Objective of Experiment:
To study the basic functions of an oscilloscope.
The oscilloscope is probably the most useful and versatile laboratory instrument for the development of electronic circuits and systems. It is used for studying wave shapes of alternating currents and voltages as well as for measurement of voltage, current, power and frequency. In fact almost any quantity after suitable conversion into voltage can be analyzed as a function of time. Functionally oscilloscope is capable of displaying two quantities Y versus X in Cartesian coordinate system, however in most cases the Y axis is amplitude and the X axis is time. It is widely used for troubleshooting radio and TV receivers as well as laboratory work involving research and design. It can also be employed for studying the wave shape of a signal with respect to amplitude distortion and deviation from the normal. In true sense the cathode ray oscilloscope has been one of the most important tools in the design and development of modern electronic circuits.
The primary function of an oscilloscope is to display voltage waveforms as a function of time so that the engineer can visualize the waveforms and troubleshoot circuits. In this experiment you will learn very basic operations that include displaying two waveforms, determining their amplitude, frequency, and phase. You can choose two signals from the signal generator, their type like sine, triangular, sawtooth, and square wave, and connect them to the two channels of the oscilloscope for display. You can display one of them, both of them or their sum by selecting the 'Mode' options. The vertical axis (Y) is amplitude and horizontal axis (X) is time t on the oscilloscope display. You can change the scale of the display by varying 'V/Div' knob for Y sensitivity, and 'Time/Div' knob for X sensitivity. The other knobs are 'X-POSITION' and 'Y-POSITION' to displace the waveforms along X axis and Y axis, respectively. The process of plotting the waveforms from left end to the right end of the display is called as sweep.
Triggering is an important operation in oscilloscope. Trigger instant is the time at which the sweep starts and the instant is denoted as t = 0. Sweep must start at the identical point on the input periodic waveform so that refreshing the display with identical waveform segments at fast rate results in the appearance of a stable display. You will get a stable display in most cases, if you do the following two operations correctly. (i) Choose the correct 'source' of trigger (Ch 1 or Ch 2 where input is connected and with respect to which you want to synchronize the display), and (ii) adjust 'Level' knob to specify at what amplitude of the waveform you want the sweep to start i.e. t = 0. In addition you can specify the slope of the waveform at the trigger instant by using +/- switch.