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Return to Previous Lesson: Traffic Light Video

Lesson Overview:

Now we'll make roads!

Step 1: Introduction

On Conductivity Lane, traffic lights turn on when a car drives by.

How does this work? Each street lamp is connected to a pressure sensor made from aluminum foil; when the car drives over the sensor, the light next to it turns on.

The sensor simply uses the conductivity of aluminum to complete the circuit!

In this lesson, you will build one pressure-activated light. In the video lesson that follows, you will learn how to link multiple lights together to create a road that stretches across the city.

Instead of using the LED modules (like in the row of houses) you will use dome LEDs connected to Circuit Scribe traces with jumper wires.

  1. Delete the switch module by highlighting it and clicking the delete key or pressing the garbage can icon.
  2. Delete the two pad footprints that were under the switch.
  3. Finally, delete the Conductive Pen traces that connected the switch to the pressure sensor.
  4. Press the "next" button below to continue.

Step 2: Simulating the First Light (part 1)

A layout for the first light is in the Workplane.

The LED represents a street lamp. Notice that a resistor is placed in series with the LED.

Since you will use a dome LED (instead of an LED module) you will need a resistor to limit the amount of current running through the LED.

Why don't you need a resistor component for the LED module? (see hint.)

  1. Press the "next" button below to continue.
  2. Stuck? HINT: Look closely at one of your LED modules - there is already a resistor protecting it!

Step 3: Simulating the First Light (part 2)

The pressure sensor is a set of parallel lines with the same spacing as the wheels on your model car. As you drive over, you will press down on a sheet of aluminum foil, connecting the two lines and completing the circuit.

We are using the conductivity of aluminum foil to complete the circuit.

We don't have a conductive material in the simulator - so to try this circuit in the Workplane, the two lines are connected by a switch instead.

In this step, you will place a switch in the circuit.

  1. Open the Modules+ tab and drag a switch into the Workplane.
  2. Place the switch on the two component footprints that are connected to the pressure sensor lines.
  3. Simulate the Circuit by pressing the "Start Simulation" button.
  4. Flip the switch to turn the light on and off. This simulates a car driving over the sensor.
  5. Press the "next" button below to continue.

Step 4: Preparing the Pressure Sensor

In this step you will get your circuit template ready to use in the City of Lights model.

You won't need the switch module, so you can delete it from the Workplane using the instructions below.

  1. Delete the switch module by highlighting it and clicking the delete key or pressing the garbage can icon.
  2. Delete the two pad footprints that were under the switch.
  3. Finally, delete the Conductive Pen traces that connected the switch to the pressure sensor.
  4. Press the "next" button below to continue.

Step 5: Printing the Template

Now you have a template that you can use in your City of Lights model!

Print out your template by clicking "Download PDF" and printing out the file.

Watch the video tutorial in the next lesson to learn how to build your pressure-sensitive roadway.

Next Lesson:Pressure Sensitive Road Video

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