Oscilloscope: Measuring DC Voltages Experiment 17 Name:_________________________ Date:_______________________ Objectives: To learn to use the oscilloscope to measure dc voltages in a series circuit. To determine the degree of accuracy at which dc voltages can be measured using an oscilloscope, as compared to the Digital Volt Meter (DMM) Text Reference Section 6.1 and 6.2 Materials Required MultiSim Downloaded Experiment 17 Introduction The oscilloscope can be used as a dc voltmeter. A DMM is usually more accurate for this function since the accuracy of the Oscope depends on the volts/division setting used and how the voltage level is interpreted. Whenever measuring any voltage amplitude or value with the oscilloscope, always use the lowest volt/division setting that will not cause the trace to deflect off of the screen. Remember that the zero-volt point can be placed anywhere on the screen by adjusting the Y position in MultiSim (or if using a real Oscope by moving the vertical position control with the AC/GND/DC switch in the GND position). Procedures: 1. Download Experiment 17 2. View Movie about Experiment 17 3. Using MultiSim open file Experiment_17.mst 4. Insure Oscope settings are as follows a. Scale: 5 volts for channel A and B b. X and Y positions to zero c. The following buttons should be active: YT, DC, DC, Auto 5. Press F5 to activate Circuit 6. Measure voltage at Test point A with channel A of Oscope. a. Voltage measured ___________7. Measure voltage at Test point C with channel B of Oscope. a. Voltage measured ____________ 8. Measure voltage at test point C with DMM. a. Voltage measured ____________ 9. View Movie addressing the Add/Subtract method of measuring voltage across a component using an Oscilloscope. 10. Use the Oscilloscope to measure all of the voltages listed in table 17-1 11. Use the DMM to confirm all of the reading from step 10. Document the DMM values in Table 17-1. Table 17-1 Voltage Oscilloscope Measurements DMM (voltage) Measurements VAD VDA VAB 1.8 1.846 VBA -1.8 -1.846 VBC VCD VDC These values were measured in movie from step 9 above.Questions: 1. If the trace on the Oscope deflects up when measuring a dc voltage, the polarity of the voltage is ___________. 2. If the trace deflects 2.4 divisions when the scale is set to 2 volts, what voltage is being measured? __________________________ 3. In MultiSim if the Y position was adjusted to the very bottom of the screen and the scale was set to 5 volts per division, what is the maximum voltage that could be measured and have the trace remain on the screen? ___________________________________ 4. If -20 volts is to be measured and the Y position is set to zero, what should the Scale (volts/division) be set to? __________________________________ 5. Which device gave a more accurate measurement, the Oscilloscope or the DMM?