Lab: Setting Up A Breadboard

Introduction

The easiest way to get started building electronic circuits is by using a solderless breadboard. A breadboard is a tool for holding the components of your circuit, and connecting them together. It’s got holes that are the right size for hookup wires and the ends of most components, so you can push wires and components in and pull them out without much trouble. This lab shows how to set up a breadboard with an independent power supply (8-12V) through a 5V Voltage Regulator (7805).

Video: Connecting Power Supply to Breadboard with Regulator

What You’ll Need to Know

To get the most out of this lab, you should be familiar with the following concepts beforehand. If you’re not, review the links below:

Safety Warning: When inserting components on or removing components from a breadboard always unplug power supply first!

Things You’ll Need

A short solderless breadboard with two rows of holes along each side. There are no components mounted on the board.
A short solderless breadboard.
Three 22AWG solid core hookup wires. Each is about 6cm long. The top one is black; the middle one is red; the bottom one is blue. All three have stripped ends, approximately 4 to 5mm on each end.
22AWG solid core hookup wires.
A DC power jack. It pairs with a plug with a 2.1mm inside diameter, 5.5mm outside diameter plug, and has screw terminals on the back so that you can attach wires to it.
A DC Power Jack
5-volt regulator, model 7805. This component has three legs and a tab at the top with a hole in it. If you hold the component with the tab at the top and the bulging side of the component facing you, the legs will be arranged, from left to right, voltage input, ground, and voltage output.
5-volt voltage regulator, model 7805
Wire strippers. The jaws of this wire stripper have multiple hole sizes so that it can strip wires of variable sizes.
Wire stripper tool
Multimeter tool. This tool has a dial to set the function, and three holes into which to plug the testing leads. The leads are currently plugged into the center hole and the right hand hole.
Multimeter tool

Setting up the Breadboard

A solderless breadboard with a 7805 5-Volt voltage regulator mounted on it. There are several rows of holes for components. The holes on the breadboard are separated by 0.1-inch spaces, and are organized in many short rows in the center, and in two long rows down each side of the board. The short horizontal rows in the middle are separated by a center divider. The side rows are usually marked red, for voltage, and blue or black, for ground. On this breadboard, the side rows on the left side are connected to their counterparts on the right side with wires. The voltage regulator is mounted in the top three short rows on the right side of the board. The regulator faces to the left. The row holding the regulator's center pin is connected to the blue or black side row on the right side. The row holding the regulator's bottom pin is connected to the red side row on the right side.
Solderless breadboard with a 7805 voltage regulator mounted on it.

This picture above shows a typical breadboard with a 7805 5-Volt voltage regulator mounted on it. There are several rows of holes for components. The holes on the breadboard are separated by 0.1-inch spaces, and are organized in many short rows in the center, and in two long rows down each side of the board. The short horizontal rows in the middle are separated by a center divider. The pattern varies from model to model; some breadboards have only one strip down each side, others have multiple side rows, and some have no side rows at all.

Related Video: Introduction to breadboards

On each side of the board are two long rows of holes, with a black or a red line next to each row (on many boards, you’ll see a blue row instead of black).  All the holes in each of these lines are connected together with a strip of metal in the back. In the center are several short rows of holes separated by a central divider. All of the five holes in each row in the center are connected with a metal strip as well. This allows you to use the holes in any given row to connect components together. To see which holes are connected to which, take a multimeter and a couple of wires, set the multimeter to measure continuity, stick the two wires in two holes, and measure them with the multimeter. If the meter indicates continuity, then the two holes in question are connected.

What’s Inside A Breadboard?

The image below of the back of a breadboard may help to clear up how the holes on the front of the board are connected. The backing of the board has been removed (don’t remove the backing on your own board! It will make the board useless) to expose the metal strips connecting the holes. You can clearly see the short strips in the center separated by the divider, and the long strips down the side. The detailed photo below illustrates how the holes and strips are related.

The back of a breadboard with the adhesive backing removed, showing the metal strips underneath. Each long row down the side has a continuous metal strip underneath, running vertically down the board. The metal strip connects all the holes in its row. The holes of the short rows are connected with short metal strips running perpendicular to the long strips on the side. There is a break in the middle of the board, so that there is no connection between the right side and the left side.
The back of a breadboard, shown with the backing removed.
A close-up picture of the front of the breadboard. The green lines indicate which holes are connected by a metal strip behind. Each short horizontal group of five holes is connected, and each long vertical group of holes is connected. The vertical groups are not connected to each other or to the horizontal groups, however.
A close-up picture of the front of the breadboard. The green lines indicate which holes are connected by a metal strip behind.

The reason for the center divider is so that you can mount integrated circuit chips, like a microprocessor, on the breadboard. IC chips in a DIP package (Dual In-line Package) have two rows of pins that to which you need to connect other components. The center row isolates the two rows from each other, and gives you several holes connected to each pin, so that you can connect other components.

Powering the Breadboard

Avoid adding, removing, or changing components on a breadboard whenever the board is powered. You risk shocking yourself and damaging your components.

Close-up showing a 7805 5-volt voltage regulator connected to a breadboard. The breadboard is oriented so that the long rows are horizontal this time, and you are looking at the back of the regulator. The regulator is connected to the right-most three rows of the board.
Close-up showing a 7805 5-volt voltage regulator connected to a breadboard.

The regulator in the picture above is used to supply 5 Volts to the two red side rows of the breadboard. You’re looking at the back of the regulator, so that the pins are, from left to right: voltage out, ground, voltage in. Notice that the regulator’s voltage out pin on the left is connected to the red row with a wire. The two black side rows are connected to ground pin of the regulator. These will be your voltage and ground bus rows. They give you lots of convenient places to connect to voltage or ground as needed.

Related Video: Using a voltage regulator on a breadboard

With your board connected like this, you’ll be able to build many different 5-Volt circuits on the board. The last thing you need to add is a power connector to connect 8 – 12 volts DC to supply power for the voltage regulator. The image below shows a power connector connected to the voltage input and ground pins of the voltage regulator.

Related Video: Wiring a power supply using a DC power jack

breadboard_power_jack
Board with 5V voltage regulator and power connector ready to go.

Will it Light? Test Your Understanding

The photos below show an LED and a resistor connected in a breadboard. Some are connected correctly and others are not. Take a guess as to whether the LED will light or not, then click the links below the image to find out. All of the circuits below should realize the same circuit, shown in the schematic below:

Schematic image of a 220-ohm resistor and an LED connected to a 7805 5-volt regulator. At left, there is a power plug. The positive terminal of the power plug is connected to the voltage input of a 7805 voltage regulator. The negative terminal of the power plug is connected to the ground terminal of the regulator. The voltage output of the regulator is connected to a 220-ohm resistor. The other side of the resistor is connected to the anode of an LED. The cathode of the LED is connected to the ground terminal of the regulator.
Schematic image of a 220-ohm resistor and an LED connected to a 7805 5-volt regulator.

Will the LED below light up when you power the board? Take a guess, then click the link below the image to find out.

Photo of a solderless breadboard with a 7805 voltage regulator mounted on it, as in the images above. The regulator is connected to a DC power plug, and the ground and voltage output of the regulator is connected to the voltage and ground bus rows on the right side of the breadboard. The ground and voltage bus rows on the right are connected to the ground and voltage bus rows on the left with wires at the bottom of the board. A 220-ohm resistor is connected to the voltage bus on the left. Its other end is connected to row twelve in the center area. An LED is connected to another hole in row twelve. The other side of the LED is connected to a hole in row fourteen. Another hole in row fourteen connects to the ground bus on the right side of the board.

Try another one. Will the LED below light up when you power the board? Take a guess, then click the link below the image to find out.

Photo of a solderless breadboard with a 7805 voltage regulator mounted on it, as in the images above. The regulator is connected to a DC power plug, and the ground and voltage output of the regulator is connected to the voltage and ground bus rows on the right side of the breadboard. The ground and voltage bus rows on the right are connected to the ground and voltage bus rows on the left with wires at the bottom of the board. A 220-ohm resistor is connected to the voltage bus on the left. Its other end is connected to row twelve in the center area. An LED is connected to a hole in row twelve on the right side. The other side of the LED is connected the ground bus on the right side.

Here’s a third one. Will the LED below light up when you power the board? Take a guess, then click the link below the image to find out.

Photo of a solderless breadboard with a 7805 voltage regulator mounted on it, as in the images above. The regulator is connected to a DC power plug, and the ground and voltage output of the regulator is connected to the voltage and ground bus rows on the right side of the breadboard. The ground and voltage bus rows on the right are connected to the ground and voltage bus rows on the left with wires at the bottom of the board. A 220-ohm resistor is connected to the voltage bus on the left. Its other end is connected to row thirteen in the center area. A red wire connects row thirteen on the left with row thirteen on the right. An LED is connected to a hole in row thirteen on the right side. The other side of the LED is connected the ground bus on the right side.

Here’s another test. Will the LED below light up when you power the board? Take a guess, then click the link below the image to find out.

Photo of a solderless breadboard with a 7805 voltage regulator mounted on it, as in the images above. The regulator is connected to a DC power plug, and the ground and voltage output of the regulator is connected to the voltage and ground bus rows on the right side of the breadboard. The ground and voltage bus rows on the right are connected to the ground and voltage bus rows on the left with wires at the bottom of the board. A 220-ohm resistor is connected to the voltage bus on the left. Its other end is connected to row fifteen in the center area. An LED is connected to two holes in row fifteen of the left side of the board as well. A black wire connects row fifteen on the left side of the board to the ground bus on the right side of the board.

Here’s a final test. Will the LED below light up when you power the board? Take a guess, then click the link below the image to find out.

Photo of a solderless breadboard with a 7805 voltage regulator mounted on it, as in the images above. The regulator is connected to a DC power plug, and the ground and voltage output of the regulator is connected to the voltage and ground bus rows on the right side of the breadboard. The ground and voltage bus rows on the right are connected to the ground and voltage bus rows on the left with wires at the bottom of the board. A 220-ohm resistor is connected to the voltage bus on the right. Its other end is connected to row twenty in the on the right side of the center area. An LED is connected to a hole in row twenty on the right side as well. The other side of the LED is connected row twenty on the left side. A black wire connects row twenty on the left with the ground bus on the left side.

 

Below, the three LED’s are connected in parallel using two rows. They are then connected to power and ground by connecting the rows to the voltage row and the ground row. These three LEDs are in parallel with each other.

Three LEDs mounted on a solderless breadboard. The three LEDs in this photo are connected in parallel using two rows. All of their anodes are connected to row 37 on the left side of the center area. All of their cathodes are connected to row 40 on the left side. They are then connected to voltage and ground through wires connecting the rows to the voltage row and the ground rows on the left side of the board.
LEDS in parallel on a breadboard

Many options are possible using a breadboard, which is what makes them very useful and convenient for building circuits. Once you understand which holes are connected to each other (and which ones are not), you can build any circuit very quickly.

It’s a good idea to keep your circuits neat. When possible, shorten the leads on components so there is no bare metal sticking up from the breadboard. Make sure no wires cross each other with metal touching (this is the biggest source of short circuits on a breadboard). Lay things out as sensibly as possible, so each component of the circuit is near the components it needs to connect to. Use wires when needed to separate parts of the circuit that are crowded together. Use consistent colors of wires when possible; for example, use green or black for ground connections, red for power connections, white or blue for data connections, and so forth. This will make your troubleshooting much easier.

Originally written on July 18, 2014 by Benedetta Piantella Simeonidis
Last modified on August 21, 2018 by Tom Igoe