SIGNAL INPUT OUTPUT CIRCUIT FOR AUDIO EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To make the equipment small and to prevent mis-plug-in of a headphone or a microphone by using one connection jack in common for a connection jack for a stereo headphone and a connection jack for a monaural microphone in an audio equipment such as a tape recorder. ;SOLUTION: In the case of connection to a stereo headphone, a signal from a headphone right channel signal amplifier 2 is given to a control transistor(TR) 3 via an amplifier 5 and a DC transformation circuit 6 to make the TR 3 conductive and also a 1st switching TR 1 nonconductive and a 2nd switching TR 2 conductive thereby blocking a signal input to a microphone input signal amplifier 4. In the case of connection to a monoral microphone, the 2nd switching TR 2 and the control TR 3 are made nonconductive so as to make the 1st switching TR 1 conductive, then an output signal from a head phone left channel signal amplifier 3 is not inputted to the microphone input signal amplifier 4.;COPYRIGHT: (C)1997,JPO