FIGURE 8. A low pass filter.
FIGURE 9. A diode.
FIGURE 11. An
FIGURE 12. An integrated circuit.
FIGURE 10. A normally open
basic circuit components, but
thankfully tinkerers do not need to
completely understand the complex
subtleties of their inner workings to
use them properly. Just think of
them as a fast electronic switch.
Putting the Pieces Together
After being able to identify and understand the
basic symbols, the next step in learning the language of
schematics is to know how everything fits together.
Everything is connected by wires, which are simply
represented by lines. In schematics, wires are assumed to
have no resistance, and the wires can be stretched,
shrunk, and take crazy paths with no effect on the circuit.
(Okay, that is a bit of a generalization since some more
sensitive circuits are adversely affected by wire routing
and length.) Just keep your wiring tidy and as short as
possible, and your circuit will perform as designed.
Most schematics try to show the most efficient path
from point A to point B, so the web of wires stays pretty
clear. One important note is the distinction between wire
62 May 2008
junctions and wires crossing over each
other with no connection. Wire junctions
are shown by wire lines that physically
intersect; most often at a point that is
shown as a dot at the intersection. Wires
that only cross over one another without
physically connecting should be shown
by one solid wire and one broken wire that avoid a point
of intersection (but this may not always be the case).
A good number of schematics find it too much of a
bother to have the one broken line, so they will simply
show wires crossing over each other like two lines that do
physically intersect, but do not have a dot at the intersection. Some schematics show one of the wires at a crossing
with a half circle going over the other wire to indicate
there is no connection. Complicated schematics will often
have many more crossovers than junctions, so just be
careful and don’t be confused by crisscrossing wires.
Another fundamental is polarity. Many components like
resistors and some capacitors could care less about what
orientation you place them in the circuit, but sometimes
polarity does matter, and ignoring it can be disastrous.
Thankfully, schematics are usually designed to make things