(https://www.nutsvolts.com/magazine/article/turn-your-computers-sound-card-into-a-scope)

https://www.instructables.com/Oscilloscope-Arduino-Processing/

Bill of Materials: (USD conv rate on 10 Nov 2020 apply)

Probes: USD 1.34

Aux cable: USD 0.73

Breadboard: USD 1

Resistors: USD 0.13

Potentiometer: USD 0.3

Results:

• The frequency of operation is limited at 22 kHz, the auditory range of human beings
• Protective circuit in the soundcard clips mic input if amplitude of signals exceed limits