Frequency modulator composed of NE566

The frequency modulator composed of the integrated voltage controlled oscillator NE566 is shown in the figure. When the potential of
    the signal input terminal ⑤ is a DC potential, a constant frequency oscillation is formed over and over again; changing the potential of the input terminal ⑤ , the output frequency of the integrated circuit frequency modulator circuit also changes accordingly.     The reference values ​​of the component parameters in the figure are when the resistance: Ri - R2 - lOOfl. When Rd - lOkZRP2 - 50kfl, the output frequency can change accordingly around 20 ~ 40kHz; changing the value of RP2 or G, the output frequency will also change accordingly.