Using two op amps, this circuit produces a full-wave rectified version of the input signal. Op amp IC1 invert
s the negative-going signal, but because of D2, it stays near zero. IC2 produces a positive-going signal. For positive-going signals, IC1 produces a negative output through Dl to IC2, where it is combined with positive from R4/R5. At the summing junction of IC2, the negative output of IC1 is doubled and inverted via IC2, R3, and R5 to produce + V0ut- This is summed with negative output of IC1 to produce +Vout.