LM741 op-amp, converting positive output to negative
Generally, an inverting op-amp circuit with a gain of 1 will accomplish that. Choose R1 and R2 to be the same and you will get a gain of 1, with an inverted signal. I am not a proponent of the 741 since there are newer op-amps that don't require as much fussing. But the concept is the same regardless of which op-amp you use. Operationally, in the circuit shown, the output will swing to whatever voltage is needed to keep the (-) input at 0v, which turns out to be equal in magnitude, but opposite in sign to your input signal. Your choice for R1/R2 is flexible, but as an example you could use R1=R2=10K.







simulate this circuit &ndash; Schematic created using CircuitLab