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Usage of Oscilloscope

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Oscilloscope An oscilloscope is a type of electronic test equipment

that allows observation of constantly varying signal voltage

It stores it with 8 bits of precision Then makes a graph of voltage

versus time

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OBJECTIVES

In this module we will see how use an oscilloscope to . . .

Measure direct current (D.C.) voltage and

Measure alternating current (A.C.) voltage

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Oscilloscope Screen The screen has ruled

divisions both horizontally and vertically

The major divisions are marked off in centimeters, the middle lines also have minor divisions every 0.2 of a centimeter

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Input Channel Selector• This area is broken into two parts: the left half for

channel A and the right half for channel B

• In the center of this section lies the mode switch that determines which channel will serve as an input to the scope: A, B or Dual.

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Control Panel The section to the

right of the screen contains the controls necessary to adjust the triggering and sweep time of the waveform

This section is generally used when measuring the period of A.C. waveforms

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Mode Switch

The oscilloscope is capable of measuring voltages from two different sources

The mode switch is used to alternate between sources

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Function Buttons These button are

located at the upper right corner of the generator. Selecting a button sets the type of voltage change over time as a square, triangular or sine wave

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Connecting the Function Generator to the Oscilloscope

• Connect the alligator clip of the black lead from the function generator to the alligator clip of the black lead from the oscilloscope

• Do the same with the red leads

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Position the wave so that the bottom of a wave is lined up with one of the cm markings

Measure the number of cm’s from the bottom of the wave to the top

Multiply the number of cm’s by the volts/cm sensitivity to get the maximum peak voltage

Measuring Voltage

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Changing the Oscilloscope Settings• Watch the wave form change

as you change the volts/cm dial to 10 and the sweep time/cm dial to 5 ms/cm

• Adjust the triggering level knob if necessary to get a stable image

• We should still be reading 20-25 V and 100 cycles/sec

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Using the 5X Feature on Horizontal Knob

Pull the horizontal knob OUT

Notice that it spreads out wave magnifying it 5 times. We can use this feature to zero in on part of the wave

Push it back in before continuing

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Make sure the picture is centered on the screen using the vertical and horizontal position dials

Flip the source switch to internal If necessary, adjust the triggering level knob until you

get a steady picture Adjust the intensity and focus to get a good sharp

image

Summary Measuring AC Voltage

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