# Row of Houses

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## Introduction: Row of Houses

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

here.

Lesson Overview:

Now we'll add a row of houses to our city!

## Step 1: Introduction

A neighborhood on Conductivity Lane has three houses that all draw power from the same 9V battery.

1. Continue to the next step.

## Step 2: Connecting Lights in Parallel (part 1)

The lights are connected to this power source in parallel.

You may have seen a parallel circuit exercise before. It means that components share a connection at two terminals. In this case, you can turn off or remove any LED from the circuit and the rest stay on! That's pretty important for a row of houses - you would want to be able to control each house light independently! Look at the circuit in the Workplane. Can you figure out how to connect a row of LEDs to the battery, in parallel? (Instructions are in the next step)

1. Select the conductive ink pen.
2. Try connecting the LEDs in parallel and simulating the circuit.
3. Continue to the next step

## Step 3: Connecting Lights in Parallel (part 2)

Follow the instructions below to connect the LEDs in parallel.

1. If the simulation is running, turn it off, then select the conductive ink pen.
2. Use the pen to connect the positive (+) top terminal of the battery to the top terminals of each LED.
3. Then use the pen to connect the negative (-) bottom terminal of the battery to the bottom terminals of each LED.
4. Simulate the circuit! All three lights should turn on.
5. Continue to the next step.

## Step 4: Turning Lights on and Off

In the City of Lights model that you will create, each of these LEDs will have a house on top of it.

Since the lights are in parallel, each light can be turned on and off independently. Try it out for yourself! Stop the simulation and drag one LED off of the circuit at a time to see if all of the other lights are still connected.

1. Stop the simulation.
2. Drag one LED off of the circuit to reveal its circuit pads, still connected to the circuit.
3. Simulate the circuit again. Do the remaining two lights stay on?
4. Try it with the other LEDs! You can even drag two off of the circuit at the same time.
5. Continue to the next step.

## Step 5: Providing Voltage Rails

Try taking all three LEDs off of the circuit. What remains?

You have the battery with a long circuit trace coming off each. These are called "voltage rails." The top line is always at 9 volts and the bottom line is always at 0 volts.

When an LED is connected anywhere along these rails, there is a 9 volt drop across it.

In your city model, you can think of the battery as providing a 9 volt and 0 volt rail to each house. The resident of that house can plug different components into them - like lights!

1. Stop the simulation.
2. Remove all of the LEDs from the circuit, and look at the voltage rails!
3. At this point, you can put all three LEDs back in place.
4. Continue to the next step.

## Step 6: Switch Challenge (part 1)

Since each house can control its LEDs independently, let's try adding a switch for each light!

You will start by deleting the top voltage rail to make room for three switches.

Can you figure out the rest?

1. Delete the top voltage rail (9V).
2. "Click Module+ and drag three SPST switches into the Workplane and place them above the three LEDs.
3. Try using the conductive pen to complete the circuit. Each LED is operated by its own switch.
4. Continue to the next step.

## Step 7: Switch Challenge (part 2)

The instructions for connecting the switches are below.

When your circuit is complete, start the simulation and try flipping each switch.

1. Select the conductive ink pen.
2. Draw a trace between the first switch and first LED. Do the same with the second and third switch-LED pairs.
3. Connect the positive (+) top terminal of the battery to the top terminal of each switch.
4. Start the simulation and flip each switch on and off!
5. Continue to the next step.

## Step 8: Preparing the Circuit Template

In the city model, you will only need to put lights inside the houses (switches are optional).

Right now the lights are little too close together, so you will use every-other-LED and put two circuit templates next to each other. Use the instructions below to get the template ready for printing.

1. Stop the simulation if it is currently running.
2. Delete the three switches from the circuit, as well as their component footprints (round gray circles).
3. Delete the circuit trace leading from the positive (+) terminal of the battery.
4. Connect the positive (+) terminal of the battery to the top terminals of the LEDs again.
5. Delete the first and third LEDs as well as their component footprints. You might have to zoom in a little to select the footprints.
6. Keep the voltage rails that are hanging off the edge of the circuit! You will need this when you build the city model.
7. Continue to the next step.

## Step 9: Printing Out Your Template

Now you are ready to print out the circuit template!

In the next video tutorial you will learn how to piece several templates together using jumper stickers and then light up a row of houses!

We use paper house template that we found at littleglitterhouses.com. There are many more that you can search for, or you can design your own!

1. Make sure you select the appropriate paper size using the "select paper" dropdown menu.
2. Print the circuit template by first clicking "Download PDF" and opening the file. Print at least two copies.
3. Continue on to the video tutorial!

In the next lesson you will see more about the row of houses!

Next Lesson:Row of Houses Video

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