<s>
A	O
circuit	B-Application
diagram	I-Application
(	O
or	O
:	O
wiring	O
diagram	O
,	O
electrical	B-Application
diagram	I-Application
,	O
elementary	O
diagram	O
,	O
electronic	B-Application
schematic	I-Application
)	O
is	O
a	O
graphical	O
representation	O
of	O
an	O
electrical	O
circuit	O
.	O
</s>
<s>
A	O
pictorial	O
circuit	B-Application
diagram	I-Application
uses	O
simple	O
images	O
of	O
components	O
,	O
while	O
a	O
schematic	B-Application
diagram	I-Application
shows	O
the	O
components	O
and	O
interconnections	O
of	O
the	O
circuit	O
using	O
standardized	O
symbolic	O
representations	O
.	O
</s>
<s>
The	O
presentation	O
of	O
the	O
interconnections	O
between	O
circuit	O
components	O
in	O
the	O
schematic	B-Application
diagram	I-Application
does	O
not	O
necessarily	O
correspond	O
to	O
the	O
physical	O
arrangements	O
in	O
the	O
finished	O
device	O
.	O
</s>
<s>
Unlike	O
a	O
block	B-Application
diagram	I-Application
or	O
layout	O
diagram	O
,	O
a	O
circuit	B-Application
diagram	I-Application
shows	O
the	O
actual	O
electrical	B-Protocol
connections	I-Protocol
.	O
</s>
<s>
Circuit	B-Application
diagrams	I-Application
are	O
used	O
for	O
the	O
design	O
(	O
circuit	O
design	O
)	O
,	O
construction	O
(	O
such	O
as	O
PCB	O
layout	O
)	O
,	O
and	O
maintenance	O
of	O
electrical	O
and	O
electronic	O
equipment	O
.	O
</s>
<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
circuit	B-Application
diagrams	I-Application
are	O
useful	O
when	O
visualizing	O
expressions	O
using	O
Boolean	O
algebra	O
.	O
</s>
<s>
Circuit	B-Application
diagrams	I-Application
are	O
pictures	O
with	O
symbols	O
that	O
have	O
differed	O
from	O
country	O
to	O
country	O
and	O
have	O
changed	O
over	O
time	O
,	O
but	O
are	O
now	O
to	O
a	O
large	O
extent	O
internationally	O
standardized	O
.	O
</s>
<s>
On	O
a	O
circuit	B-Application
diagram	I-Application
,	O
the	O
symbols	O
for	O
components	O
are	O
labelled	O
with	O
a	O
descriptor	O
or	O
reference	O
designator	O
matching	O
that	O
on	O
the	O
list	O
of	O
parts	O
.	O
</s>
<s>
For	O
example	O
,	O
C1	O
is	O
the	O
first	O
capacitor	O
,	O
L1	O
is	O
the	O
first	O
inductor	O
,	O
Q1	O
is	O
the	O
first	O
transistor	B-Application
,	O
and	O
R1	O
is	O
the	O
first	O
resistor	O
.	O
</s>
<s>
It	O
is	O
a	O
usual	O
(	O
although	O
not	O
universal	O
)	O
convention	O
that	O
schematic	B-Application
drawings	I-Application
are	O
organized	O
on	O
the	O
page	O
from	O
left	O
to	O
right	O
and	O
top	O
to	O
bottom	O
in	O
the	O
same	O
sequence	O
as	O
the	O
flow	O
of	O
the	O
main	O
signal	O
or	O
power	O
path	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
schematic	B-Application
for	O
a	O
radio	O
receiver	O
might	O
start	O
with	O
the	O
antenna	O
input	O
at	O
the	O
left	O
of	O
the	O
page	O
and	O
end	O
with	O
the	O
loudspeaker	O
at	O
the	O
right	O
.	O
</s>
<s>
Schematic	B-Application
drawings	I-Application
intended	O
for	O
maintenance	O
may	O
have	O
the	O
principal	O
signal	O
paths	O
highlighted	O
to	O
assist	O
in	O
understanding	O
the	O
signal	O
flow	O
through	O
the	O
circuit	O
.	O
</s>
<s>
More	O
complex	O
devices	O
have	O
multi-page	O
schematics	B-Application
and	O
must	O
rely	O
on	O
cross-reference	O
symbols	O
to	O
show	O
the	O
flow	O
of	O
signals	O
between	O
the	O
different	O
sheets	O
of	O
the	O
drawing	O
.	O
</s>
<s>
Detailed	O
rules	O
for	O
the	O
preparation	O
of	O
circuit	B-Application
diagrams	I-Application
,	O
and	O
other	O
document	O
types	O
used	O
in	O
electrotechnology	O
,	O
are	O
provided	O
in	O
the	O
international	O
standard	O
IEC	O
61082-1	O
.	O
</s>
<s>
Circuit	B-Application
diagrams	I-Application
are	O
often	O
drawn	O
with	O
the	O
same	O
standardized	O
title	O
block	O
and	O
frame	O
as	O
other	O
engineering	B-Architecture
drawings	I-Architecture
.	O
</s>
<s>
Relay	O
logic	O
line	O
diagrams	O
,	O
also	O
called	O
ladder	O
logic	O
diagrams	O
,	O
use	O
another	O
common	O
standardized	O
convention	O
for	O
organizing	O
schematic	B-Application
drawings	I-Application
,	O
with	O
a	O
vertical	O
power	O
supply	O
rail	O
on	O
the	O
left	O
and	O
another	O
on	O
the	O
right	O
,	O
and	O
components	O
strung	O
between	O
them	O
like	O
the	O
rungs	O
of	O
a	O
ladder	O
.	O
</s>
<s>
Once	O
the	O
schematic	B-Application
has	O
been	O
made	O
,	O
it	O
is	O
converted	O
into	O
a	O
layout	O
that	O
can	O
be	O
fabricated	O
onto	O
a	O
printed	O
circuit	O
board	O
(	O
PCB	O
)	O
.	O
</s>
<s>
Schematic-driven	B-Application
layout	I-Application
starts	O
with	O
the	O
process	O
of	O
schematic	B-Application
capture	O
.	O
</s>
<s>
Students	O
are	O
expected	O
to	O
understand	O
the	O
rudiments	O
of	O
circuit	B-Application
diagrams	I-Application
and	O
their	O
functioning	O
.	O
</s>
<s>
Use	O
of	O
diagrammatic	O
representations	O
of	O
circuit	B-Application
diagrams	I-Application
can	O
aid	O
understanding	O
of	O
principles	O
of	O
electricity	O
.	O
</s>
<s>
Principles	O
of	O
the	O
physics	O
of	O
circuit	B-Application
diagrams	I-Application
are	O
often	O
taught	O
with	O
the	O
use	O
of	O
analogies	O
,	O
such	O
as	O
comparing	O
functioning	O
of	O
circuits	O
to	O
other	O
closed	O
systems	O
such	O
as	O
water	O
heating	O
systems	O
with	O
pumps	O
being	O
the	O
equivalent	O
to	O
batteries	O
.	O
</s>
