# Build a Simple Circuit

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## Introduction: Build a Simple Circuit

The following information is a single lesson in a larger project. Find more great projects here.

Lesson Overview:

Now we'll build our first simple circuit!

## Step 1: Project Description

This is your first interactive circuit, using a button, a resistor and an LED.

￼￼￼￼￼￼￼￼￼You’re going to use the Arduino in this project, but only as a source of power. When plugged into a USB port or a 9-volt battery, the Arduino will provide 5 volts between its 5V pin and its ground pin that you can use.

5V = 5 volts. You’ll see it written this way a lot.

In the circuit schematic, shown below, a button is used to create and break a connection that allows current to flow through the LED and resistor.

1. Continue to the next step.

## Step 2: Connecting Power

Note: if you are using a physical kit, unplug any battery or USB cable connected to the board! The Arduino should not be receiving power while you are building the circuit.

In this step, you will provide power to the breadboard "voltage rails" from the Arduino. The rails are the four horizontal rows of sockets at the top and bottom of the breadboard (red = power, black = ground).

As the picture shows, it’s helpful to keep your wire color consistent (red for power, black for ground) throughout your circuit.

1. Connect a wire between the 5V pin on the Arduino, and the red power rail on the breadboard.
2. Next connect ground (GND) on the Arduino to the black ground rail with a wire.
3. Change the color of the second (GND) wire to black by highlighting it and using the drop down menu.
4. Continue to the next step.

## Step 3: Add LED and Button

Now that you have power on your board, you can place the button and LED.

The button will sit across the center in one direction. In your kit, the bend in the button legs point to the center of the board. In the simulator, the button is already oriented the right way!

When assembling circuits, you can use the picture directly as a guide and find more specific instructions below. The circuit picture below is zoomed in to show the breadboard in more detail.

1. Drag the LED and button components into the Workplane from the Components + menu.
2. Add the button across the center break in the breadboard near column 9.
3. Add the LED to the breadboard in row E, leaving a couple sockets between the LED and button. Pay attention to the length of the LED terminals -- place the longer terminal towards the right.
4. Continue to the next step.

## Step 4: Add Resistor and Wires

You will finish the circuit in this step using a 220-ohm resistor and wires.

You will set the resistor value by highlighting the resistor and using the dropdown menu. You can review the resistor color code in the project Spaceship Interface. In fact, you will need this code to identify the resistors that come in your kit, since they are not labeled with numbers!

1. Drag a resistor into the Workplane from the Components + menu. Change its value to 220 ohms by highlighting it and using the dropdown menu.
2. Use the resistor to connect the left terminal of the button with the ground rail on the breadboard (black).
3. Connect a wire from the right terminal of the button to the left (shorter) terminal of the LED.
4. Connect a wire from the right (longer) terminal of the LED to the 5 volt rail on the breadboard (red).
5. Continue to the next step.

## Step 5: Use It! (simulator)

Once the circuit is complete, you can try simulating it!

1. Click "Start Simulation" button is in the upper right corner of the Workplane.
2. Try pressing the button! When you press the button, you should see the LED light up.
3. Continue to the next step.

## Step 6: Use It! (Arduino Kit)

Now you can try out your simple button circuit with the Arduino kit! Start by plugging your Arduino board into a USB port on your computer.

1. Plug in your Arduino Uno.
2. Try pressing the button! When you press the button, you should see the LED light up.
3. Congratulations, you just made a circuit!
4. Continue to the next lesson to learn how to add another button to the circuit.

Next Lesson:Build a Series Circuit

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