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Lab 05: Resistor Networks

Objectives 

  • Explore parallel and serial resistance.
  • Use the breadboard to build different circuits.
  • Practice using the resistor color code. 

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Before You Begin 

Download this Fritzing project. It contains a simple program that makes your Arduino a volt meter. You will use the meter to measure voltages in resistor networks. The project also shows the breadboard layout of the first part.

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Part 1: Resistor Voltage Divider

Build a resistor divider as shown. Pick resistors at randomAnswer the following questions: 
  1. What is the color code of R1? What is its value? 
  2. What is the color code of R2? What is its value? 
  3. Use the voltage divider equation to determine the voltage between R1 and R2.  Show your work.
Once you have calculated the above download the provided program into Arduino. The program measures the voltage between the resistors using the analog to digital converter (ADC) on Arduino. Arduino can measure analog voltages on all of the pins labeled with An
       4.  What does the Arduino report as the voltage?
       5.  If it's different than your calculation how can you explain it?

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Part 2: Variable Resistor Voltage Divider 

Resistor dividers are one of the most important circuits you will build. If you've ever used an electronic device with any kind of knob, slider or dial the control was most likely a variable resistor (called a potentiometer) connected to another resistor in the voltage divider configuration. Use the potentiometer in your kit to create a variable divider as shown.

NOTE: Use a 10k ohm resistor as shown in the picture.
  1. When your circuit is built carefully turn the knob all the way to the left. Write down the reading from Arduino. 
  2. Carefully turn the knob all the way to the right. Write down the reading from Arduino. 
You now have voltage readings for the maximum and minimum resistance on the knob. Use the voltage divider equation to calculate R2
in 1. and in 2. 

Questions:
  1. What were the readings for step 1?
  2. What were the readings for step 2?

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Part 3: Squeeze Sensor 

Replace the potentiometer in Part 2 with the pressure sensor in your kit. Watch the change in the voltage when you squeeze the sensor.

Questions:
  1. What is the reading without squeezing?
  2. What readings do you get while squeezing?

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Grading:  12 points Total - DO NOT SUBMIT CODE - Submit a text file with answers to the questions in each Part
Part 1:  4 points    5 questions
Part 2:  4 points    2 questions
Part 3:  4 points    2 questions

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