As shown for the wideband sinusoidal voltage controlled oscillator circuit. The circuit oscillation frequency is determined by integrating resistor R and a capacitor C, voltage
-controlled oscillator is constituted by the applied voltage Vc control resistor R. Variable resistor circuit using photocoupler PC1 and PC2, rectifier circuit using the average detection mode. The actual operation of the circuit in the frequency of several tens of hertz. In addition, with respect to the control voltage Vc oscillation frequency depends on the characteristics of the circuit optocoupler used features. Optocoupler light source is a light emitting diode driving current needs, therefore, using an op amp circuit 4559 constitute a constant current source circuit. Voltage/current conversion using Rs, the resistance Rs are free to choose the maximum control voltage Vc. Circuit, IFmax 30mA, Vcmax 5V, the resistance Rs 180 .