Schematic Symbols

Reading a schematic without fear

Signal flows left to right, positive rails live along the top, ground along the bottom. A dot where wires cross means connected; no dot, or a little hop, means they merely pass. Values sit beside their symbols with units often dropped: a resistor marked 4k7 is 4.7 kΩ, a capacitor marked 100n is the 104 everyone knows.

US versus IEC

The zigzag resistor here is the ANSI style used across North America and most hobby documentation. European schematics draw it as a plain rectangle. Both mean exactly the same component, and mixed schematics are common enough that recognizing each is worth the two seconds it takes.