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Instrumentation B.S.E.E. Series Seventh Edition. Charles A. Schuler. Lab 2 Introduction to the Oscilloscope. ©2008 The McGraw-Hill Companies, Inc. All rights reserved. Triggering. Triggering. Triggering. Triggering. Time/Division. Time/Division. Time/Division. Time/Division.
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Instrumentation B.S.E.E. Series Seventh Edition Charles A. Schuler Lab 2 Introduction to the Oscilloscope ©2008 The McGraw-Hill Companies, Inc. All rights reserved.
Triggering Triggering Triggering Triggering Time/Division Time/Division Time/Division Time/Division Channel 1 input Channel 1 input Channel 1 input Channel 1 input Volts/Division Volts/Division Volts/Division Volts/Division Volts/Division Power On/Off Power On/Off Power On/Off Vertical Position Vertical Position Vertical Position Vertical Position Oscilloscope Basics
5 Div 4 Div Oscilloscope Settings A typical display with correct settings: Multiply 4 Div x Volts/Div to obtain the peak-to-peak amplitude. Multiply 5 Div x Time/Div to obtain the period.
Oscilloscope Settings Blank display can be caused by: no valid trigger, position error, intensity (or brightness) turned off, and other errors depending on oscilloscope model. Volts/Division error (poor resolution) Volts/Division error (overrange) Vertical Position error Time/Div error (too many cycles displayed) Trigger level set at 0 volts Time/Div error (only a part of one cycle displayed) Trigger level set negative Trigger level set positive
Oscilloscope Settings When is ac coupling used? ac Here is ac ripple riding on a dc signal. To see it better, choose ac coupling and then decrease the Volts/Div setting (this increases vertical sensitivity).
Oscilloscope Settings If a waveform moves on the screen: Check the trigger source, trigger level, trigger mode, trigger slope, and the trigger coupling. An example of a common error: the trigger source is set for Channel 2 but the input signal is fed to Channel 1.
Oscilloscope Quiz The Volts/Div control is set at 100 mV/Div. What is the peak-to-peak amplitude of this signal? 800 mVP-P Using the above, what is the RMS value of this signal? 283 mV The Time/Div control is set at 50 ms/Div. What is the period of this signal? 250 ms Using the above, what is the frequency of this signal? 4 Hz
Oscilloscope Quiz The Volts/Div control is set at 1V/Div. What is the dc amplitude of this signal? -3V 0 V Using the above, what will be displayed if the Volts/Div control is changed to 500 mV/Div? Blank screen Using the above, what will be displayed if the coupling is changed to ac? The waveform will move to the vertical center What does ac coupling do to the dc component of a signal? Removes it
Oscilloscope Quiz What can cause the displayed waveform to move on the screen? No valid trigger