Abstract: The invention relates to power supply circuits, and in particular those used for directly supplying, from a telephone line, the bell or other items in a telephone set. In order to avoid unacceptable crosstalk or distortion due to saturation of the power supply circuit when the AC signal on the line drops below the value (Vs) of the regulated output voltage of the power supply, there is provision for detection of this saturation (56) and current shunting (T2, T3) that increases progressively with saturation, such that, seen from the line, the current consumption or impedance of the set remains constant despite the disturbances due to saturation.

Abstract: The invention relates to a circuit for a telephone set. In order to eliminate the mouthpiece signal between the receiver and the telephone set, there are provided a subtraction means receiving the mouthpiece signal and the composite signal present on the telephone line, one of the two being produced by different compensation impedances, and on the other hand a mixer controlled by a circuit as a function of the telephone line impedance. The two compensation impedances respectively correspond to the compensation of a long line and the compensation of a short line and the output of the mixer supplies a signal mixture, with variable proportions, which effectively suppresses the mouthpiece signal, no matter what the length of the telephone line.