Introduction: Prototype With a Breadboard

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

Return to Previous Lesson: A Map of Your Circuit

Lesson Overview:

Now we'll learn to make simple prototype circuits with a breadboard!

Step 1: Breadboarding

In this lesson you will learn how to use a breadboard, which appears in the Workplane to the right. The breadboard has hundreds of holes - also called sockets - that you can plug wires and components into. On the inside there is a pattern of wires that connects some of the sockets together. You can quickly make connections between components by plugging them into the sockets in the board.

Breadboards are used for circuit "prototyping," a process of testing out a new design before producing a final project or product without having to solder. Most engineers use prototypes. If you were making a new kind of chair out of wood, you might make a prototype out of cardboard first.

But why is an electronics prototyping tool called a breadboard? Electrical components used to be a lot bigger and bulkier than they are today. When engineers prototyped circuits they would find a wooden cutting board and press thumb tacks or nails into it to connect wires.

Breadboards have come a long way! The one that you are using is a virtual breadboard within the circuit editor.

  1. Continue to the next step.

Step 2: Looking Inside the Breadboard

Try moving your mouse over the sockets on the virtual breadboard. Some of the sockets will turn green. This means that the sockets are connected by a wire inside the board.

The picture below shows all of the internal connections in the breadboard.

At the top and bottom, you can see two horizontal rows (blue and red). These long rows are called “rails.” All of the blue sockets on the top are connected to each other. The same is true for bottom row of blue sockets and both rows of red sockets.

The image below shows the pattern of connections inside the breadboard.

  1. Continue to the next step.

Step 3: Understanding Breadboard Coordinates

If you want to tell someone an exact location on the board, you can tell them a number-letter coordinate, like C25. It’s a little like a chess board! Here’s how it works:

The upper 5 sockets of each horizontal row are labeled A, B, C, D, and E. The lower 5 sockets are labeled F, G, H, I, and J.

Columns of sockets are labeled with numbers 1 to 60. These numbers run horizontally across the board and only every 5th column has a number written on it.

In the picture below, socket C3 is highlighted.

  1. Can you locate socket B57? What other sockets is it connected to? (see hint)
  2. Press the button below to continue.
  3. Stuck? HINT: A, C, D, and E 57

Step 4: Connecting the Power Rails

The red and blue horizontal rows or “rails” are usually connected to the battery. These are called power rails because any socket on either of these two rails has a direct connection to the battery. When the battery is connected, both entire rows of sockets become a voltage source for the breadboard.

To get started, add a battery to the bottom rails.

  1. Add a 9V battery to your Workplane by clicking on the Components+ menu and dragging the 9V battery up.
  2. Move the battery terminals so they overlap with the bottom rails below the number “50.” When you successfully connect the battery, the sockets will be highlighted with a red spot.
  3. Press the "next" button below to continue.

Step 5: Wiring Up a Breadboard

Notice that the blue rails on the breadboard have a blue (-) sign next to them. Likewise, the red rails have a red (+) sign. With the battery attached, the negative terminal (black) of the battery is connected to the negative rail and the positive terminal (red) is connected to the positive rail.

The battery schematic symbol shows where the red and blue rails are connected.

Let’s create voltage rails from the top red and blue rows. We do this by connecting wires between the top and bottom rails.

  1. Move your mouse over the top red rail, and notice that the entire row is highlighted.
  2. Click on a red socket and drag a wire down to the bottom red rail to connect them. Click once to release the wire.
  3. Now hover over the top blue rail, and drag a wire down to the bottom blue rail.
  4. You can change the color of the wire by clicking on it, then selecting a new color from the dialog box. You might want to change the color of wire connecting the blue rails to match.
  5. Press the "next" button below to continue.

Step 6: Adding a Light Bulb

It’s time to try adding an output component - the light bulb! Remember you need to form a complete loop between the light bulb and battery. In this step we create most of that loop through the internal wires of the breadboard.

For example, instead of connecting wires directly from the light bulb terminals to the battery terminals, you’ll connect the light bulb to the voltage rails.

Using our car analogy, connecting a component to a voltage rail with a wire is like taking a shortcut home!

  1. Click the Components+ button and add a light bulb to the Workplane.
  2. Place the bulb in the middle of the breadboard in sockets A26 and A27.
  3. Clicking your mouse to create a wire, connect a breadboard socket under the left leg of the bulb with the red voltage rail at the bottom. You can use any socket on the red rail!
  4. Connect a socket under the right leg of the bulb with the blue ground rail at the bottom.
  5. Simulate the circuit by clicking the \u201cStart Simulation\u201d button.
  6. Can you follow the current path that starts at the battery, goes through the light bulb, and back to the battery? Notice that many of the wires in this circuit are inside the breadboard!
  7. Press the "next" button below to continue.
  8. Stuck? HINT: You change the color of the wire to match the color of the rail using the window that pops up when you click on the wire.

Step 7: Understanding the Breadboard

In this part of the lesson you will practice forming connections on the breadboard using the letter and number coordinates. At the end you’ll reveal a secret image!

  1. Pause the simulation by pressing the Stop Simulation button
  2. Delete the wires by clicking on each one and pressing the garbage can button
  3. Make sure the bulb is connected to the breadboard at coordinates A26 and A27.
  4. Connect a wire from B27 down to the blue (negative, ground) rail under the number 35.
  5. Connect a wire from B26 to I-22
  6. Connect a wire from J22 to E35
  7. Connect a wire from D35 to D20
  8. Connect a wire from E20 to I-32
  9. Finally, connect a wire from J32 straight down to the red (positive) rail to complete the circuit.
  10. Simulate the circuit! What shape appeared in the wires? (see hint) Can you follow the current path from the battery, through the wire and light bulb, back to the battery?
  11. Press the "next" button below to continue.
  12. Stuck? HINT: The wires form a star pattern!

Step 8: Making Your Own Connections

Did you see a star appear on the breadboard? Check out the image below for the answer.

In your remaining time, try creating your own message with colored wires! Make sure the wires form a complete loop by simulating your circuit and seeing if the light bulb lights up.

Congratulations, you have completed your first breadboard circuit! In the next lesson you will learn how to slow down current flow to change the brightness of light bulbs and LEDs.

Next Lesson:Light Bulb vs. LED and Limiting Current

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