title: Python amplitude spectrum plot
body: <p>I have two lists of float values, one for time and other for voltage values taken from an oscilloscope (I assume). I have to draw an amplitude spectrum plot, but i'm not exactly sure what function I need to use and what parameters I need to give it, I tried fft(u), but it didn't work.</p>
  
  <p>Any help is appreciated, let me know if you need more info.</p>