Abstract: The invention relates to an improvement in the use of tape recorders and enables by speech action, the automatic start and stop of these apparatuses.The device uses the main existing output plugs of a cassette recorder without introducing any modification whatsoever in the apparatus.It comprises an amplifier with transistors of which the input receives the modulation delivered by a microphone; the output signals of the amplifier after detection by the diode D.sub.1, control a flip-flop to a stable state which is constituted by a C MOS integrated circuit which delivers a positive pulse controlling an electronic switch TR.sub.4 triggering the automatic start-stop.Amongst the most interesting applications are conference recordings, letter dictations, surveillance of premises, language studies, preparation to speech, without manipulating the manual control start-stop of the apparatus.