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The Oscilloscope

 - The oscilloscope is basically a graph-displaying

device - it draws a graph of an electrical signal.

- In most applications the graph shows how signalschange over time: the vertical (Y) axis represents

voltage and the horizontal (X) axis represents

time.

-The intensity or brightness of the display is

sometimes called the Z axis. (See Figure 1.)

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Figure 1: X, Y, and Z Components of a Displayed Waveform

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This simple graph can tell you many things about asignal. Here are a few:

You can determine the time and voltage values of a signal.

You can calculate the frequency of an oscillating signal.

You can see the "moving parts" of a circuit represented by the signal.

You can tell if a malfunctioning component is distorting the signal.

You can find out how much of a signal is direct current (DC) oralternating current (AC).

You can tell how much of the signal is noise and whether the noise ischanging with time.

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The function of an oscilloscope is extremely simple: it draws

a V/t graph, a graph of voltage against time, voltage on the

vertical or Y-axis, and time on the horizontal or X-axis.

-As you can see, the screen of this oscilloscope has 8 squares

or divisions on the vertical axis, and 10 squares or divisions

on the horizontal axis. Usually, these squares are 1 cm in

each direction:

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The diagram shows a Hameg HM 203-6 oscilloscope

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- Many of the controls of the oscilloscope allow you to

change the vertical or horizontal scales of the V  /t 

graph, so that you can display a clear picture of the

signal you want to investigate.

- 'Dual trace' oscilloscopes display two V  /t graphs at

the same time, so that simultaneous signals fromdifferent parts of an electronic system can be

compared.

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Important Setting up

1-The TIME/DIV control:- determines the horizontal scale of the graph which appears

on the oscilloscope screen.

- With 10 squares across the screen and the spot moving at0.2 s/DIV, how long does it take for the spot to cross the

screen? The answer is 0.2 x 10 = 2 s.

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The "Time/Div." wheel determines, how long

the electronic beam which draws the curveneeds for moving from the left to the right

edge of a division. The wheel controls the

"time scale". A "division" is one square on thescreen of the oscilloscope.

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The VOLTS/DIV controls

-determine the vertical scale of the graph drawn on the

oscilloscope screen.

-Check that VOLTS/DIV 1 is set at 1 V/DIV and that the

adjacent controls are set correctly.

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What Can You Do With It? 

Oscilloscopes are used by everyone from television

repair technicians to physicists. They are indispensable

for anyone designing or repairing electronic

equipment.The usefulness of an oscilloscope is not limited to the

world of electronics. With the proper tr ansducer , an

oscilloscope can measure all kinds of phenomena. A

transducer is a device that creates an electrical signalin response to physical stimuli, such as sound,

mechanical stress, pressure, light, or heat. For example,

a microphone is a transducer.

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An automotive engineer uses an oscilloscope to measure

engine vibrations. A medical researcher uses an oscilloscope

to measure brain waves. The possibilities are endless.