Getting Started with Arduino

Appendix A. The Breadboard

The process of getting a circuit to work involves making lots of changes to it until it behaves properly; it's a very fast, iterative process that's something like an electronic equivalent to sketching. The design evolves in your hands as you try different combinations. For the best results, use a system that allows you to change the connections between components in the fastest, most practical, and least destructive way. These requirements clearly rule out soldering, which is a time-consuming procedure that puts components under stress every time you heat them up and cool them down.

The answer to this problem is a very practical device called the solderless breadboard. As you can see from Figure A-1, it's a small plastic board full of holes, each of which contains a spring-loaded contact. You can push a component's leg into one of the holes, and it will establish an electrical connection with all of the other holes in the same vertical column of holes. Each hole is a distance of 2.54 mm from the others.

Because most of the components have their legs (known to techies as "pins") spaced at that standard distance, chips with multiple legs fit nicely. Not all of the contacts on a breadboard are created equal—there are some differences. The top and bottom rows (coloured in red and blue and marked with + and –) are connected horizontally and are used to carry the power across the board so that when you need power or ground, you can provide it very quickly with ...