Abstract: An integrated circuit which includes a detection circuit for detecting the condition of saturation of an output transistor (Q.sub.0) whose collector-emitter path is intended to pass an output current. A threshold circuit (A) of the detection circuit is arranged to perform a switching operation when a representative parameter of the condition of saturation crosses a given threshold. A control transistor (Q) is arranged to supply at least a part of the base current of the output transistor (Q.sub.0) and the threshold circuit (A) performs its switching operation when the value of the current passing through the collector-emitter path of the control transistor exceeds a given level.

Abstract: The invention relates to a control circuit for amplified listening having a shunt regulator (A.sub.0, T.sub.1) controlling at a value V.sub.0 the supply voltage V.sub.B of an amplifier feeding a loudspeaker (1) for amplified listening, having a gain control input (G). When the regulator conducts an excessive current I.sub.s, a switch (20) is closed and a storage capacitor (C.sub.1g) is charged by a current source (SC). A threshold amplifier (A.sub.2) opens a transistor (T.sub.4) when the voltage V.sub.B falls below V.sub.1 (V.sub.1 <V.sub.0). The capacitor (C.sub.1g) is then rapidly discharged through resistor R.sub.1g (and R.sub.2g).

Abstract: An electronic telephone set which includes first and second connection points for a telephone line and a transmission circuit having a send output stage including a first transistor whose first main electrode is coupled to the first connection point by means of a first resistor. The telephone set includes a supply circuit for peripheral circuits. The supply circuit has a first output terminal coupled to the first main electrode of the first transistor and has a second transistor whose first main electrode is coupled to the second connection point and whose second main electrode is coupled to the second output terminal of the supply circuit. This circuit includes an operational amplifier whose output is coupled to the gate electrode of the second transistor. the set also includes a first voltage source connected between the first main electrode of the second transistor and a first input of the operational amplifier.