A sinusoidal voltage controlled oscillator whose frequency is determined by a DC voltage between 0 and 15 volts can be designed using this electronic circuit diagram.
Distortion signals output not exceeding 10Vvv will be less than 1%, when, with the P1 potentiometer, the output signal is reduced to a 1Vvv, distortions fall below 1%. If input signals are under 1Vvv, the oscillator becomes unstable and dependent on temperature.
Oscillator consists of two operational transconductance amplifiers (AOT) closed in the same capsule.
With switch S1, the oscillator output can be adjusted in two areas: 6.7 + 400 Hz and 400 Hz + 23.8 kHz. The whole area needs a control voltage ranging between 1.34 V and 15 V. If frequency is modified by variation of Ug, and adjustment of P1 remains the same, the output signal could be distorted.