The symbols drawn on circuit diagrams, as distinct from the markings printed on equipment. Grouped because they are read together and are useless in isolation: a schematic is unreadable until its parts can be named, and the parts carry no labels. Unlike most of the catalogue these denote physical components rather than carrying meaning, and the records say so rather than inventing significance. Several are drawn two incompatible ways — a resistor is a zigzag in North American practice and a plain rectangle under IEC practice — which is the single most common reason a reader cannot identify what they are looking at.
A zigzag or a plain rectangle in a circuit, marking a resistor.
Two parallel lines across a break in a wire, marking a capacitor.
A row of humps or a filled rectangle in a wire, marking an inductor.
A triangle pointing at a bar, marking a diode.
A diode symbol with two arrows pointing away, marking a light-emitting diode.
A line with two angled leads inside a circle, one carrying an arrow.
Alternating long and short parallel lines, marking a cell or battery.
A break in a wire bridged by a hinged line, marking a switch.
A rectangle with a line through it, marking a fuse.
Two coils facing each other across parallel lines, marking a transformer.
A circle with a cross inside it, marking a lamp or indicator.
A circle containing the letter M, marking an electric motor.