node %d isn't zero" % node# find the node going in the entrance and the current going out the exitin_current = 0for i in xrange(len(A)):   if adj_matrix[0][i]:      in_current += b[0] - b[i]out_current = 0for i in xrange(len(A)):   if adj_matrix[-1][i]:      out_current += b[i] - b[-1]if in_current != out_current:   raise "Entrance and exit currents aren't equal"# Our test voltage was 1V, so our net resistance is 1/currentprint "Equivalent resistance: %s = %f" % (1/in_current,1/in_current)`

So yeah, that's where you messed up... I'm pretty sure my answer is right.

 Ninjaed...

hthall wrote:In this case, the adjacency matrix is also the matrix of conductances (except that the diagonal should be infinite). From this matrix you can eliminate any column and the corresponding row by taking their outer product (column vector times row vector), dividing it by their common sum (not counting that diagonal entry), and adding the result to the original matrix before crossing out that row and column. Once you have eliminated everything down to a 2 x 2 matrix, the off-diagonal entry is the reciprocal of the resistance between those two nodes.

Yeah, I know there are other ways of manipulating this... I just went with the flat adjacency matrix 'cause it was the easiest to type, and then turned that into the system of linear equations (via Kirchoff's current law) 'cause that's the systematic method I'm most familiar with... which meant I could code it quicker (I could write Gauss-Jordan in my sleep), and have a better chance of being the first one to get the answer... 'cause minor bragging rights are more important than elegance.
Last edited by phlip on Wed Apr 21, 2010 7:31 am UTC, edited 2 times in total.

Code: Select all

`enum ಠ_ಠ {°□°╰=1, °Д°╰, ಠ益ಠ╰};void ┻━┻︵​╰(ಠ_ಠ ⚠) {exit((int)⚠);}`
[he/him/his]

mu-zak
Posts: 1
Joined: Wed Apr 21, 2010 5:49 am UTC

### Re: "Circuit Diagram" Discussion

So, I wasted two sheets of paper doing delta-Y transforms and got about half way through, then gave up and made a spice simulation that just hooked the whole mess up to a 12V source and measured the current going through the source... much faster. I got about 0.77Ohms

edit: so I didn't see the python solutions until after I was finished and had posted. Glad i was close.
Last edited by mu-zak on Wed Apr 21, 2010 7:32 am UTC, edited 1 time in total.

somebody_else
Posts: 8
Joined: Fri Mar 05, 2010 8:08 am UTC

### Re: "Circuit Diagram" Discussion

Anyone else notice the PPP transistor (or that's what I think it is). Between the glued open switch and scarab beetles.

keithc
Posts: 124
Joined: Thu Mar 08, 2007 11:12 pm UTC
Contact:

### Re: "Circuit Diagram" Discussion

nathanst wrote:"Brown, Blue, Orange"
1,6,x1000, (no tolerance band)
or
(no initial band),1,X1000000,+/-3%

is there a joke here?

long, long (long, long, long...) time since I did this stuff, but from memory it's the tolerance band that's optional, so that would be a 16k resistor (which I think is one of the standard values). And I seem to recall that 10% tolerance is the default.

keithc
Posts: 124
Joined: Thu Mar 08, 2007 11:12 pm UTC
Contact:

### Re: "Circuit Diagram" Discussion

elendia wrote:The lack of a particular observation galled me so much that I created an account to post it.

Anyone see the "1 mile" scale bar at the upper left corner? This thing is HUGE....

Plus the fact that the way it is drawn 1 mi = 1 km, so some serious warping of space going on.

a_fuzzyduck
Posts: 435
Joined: Sun Apr 11, 2010 9:42 pm UTC
Location: Clydebank
Contact:

### Re: "Circuit Diagram" Discussion

all it needs is a lion...
wkw
"GRAPHICS WERE NOT AS GOOD IN THE PAST BUT WE WERE HAPPIER AND MORE INNOCENT THEN" - every retro gaming review, ever

Maniac
Posts: 19
Joined: Wed Jun 20, 2007 7:43 am UTC
Location: CERN

### Re: "Circuit Diagram" Discussion

Am I the only one who can't read wimp without thinking of SUSY?

jacog
Posts: 56
Joined: Tue Dec 15, 2009 9:55 am UTC

### Re: "Circuit Diagram" Discussion

It needs Phlebotinum to work.

EngPhys
Posts: 2
Joined: Wed Apr 21, 2010 7:41 am UTC

### Re: "Circuit Diagram" Discussion

mu-zak wrote:So, I wasted two sheets of paper doing delta-Y transforms and got about half way through, then gave up and made a spice simulation that just hooked the whole mess up to a 12V source and measured the current going through the source... much faster. I got about 0.77Ohms

edit: so I didn't see the python solutions until after I was finished and had posted. Glad i was close.

I also did a spice simulation and ended up with about 0.758 ohms. More than good enough for 2 minutes worth of work I say.

bitwiseshiftleft
Posts: 295
Joined: Tue Jan 09, 2007 9:07 am UTC
Location: Stanford
Contact:

### Re: "Circuit Diagram" Discussion

Good comic, but it needs one of these switches.

LTK
Posts: 293
Joined: Sat May 09, 2009 8:46 pm UTC

### Re: "Circuit Diagram" Discussion

This looks like it was made under the influence of... something.

RebeccaRGB
Posts: 336
Joined: Sat Mar 06, 2010 7:36 am UTC
Location: Lesbians Love Bluetooth
Contact:

### Re: "Circuit Diagram" Discussion

I don't know which to be more surprised at: the lack of a "Magic" / "More Magic" switch in the schematic, or the fact that it's been three pages with nobody mentioning it. Tsk tsk tsk.

EDIT: Dammit, ninja'd!

The parts that really burnt my cheese were "May use actual sandal instead", "Pull this wire really tight", and "Not a resistor; wire just does this".

EE 201 happens to be the class number for introductory EE for non-EE majors at Cal Poly as well. I took it as a technical elective.
Stephen Hawking: Great. The entire universe was destroyed.
Fry: Destroyed? Then where are we now?
Al Gore: I don't know. But I can darn well tell you where we're not—the universe!

Plasma Man
Posts: 2035
Joined: Tue Jan 15, 2008 9:27 am UTC
Location: Northampton, Northampton, Northampton middle England.

### Re: "Circuit Diagram" Discussion

I did wonder if the random rodent might be a mouse.
Please note that despite the lovely avatar Sungura gave me, I am not a medical doctor.

Possibly my proudest moment on the fora.

EdyScissorhands
Posts: 4
Joined: Wed Mar 04, 2009 10:58 am UTC

### Re: "Circuit Diagram" Discussion

He wouldn't need the "not a resister" if he used the proper symbols...

richardosx
Posts: 2
Joined: Wed Apr 21, 2010 9:56 am UTC

### Re: "Circuit Diagram" Discussion

I can't believe nobody's pointed out that the motor's nearly half a mile long...

ShadowDweller
Posts: 1
Joined: Wed Apr 21, 2010 10:50 am UTC

### Re: "Circuit Diagram" Discussion

Is it just me or is that neck strap really somehow related to Eureka Seven? :-/

digitrev
Posts: 124
Joined: Fri Dec 15, 2006 10:22 pm UTC
Location: Ontario, Canada
Contact:

### Re: "Circuit Diagram" Discussion

My first thought upon seeing this comic? Faerie's Aire and Death Waltz.
Together we will make the octopus nervous.

happyhamsterchan
Posts: 3
Joined: Wed Apr 21, 2010 11:33 am UTC

### Re: "Circuit Diagram" Discussion

You know, I really wish this comic had more nerd inside jokes, instead of just drawing "electric eels" and stuff... I mean, the point of xkcd is so you can boast that you are nerdy... if it becomes a regular comic, I don't see what makes it different from the googol other webcomics out there....

funknjam
Posts: 5
Joined: Wed Jun 10, 2009 11:13 am UTC

### Re: "Circuit Diagram" Discussion

I got probably 20% of the jokes in there and have always considered myself nerdy (nerdish? nerdlike? nerdesque?). My point being, there are many types of "nerds." I count myself among their ranks but am NOT an engineer nor an electrician.

Wait a minute. If you have to be a "nerd' to get the jokes, maybe I'm a geek. Poindexter? Melvin?

Please. If I'm going to be disincluded from the nerd category because I don't get these jokes, just don't consider me "normal!"

King of all the "nerds" replying here is the guy who said, "I think I'll work out the equivalent resistance on the train tomorrow." WINNER!

johonn
Posts: 7
Joined: Wed Dec 03, 2008 5:47 am UTC

### Re: "Circuit Diagram" Discussion

keithc wrote:
elendia wrote:The lack of a particular observation galled me so much that I created an account to post it.

Anyone see the "1 mile" scale bar at the upper left corner? This thing is HUGE....

Plus the fact that the way it is drawn 1 mi = 1 km, so some serious warping of space going on.

Not only that, but don't miss the 3/8" gap near the blender...

monkeyman8
Posts: 7
Joined: Mon Apr 27, 2009 4:41 am UTC

### Re: "Circuit Diagram" Discussion

I had to look up that brown blue orange = 16K resistance, I feel shamed

GunJack
Posts: 47
Joined: Thu Mar 18, 2010 9:36 pm UTC

### Re: "Circuit Diagram" Discussion

pretty sure that Randall posted this, sat back with a chronometer, and counted the time to see the first post trying to resolve this...maybe there's a poll... some betting.... yeah...
and the "one mile=one kilometer" joke is for THOSE COUNTRIES that still uses miles...
Don't protest against my methods, if you want to continue living of my results

Andrusi
Posts: 52
Joined: Wed Mar 28, 2007 9:43 pm UTC
Location: YES TOWN
Contact:

### Re: "Circuit Diagram" Discussion

I approve of the use of yarn in a circuit.
Not named Dennis Miller.

samureyed
Posts: 7
Joined: Wed Apr 14, 2010 4:59 pm UTC

### Re: "Circuit Diagram" Discussion

No raptors? I'd say im disappointed, but I enjoyed this one a lot. "touch tongue here" haha!
If the moon were made of barbecue spare ribs, would you eat it?

odog1999
Posts: 11
Joined: Mon Jan 05, 2009 1:55 pm UTC

### Re: "Circuit Diagram" Discussion

Quicksilver wrote:Why is there a North, Five, East and West sign? Where's south?

If you look closely, it's an "S", not a "5"

BioTube
Posts: 362
Joined: Sat Apr 11, 2009 2:11 am UTC

### Re: "Circuit Diagram" Discussion

GunJack wrote:and the "one mile=one kilometer" joke is for THOSE COUNTRIES that still uses miles...
Because nobody else has EVER heard of a mile.
Frédéric Bastiat wrote:Government is the great fiction through which everybody endeavors to live at the expense of everybody else.

lugnut92
Posts: 1
Joined: Wed Apr 21, 2010 1:03 pm UTC

### Re: "Circuit Diagram" Discussion

As a Biochem/Biophysics major, I got the most out of the random methyl group near the "touch tongue here".

And yes, I joined just now to make this post.

Return to “Individual XKCD Comic Threads”

### Who is online

Users browsing this forum: Archgeek, Majestic-12 [Bot], mscha and 79 guests