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Fourier Series Builder

How to Use

  • Drag the H1–H7 sliders to set the amplitude of each harmonic (0 to 1)
  • Use preset buttons to load classic waveforms: Square, Sawtooth, or Triangle
  • The left panel shows individual harmonics (colored thin lines) and the composite (purple)
  • The right panel shows the frequency spectrum (bar heights = amplitude of each harmonic)

What to Observe

  • A square wave uses only odd harmonics (H1, H3, H5...) in a 1/n pattern
  • A sawtooth wave includes all harmonics in a 1/n pattern
  • A triangle wave uses odd harmonics in a 1/n² pattern — much smoother rolloff
  • Adding more harmonics makes the composite waveform sharper and more "digital" looking
  • This is the essence of Fourier analysis: any periodic signal is a sum of sinusoids