Editing 730: Circuit Diagram

{{comic
| number    = 730
| date      = April 21, 2010
| title     = Circuit Diagram
| image     = circuit_diagram.png
| titletext = I just caught myself idly trying to work out what that resistor mass would actually be, and realized I had self-nerd-sniped.
}}

==Explanation==
Another fine example of [[356|nerd sniping]], as mentioned in the title text.
There are pieces of circuit diagrams, road maps, chemical diagrams, and other things all mixed in.
Explanations for each below!

{|class="wikitable table-padding left-align"
!Image Fragment
!width="130px" | Image Location
!Description
|-
{{circuit-diagram-part|X=19|Y=25|W=106|H=37|image=circuit_diagram-019-025-106-037-scale.png|text=A map scale. Lists kilometers and miles as equivalent. (And makes the diagram many miles wide.)}}
{{circuit-diagram-part|X=15|Y=62|W=40|H=85|image=circuit_diagram-015-062-040-085-antenna.png|text=An antenna. Typical of radio receivers or transmitters. Or the Turtle in {{w|Logo (programming language)|LOGO programming language}}.}}
{{circuit-diagram-part|X=53|Y=60|W=41|H=87|image=circuit_diagram-053-060-041-087-inductor.png|text=A coil or {{w|inductor}}. Normal, but unlabeled.}}
{{circuit-diagram-part|X=107|Y=86|W=85|H=93|image=circuit_diagram-107-086-085-093-cloverleaf.png|text=A {{w|cloverleaf interchange}} or junction is a feature of road networks that does not belong in a circuit diagram. Of course, other types of {{w|p–n junction|junctions}} are important in electronics. 
A cloverleaf junction has previously been used in comic: [[253: Highway Engineer Pranks]].}}
{{circuit-diagram-part|X=184|Y=12|W=87|H=63|image=circuit_diagram-184-012-087-063-battery.png|text=A battery. The voltage of square root of two is strange, but getting about 1.41412... volts is not unheard of. This could also indicate an {{w|Root_mean_square|RMS}} voltage, although this is unlikely given that this is a DC power supply and not an AC generator. The marked polarity is also the reverse of what is implied by the symbol (where the larger terminal is positive). A possible reference to [[567: Urgent Mission]].}}
{{circuit-diagram-part|X=187|Y=110|W=94|H=71|image=circuit_diagram-187-110-094-071-resister.png|text=A 120 ohm {{w|resistor}} is normal enough. "Or to taste" is odd for a circuit diagram and more like instructions from a recipe, e.g., "1 tbsp tomato purée, or to taste".}}
{{circuit-diagram-part|X=283|Y=50|W=90|H=63|image=circuit_diagram-283-050-090-063-switch.png|text=A normal {{w|switch}}, with a notation to glue it open. Reminiscent of the [http://catb.org/esr/jargon/html/magic-story.html MAGIC/MORE MAGIC] switch.}}
{{circuit-diagram-part|X=337|Y=101|W=69|H=64|image=circuit_diagram-337-101-069-064-transisitor.png|text=A {{w|Bipolar_junction_transistor#PNP|bipolar PNP transistor}}, except that it has two emitters and no collector. It also resembles one of the schematic symbols for a {{w|DIAC}}, except the arrows are backwards.}}
{{circuit-diagram-part|X=52|Y=141|W=79|H=107|image=circuit_diagram-052-141-079-107-compass-points.png|text=Compass points. A map feature, not a circuit feature, but possibly useful given the circuit is many miles wide.}}
{{circuit-diagram-part|X=415|Y=18|W=63|H=58|image=circuit_diagram-415-018-063-058-resister.png|text=A normal resistor, labeled with color code. Brown-Blue-Orange would be 16000 ohms. {{w|Electronic color code|Resistor color codes}} are for reading the value on the physical device itself. They would not normally be shown on the circuit diagram, where it's much easier to just write the number, e.g. 16K.}}
{{circuit-diagram-part|X=517|Y=14|W=42|H=32|image=circuit_diagram-517-014-042-032-diode.png|text=A normal {{w|diode}}.}}
{{circuit-diagram-part|X=615|Y=55|W=73|H=74|image=circuit_diagram-615-055-073-074-666timer.png|text=A chip. The normal timer is a "{{w|555_timer_IC|555}}". "666" would be the number of the beast in [http://www.blueletterbible.org/Bible.cfm?b=Rev&c=13&v=18&t=KJV#18 Rev. 13:18]. The pin connected to "?" is the CTRL pin on a normal 555 timer, which would typically be connected to ground (via a decoupling capacitor) if used at all; the implication here seems to be that it would be connected directly to Hell itself.}}
{{circuit-diagram-part|X=632|Y=138|W=69|H=41|image=circuit_diagram-632-138-069-041-bat.png|text=A Batman logo.}}
{{circuit-diagram-part|X=650|Y=211|W=75|H=71|image=circuit_diagram-650-211-075-071-squirrel.png|text=A squirrel, or perhaps a wire bent into the shape of a squirrel. {{w|Electrical disruptions caused by squirrels|Squirrels are among the leading causes of disruptions to electrical grids,}} so having one as part of a circuit is inviting disaster. [[:Category:Squirrels|Squirrels]] also appear in past and future xkcd comics.}}
{{circuit-diagram-part|X=606|Y=165|W=54|H=53|image=circuit_diagram-606-165-054-053-inductor.png|text=A coil or inductor.  An inductor in an AC circuit is analogous to a mass in an oscillating mechanical system; rather than listing the coil's inductance, the measurement of an analogous mechanical element is given: 11 kilograms of mass.}}
{{circuit-diagram-part|X=538|Y=209|W=99|H=59|image=circuit_diagram-538-209-099-059-generator.png|text=A 240-volt AC generator (or other power source).}}
{{circuit-diagram-part|X=483|Y=186|W=111|H=103|image=circuit_diagram-483-186-111-103-shorted-generator.png|text=A shorting wire around a generator. The label reads "Omit this if you're a <u>wimp</u>." If this wire is included, it will quickly melt - or worse. 
Theoretically, wimps will omit the wire, and people who know this fact will also, so it would be fine.}}
{{circuit-diagram-part|X=419|Y=78|W=57|H=75|image=circuit_diagram-419-078-057-075-scarab-beetles.png|text=A jar of {{w|Scarabaeidae|scarab beetles}}. Possibly a conflation of a {{w|Leyden jar}}, that is an actual very old-style electrical/electronic component, and something like a {{w|killing jar}} or other {{w|Insect trap|insect-collection equipment}}. Or even, due to the traditionally Egyptian beetles, a repurposed {{w|canopic jar}}.}}
{{circuit-diagram-part|X=482|Y=47|W=28|H=44|image=circuit_diagram-482-047-028-044-variable-resister.png|text=A {{w|variable resistor}} with center tap. Normally, there would be an arrowhead on the center tap.}}
{{circuit-diagram-part|X=507|Y=53|W=22|H=27|image=circuit_diagram-507-053-022-027-capacitor.png|text=A normal {{w|capacitor}}.}}
{{circuit-diagram-part|X=577|Y=318|W=96|H=62|image=circuit_diagram-577-318-096-062-magic.png|text="{{w|Magic Smoke}}" is the legendary stuff that all circuit components require to function. This is why all components cease to function after releasing smoke. When an electrical component is subject to excessive current it often fails due to heat. This heat is often accompanied by a burning smell and smoke, right at the moment that the circuit fails. Hence the joke that the reason that the circuit failed is that "the magic smoke that makes it work has been released." }}
{{circuit-diagram-part|X=669|Y=315|W=51|H=66|image=circuit_diagram-669-315-051-066-frayed-wires.png|text=Some frayed or dangling wires. The wire on the left seems confused because it did not manage to cross with the one on the right.}}
{{circuit-diagram-part|X=567|Y=392|W=58|H=48|image=circuit_diagram-567-392-058-048-buoy.png|text=An object which is either a {{w|Fishing float|float}} used in fishing, a {{w|Tippe top}}, or perhaps a {{w|Naval mine|mine}}.}}
{{circuit-diagram-part|X=458|Y=336|W=111|H=86|image=circuit_diagram-458-336-111-086-moral-rectifier.png|text=A {{w|Diode_bridge|bridge rectifier}}, which would normally turn alternating current at the top and bottom into direct current on the left and right. In this case, it is labeled as a "moral rectifier". This is presumably a play on the idea of moral rectitude – it makes your circuit more moral. Why this matters in a circuit is unclear.}}
{{circuit-diagram-part|X=423|Y=259|W=80|H=85|image=circuit_diagram-423-259-080-085-warm-front.png|text=This resembles both the schematic symbol for part of a {{w|transformer}} and the meteorological symbol for a warm front.  A {{w|warm front}} is a feature on a {{w|Surface weather analysis|synoptic weather map}}.}}
{{circuit-diagram-part|X=190|Y=199|W=54|H=52|image=circuit_diagram-190-199-054-052-battery.png|text=A normal 50-volt battery.}}
{{circuit-diagram-part|X=173|Y=200|W=89|H=56|image=circuit_diagram-173-200-089-056-shorted-battery.png|text=A battery is grounded on both sides. Something will melt or burn out quickly, unless these are separate "earth ground"s, in which case the ground might get a bit cooked.}}
{{circuit-diagram-part|X=259|Y=198|W=174|H=25|image=circuit_diagram-259-198-174-025-pull-wire.png|text=Text reads "Pull this wire really tight". This kind of physical-property issue may indicate a high-frequency radio device.  Or, given the absurdity of the context, it's a silly reference to a "high tension wire."}}
{{circuit-diagram-part|X=141|Y=211|W=41|H=91|image=circuit_diagram-141-211-041-091-3-8-inch.png|text=A specified 3/8-inch separation. This probably indicates a carefully controlled capacitance issue. Also contradicts the scale of the drawing, by which the distance shown would be about 0.8 miles or 0.8 km. Or both.}}
{{circuit-diagram-part|X=173|Y=309|W=92|H=59|image=circuit_diagram-173-309-092-059-eel.png|text=An {{w|electric eel}}.  This may be an effective power source in the circuit, capable of producing a shock at up to 600 volts and 1 ampere of current (600 watts), but for less than 2 ms.}}
{{circuit-diagram-part|X=266|Y=307|W=35|H=41|image=circuit_diagram-266-307-035-041-resistor.png|text=A normal resistor.}}
{{circuit-diagram-part|X=222|Y=358|W=34|H=29|image=circuit_diagram-222-358-034-029-capacitor.png|text=A normal capacitor.}}
{{circuit-diagram-part|X=130|Y=335|W=44|H=40|image=circuit_diagram-130-335-044-040-resistor.png|text=A normal resistor, labeled "&euml;".  This may be a play on {{w|e (mathematical constant)|Euler's Number}}, which doesn't normally have a {{w|tréma}} or an {{w|umlaut (linguistics)|umlaut}}. Alternatively instead of being an umlaut or tréma it may indicate the second {{w|derivative}} of e with respect to time in {{w|Newton's notation}}, in which case, as e is a constant, the resistance of this element is zero.}}
{{circuit-diagram-part|X=65|Y=249|W=61|H=92|image=circuit_diagram-065-249-061-092-blender.png|text=Our best guess is that this is a {{w|blender}}. Due to the scale, this would certainly be the worlds largest blender.  Record setting blenders are not typically part of computer circuits{{Citation needed}}}}
{{circuit-diagram-part|X=20|Y=342|W=115|H=73|image=circuit_diagram-020-342-115-073-arduino.png|text=An {{w|arduino}}, labeled "Arduino, just for blog cred". May refer to the fact that inexpensive, easy-to-integrate single-board computers like the arduino, which have contributed to the rise of {{w|Maker culture}}, are used and discussed frequently in that culture, and the use of one might impress readers.  The comment implies that an arduino is not otherwise needed in this circuit, although it is necessarily hard to tell, given the other components of the circuit.}}
{{circuit-diagram-part|X=39|Y=423|W=118|H=82|image=circuit_diagram-039-423-118-082-meca.png|text=A chip labeled "Most expensive chip available". The small curve at the top is a part of the packaging designed to show its orientation.}}
{{circuit-diagram-part|X=159|Y=428|W=91|H=50|image=circuit_diagram-159-428-091-050-neck-strap.png|text=Labeled "Neck Strap". Perhaps a piece of torture equipment or indicating that the circuit is part of an {{w|electric chair}}?  May also be a reference to the grounded wrist straps people working with electronics commonly wear, to prevent accidental static discharges from frying the circuitry.}}
{{circuit-diagram-part|X=147|Y=480|W=110|H=88|image=circuit_diagram-147-480-110-088-switch.png|text=A switch labeled "Hire someone to open and close switch real fast." Possibly meant to perform the function of an {{w|Electronic oscillator|oscillator}} in a more hackish manner and the reason for the neck strap. Could also be a reference to {{w|Maxwell's Demon}}.}}
{{circuit-diagram-part|X=273|Y=498|W=61|H=64|image=circuit_diagram-273-498-061-064-resistor.png|text=A 5 ohm resistor labeled "(decoy)". One end is not attached to anything. Perhaps this indicates wishful thinking that electrons might be tricked into entering this part of the circuit despite the fact that there's nowhere for them to go?}}
{{circuit-diagram-part|X=307|Y=453|W=103|H=56|image=circuit_diagram-307-453-103-056-tongue.png|text=A pair of contacts, labeled "Touch Tongue Here".  Could be referring to the practice of daring someone to touch their tongue to the contacts of a 9V battery.}}
{{circuit-diagram-part|X=301|Y=270|W=45|H=45|image=circuit_diagram-301-270-045-045-frown.png|text=A frowny-face. See the float/mine.}}
{{circuit-diagram-part|X=294|Y=311|W=128|H=124|image=circuit_diagram-294-311-128-124-IC.png|text=A small integrated circuit. The lower gate is an {{w|Inverter (logic gate)|inverter}}, wired as a free-running oscillator. The upper gate is an {{w|XOR gate|XOR}} wired to act as either a free-running oscillator or a latch. Since the XOR will be slower than the inverter, the overall output of the upper gate is probably very chaotic. Two "input" wires are not connected at all. An additional wire is attached to the top with hot glue. This last wire probably acts to control static electricity and leakage.}}
{{circuit-diagram-part|X=302|Y=235|W=91|H=25|image=circuit_diagram-302-235-091-025-curve.png|text=A caution sign at a curve. Another road feature in the circuit.  This is a play on the notion that 90-degree corners on printed circuit board traces can disrupt signal integrity.}}
{{circuit-diagram-part|X=401|Y=455|W=67|H=68|image=circuit_diagram-401-455-067-068-CH3.png|text=A {{w|methyl group}} (chemistry) attached to a corner. If the circuit were an organic chemical, it would be reasonable to find a number of these.}}
{{circuit-diagram-part|X=453|Y=167|W=43|H=93|image=circuit_diagram-453-167-043-093-baloon.png|text=A balloon, possibly blowing in a breeze.}}
{{circuit-diagram-part|X=572|Y=68|W=22|H=43|image=circuit_diagram-572-068-022-043-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=508|Y=96|W=42|H=20|image=circuit_diagram-508-096-042-020-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=534|Y=61|W=22|H=31|image=circuit_diagram-534-061-022-031-ground.png|text=A ground connection.}}
{{circuit-diagram-part|X=472|Y=49|W=134|H=140|image=circuit_diagram-472-049-134-140-solderr-blob.png|text=A {{w|Soldering#Soldering_defects|solder blob}} covering a portion of the circuit. Normally, this would not be part of the circuit diagram, but a mistake in building the circuit.}}
{{circuit-diagram-part|X=493|Y=443|W=207|H=158|image=circuit_diagram-493-443-207-158-res-rats-nest.png|text=A rat's nest of 1 ohm resistors. It is labeled "Oh, so you think you're such a whiz at EE201?" The name EE201 (Electrical Engineering 201) follows US course naming conventions for what appears to be a basic level course in electrical engineering (compare the term {{w|101 (term)|101}}), which would include being taught how to [http://www.wikihow.com/Calculate-Series-and-Parallel-Resistance calculate the effective resistance of various resistor networks]. Performing the calculation on a network this complex would probably be very difficult. Experimentally, the resistance of the mass can be measured as, likely coincidentally, about π/4.
A grid of 1 ohm resistors has appeared earlier in [[356: Nerd Sniping]], a comic also referred to in the title text.}}
{{circuit-diagram-part|X=315|Y=533|W=232|H=200|image=circuit_diagram-362-531-151-167-arena.png|text=An {{w|arena}}, with a few bodies in it. Note the direction of movement enforced by the surrounding diodes, {{w|Mad_Max_Beyond_Thunderdome|"two men enter, one man leaves"}}, a film reference.}}
{{circuit-diagram-part|X=569|Y=653|W=47|H=51|image=circuit_diagram-569-653-047-051-resistor.png|text=A "{{w|pi}}" ohm resistor.}}
{{circuit-diagram-part|X=610|Y=655|W=75|H=70|image=circuit_diagram-610-655-075-070-generator.png|text=A 500-volt AC generator. The wiring to the right shorts out this generator.}}
{{circuit-diagram-part|X=481|Y=682|W=85|H=64|image=circuit_diagram-481-682-085-064-ground.png|text=A ground connection, labeled "Bury deep, but not too deep". This type of ground connection is called an "earth ground" The "too deep" part might be a reference to {{w|Moria (Middle-earth)|Moria}} in Lord of Rings. The dwarves dug too deeply and disturbed a Balrog. See also comic [[760]].}}
{{circuit-diagram-part|X=17|Y=610|W=75|H=73|image=circuit_diagram-017-610-075-073-fishhook.png|text=A ground connection at the end of a curve, looking like a fishhook. Means perhaps "earthed down under", i.e., Australia or the southern hemisphere.}}
{{circuit-diagram-part|X=206|Y=662|W=66|H=45|image=circuit_diagram-206-662-066-045-yarn.png|text=A length of "wire" is labeled "yarn". This probably makes it a terrible conductor.}}
{{circuit-diagram-part|X=102|Y=590|W=93|H=88|image=circuit_diagram-102-590-093-088-fluxcapacitor.png|text=The {{w|DeLorean time machine#Flux capacitor|flux capacitor}} from {{w|Back to the Future}}.  This may be difficult to implement, since flux capacitors are not available to most people,{{Citation needed}} and connecting one to power may cause time travel or time distortions in the local area.}}
{{circuit-diagram-part|X=138|Y=685|W=54|H=24|image=circuit_diagram-138-685-054-024-I95.png|text=A road sign for "I-95". {{w|Interstate 95}} is the main north-south highway on the east coast of the United States, running from Maine to Florida.}}
{{circuit-diagram-part|X=12|Y=713|W=134|H=36|image=circuit_diagram-012-713-134-036-tothesun.png|text=A connection labeled "To center of Sun". A 93-million-mile or 150-million-km circuit is rather large.{{Citation needed}}}}
{{circuit-diagram-part|X=31|Y=753|W=144|H=177|image=circuit_diagram-031-753-144-177-rats-nest.png|text=A rat's nest of wires. Everything winds up being connected. May also be a parody diagram of an [http://i.stack.imgur.com/np2p9.png undirected graph], from graph theory.}}
{{circuit-diagram-part|X=22|Y=513|W=97|H=61|image=circuit_diagram-022-513-097-061-esf.png|text=A label reading "Electrons Single File". If this happens, the resistance in this section of wire would be rather high.}}
{{circuit-diagram-part|X=256|Y=619|W=29|H=39|image=circuit_diagram-256-619-029-039-ground.png|text=A ground connection.}}
{{circuit-diagram-part|X=589|Y=600|W=58|H=46|image=circuit_diagram-589-600-058-046-vibrator.png|text=A vibrator, which would be a motor with an off-center weight attached to it.}}
{{circuit-diagram-part|X=532|Y=779|W=74|H=52|image=circuit_diagram-532-779-074-052-motor.png|text=A motor, labeled "To Scale". This indicates that the physical size and shape of the motor must match the size of the parts around it, or is consistent with the specified scale of the drawing. }}
{{circuit-diagram-part|X=662|Y=822|W=73|H=109|image=circuit_diagram-662-822-073-109-holy-ground.png|text=A ground connection, in a beaker labeled "{{w|Holy Water}}", possibly creating {{w|Holy ground (religion)|holy ground}}.}}
{{circuit-diagram-part|X=197|Y=740|W=48|H=55|image=circuit_diagram-197-740-048-055-speed.png|text=A sign indicating a speed limit of 55 MPH. This is a rather typical road sign, but inappropriate for a circuit diagram. It is presumably referring to the speed of individual electrons, which can normally vary up to almost the speed of light - although based on the width of the wire and assuming about 1A of current, the ''average'' speed of all electrons, the drift velocity, is likely to be in the order of 10<sup>-17</sup>mph.}}
{{circuit-diagram-part|X=238|Y=706|W=100|H=116|image=circuit_diagram-238-706-100-116-flipflop.png|text=A pair of {{w|NOR gate}}s wired as a SR (set-reset) {{w|Flip-flop (electronics)|flip-flop}}. The label reads "May use an actual sandal instead", which is a play on the meanings of the term "{{w|Flip-flops|flip-flop}}". Also,the gate looks like a sandal.}}
{{circuit-diagram-part|X=322|Y=708|W=70|H=54|image=circuit_diagram-322-708-070-054-holdingpen.png|text=Something that could be the side view of a fence, labeled "Holding Pen".}}
{{circuit-diagram-part|X=339|Y=777|W=42|H=49|image=circuit_diagram-339-777-042-049-knot.png|text=A simple {{w|overhand knot}}. Also looks like a pretzel, which would have pretty high resistance.}}
{{circuit-diagram-part|X=191|Y=889|W=149|H=33|image=circuit_diagram-191-889-149-033-ecg.png|text=This appears to be an {{w|Electrocardiography|electrocardiograph}} (ECG) trace, but not the sort that would be seen in a healthy person. If this were a real ECG trace, the absence of large, clear {{w|P wave (electrocardiography)|P waves}} might indicate {{w|Atrial Fibrillation|fine atrial fibrillation}}, but in some recording configurations, P waves are sometimes lost in the noise anyway. Additionally, without a time scale to tell us the ventricular heart rate, it is impossible to make a strong educated diagnosis of any hypothetical disease at all. If we assume it is atrial fibrillation, it is not clear if Randall intended this, or if he is just not familiar with how a normal ECG should look. Lastly, it does not appear that this is an actual ECG machine, but simply a bent wire, much like the "Not a resistor" label nearby.}}
{{circuit-diagram-part|X=223|Y=826|W=82|H=68|image=circuit_diagram-223-826-082-068-photodiode.png|text=A {{w|photodiode}}, labeled "Tear Collector". A photodiode is a light-sensing device.}}
{{circuit-diagram-part|X=373|Y=859|W=49|H=68|image=circuit_diagram-373-859-049-068-lamp.png|text=A lamp. This is not [http://electronicsclub.info/circuitsymbols.htm the symbol used in electrical circuits], but a drawing of a lightbulb.}}
{{circuit-diagram-part|X=450|Y=887|W=65|H=32|image=circuit_diagram-450-887-065-032-inductor.png|text=A coil or inductor.}}
{{circuit-diagram-part|X=537|Y=847|W=120|H=72|image=circuit_diagram-537-847-120-072-inductor.png|text=A coil or inductor, labeled "Take off shirt while wiring this part. Ooh, yeah, I like that." Stripping while wiring plays on the more mundane action of stripping a wire.}}
{{circuit-diagram-part|X=504|Y=860|W=34|H=41|image=circuit_diagram-504-860-034-041-resistor.png|text=A resistor labeled "?". Presumably this means the resistance is unknown.}}
{{circuit-diagram-part|X=459|Y=828|W=55|H=38|image=circuit_diagram-459-828-055-038-resistor.png|text=A resistor labeled "YES". Likely another improper unit - a reference to boolean values YES (TRUE) and NO (FALSE). Depending on the limits of a circuit, a resistor would still have a YES boolean value. Possibly indicating that this is a real resistor, as opposed to the one above it in the circuit, labeled "not a resistor." This may also be a reference to the question: "How much INSERT OBJECT HERE do you want?, Yes."}}
{{circuit-diagram-part|X=389|Y=774|W=58|H=53|image=circuit_diagram-389-774-058-053-resistor.png|text=A resistor labeled "8 mm". Resistance is measured in ohms, and while it might be useful to specify the dimensions of a component to be used (usually on an actual assembly template, or other written documentation, rather than upon a connectivity diagram) the lack of required resistance rating/acceptable range adds far more doubt.}}
{{circuit-diagram-part|X=443|Y=747|W=93|H=84|image=circuit_diagram-443-747-093-084-resistor.png|text=A resistor labeled "Not a resistor; wire just does this". Apparently the wire is or must be physically bent into a zig-zag shape, which would not serve much useful purpose in a low frequency or DC circuit, or perhaps it reflects the fact that any wire has a certain (small) amount of resistance just by being a wire. In a {{w|Radio frequency|high frequency circuit}} this can be actually useful, as the shape and length of the {{w|Transmission line|transmission line}} alters the {{w|Electrical impedance|impedance}} of the line. ([https://commons.wikimedia.org/wiki/File:Phaseshifter2.png Example])}}
{{circuit-diagram-part|X=415|Y=863|W=82|H=24|image=circuit_diagram-415-863-082-024-unsure.png|text=A symbol for a feedthrough capacitor, labeled "3 Liters". Probable word-play on "capacity/capacitor." Also similar to the symbol for an orifice or flow restriction used on plumbing or hydraulic diagrams, in which case the "3 Liters" might mean 3 liters per minute or per second.}}
|}

==Transcript==
:[In the upper left corner there is a map scale, labeled with 1 mi (1 km).]
:[Underneath the scale is a circuit diagram with the following items connected:]
:An antenna symbol.
:A blender.
:An Arduino, labeled with "Arduino, just for blog cred".
:A chip, labeled "Most expensive chip available".
:A symbol for an inductor.
:A pattern that looks like a highway cloverleaf.
:A battery symbol (with the + and - symbols on the wrong ends) with a value of √2V.
:A resistor symbol label "120Ω or to taste". 
:A switch that is labeled "glue open".
:A transistor with two emitters, one P and one N, and no collector.
:A jar of scarab beetles.
:A resistor labeled "brown blue orange".
:An unlabeled resistor with a center tap.
:A capacitor.
:A diode.
:A ground.
:An inductor.
:An another inductor.
::The two inductors and ground are all covered by a "solder blob".
:A "666 timer" that has pin 5 going into a question mark.
:A compass rose.
:A battery, labeled 50V, with grounds on both sides.
:A long horizontal wire that is labeled "pull this wire really tight". 
:An AC source that is labeled 240V, shorted out, with a label on the short "Omit this if you're a wimp."  
:An inductor that is labeled with "11kg".
:A Batman symbol.
:A squirrel.
:A wire that is labeled as a distance 3/8".
:A 50V battery.
:A frowny face.
:A vertical wire with a 90 degree bend labeled "caution".
:A balloon.
:An inductor symbol with a line on the bottom edge labeled as "warm front".
:A resistor labeled "ë".
:An electric eel.
:A capacitor.
:An unlabeled resistor.
:A gob of hot glue attached to a chip with an inverter hooked to an XOR gate, both with feedback into each other.
:A neck strap.
:A bridge rectifier labeled as "Moral rectifier".
:A bottle of magic smoke.
:A fishing bobber.
:A broken wire labeled with a question mark.
:A vertical wire labeled with "electrons single file".
:A switch labeled "Hire someone to open and close switch real fast."
:A contact labeled "touch tongue here".
:A resistor labeled "5Ω (decoy)" with only one terminal connected.
:A methyl group attached to a wire.
:A complex mesh of 1Ω resistors labeled with "Oh, so you think you're such a whiz at EE201?"
:A wire labeled "electrons single file".
:A wire bent in a U shape with an upside-down ground on the end.
:A flux capacitor with the bottom wire labeled "I-95".
:A wire labeled "yarn".
:An arena with two diodes going in and one leaving.
:An anode labeled "Bury deep, but not too deep."
:A motor labeled "vibrator".
:A resistor with a value of π.
:A 500V AC source.
:A wire that leads out of frame with a label "to center of sun".  
:A 55 MPH speed limit sign.
:An SR latch (flip-flop) labeled "may use an actual sandal instead". 
:A holding pen.
:A wire in a knot.
:A resistor labeled "8mm".
:A resistor symbol labeled "not a resistor; wire just does this".
:A motor symbol labeled "to scale".
:A tangled mess of wires connected and jumping over each other.
:A photo diode labeled "tear collector".
:A wire in the shape of a ECG.
:A light bulb.
:A capacitor-looking symbol labeled "3 liters".
:A resistor labeled "yes".
:An unlabeled inductor.
:A resistor with a question mark as a label.
:An inductor labeled "Take off shirt while wiring this part.  Ooh, yeah, I like that."
:A ground symbol immersed in a beaker of holy water.

==Trivia==
This is one of the six [[Footer comics|footer comics]] featured in the bottom segment of [https://xkcd.com xkcd.com].

{{comic discussion}}

[[Category:Physics]]
[[Category:Engineering]]
[[Category:Maps]]
[[Category:Footer comics]]
[[Category:Squirrels]]
[[Category:Back to the Future]]