MarkT:
Use a rail-to-rail opamp from 5V. How are you connecting the current transformer (that circuit appears to be
a slice of a diagram for an electret condenser microphone amplifier).Does your CT have a built-in burden resistor? What value is it? You'll need to not load down that
burden resistor load significantly or you'll change the output level. Use a non-inverting opamp
circuit to avoid loading the source perhaps?
There is a burden resistor of 200ohm parallel to the CT. So you are saying in should use connect the CT output into the non inverting input of the OPAMP? I don't have access to - + dual supplies only a few adaptors. So I will power it with 12v supply and see what it does.