A harmonic oscillator with low harmonic distortion and stable amplitude

A generator of the harmonic signal is described for frequencies in the acoustic region with the reference stabilized amplitude, linear frequency scale and total harmonic distortion below 2 × 10−3. The signal is produced as the solution of the corresponding differential equation where the constant amplitude is maintained by periodic control of the first derivative value [xdot](t) at the moments when x(t) crosses zero and has a positive slope.