With an oscilloscope you can analyze complex signals in both projects such as in maintenance. However, It's still an expensive device, and one option is this small digital oscilloscope DSO-112 to 2 MHz.
Comes with instructions in English for all functions.
It also comes with two end pieces with the mini-bnc connector on one side and the other alligator claws. I chose to buy the model without internal battery, that only works plugged into the source. In this case, came a connector if I ever buy a battery.
This is the oscilloscope. We have a test signal output (BNC left) a central button and a signal input (BNC right).
At the top we have a miniUSB connector used to connect to the source and charging the battery, in models with battery.
Below I connected an audio output of 2, 5 kHz to test.
Increasing the frequency to 20 kHz it is still possible to see the sign perfectly.
There are ways to measure the peak-to-peak voltage and frequency directly on screen.
See the video I made about the product:
I really enjoyed this oscilloscope. At least up to 1 MHz still managed to see the sign perfectly. Considering the price, is a great product. I leave below link to DealExtreme: