Real World Instrumentation with Python

Circuit Schematics

Before moving on, we need to acquire some symbols to help describe what we’re talking about. Electrical circuits are described graphically using diagrams called schematics. There are industry-standard symbols for every type of electrical component available, and how one graphically arranges these describes how the actual components are connected in the physical circuit. Figure 2-5 shows a small sampling of some of the more common symbols one might encounter regularly for what are called “passive” components.

Figure 2-5. Common electronic schematic symbols

Figure 2-6 shows the symbols for diodes (rectifiers) and transistors of various types. These are referred to as solid-state components and are considered to be active components in that they are capable of altering the current flow in a nonlinear fashion.

Figure 2-6. Solid-state components

The wires (or circuit board traces) in a real circuit are shown as lines in a schematic. Connections between wires are shown with a solid circle where they meet; otherwise, they simply cross. This is illustrated in Figure 2-7. Some older schematic styles use a small hump in one wire to show that it doesn’t connect to the wire it is crossing, but this has become rather rare in modern diagrams. Also note that in order to avoid drawing ...