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The Control Functions of Oscilloscope

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At the end of this chapter, the students should be able to:

describe the basic control functions of an oscilloscope.

practice their knowledge in using an oscilloscope to display various electrical

signals.

Objectives

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Introduction The Oscilloscope is nothing more than just an instrument for displaying electrical signals in the TIME domain. Meaning that, you can view waveforms on it.

Some of the uses of the scope may not be obvious but if you already possessed one, then you will most probably regard it as the most useful tool on your workbench.

So, what is actually an oscilloscope?

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Basic Oscilloscope A basic Oscilloscope is as shown below.

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The basic controls are:

Bright – To adjust the intensity of display. Focus – To adjust the focusing of display. Grat (Graticule) – To illuminate a scale

used to measure a trace. Trigger – To select a trigger source. Trace – To select which trace is to be

displayed.

Basic Oscilloscope

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Timebase – To select the speed which the trace moves across the tube face.

Input Level- To adjust the input level. Pos (Position) – To set the position of

the trace on the display.

Basic Oscilloscope

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Brightness This is self-explanatory, it controls the intensity of the display. It is well worth remembering that one cannot execute screen-saver programs on an oscilloscope, so leaving the scope with a high brilliance will certainly burn the trace into the tube face.

If you must leave your scope switched ON for any length of time then turn the brilliance control down.

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Focus The focus control is also quite self-explanatory but most "scopes" seem to adjust a single spot from a short horizontal to a vertical line.

A single horizontal line is therefore not the best waveform to adjust the focusing, this is best done whilst viewing a waveform.

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Trace Selects which trace is to be displayed. There are usually two or more selections possible:

• A - Selects trace A only (single channel).• B - Selects trace B only (single channel).• A+B - Selects both trace A and trace B (dual channel). • ADD - Both channel inputs are added and displayed as a single trace.

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Timebase The speed the spot travels across the screen of the tube may be varied by means of the Timebase selector switch.

This is calibrated in Seconds (S), MilliSeconds (mS = 0.001 seconds) or MicroSeconds (uS = 0.000001 seconds).

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Conclusion We have learned at brief about the control functions of a basic oscilloscope.

Various control buttons on the oscilloscope serve their own purpose in control.