Compensate frequency dependency of an Ammeter
What am I doing wrong?


Adding C1 to the circuit makes a complex series resonant circuit and doesn't look like it will ever work. 

If you want to make the transfer function constant across frequency then you need to add an inductor (L2) in series with R1 such that the scaling of L2 is R1/R2 times bigger than L1.

In your particular circuit L2 would be 200 mH.