EE 212 Lab

Lab 3: Sine Waves and the Oscilloscope

Prelab 3

The purpose of this lab is become acquainted with the operation of an oscilloscope, function generator, and AC function of your multimeter by investigating the sinusoidal responses of simple RC circuits.

Laboratory Procedure:

1. The Oscilloscope as a Voltmeter

Turn on the oscilloscope, display the trace for Channel (Ch) 1, and check trigger settings (trigger menu => edge, rising (slope), CH1 (source), auto (mode), DC (coupling)). Apply 0V then 5V to Ch 1 and compare the measured voltages to multimeter readings. More accurate measurements may be obtained by using cursors (cursor => voltage or time (type), CH1 or CH2 (source), then move vertical or horizontal position knobs) or the measure mode (top menu button followed by selecting time or voltage measurements).

2. Sine Waves on the Oscilloscope

a) Apply a small amplitude (less than 5V), 1kHz sine wave from your function generator to Ch 1. Adjust the trigger controls to get a stable waveform display. Experiment with the trigger level, slope, and other controls. Finish with the display being triggered as the waveform crosses zero while rising.

b) Experiment with the time base control. Adjust the sine wave frequency on the frequency generator to be exactly 1kHz. Use the cursors to measure the period. What frequency is displayed on the oscilloscope? Is the reading what you expect? Check the period of ten cycles.

c) Adjust the amplitude of the sine wave to be 1V peak-to-peak (p-p). Measure the amplitude of the sine wave using the oscilloscope. What error do you estimate for this amplitude measurement? Measure the amplitude with the AC Volts function of the multimeter. How should and how do these numbers compare?

3. Voltage Divider and Superposition

a) Consider the circuit in figure 1.

b) Consider the circuit in figure 2 where a source and resistor have been added to the circuit shown above in figure 1.

4. Phase Measurements

a) Consider the RC circuit shown in figure 3.

5. Summary

Before you go, make sure you understand the following concepts about the oscilloscope:

Fig. 4

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