Electronic Diagrams and Schematics
ELECTRONIC DIAGRAMS, PRINTS, AND SCHEMATICS
Figure 7 NPN Transistor-Conducting
Figure 8 NPN Transistor-Nonconducting
the arrow indicates type, as shown in Figure 2. There are, however, many different ways to install
a transistor to achieve different operational characteristics. These are too numerous to cover here,
so only the most common and basic configuration (the common emitter) will be shown.
Even though transistors contain multiple junctions of p- or n-type material, current flow is
generally in the same direction. Using conventional current flow (i.e. from + to -), current will
travel through the transistor from most positive to least positive and in the direction of the arrow
on the emitter. In Figure 7, the transistor has a positive power supply with ground on the emitter.
If the input is also positive, the transistor will conduct.
If the input goes negative, as in Figure 8, the conduction of the device stops because the input,
or in this case the base junction, controls the transistor condition. Notice that when current flows,
it does so in the direction of the arrow.