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Using the BreadboardUse a solderless breadboard to construct simple circuits.
Site: iCODECourse: Machine Science Guides (Arduino Version)Book: Using the BreadboardPrinted by: Ivan RudnickiDate: Wednesday, July 30, 2014, 03:17 PM
ContentsAbout the Breadboard
Internal Connections
Preparing the Breadboard
About Power and Ground
About Jump Wires
Connecting the Battery Pack
About LEDs
About Resistors
Building the LED Circuit
About the BreadboardA solderless breadboard (Figure 1) is a tool that allows you to construct simple circuits withoutmaking permanent solder connections. To make connections among components, you simply plugthem into the holes in the breadboard. If you need to change a connection, you can easily extract andreconfigure the components.
Figure 1. Breadboard.
The breadboard's name dates from the early days of electrical engineering, when engineers wouldcreate circuits by driving nails into wooden boards and then wrapping conductive wire around thenails.
Internal ConnectionsThe breadboard has hundreds of tiny holes that hold wires and electronic components. Figure 2shows a closeup view of one end of the breadboard. Notice that each row of holes is assigned anumber, and each column is assigned a letter. This way, the exact position of any hole on thebreadboard can be specified by a combination of a letter and a number. For example, in Figure 2, thehole in the upperleft corner is hole A1.
Figure 2. Closeup view of breadboard.
Metal clips inside the breadboard make electrical connections between the wires and componentsthat you plug into certain holes. Look closely at the long edges of the breadboard. On each side,there are two columns: one marked with a red line, and the other marked with a blue line. All of thered line holes on a side are connected to one another, and all of the blue line holes on a side areconnected to one another.
Now, look at the breadboard's numbered rows of holes. Notice that each row has 10 holesfive incolumns A to E, and five in columns F to Jseparated down the middle by a shallow groove. Withineach row, the five holes in columns A to E are connected, and the five holes in columns F through Jare connected. However, the breadboard has no builtin connections across the central groove. Theinternal connections at one end of the breadboard are marked with green lines in Figure 3.
Figure 3. The breadboard's internal connections, highlighted in green.
Preparing the Breadboard
Before you begin building circuits on yourbreadboard, a metal plate should be affixed tothe bottom of the board. The metal plate willhelp all of your components function moreconsistently. NOTE: If your board already hasa metal plate on the bottom, you can skip thisstep.
1. Peel the backing from the breadboard,leaving the sticky foam layer in place, asshown in the video on in Figure 4.
2. Apply the metal plate to the bottom of thebreadboard, as shown in the video and inFigure 4.
Figure 4. Applying the metal plate.
About Power and GroundThe holes marked with red and blue lines along the edges of the breadboard (Figure 5) are calledpower holes and ground holes, respectively. These holes have a special purpose: making it easy tosupply electricity to the components in your circuit. No matter where you put a component, there'salways a power hole and a ground hole nearby. Think of the power and ground holes as a "powerstrip" for your breadboard.
Figure 5. Power holes and ground holes.
Later, you will set up this "power strip" by establishing a 5volt difference between the power holesand the ground holes.
About Jump WiresA jump wire is a length of insulated wire specifically designed to work with the solderlessbreadboard. Each jump wire has a short uninsulated section at either end. Inserting these sections intoany two breadboard holes creates an electrical connection between the two holes. The kit containstwo types of jump wires: 1) prebent jump wires, which come in various, colorcoded lengths; and 2)flexible jump wires, which are all the same length. Figure 6 shows these two types of jump wires.
Figure 6. Prebent (left) and flexible (right) jump wires.
Although the two types of wires can be used interchangeably, a prebent jump wire is typically usedto make a semipermanent connection between two holes in the same row or column on thebreadboard, whereas a flexible jump wire is typically used to make a more temporary connectionbetween two holes that are not in the same row or column.
Connecting the Battery PackThe battery pack included with your kit holds four AA batteries, which together supply power to theboard. The battery pack has a red (power) lead and a black (ground) lead, terminating in a threewaywire harness. The following instructions show how to connect the harness to the breadboard toreduce the risk of accidentally reversing power and ground.
1. Insert three prebent jump wires into the breadboard, making two connections to groundand one to power, as shown in Figure 7.
Figure 7. Inserting jump wires.
2. Using pliers or scissors, break off a threesegment piece of the 36prong bent connectorincluded in the kit, making a threeprong connector, as shown in Figure 8.
Figure 8. Breaking off a threeprong connector.
3. Insert the threeprong bent connector into the board, aligning it with the three jump wires,as shown in Figure 9.
Figure 9. Inserting threeprong connector.
4. Connect the battery pack wire harness to the threeprong connector, taking care to alignthe red (power) wire with the center prong, as shown in Figure 10. Notice that, even if theharness is inverted, the proper power and ground connections will be maintained, as long asyou line up the harness correctly with the threeprong connector.
Figure 10. Connecting the wire harness.
5. Connect the red line holes and the blue line holes on each side of the board by inserting twored prebent wires, as shown in Figure 11. NOTE: You will need to bend the wires slightly toget them to fit.
Figure 11. Connecting power and ground from one side of the breadboard to the other.
About LEDsLight emitting diodes (LED) are electronic components that emit light when electricity passesthrough them. Figure 12 shows yellow, red, and green LEDs.
Figure 12. LEDs.
Because LEDs generate lots of light, use very little electricity, and last for thousands of hours, theyare becoming ubiquitous in modern electronic devices. Your computer keyboard probably has a fewLEDs to indicate when the Caps Lock or Num Lock keys have been pressed. Grouped together,LEDs can produce enough light to be used as a source of household illumination, as in the lampshown in Figure 13.
Figure 13. LED lamp.
Every LED has a specific polarity, meaning one of its two pins must connect to the power side of thecircuit and the other pin must connect to the ground side. A tiny flat segment on the round rim of theLED's circular base marks the ground pin. The power pin is typically longer than the ground pin, butthis is an unreliable indicator, since the pins may be trimmed during installation. Figure 14 showsthese distinguishing features.
Figure 14. LED polarity.
About ResistorsA resistor is a component that limits the flow of electricity in an electronic circuit. In some cases,resistors are needed to protect other components, which may be unable to operate at the full voltagesupplied by the batteries in a circuit.
Resistors vary widely in terms of their resistance, a property measured in Ohms, which determineshow much current passes through them. The resistors included in your kit have colored bands toindicate their resistance. (To learn how to interpret these colored bands, see the Resistors QuickReference document.) For the activity in the next section, you need to use a 1.0K Ohm (1,000 Ohm)resistor. Figure 15 shows two ways to identify this resistor.
Figure 15. Two ways to identify a 1.0K Ohm resistor.
Building the LED CircuitUsing one resistor, one jump wire, and one LED, create the circuit shown in Figure 16. Be sure toorient the LED so that its longer (power) pin aligns with the jump wire connected to power, and itsshorter (ground) pin aligns with the resistor connected to ground. Before turning on the power,double check all your connections to ensure that you do not create a short circuit. The LED shouldlight when power is supplied!
Figure 16. LED circuit.
