1. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. In this lesson you will learn: How a potentiometer works as a variable resistor and a voltage divider How to use a multimeter as an ohmmeter, voltmeter and ammeter How to use Ohm’s Law How to predict values of dependent variables How to calculate experimental error CAN I MAKE MY OWN SENSOR 1 Overview

2. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. In this investigation, you will learn how a potentiometer can be used in an electronic circuit as a variable resistor or as a voltage divider. Students will construct simple electronic circuits that use a DC voltage source, a fixed value resistor and a rotary potentiometer. This investigation consists of two activities. CAN I MAKE MY OWN SENSOR 1 Overview

3. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Part 1: Potentiometer as Variable Resistor Set R(pot) to 1st value in Table 1-2 (125 Ohms) CAN I MAKE MY OWN SENSOR 1 Lesson

4. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. CAN I MAKE MY OWN SENSOR 1 Lesson Replace the potentiometer back in circuit and measure current (8.1 mA)

5. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. CAN I MAKE MY OWN SENSOR 1 Lesson Part 2: Potentiometer as Voltage Divider Measure Component Values Battery (unloaded)

6. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. CAN I MAKE MY OWN SENSOR 1 Lesson Measure Component Values (potentiometer’s maximum resistance)

7. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. CAN I MAKE MY OWN SENSOR 1 Lesson Connect Circuit (battery is connected across the potentiometer.)

8. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. CAN I MAKE MY OWN SENSOR 1 Lesson Turn potentiometer dial to the required output voltage reading. In this case, Vout = 4.5 Volts)

9. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Measure the potentiometer’s resistance corresponding to R2 CAN I MAKE MY OWN SENSOR 1 Lesson