What is an Oscilloscope?

An oscilloscope is an electrical diagnostics tool that can display electrical signal waveforms so that they can be be visually understood by a technician. They can be costly, especially since they can be damaged beyond repair if used improperly, but they can provide valuable information that otherwise wouldn't be seen.

One of the main settings on a oscilloscope is showing voltage change over time, which is like having a voltmeter that shows you a graph instead of semi-frequently updating a number on a screen. While a multimeter is often the tool for the job when it comes to voltage testing, an oscilloscope can tell you much more about the voltage over time, and is able to show signals that are found in voltage changes.

Oscilloscope Features

Oscilloscopes will need different features depending on the work being done. Some features can dramatically add to the cost, especially when combined together.

Bandwidth

For analog signal measurements only, you will need an oscilloscope that has a bandwidth specification at least three times higher than the highest sine wave frequencies that you might need to measure. For digital applications, in general, choose a bandwidth at least five times the highest clock rate in your systems.

Oscilloscope Channels

The number of channels will dictate how many electrical signal waveforms can be displayed at once. Being able to compare multiple signals may be important for some testing, but every added channel stacks many of the other features, so many hobbyists end up starting with just a one or two channel model.

Real-Time Sample Rate

The real-time sample rate (which will be RTS Rate in the table below") determines how much information can be displayed while watching a live signal. The higher the frequency, the more detail you can see as you zoom in. Sometimes a signal may be too high frequency to see on a given oscilloscope, which is a consideration that needs to be made when choosing one. Generally, you want the real-time sample rate that is at least five times the maximum frequency of the circuit you are testing.

Memory Depth

The amount of past data an oscilloscope can scroll through on screen is called memory depth. An oscilloscope with more memory depth saves a longer span of signal data, which may be needed for a wider signal capture, or just to provide more comparison points of a repeating signal over time.