When working on a new project, electronic engineers prefer to test their circuits on a prototype board. This is a printed circuit board on which they mount electronic components and test the circuit functionally. If necessary, they make the necessary changes in the circuit and the layout of the board. Once the changes are satisfactory, the circuit proceeds to the final design. However, even before they go for a prototype board, the designers can do some preliminary testing with electronic components.
What is an Electrical Breadboard?
An electrical breadboard is a rectangular plastic board with numerous holes on its top surface. The holes allow plugging-in the leads of through-hole electronic components. This allows building prototype circuits and testing them without soldering the component leads. Unfortunately, it is not possible to use surface mount components with electrical breadboards. Therefore, designers test their circuits using through hole components and move over to using surface mount components when going for prototype PCBs.
The name breadboard is a leftover from early days of electronics, when people would use nails and screws driven into wooden boards to connect components. As the boards were initially meant for cutting bread, the name stuck.
Structure of Breadboards
The modern breadboard is made of plastic, and is available in various shapes, sizes, and colors. Most common are the full size, half size, and mini size of breadboards. Most breadboards come with notches and tabs on their sides. This allows snapping more boards together to build one large breadboard.
Figure 1: Electrical Breadboard
A full size breadboard has its holes arranged in rows and columns. The longer sides have two rows of holes each, and the arrangement of 30 columns are in two groups, A to E and F to J.
The breadboard does not require soldering components to connect them. Under the board, each hole has a brass connector with spring leaves. When the designer pushes the lead of a component through a hole, the spring leaves of the connector anchor it securely. The design of the spring leaves is such that it is easy to pull out the lead and plug it into another hole.
The interconnection between the brass connectors makes the breadboard so convenient for building circuits. The two rows along the longer side of the board have the connectors joined individually. Therefore, the designer can use them as power buses. They can designate the outermost rows on the two longer sides as the ground or the negative bus and the rows immediately on the inner side as the positive bus of a DC power supply.
Likewise, the two groups of 30 columns also have their connectors interconnected individually. However, there is no interconnection between the two groups. They are also isolated from the power buses.
Using the Breadboard
The design of the breadboard is such that the rows E and F have a separation of 0.25 inches between them. This allows placing an IC such that it straddles the rows E and F. Each pin of the IC is then extended by four connections. The designer can plug in resistors, capacitors, and other components between the pins of the IC. They can make other electrical connections with the help of wire jumpers.
