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Introduction to the Oscilloscope
Introduction to the Oscilloscope
OBJECTIVES
OBJECTIVES
Lab Safety
Lab Safety
Example Electrical Signal
Example Electrical Signal
The Theory
The Theory
What are the major components
What are the major components
What is the purpose of an oscilloscope
What is the purpose of an oscilloscope
What do we now know about the scope
What do we now know about the scope
Oscilloscope: Screen
Oscilloscope: Screen
Oscilloscope: Control Panel
Oscilloscope: Control Panel
Oscilloscope: Input Channels
Oscilloscope: Input Channels
Equipment: Function Generator
Equipment: Function Generator
The Setup
The Setup
Simple Signals We Can Measure
Simple Signals We Can Measure
Turning on the Oscilloscope
Turning on the Oscilloscope
Channel Mode Switch
Channel Mode Switch
Cables
Cables
Making Your First Connection
Making Your First Connection
Time Per Division Dial
Time Per Division Dial
Horizontal Position
Horizontal Position
Adjusting the Display
Adjusting the Display
At this point
At this point
Measuring a DC signal
Measuring a DC signal
Measuring a Direct Current Voltage
Measuring a Direct Current Voltage
Volts/Div Dial
Volts/Div Dial
Setting Up the DC Power Supply
Setting Up the DC Power Supply
Setting Up the DC Power Supply
Setting Up the DC Power Supply
Setting Up the DC Power Supply
Setting Up the DC Power Supply
Setting Up the DC Power Supply
Setting Up the DC Power Supply
Setting Up the Power Supply
Setting Up the Power Supply
Observing the DC Output
Observing the DC Output
Important Observations at This Point
Important Observations at This Point
Finishing Up the DC Measurements
Finishing Up the DC Measurements
Measuring an AC signal
Measuring an AC signal
Measuring a Time Varying (A
Measuring a Time Varying (A
Function Generator Controls: Wave Shape
Function Generator Controls: Wave Shape
Function Generator Controls: Frequency Range
Function Generator Controls: Frequency Range
Function Generator Controls
Function Generator Controls
Function Generator Controls: Amplitude Dial
Function Generator Controls: Amplitude Dial
Making the Connection
Making the Connection
Making the Connection
Making the Connection
Making the Connection
Making the Connection
Triggering
Triggering
Triggering
Triggering
Triggering
Triggering
Triggering: Setup
Triggering: Setup
Measuring the Voltage
Measuring the Voltage
Measuring the Frequency
Measuring the Frequency
Mixing It Up
Mixing It Up
Changing the Frequency Generator
Changing the Frequency Generator
Summary: Measuring A.C. Voltage
Summary: Measuring A.C. Voltage
Summary: Measuring AC Voltage
Summary: Measuring AC Voltage
Your turn
Your turn
Oscilloscope Problem
Oscilloscope Problem

: Introduction to the Oscilloscope. : Robert Proie Jr.. : Introduction to the Oscilloscope.ppt. zip-: 9426 .

Introduction to the Oscilloscope

Introduction to the Oscilloscope.ppt
1 Introduction to the Oscilloscope

Introduction to the Oscilloscope

Professor Ahmadi ECE002

George Washington University

2 OBJECTIVES

OBJECTIVES

Lab Safety Review Electrical Signals Quick Overview Explain Common Lab Equipment Oscilloscope, Function Generator, etc. Learn how to use an Oscilloscope to: Measure D.C. (Direct Current) Voltage Measure A.C. (Alternating Current) Voltage

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3 Lab Safety

Lab Safety

No Food or Drinks Use Common Sense In Case of Emergency If electrical, turn off the main circuit breaker Call UDP at 4-6111 Notify the staff in Room 304

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4 Example Electrical Signal

Example Electrical Signal

Above, this sine wave represents a voltage that is changing over time So at time=2.5s, what is the voltage? And again at 10seconds?...15 seconds? We can see that as time moves forward, the voltage is changing Is this an AC or DC voltage? What does that mean?

5 2.5 -2.5 -5

Y=VOLTAGE (volts)

X=TIME (seconds)

5 10 15 20

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5 The Theory

The Theory

Why do we need an oscilloscope?

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6 What are the major components

What are the major components

Display Screen Displays an input signal with respect to time. Control Panel Adjusts how the input signal is displayed.

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7 What is the purpose of an oscilloscope

What is the purpose of an oscilloscope

The purpose of an oscilloscope is to measure a voltage that changes with time and show it in a graphical format

Here is the oscilloscope in our lab

-Notice the X-Y axes

2) Here is our alternating voltage signal from before

3) If we measure our signal with the scope, it would look like this!

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8 What do we now know about the scope

What do we now know about the scope

What must the X-Axis represent? What must the Y-Axis represent?

Sowhat do the dials do?

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9 Oscilloscope: Screen

Oscilloscope: Screen

Notice that the screen has ruled divisions both horizontally and vertically. The axes can be scaled, for example If each vertical division is worth 5 seconds, what time is represented by this point? If each horizontal line represents 1 volt, what voltage is represented by this point?

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10 Oscilloscope: Control Panel

Oscilloscope: Control Panel

The section to the right of the screen contains the controls necessary to adjust how the waveform is displayed on the screen. The controls allow you to alter the sweep time, amplitude, and triggering method. (Note, these topics will be discussed later)

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11 Oscilloscope: Input Channels

Oscilloscope: Input Channels

How do we get the voltage into the scope? This area is broken into two parts Left Half for Channel 1 (X) Right Half for Channel 2 (Y) In the center is a switch that determines which channel will serve as the input to the scope: 1, 2, Dual or Add. Why would we want more than 1 channel?

Channel 2

Channel 1

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12 Equipment: Function Generator

Equipment: Function Generator

Purpose: Produces waves of different Shapes (sinusoidal, square, etc.) Amplitude Frequency Several available in the lab, but we will use the one built into the Instek Oscilloscope. (Shown)

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13 The Setup

The Setup

In this section, we will power on the oscilloscope and set it up to display a signal connected to the CH1 input.

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14 Simple Signals We Can Measure

Simple Signals We Can Measure

Is this signal changing over time? What do we call this type of signal? If we made a chart at the different time intervals

5 2.5 -2.5 -5

Y=VOLTAGE (volts)

X=TIME (seconds)

5 10 15 20

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15 Turning on the Oscilloscope

Turning on the Oscilloscope

Press the POWER button located below the bottom right corner of the Oscilloscopes screen. Set the Channel Mode to CH1. Set the Trigger Mode to AUTO. A green line or dot should appear on the screen. If not, try adjusting the Intensity or Position dials.

Set Trigger To Auto

Set Mode to CH1

Press Power

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16 Channel Mode Switch

Channel Mode Switch

The oscilloscope is capable of measuring voltages from two different sources. The channel mode switch is used to alternate between these sources. For this lab, we will be using Channel 1, so set the switch to the CH1 position.

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17 Cables

Cables

We will use three types of connecters in this lab. BNC Banana Mini-Grabber

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18 Making Your First Connection

Making Your First Connection

Obtain a BNC cable, Mini-Grabber attachment and connection them together. Connect the free end of the BNC cable to CH1 on the oscilloscope

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19 Time Per Division Dial

Time Per Division Dial

Find the Time/Div dial on the oscilloscope. This dial controls the amount of time per centimeter division. Adjust to dial to 2 milliseconds per centimeter.

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20 Horizontal Position

Horizontal Position

Adjust the Position dial for Channel 1 to center the horizontal line.

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21 Adjusting the Display

Adjusting the Display

If the display is difficult or out of focus, the Intensity and Focus dials can be used to adjust it. The INTEN dial controls the brightness of the line. The FOCUS dial controls the sharpness of the line. Take a moment to adjust each one and notice the difference.

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22 At this point

At this point

The channel mode should be set to 1. The TIME/DIV should be set to 2mS per centimeter. A BNC cable should be connected to the channel 1 input. The other end should have a free Mini-Grabber connection. The Trigger Mode should be set to AUTO. The Oscilloscope should be ON. The intensity and focus should be adjusted so the line is clear to see. The channel 1 position dial should be adjusted so that the green line is centered on the screen.

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23 Measuring a DC signal

Measuring a DC signal

In this section, we will use an external DC POWER SUPPLY to create a DC signal to measure with the oscilloscope

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24 Measuring a Direct Current Voltage

Measuring a Direct Current Voltage

Set the VOLTS/DIV to 1 by adjusting the outer dial. Turn the inner dial all the way to the right, which will put it in the calibrated position. Switch the AC-GND-DC switch for channel 1 to DC.

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25 Volts/Div Dial

Volts/Div Dial

The volts/div dial tells you the number of volts to be represented by each centimeter vertically on the screen. Here the outer dial is set to one, so each centimeter equals one volt.

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26 Setting Up the DC Power Supply

Setting Up the DC Power Supply

This DC Power supply is capable of generating voltages from -25V to 25V. For this lab, we will be using the 6V supply terminals. First, press the Power Button to turn it on.

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27 Setting Up the DC Power Supply

Setting Up the DC Power Supply

Press Output On/Off once to turn on the output. Press the +6V button to tell the power supply that we want to alter the output from the 6V terminals. Once done, your screen should look the same as it does on this slide.

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28 Setting Up the DC Power Supply

Setting Up the DC Power Supply

The dial on the right hand side is used to increase and decrease the output value. The arrows under the dial are used to determine which digit is affected by the dial.

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29 Setting Up the DC Power Supply

Setting Up the DC Power Supply

Press the left arrow until the digit to the left of the decimal point is blinking. Use the dial to increase the display value to 3 volts as shown. Note: You can safely ignore the value of the right most digit for this experiment.

Press this arrow to Select the desired digit

This is the digit we want to adjust

Rotate this dial to alter the output value.

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30 Setting Up the Power Supply

Setting Up the Power Supply

Now it is time to connect the DC Power Supply to the Oscilloscope. Locate Mini-Grabber connectors on the other end of the cable that was previously attached to the Oscilloscope. Attach the connecters to the DC Power Supply as shown. Note: You may need to partially unscrew the terminal knobs before connecting the Mini-Grabbers.

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31 Observing the DC Output

Observing the DC Output

Once connected, the line on the Oscilloscope display will move up three divisions. At 1Volt/Division, this equals 3 Volts. Adjust the DC Power Supply output and the Volts/Division dial and observe the changes.

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32 Important Observations at This Point

Important Observations at This Point

Volts/Division Dial It does not change the voltage. It is a sensitivity dial that allows us to measure a wide range of voltages by indicating how many volts are represented by each division.

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33 Finishing Up the DC Measurements

Finishing Up the DC Measurements

Go ahead and Turn off the DC Power Supply Disconnect the Mini-Grabbers

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34 Measuring an AC signal

Measuring an AC signal

In this section, we will use the built-in FUNCTION GENERATOR to create an AC signal to measure with the oscilloscope

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35 Measuring a Time Varying (A

Measuring a Time Varying (A

C.) Voltage

Now look at the function generator built into your Oscilloscope. This device produces a voltage that varies over time. In the upcoming slides we will exam each of the controls that allow us to shape the output.

Built In Function Generator

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36 Function Generator Controls: Wave Shape

Function Generator Controls: Wave Shape

An important part of a function generator is the shape of the wave it creates. This function generator can produce a Square Wave Triangle Wave Sine Wave Press the FUNC key to change until the light below the Sine wave is lit. (Note: The Oscilloscope must be on in order to change the this option.)

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37 Function Generator Controls: Frequency Range

Function Generator Controls: Frequency Range

This generator allows you to change the frequency (Cycles per Second) of the output wave. There are two main settings: Range/Order of Magnitude Scaling Factor First, set the range to 1K (1 kilohertz) by pressing the RANGE button until the light below 1K is on. Then, turn the frequency dial (Scaling Factor) so it points straight up. This represents a Scaling Factor of 1. Turning the dial to the left will reduce the output frequency and to the right will increase it.

1. Set the Range to 1K

2. Turn the Frequency Dial Until it Points Straight Up.

What will the output frequency be with this setup? What if the scaling was set to 1.5?

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38 Function Generator Controls

Function Generator Controls

5 Volts Peak-to-Peak

2 Volts Peak-to-Peak

1 Volt Amplitude

2.5 Volt Amplitude

Not only can we change the shape and frequency of a wave, but we can also change the amplitude.

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39 Function Generator Controls: Amplitude Dial

Function Generator Controls: Amplitude Dial

Another 2 Parameter Control DC-Offset (Inner Dial) Amplitude (Outer Dial) Adjusting the outer dial Clockwise will increase the amplitude. Counterclockwise will decrease the amplitude. Turn the inner dial until it points straight up. Turn the outer until it points straight up.

Amplitude

DC-Offset

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40 Making the Connection

Making the Connection

Locate the Function Generators Output. Using a B.N.C. Cable, Connect the Function Generators Output to the CH1 Input.

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41 Making the Connection

Making the Connection

Set the Volts/Division dial to 2. The inner dial should be turned fully clockwise. Change the AC-GND-DC switch to AC. Use the Position dial to raise or lower the image until it is centered on the screen.

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42 Making the Connection

Making the Connection

The Time/Division dial corresponds to the amount of time in each division along the X-direction. Set this dial to 0.5ms. If it isnt already, turn the SWP. VAR. dial to CAL With 10 divisions per screen, what is the total time span represented?

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43 Triggering

Triggering

Now we need to tell the scope when to display the signal. Electric signals change much faster than we can observe, so we must tell the Oscilloscope when to refresh the display. We accomplish this by setting a Triggering Level.

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44 Triggering

Triggering

Without Triggering

With Triggering

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45 Triggering

Triggering

We want to tell the oscilliscope when it is the best time for it to refresh the display In our wave below, we tell the scope to trigger or capture the signal when it is going upward AND hits 2.0Volts

SO, trigger condition is: When were

AND When at 2.0 Volts on our waveform!

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46 Triggering: Setup

Triggering: Setup

If it isnt already, set the Trigger Source to CH1. Set the Trigger Mode to Auto. In some cases, this is enough to produce a clear output, but often we will need to adjust the Trigger Level. If the output is unstable, turn the triggering knob until it stabilizes.

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47 Measuring the Voltage

Measuring the Voltage

Using the CH1 Position Dial, move the wave until the bottom line up with one of the division lines. Measure the number of divisions from the bottom to the top.

At 2 Volts Per Division, This wave has an amplitude of 5V.

Peak to Peak Voltage = (Volts/Division) *(# of Division) Amplitude = (1/2) * Peak to Peak Voltage

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48 Measuring the Frequency

Measuring the Frequency

Position to wave so that the beginning lines up with one of the vertical division markers. Count the number of divisions until the beginning of the next wave.

With 0.5ms/division, this wave has a frequency of 1kHz

Period = (Time/Division) *(# of Division) Frequency = 1/Period

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49 Mixing It Up

Mixing It Up

Increase the Volts/Division Dial to 5. Decrease the Time/Division Dial to 0.2ms. Recalculate the Peak to Peak Voltage Amplitude Period Frequency How do these results compare to the ones you previously measured?

Note: If the signal becomes unstable, you may need to readjust the triggering level.

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50 Changing the Frequency Generator

Changing the Frequency Generator

Now, change the amplitude on the frequency generator. Note that waves height grows and shrinks as this dial is adjusted. Next, try changing the frequency and the shape of the wave. Remember that the Volts/Division, Time/Division and Triggering Level may need to be adjusted.

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51 Summary: Measuring A.C. Voltage

Summary: Measuring A.C. Voltage

Turn on the Oscilloscope. Use the built in function generator to set the shape, frequency and amplitude of the desired output wave. Connect the generators output to the channel 1 input and set the input channel to AC. Approximate the Time/Division and Volts/Division. Use the Position Dial to center the wave on the screen.

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52 Summary: Measuring AC Voltage

Summary: Measuring AC Voltage

Set the Triggering Source to CH1. Set the Triggering Mode to Auto. Adjust the Triggering Level until the output wave stabilizes. Adjust the Volts/Division and Time/Division dials until the desired output is produced. If needed, use the Focus and Intensity Dials to sharpen the picture displayed.

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53 Your turn

Your turn

In this section, you are put to the test!

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54 Oscilloscope Problem

Oscilloscope Problem

Using the function generator, create a wave with the following output: 3 kHz Frequency Sinusoidal Shape 2 Volt Amplitude Adjust the output so that only 2 complete cycles are showing. When are you finished, call over your TA to inspect it.

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Introduction to the Oscilloscope
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