What Is an Oscilloscope, and What Is It For?

An oscilloscope is a measuring instrument that displays, as a graph on a screen, how an electrical signal changes over time. Unlike a multimeter, it lets you see not just a single number but the shape of the signal.

What Is It For?

It's used to see a signal's frequency, amplitude, waveform and the noise within it. You can see a PWM duty cycle, whether a signal is distorted, or the delay between two signals with an oscilloscope.

The Screen: Time and Voltage Axes

On the oscilloscope screen, the horizontal axis shows time and the vertical axis shows voltage. By adjusting the horizontal and vertical scales (seconds/div and volts/div) you fit the signal on the screen.

The Difference From a Multimeter

Where Is It Used?

It's a basic tool for examining analog and digital signals, checking AC waveforms, fault-finding and signal-timing analysis.

Common Mistakes

• Wrong probe scale: if you use a 10x probe without setting the scale, the reading is off by a factor of 10.
• Not connecting the ground: if the probe ground isn't connected to the signal reference, the display is noisy/unstable.
• Trigger not set: if the trigger isn't set up correctly, the waveform drifts and you can't get a stable image.