| 摘要 |
PURPOSE:To make a start singing indicator operate even if the music of a sound multiplex tape is started to be reproduced from the part of the way by providing a decision circuit which decides the state of an output from a presence of signal discrimination circuit to detect the presence or the absence of a channel signal, a singing voice is recorded in. CONSTITUTION:The presence or the absence of a left channel signal (accompaniment signal in the case of the sound multiplex tape) and of a right channel signal (voice signal) are decided by the presence of signal discrimination circuits 4 and 3, and at the time of the input of the left channel signal, a one shot pulse generation circuit 5 generates a one pulse. The decision circuit 11, consisting of a D flip-flop, makes the one shot pulse generation circuit 6 operate and performs a decision at the time of the disappearance of the right channel signal after the finish of one phrase, and decides the sound multiplex tape, and at the time of the input of the next right channel signal, it makes the one shot pulse generation circuit 7 operate, and during that time, it lights, for instance, a red colored LED 17, and afterwards, lights a green colored LED 18. Thus, the indication of the start singing is indicated only for the time of the sound multiplex tape.
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