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Lesson Overview:

Now we'll learn the layout of circuits!

Step 1: Introduction

Circuits are just about everywhere in our daily lives. They take on a lot of different shapes so they can be stuffed into different kinds of devices. A flat circuit board in your computer would look a lot different from the big wires and light bulb in a lamp.

All circuits have some things in common, though. They all need the following parts:

Energy: The circuits need a source of energy to make electrons move around the circuit. We use batteries in this course.

Components: These are the parts of the circuit that use electrical current, like lights or motors, or they modify it (start, stop, slow down or direct the flow of current).

Wires: The conductive material that connects components to each other.

  1. Continue to the next step.

Step 2: Comparing Circuits to Streets

Take a look at the circuit in the Workplane. You can think about electrical current as cars driving around a neighborhood.

1) Current begins from the (+) end of the battery

2) it flows through the red wire

3) it flows through the bulb, lighting it up

4) and it flows through the black wire back to the (-) terminal of the battery.

If you are driving around town, you would start at home (battery), drive down streets (wires), encounter stop signs and speed bumps (components), and return home (the battery).

  1. Simulate the circuit by pressing the “Start Simulation” button
  2. Can you visualize the flow of current through the circuit? Trace it with your cursor.
  3. Press the "next" button below to continue.

Step 3: Drawing a Map of Your Circuit

If a circuit is like a neighborhood, a circuit diagram, or “schematic,” is like the map of your circuit.

Components, like the battery and light bulb, are represented as symbols and the wires are represented as lines between them.

When you create a circuit in the Workplane, you can look at its schematic by clicking the “Schematics View” button.

  1. Click on the “Schematics View” button to look at a map of the light bulb circuit.
  2. Drag the symbols around the Workplane, and try to rearrange the circuit schematic to look like our picture.
  3. Press the "next" button below to continue.

Step 4: Creating a Button Circuit (part 1)

Return to the Breadboard Editor by pressing the “Breadboard View” button.

Let’s modify the light bulb circuit to create a circuit with a button. In this circuit, the light will turn on and off when you press down on the button – a lot like the way a lamp works!

  1. Click on the black wire to highlight it. Delete this wire by pressing the delete key on your keyboard or clicking the trash can button.
  2. Click on the Components + button to view the component library.
  3. Find the pushbutton and drag it into the Workplane. Position the button to the right of the light bulb.
  4. Connect a wire from the right terminal of the light bulb to the bottom left terminal of the button (Terminal-11).
  5. Finally, connect a wire from the bottom right terminal of the button (Terminal-21) to the black (negative) terminal of the battery.
  6. Press the "next" button below to continue.

Step 5: Creating a Button Circuit (part 3)

A circuit requires a continuous path for current to flow through. When the button is off, there is a gap in the circuit so current can’t flow. When you press the button, the gap is filled!

Hover your cursor over each terminal of the button. The terminals are numbered 11, 12, 21, and 22.

The diagram below shows that Terminal-11 is always connected to Terminal-12.

Likewise, Terminal-21 is always connected to Terminal-22.

When the button is pressed, the two sides of the button are linked together by the button's plunger. In the simulator, when the button is turned on, a small green indicator comes on too.

The diagram below illustrates what happens inside the button when it is off (top row) and when it is pressed (bottom row).

  1. Hover your cursor over the four button terminals. Which terminals are used in the circuit? (see hint.)
  2. Press the "next" button below to continue.
  3. Stuck? HINT: Terminal-11 and Terminal-21 are used.

Step 6: Creating a Button Circuit (part 2)

Use the instructions below to try your button circuit.

There are two ways to use the button: as a momentary button or a latching button.

Momentary: Simply press and release the button with your mouse. The button is turned on while you are holding it, and turned off when you release it.

Latching: Hold down the shift key while clicking the button. When you release the button, it stays on! Click it again to turn the button off.

  1. Try simulating the circuit by pressing the “Start Simulation” button. The light bulb is off.
  2. Now click on the button and release it. What happens?
  3. Next try holding down the shift key while pressing the button and then release the button. Does the light stay on?
  4. Press the "next" button below to continue.

Step 7: Interpreting Circuit Schematics

In the circuit that we just created, you might notice that the component symbols look like the components!

-The bulb symbol looks a lot like a round light bulb. We colored ours yellow to make it more clear, but in the Schematics view, it is a circle with an X through it.

-The Pushbutton looks like a gap in the circuit with a plunger over it. This is exactly what is happening inside the component. A gap in the circuit closes up when you push down on the button.

-The battery symbol also looks like the structure of a battery – you’ll learn more about this in Lesson 5.

  1. Stop the circuit simulation by pressing the “Stop Simulation” button.
  2. Press the “Schematics View” button. Try to rearrange the component symbols to match our illustration, above.
  3. Press the "next" button to continue.

Step 8: Understanding Circuits

Congratulations on making a button and bulb circuit! This is very similar to a circuit that you would find in a flashlight or a lamp.

Let’s review a few things that all circuits need:

1) A source of energy! We will use batteries in this course.

2) Circuit components. They use or modify the flow or current.

3) A complete loop for current to flow around. We form connections using wires.

In the next lesson you will learn how to create circuits in a new way: using a breadboard.

In the next lesson you will learn to make circuits with a breadboard!

Next Lesson:Prototype with a Breadboard

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