How to Use a Breadboard
Introduction
The term breadboard may sound like a strange material to use when you're talking about building a circuit. The term is derived from the time of early circuit building. In those days, a breadboard was a large wooden plank used to slice a loaf of bread on. Because the components to build a circuit used to be so large, experimenters needed to build circuits on a large stable surface, like a breadboard. Of course technology has advanced, and now a breadboard is no longer a large wooden plank, but a perforated plastic base upon which an electronic circuit is built. A breadboard is a reusable piece of equipment that circuit designers use to build prototype circuits and to experiment.
Breadboard Construction
Figure 1 shows an example of a solderless breadboard. The breadboard has a series of holes, each containing an electrical contact. Holes in the same column (examples highlighted in yellow and green) are electrically connected. When you insert wires into the holes that are in the same column, the wires are then electrically connected. The gap (highlighted in orange) marks a boundary between the electrical connections. A wire inserted in one of the green holes would not be connected to a wire inserted in one of the yellow holes. Finally, the two single rows of holes at the top and bottom are highlighted in red and blue. All of the red holes are electrically connected and all of the blue holes are electrically connected. The red row is called the power bus and the blue row is called the ground bus. These come in handy for more complicated circuits with multiple components that need to be connected to the power supply.
 |
 |
| Figure 1. This is an example of a solderless breadboard. |
Figure 2. Another kind of solderless breadboard. |
Most circuits require power and ground. Ground is the reference point in an electrical circuit from which other voltages are measured, a common return path for electric current (earth return or ground return), or a direct physical connection to the Earth. Usually on a solderless breadboard there are two terminals that serve as the main power connection and the main ground connection. Conventionally, the power connection is the large red screw terminal (or binding post), while the ground connection is the large black screw connection (also known as the binding post).
Using a Breadboard
- Before building a circuit, connect power to the red terminal. For a battery pack, connect the positive (+) from the battery pack to the red screw terminal. Since ground is a reference voltage, connect the negative (-) from the battery pack to the black screw.
- Unscrew the terminals and connect the battery pack, as described above. Screw the wire down firmly so that it doesn't move, but not so firmly that the wire is cut.
- If you are using a power supply, simply connect power to the red terminal on the breadboard with a banana plug to a banana plug cable. There will be a ground connection on the power supply that can be connected to the ground terminal.
- Once power and ground have been connected to the board, connect a wire, also known as a jumper wire, from the red terminal to the power bus (the red highlighted row). The wire should be just long enough to span the distance between the terminal and the bus.
- Take the wire and strip off ¼ inch of insulation from both ends. Connect the ground to the blue highlighted bus. Make sure the wire is just long enough to span the distance between the black terminal and the bus.
- Strip off ¼ inch from both ends and connect the ground bus to the black terminal. The breadboard is now ready to have a circuit built upon it.
