Oscilloscopes

An oscilloscope is easily the most useful instrument available for testing circuits because it allows you to see the signals at different points in the circuit. The best way of investigating an electronic system is to monitor signals at the input and output of each system block, checking that each block is operating as expected and is correctly linked to the next. With a little practice, you will be able to find and correct faults quickly and accurately. Also informally known as a scope, CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope).

How to use an oscilloscope

Oscilloscopes are used in the sciences, medicine, engineering, and telecommunications industry. General-purpose instruments are used for maintenance of electronic equipment and laboratory work.

https://learn.sparkfun.com:443/tutorials/how-to-use-an-oscilloscope

Technical

https://en.wikipedia.org/wiki/Oscilloscope

Extech MS420: 20MHz 2-Channel Digital Oscilloscope

Dual-channel Oscilloscope with 3.8″ (97mm) color LCD display

Features:

Auto-set function optimizes the position, range, timebase, and triggering to assure a stable display of waveforms
Peak Detect function for 50ns glitch capture
XY Mode and FFT function to view component frequencies
Twenty Automatic Measurements including Frequency, Cycle, Average, Peak to Peak, RMS and more
Waveform Math: Add, Subtract, Multiply, and Divide
Average Mode for smoothing waveforms
Persistence Mode for observing dynamic signals
Store and recall up to 4 waveform screens and setups
USB interface and software for transferring waveforms and data