Method and circuit for suppressing oscillations sustained by the Larsen effect in a loop comprising a microphone and a loudspeaker

摘要

The invention relates to a method and circuit for suppressing oscillations sustained by the Larsen effect in a loop comprising a microphone and a loudspeaker. The proposed circuit comprises a proximity detector composed of a transmissive loop BCE arranged near one of the transducers HPL and traversed by a current of high frequency, of an inductive receiver loop BCR arranged near the other transducer MIC and closed by a capacitor C1 so as to constitute an oscillating circuit tuned to the said high frequency, as well as a control circuit T1 receiving the output signal from the receiver loop BCR in order to break the electrical connection between the two transducers HPL, MIC when the amplitude of this signal reaches a predetermined value. The invention is applicable, in particular, in telephone sets with amplification. <IMAGE>