Gyrator is usually used to form bandpass filter. For the active buffering device, a transistor or op amp can be used. The following type of bandpass filter is commonly used in graphic equalizers and frequency control schematic such as the tone controls. Here is the circuit :
To use the gyrator frequency calculator, enter the values of R1,R2,C1,and C2, then click the Calculate button. The center frequency of the bandpass filter will be displayed as Q. The bandpass will be narrow if the Q is high. A typical 1/3 octave bandpass will have a Q of about 4.3 and a 2/3 octave filter Q value could be around 2.4.