Breadboard

When building a "permanent circuit" the components can be "grown" together (as in an integrated circuit), soldered together (as on a printed circuit board), or held together by screws and clamps (as in house wiring). In lab, we want something that is easy to assemble and easy to change. We also want something that can be used with the same components that "real" circuits use. Most of these components have pieces of wire or metal tabs sticking out of them to form their terminals.

How it Works: The heart of the solderless breadboard is a small metal clip that looks like this:

The clip is made of nickel silver, a material which is reasonably conductive. Since each of the pairs of fingers is independent, we can insert the end of a wire between any pair without reducing the tension in any of the other fingers. Hence, each pair can hold a wire with maximum tension. Depending on the size and arrangement of the clips, we get either a socket strip or a bus strip. The socket strip is used for connecting components together. It has two rows of short (5 contact) clips arranged one above another.

The bus strip is used to distribute power and ground voltages through the circuit. It has four long (25 contact) clips arranged lengthwise, like this:

The breadboard has many strips of metal (copper usually), which run underneath the board. The metal strips are laid out as shown below.

These strips connect the holes on the top of the board. This makes it easy to connect components together to build circuits. To use the breadboard, the legs of components are placed in the holes (the sockets). Each hole is connected to one of the metal strips running underneath the board. Each wire forms a node. A node is a point in a circuit where two components are connected. Connections between different components are formed by putting their legs in a common node. On the breadboard, a node is the row of holes that are connected by the strip of metal underneath.The long top and bottom row of holes are usually used for power supply connections. The rest of the circuit is built by placing components and connecting them together with jumper wires. Then when a path is formed by wires and components from the positive supply node to the negative supply node, we can turn on the power and current flows through the path and the circuit comes alive. For chips with many legs (ICs), place them in the middle of the board so that half of the legs are on one side of the middle line and half are on the other side. A completed circuit might look like the following. This circuit uses two small breadboards.

Electronic Laboratory
Breadboard
Resistors and Color Code Rings
Capacitors
Soldering
Timer
Electronic Meters



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