The purpose of the work is simulation of two circuits for transmitting analog signals within the audio range with low distortion and good galvanic separation by means of a PSPICE software package. Phototransistor optocouplers of a normal and inverse operating mode of the optocoupler phototransistor have been used. The time diagrams of the signals and the amplitude-frequency characteristic have been given. Methods for calculating the basic parameters have been elaborated. The circuits have been developed in practice. The sim ulation and calculation error has been determined – it does not exceed 10 %. When the optocoupler phototransistor operates in an inverse mode, the frequency band of the stage expands notwithstanding the decrease of the adjacent voltage amplification factor. Ill. 7, bibl. 4, tabl. 1 (in English; abstracts in English, Russian and Lithuanian).