An oscilloscope is a device based on a cathode-ray tube used to produce a visual display of electrical signals. Typically the horizontal position of the illuminated point is controlled by the value of the independent variable, and the vertical position is controlled by the dependent variable. A third signal is often used to control the brightness of the point.

Oscilloscopes measure two things, voltage and time. With time, frequency is often measured. An electron beam is passed across a phosphorescent screen horizontally on the X-axis at a known rate (say one pass in a millisecond). An input signal is used to change the position of the beam on the Y-axis. The trace left behind can be used to measure the voltage of the input signal off of the Y-axis, and the duration or frequency can be read off of the X-axis.

An oscilloscope is useful for making measurements in both the alternating current (AC) and direct current (DC) domains and allows you to view the input waveforms and verify their validity. Thus, if you expect a square wave but receive a triangle wave, you are able to conclude that the circuit is not functioning correctly.

Oscilloscopes are extremely useful in the engineering and computer fields as well as in electrical repair. They allow us to determine the time and voltage values of a signal and calculate the frequency of an oscillating signal. You are able to see the "moving parts" of a circuit represented by the signal. You can tell if a malfunctioning component is distorting the signal, how much of the signal is noise, and whether or not the noise is changing with time. You can also find out how much of a signal is DC or AC.

I have included a few links that include in-depth tutorials on oscilloscope functions.

---

TUTORIALS