Finding Input Impedance of a Gyrator
For ideal opamps (infinite input impedance and infinite gain) the shown circuit has a pure inductive input impedance Zin=sR1*R2*C*(Rg1/Rg2). 

Therefore, Leq=(R1*R2*C)(Rg1/Rg2).

The calculation is straight-forward:


Step 1: Find the output voltage Vo for the upper opamp;
Step 2: Find the output voltage Vo2=f(Vo, Vi) for the lower opamp; 
Step 3: Combine both expressions (replace Vo by Vi);
Step 4: With i2=(Vi-Vo2)/R2 and Vo2=f(Vi) you can solve for Zin=Vi/i2


Comment: The whole circuit mimics an ideal grounded inductor. That`s all. No output voltage (the inductor is a two pole element). Hence, the equivalent circuit diagram consists of the inductor only!