Hi Steve,

Thanks for your reply.

But I am still using the same unipolar 8bit ADC PCF8591 and the precision full wave rectifier. I take 180 samples from rogowski per cycle and do the integration in software to get i. Than I square this integrated value then take their mean and finally square root to get RMS current. Now the only problem is these coils are not interchangeable The recitifier scaling pot need to be adjusted every time a diffrent coil is used. I want to have some solution so that interchanging the coils is on the fly without touching any pot it should be some what like Erik's No Touch :) Interchanging without opening the circuit box.

Thanks & Regards,
Prahlad Purohit