Appendix C. Building and Connecting the Circuit

C.1. Using a Breadboard

A breadboard enables you to prototype circuits quickly, without having to solder the connections. Figure C-1 shows an example of a breadboard.

Breadboard for prototyping circuits
Figure C-1. Breadboard for prototyping circuits

Breadboards come in various sizes and configurations. The simplest kind is just a grid of holes in a plastic block. Inside are strips of metal that provide electrical connection between holes in the shorter rows. Pushing the legs of two different components into the same row joins them together electrically. A deep channel running down the middle indicates that there is a break in connections there, meaning you can push a chip in with the legs at either side of the channel without connecting them together.

Some breadboards have two strips of holes running along the long edges of the board that are separated from the main grid. These have strips running down the length of the board inside, and provide a way to connect a common voltage. They are usually in pairs for +5 volts and ground. These strips are referred to as rails and they enable you to connect power to many components or points in the board.

While breadboards are great for prototyping, they have some limitations. Because the connections are push-fit and temporary, they are not as reliable as soldered connections. If you are having intermittent problems with a circuit, ...

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