Page 100 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

FIGURE 4-16 The components in the correct positions.

Adding the Supplies

In our first design, back in Chapter 2, we glossed over the whole idea of supplies. Power came from

two pins of a connector, and we did not do anything special to identify them as power rails. We
didn’t have to. It worked as it was, and that was our rough and ready chapter.
However, generally, except from the very simplest designs, there are good reasons to identify

which nets are supply nets and both name them appropriately and associate them with special
“supply” parts. This can help to keep diagrams neat because you can repeat GND and other supply
symbols so that you do not need to connect every point on the diagram that is GND to every other
GND with a line—something that very rapidly gets unmanageable as a design becomes more
complex. You can just use the GND symbol as a stand-in.

Therefore, we are going to add two new supply parts, one for GND and one for V+. Select the
Add command, and then search for “supply” (Figure 4-17).